Celstran - Hi Polymers brochure... · 1.2 Quality Management Celstran is a unit of Ticona, ... model of the European Quality Award (EQA) of the European Foundation of Quality Management

Long-fibre-reinforced thermoplastics (LFT)

Celstran® Compel®

Cel

stra

n® C

om

pel

® L

ong-

fibre

-rei

nfor

ced

ther

mop

last

ics (

LFT

)

• markedly highermechanical properties

• high notchedimpact strength

• reduced creep tendency• very good stability

over a broad range oftemperatures andclimatic conditions

long-fibre-reinforced thermoplastics (LFT)

Celstran® Compel®

1. Introduction 4

1.1 General information 41.2 Quality Management 51.3 Brief description 5

2. Grades 7

2.1 Overview of grades 72.2 Survey and nomenclature of Celstran 82.3 Survey and nomenclature of Compel 82.4 Form supplied 92.5 Colours 9

3. Material Data 10

4. Physical Properties 20

4.1 General information 204.2 Mechanical properties 214.2.1 Preliminary remarks 214.2.2 Short-term stress 214.2.3 Creep properties 234.2.4 Toughness 254.2.5 Fatigue 264.2.6 Surface properties 264.3 Thermal properties 274.3.1 Coefficient of expansion 274.3.2 Specific heat, enthalpy 274.3.3 Thermal conductivity 284.4 Electrical properties 284.5 Optical properties 294.6 Acoustic properties 29

5. Environmental Effects 30

5.1 Thermal properties 305.1.1 Heat deflection temperature 305.1.2 Heat ageing 305.2 Flammability 315.3 Chemical resistance 325.4 Weathering and UV resistance 32

® = registered trademark

Table of Contents

2

Celstran® Compel®


3

6. Processing 33

6.1 Preparation 336.2 Injection moulding of Celstran 33

including mould making6.2.1 Machine requirements 336.2.2 Processing conditions 346.2.3 Flow properties and flow path lengths 366.2.4 Shrinkage 366.2.5 Gate and mould design 386.2.6 Special methods 386.3 Blow moulding of Celstran 396.3.1 Materials 396.3.2 Machine requirements 406.3.3 Parison die 406.3.4 Temperatures 406.4 Extrusion of Celstran 416.5 Processing of Compel 416.5.1 Plasticizing/compression moulding 416.5.2 Other methods 426.6 Safety notes 42

7. Finishing 43

7.1 Machining 437.2 Assembly 437.2.1 Welding 437.2.2 Adhesive bonding 45

8. Recycling 46

9. Photo supplement showing typical applications 47

10. Subject Index 51

11. Literature 53

1

2

3

4

5

6

7

8

9

10

11Literature

Introduction

Grades

Material Data

Physical Properties

Environmental Effects

Processing

Finishing

Recycling

Photo supplement showing typical applications

Subject Index


Celstran® Compel®

4

These materials have substantially better mechanicalproperties than comparable short-fibre-reinforced thermoplastics. The long-fibre-reinforced thermo-plastics are thus suitable for the manufacture ofmouldings that are subject to high mechanical stress –even at elevated temperatures – and for products thathave in the past been made of cast metals or thermo-sets.

The most important field of application at present forCelstran is the automotive sector [3]. For example,gear levers and sunroof drainage channels are madefrom it because of the mechanical stress imposed onthem. Parts near the engine such as fan shrouds, fig.1.4, engine noise deadening casings, fig. 1.5, or hous-ings for electronic engine control systems, fig. 1.6,also have to withstand additional temperature stress.

Fig. 1.3 · Cross-section through a Celstran PP-GF50 pellet, a PP reinforced with

50% by weight long glass fibres

Short-fibre pelletfibre length = 0.2 to 0.4 mm

Wire coating

Fully impregnatedlong-fibre pelletfibre length= 10 to 25 mm

Celstran ®Compel ®

Fig. 1.2 · Diagram of a fully impregnated long-fibre pellet (right) compared with

wire coating (centre) and short-fibre pellets (left)

1. Introduction

1.1 General information

Celstran and Compel are long-fibre-reinforced ther-moplastics (LFT) made by Ticona. Various processingmethods are used to produce high-strength compo-nents from these materials, which are tailor-made tocustomers' requirements (fig. 1.1). Almost all partial-ly crystalline and amorphous thermoplastics are sui-table as thermoplastic matrix materials.

These grades are produced in a special patented pultrusion process [1]. The fibres incorporated in thisprocess can be glass, carbon, aramid or stainless steel.In pultrusion the continuous filaments are pulledthrough the thermoplastic melt. Process control anddie are optimized so that

- high impregnation quality without damage to thefibres is achieved and

- the individual filament of the reinforcing fibres isthoroughly wetted [1, 2], fig. 1.2 and 1.3.

Fig. 1.1 · Celstran and Compel are starting materials for high-strength components

Celstran® Compel®


1.2 Quality Management

Celstran is a unit of Ticona, Kelsterbach and is re-gistered to ISO 9001. QS-9000 certification is sched-uled until end of 2000.

The quality system and the associated documentationare constantly being developed. The basis for this isVDA vol. 6, 4th edition, 1998, QS-9000 and anannual self-assessment in accordance with the criteriamodel of the European Quality Award (EQA) of theEuropean Foundation of Quality Management.

To foster effective partnerships with our customersTicona offers to conclude quality agreements and alsoto issue test certificates. These agreements documentthe specifications for our products. 3.1B certificates inaccordance with EN 10 204 can be arranged for eachconsignment.

1.3 Brief description

The most important application properties of thelong-fibre-reinforced thermoplastics compared withthe corresponding short-fibre-reinforced materials are

- markedly higher mechanical properties- higher notched impact strength- reduced creep tendency- very good stability at elevated temperatures in

humid conditions.

Celstran is the trademark for long-fibre-reinforcedthermoplastics. They are supplied in form of cylindri-cal moulding granules (typical geometry: diameter 3 mm, length up to 12 mm), in which fibre length andpellet length are identical.

The range of Celstran products comprises a numberof possible matrix-fibre combinations. They areintended for injection moulding, extrusion and blowmoulding and produce moulded parts with markedlygreater fibre lengths than conventional short-fibre-reinforced plastics.

Celstran mouldings display fracture behaviour typicalof long-fibre reinforcement. This is demonstratedwhen the fibre length exceeds a critical value. Thisvalue depends on the fibre-matrix combination; prac-tical experience shows that it is between 0.8 and 3 mm. Above this fibre length the material has thecharacteristics of a fibre composite [1].

5

Fig. 1.4 · Fan shroud made from Celstran PP-GF40for the BMW E38 and E39 diesel vehicles

(manufacturer: Geigertechnik GmbH, Garmisch Partenkirchen, Germany)

Fig. 1.5 · Engine noise deadening casing made from Celstran PP-GF40 for the Porsche Boxster

(manufacturer: Mürdter, Mutlangen, Germany)

Fig. 1.6 · Housing made from Celstran PP-GF40 for the electronic engine control system of theMercedes Benz Roadster “SLK” (manufacturer:

Kostal GmbH & Co.KG, Lüdenscheid, Germany)

1


Celstran® Compel®

The long-fibre reinforcement is manifested by thefibre skeleton whose outer shape remains unchangedafter the resin matrix is burned off, fig. 1.7. This fibre skeleton is responsible among other things forthe good impact strength; it absorbs the impact ener-gy and dissipates it in the moulding. The long-fibrereinforcement also has a beneficial effect on the pro-perties at elevated service temperatures and on thecreep properties.

Celstran SF grades are masterbatches with 50 to 60%by weight stainless steel filaments [4, 5]. They areused to produce housings with electromagnetic shiel-ding properties and antistatic components, see sup-plement [4] (will be mailed upon request).

Compel is the trademark for even longer pellets (typical length: 25 mm). When processed, they are plasticized gently and then compression-moulded.This gentle process yields higher impact strength andenergy absorption than injection moulding, particu-larly with large-area structural components, fig. 1.8.Processing of Compel by plasticizing/compressionmoulding offers the following advantages comparedwith e.g. GMT compression moulding:

- freedom of shaping without the use of cut outs- low energy requirement due to screw plasticizing- low moulding pressure required- very good melt flowability- uniform glass fibre content even in thin ribs- good moulded part surfaces- immediate recycling of production waste.

For further details of Compel please order ourCompel brochure.

Fig. 1.8 · Instrument panel carrier for a car made from Compel PP-GF30 by plasticizing/

compression moulding

Fig. 1.7 · After burning off, a moulding (example: pump head made from Celstran

PA66-GF50, top) retains its geometry almost intact as a fibre skeleton (bottom)

6

Celstran® Compel®


2. Grades

2.1 Overview of grades

7

1

2

Celstran

Material Glass fibres Filaments of stainless Carbon fibres Aramid fibreshigh-grade steel

PP PP-GF30-04 PP-SF60PP-GF30-05PP-GF40-04PP-GF40-05PP-GF50-04PP-GF57-05

PE-HD PE-HD-GF60-01

PA66 PA66-GF40-01 PA66-SF50 PA66-CF40-01 PA66-AF35-02PA66-GF40-02PA66-GF50-01PA66-GF50-02PA66-GF60-01PA66-GF60-02

PA PA12-SF50 PA6-CF30

ABS ABS-SF50

PC PC/ABS-GF25-02 PC-SF50PC/ABS-GF40-02

PBT, PET PBT-GF40-01 PBT-SF50PBT-GF50-01PET-GF40-01PET-GF50-01

PPS PPS-GF50-01 PPS-SF 50 PPS-CF40-01 PPS-AF35-01PPS-GF40-01

TPU TPU-GF30-01 TPU-CF40-01TPU-GF40-01TPU-GF50-01TPU-GF60-01

POM POM-GF40-01 POM-SF50 POM-AF30-01

Compel

PP PP-GF30-04PP-GF30-05PP-GF40-04PP-GF40-05PP-GF50-04PP-GF57-05


Celstran® Compel®

2.2 Survey and nomenclature of Celstran

In the grade designation for Celstran, fig. 2.1,

- the first group of symbols indicates the basic polymer

- the letters after the hyphen indicate the type ofreinforcing fibres

- the number immediately following indicates thefibre content in % by weight

- the pair of numbers appended after the grade desig-nation (modification) indicate special features as viscosity, impact strength, heat stabilization etc.

- the second pair of numbers is an additional suffixfor special formulations like high light stabilization,ease of demoulding, markedly low emission rate etc.

- P with the following numbers characterise the pelletlength and with it the fibre length in mm

- the numbers after the dash symbolize the colourcode. Natural grades have no declaration.

2.3 Survey and nomenclature of Compel

Grades of Compel with polypropylene as matrixmaterial with 30-57% long-glass-fibre reinforcementare currently available.

All Compel grades are heat-stabilized.

8

Fig. 2.1 · Grade designation for Celstran

Example: Celstran PP-GF40-0414P10/10

Matrix materialType of fibreFibre content in % (w/w)ModificationAdditional suffixPellet length in mmColour

Key to abbreviations:

Matrix materials:

PP PolypropylenePA66 Polyamide 66PA6 Polyamide 6PA12 Polyamide 12PBT Polybutylene terephthalatePC PolycarbonatePE-HD High-density polyethylenePET Polyethylene terephthalatePOM PolyoxymethylenePPS Polyphenylene sulphideTPU Thermoplastic polyurethaneABS Acrylonitrile-butadiene-styrene

Fibres:

GF GlassCF CarbonAF AramidSF Stainless steel

Modification of Celstran PP:

03 chemically coupled, heat stabilized04 chemically coupled, heat stabilized,

increased flowability05 chemically coupled, heat stabilized,

high impact modificated

Modification of Celstran PA:

01 high gloss02 heat stabilized10 flame-retardant

(V-0 in accordance with UL 94)

Modification of Celstran PE-HD:

01 chemically coupled

Additional suffix:

16 easily demouldable05 highly light-stabilized53 markedly low C emission55 markedly low C emission and light stabilized

Colours:

without natural 50-59 yellow10-19 black 60-69 brown20-29 white 70-79 green30-39 grey 80-89 blue40-49 red 90-99 specialities

Celstran® Compel®


2.4 Form supplied

To a large extend Celstran and Compel are suppliedto individual requirements both in terms of the thermoplastic matrix and of the fibres used for rein-forcement. Possible matrix systems are

- high-density polyethylene, PE-HD- polypropylene, PP- polyacetal, POM (Hostaform®)- polybutylene terephthalate, PBT (Celanex®)- polyethylene terephthalate, PET (Impet®)- polyphenylene sulphide, PPS (Fortron®)- thermoplastic polyurethane, TPU- acrylonitrile-butadiene-styrene copolymer, ABS- polycarbonate, PC, and PC blends with ABS- polyamide 66, PA66- polyamide 6, PA6- polyamide 12, PA12.

Other matrix systems are being prepared.

The following reinforcing fibres are available:

- glass- carbon- aramid- stainless steel filaments.

Celstran is supplied in 25-kg bags and 500-kg largecontainers.

Silo truck delivery is also possible (à 20 t) withCelstran. Because of the high impregnation of the fibres pneumatic conveyance is possible.

Compel is supplied in 20-kg bags and 400-kg large containers.

2.5 Colours

Celstran PP and Compel PP are normally supplied in natural and black. In-house coloration by the pro-cessor is not recommended because of the need forgentle plasticization.

Coloration of Celstran PP and Compel PP is subject to limitations; colours on request. Celstran PA can be supplied coloured.

9

2


Celstran® Compel®

10

3. Material DataPhysical property Unit Test method Test specimen

Content of reinforcing material % by wt. ISO 3451, part 1 No test specimen (pellets)

Density g/cm3 ISO 1183 10 x 10 x 4 mm

Water absorption at 23°C after 24 h % by wt. ISO 62 80 x 80 x 1 mm

Mechanical properties, measured under standard conditions, ISO 291-23/50

Tensile strength at 23°C MPa ISO 527 part 1/2; Multi-purpose test specimentest speed 5 mm/min to ISO 3167


Elongation at break at 23°C % ISO 527 part 1/2; Multi-purpose test specimentest speed 5 mm/min to ISO 3167


Tensile modulus at 23°C MPa ISO 527 part 1/2; Multi-purpose test specimentest speed 1 mm/min to ISO 3167


Flexural strength at 23°C MPa ISO 178 80 x 10 x 4 mm from multi-pur-pose test specimen to ISO 3167


Flexural strain at flexural strength at 23°C % ISO 178 80 x 10 x 4 mm from multi-pur-pose test specimen to ISO 3167


Flexural modulus at 23°C MPa ISO 178 80 x 10 x 4 mm from multi-pur-pose test specimen to ISO 3167


Impact strength (Charpy) at 23°C kJ/m2 ISO 179 1eU 80 x 10 x 4 mm from multi-pur-pose test specimen to ISO 3167

Impact strength (Charpy) at -30°C kJ/m2 ISO 179 1eU 80 x 10 x 4 mm from multi-pur-pose test specimen to ISO 3167

Notched impact strength (Charpy) at 23°C kJ/m2 ISO 179 1eA 80 x 10 x 4 mm from multi-pur-pose test specimen to ISO 3167

Notched impact strength (Charpy) at -30°C kJ/m2 ISO 179 1eA 80 x 10 x 4 mm from multi-pur-pose test specimen to ISO 3167

Notched impact strength (Izod) at 23°C J/m ASTM D 256 80 x 10 x 4 mm from multi-pur-pose test specimen to ISO 3167

Notched impact strength (Izod) at -30°C J/m ASTM D 256 80 x 10 x 4 mm from multi-pur-pose test specimen to ISO 3167

Puncture energy at 23°C J/mm ISO 6603 part 2 60 x 60 x 2 mm

Puncture energy at -30°C J/mm ISO 6603 part 2 60 x 60 x 2 mm

Maximum force N ISO 6603 part 2 60 x 60 x 2 mm

Thermal properties

Heat deflection temperature HDT/A (1.8 MPa) °C ISO 75 part 1/2 80 x 10 x 4 mm from multi-pur-pose test specimen to ISO 3167

Heat deflection temperature HDT/C (8.0 MPa) °C ISO 75 part 1/2 80 x 10 x 4 mm from multi-pur-pose test specimen to ISO 3167

Celstran® Compel®

11


PP-GF30-04 PP-GF30-05 PP-GF40-04 PP-GF40-05 PP-GF50-04 PE-HD-GF60-01

30 30 40 40 50 60

1.12 1.12 1.22 1.22 1.33 1.51

– – – – – –

95 75 110 100 125 90

52 – 63 – 70 –

2.3 2.8 2 2.3 1.8 1.6

2.9 – 2.5 – 2.4 –

7,200 5,300 9,100 7,300 11,700 12,000

4,400 – 6,500 – 7,200 –

160 135 190 155 200 88

95 – 100 – 105 –

2.9 3.7 2.7 3.2 2.4 –

3.7 – 3.6 – 3.2 –

7,000 5,300 9,500 7,100 11,100 9,000

4,800 – 6,400 – 7,200 –

48 60 59 70 59 –

44 – 55 – 57 –

18 23 16 25 19 –

20 – 13 – 14 –

– – – – 296

– – – – – –

3.9 – 4.8 – 6.3 –

4.9 – 5.1 – 6.1 –

– – – – –

148 – 152 – 155 121

122 – 128 – 132 –

Celstran PP Celstran PE-HD

3


Celstran® Compel®

12

Physical property Unit Test method Test specimen


























Thermal properties



Celstran® Compel®


13

3

Celstran PA66

40 40 40 40 50 50

1.45 1.45 1.44 1.44 1.56 1.56

0.55 0.55 0.55 0.55 0.4 0.4

235 170 230 155 260 190

140 120 135 115 160 130

2.4 2.8 2.2 2.3 2.4 2.5

3 2.9 2.5 2.6 2.4 2.7

14,000 10,200 13,000 8,700 16,200 12,300

8,100 7,500 7,800 7,100 10,500 9,600

370 290 300 245 405 320

250 210 215 195 – –

3.5 4.1 3.2 3.8 3.2 3.8

4.1 3.7 3.4 3.9 – _

12,300 9,800 11,100 8,600 14,800 11,700

7,500 6,800 7,200 6,500 9,500 9,000

85 95 81 91 90 95

75 – 72 65 85 80

30 30 36 36 33 34

30 30 36 37 33 34

230 240 260 300 250 295

220 – 240 280 275 –

8.6 – – – 8.6 –

– – – – – –

4,950 – – – 4,600 –

255 255 242 242 256 256

240 240 218 218 249 249

PA66-GF40-02 PA66-GF40-02 PA66-GF40-01 PA66-GF40-01 PA66-GF50-02 PA66-GF50-02DAM cond. DAM cond. DAM cond.


Celstran® Compel®

14



























Thermal properties



Celstran® Compel®


15

50 50 60 60 35 40

1.55 1.55 1.69 1.69 1.22 1.33

0.4 0.4 0.25 0.25 – –

255 175 285 200 115 270

150 120 175 140 – –

2.1 2.4 2.2 2.3 2 1

2.4 2.4 1.9 2 – –

16,500 11,200 19,000 15,200 8,600 30,800

9,800 8,500 15,000 11,900 – –

350 260 410 330 183 440

250 210 – – – –

3.1 3.6 3 3.3 – –

4.5 3.5 – – – –

14,500 8,700 18,000 15,000 7,800 26,000

8,600 7,200 – – – –

96 107 100 100 – –

82 76 – – – –

41 40 45 – 12 21

41 41 – – – –

330 360 280 320 140 255

290 330 280 – – –

– – – – – –

– – – – – –

– – – – – –

242 242 257 257 246 260

217 217 250 250 – –

Celstran PA66

PA66-GF50-01 PA66-GF50-01 PA66-GF60-02 PA66-GF60-02 PA66-AF35-02 PA66-CF40-01DAM cond. DAM cond.

3


Celstran® Compel®

16



























Thermal properties



Celstran® Compel®


17

25 40 40 50 40 50

1.36 1.5 1.65 1.75 1.7 1.8

– – – – – –

120 152 132 166 189 165

– – – – – –

1.8 1.4 1.25 1.3 1.8 1.1

– – – – – –

8,100 12,000 13,500 15,000 15,300 16,000

– – – – – –

185 235 216 262 310 252

– – – – – –

– – – – – –

– – – – – –

7,400 11,000 11,800 13,000 13,700 14,500

– – – – – –

– – – – – –

– – – – – –

– – 28 – 36 –

18 – – – – –

213 182 352 454 267 347

– – – – – –

– – – – – –

– – – – – –

– – – – – –

107 113 213 216 249 249

– – – – – –

Celstran PC/ABS Celstran PBT/PET

PC/ABS-GF PC/ABS-GF PBT-GF PBT-GF PET-GF PET-GF25-02 40-02 40-01 50-01 40-02 50-01

3


Celstran® Compel®



























Thermal properties



18

Celstran® Compel®


50 35 40 30 40 50 60 40 30

1.72 1.35 1.46 1.43 1.52 1.63 1.76 1.72 1.42

– – – – – – – – –

148 74 158 180 209 248 230 102 106

– – – – – – – – –

1 1.3 0.5 2.8 2.55 2.4 1.6 1.1 2.3

– – – – – – – – –

18,000 8,300 35,000 8,400 11,300 15,000 18,600 12,000 8,000

– – – – – – – – –

265 138 297 272 300 363 408 182 137

– – – – – – – – –

– – – – – – – – –

– – – – – – – – –

17,000 8,380 30,000 8,000 10,000 13,000 16,000 11,000 6,000

– – – – – – – – –

– – – – – – – – –

– – – – – – – – –

23 9 – 41 48 – 58 28 –

– – – – – – – – –

359 125 161 426 588 645 692 374 421

– – – – – – – – –

– – – – – – – – –

– – – – – – – – –

– – – – – – – – –

282 260 277 85 91 96 102 160 157

– – – – – – – – –

Celstran PPS Celstran TPU Celstran POM

PPS-GF PPS-AF PPS-CF TPU-GF TPU-GF TPU-GF TPU-GF POM-GF POM-AF50-01 35-01 40-01 30-01 40-01 50-01 60-01 40-01 30-01

19

3


Celstran® Compel®

4. Physical Properties

4.1 General information

Sections 4. “Physical Properties” and 5. “Environ-mental Effects” deal with the important propertiesthat are descriptive of Celstran and Compel, specifi-cally – where available – as a function of temperatureand time.

All properties are determined by standardized testmethods wherever possible. A survey of the physicalproperties is given in section 3. “Material Data”. Thevalues are also available as a data sheet.

With gentle processing a skeleton-like fibre structure is formed in Celstran and Compel mouldings. As a result they have properties characteristic of fibrecomposites. Compared with short-fibre-reinforced plastics there is a substantial improvement particu-larly in

- impact strength, notched impact strength, low-temperature impact strength,

- energy absorption capacity under impact stress,- rigidity and strength at elevated temperatures,- mechanical and thermal properties in continuous

service (creep, fatigue),- reduced warpage.

Of particular importance to designers is the verysharply reduced creep tendency brought about by thelong-fibre reinforcement. The orientation of the rein-forcing fibres frequently contributes to a reduction innotch sensitivity. A typical example is a screw injec-tion-moulded from Celstran: the fibre orientationgives it increased strength in the thread root betweenthe thread flights, fig. 4.1.

Generally speaking, long-fibre-reinforced plasticshave a high modulus of elasticity – typical values arebetween 10,000 and 20,000 MPa – with no change intheir good impact and notched impact strength, fig.4.2. Owing to their high rigidity and strength long-fibre-reinforced plastics are able to replace metals. Inspecific strength they far surpass metals, fig. 4.3.

Long-fibre materials

30,000

20,000

10,000

0100 200 300 400 500 J/m 700

Flex

ural

mod

ulus

E

Short-fibrematerials

Unreinforced termoplastics

Izod notched impact strength �K (ASTM D 256)

MPa

Fig. 4.2 · Comparison of the typical performanceranges of unreinforced, short-fibre-reinforced and

long-fibre-reinforced thermoplasticsSp

ecifi

c str

engt

h �

sp

0

5

10

15

20

25

30

16.5 17

5.1

9.8

5.9

12.7

23.5

17.2

CelstranPA66-GF40

CelstranPA66-GF50

CelstranPA66-CF40

PA66-GF60Celstran Steel* Zinc*

Aluminium* Magnesium*

km

� =

235

N/m

m2

� =

1.4

5 g/

cm3

� =

260

N/m

m2

� =

1.5

6 g/

cm3

� =

285

N/m

m2

� =

1.6

9 g/

cm3

� =

307

N/m

m2

� =

1.3

3 g/

cm3

� =

370

N/m

m2

� =

7.4

0 g/

cm3

� =

270

N/m

m2

� =

2.8

0 g/

cm3

� =

345

N/m

m2

� =

6.0

0 g/

cm3

� =

225

N/m

m2

� =

1.8

0 g/

cm3

*typical values

Fig. 4.3 · Specific strength of Celstran PA – reinforced with glass fibres or carbon fibres –

compared with metals

Fig. 4.1 · Long-fibre reinforcement in a threaded part reduces notch sensitivity in the thread root

20

Celstran® Compel®


A special advantage of Celstran PP is its low densitycompared e.g. to short-glass-fibre-reinforced PA, fig. 4.4.

Because of their low volume price resulting fromtheir low density, Celstran PP components can offersubstantial cost advantages over short-glass-fibre-reinforced PA66 and PA6, even if the fibre content inthe PP is higher than that in the PA, fig. 4.5.

Den

sity

�

1.0

1.2

1.4

1.6

1.8

2.0

2.2

2.4

g/cm3

2.8

Mag

nesi

um

Alu

min

ium

Cel

stran

PP-

GF3

0

1.12

Cel

stran

PP-

GF4

0

Cel

stran

PP-

GF5

0

PA6-

GV

30 s

hort

fibre

s

PA66

-GV

30 s

hort

fibre

s

PA66

-GV

40 s

hort

fibre

s

1.22

1.33 1.36 1.361.45

Fig. 4.4 · Density of some long- and short-fibre-reinforced plastics compared with light metals

5.00 DM / kg(price per kilo assumed as an example)

5.00

6.00

7.00

8.00

DM/l

Volu

me

pric

e

PA66

-GV

40 s

hort

fibre

sD

ensi

ty: 1

.45

g/cm

3

PA6-

GV

30 s

hort

fibre

sD

ensi

ty: 1

.36

g/cm

3

Cel

stran

PP-

GF5

0D

ensi

ty: 1

.33

g/cm

3

Cel

stran

PP-

GF4

0D

ensi

ty: 1

.22

g/cm

3

7.25

6.65

6.10

6.80

Fig. 4.5 · Comparison of the volume price of Celstran PP and short-fibre-reinforced PA66

that result from differences in density, assuming identical prices per kilo

4.2 Mechanical properties

4.2.1 Preliminary remarks

The properties of Celstran are determined by thestandard test methods used for the ®Campus materialsdata base. These properties make it easier for de-signers to make a preliminary selection of materials.

The physical property values given in section 3.“Material Data” may vary from those reached inmouldings owing to different production conditionsand processing parameters. In the case of Compel thevalues – also given in section 3. “Material Data” –were determined on specimens taken from compres-sion-moulded parts. These values are therefore notcomparable with those for Celstran. They reflect with reasonable accuracy the property values actuallyattained in mouldings.

In dimensioning components the long-term pro-perties and possibly the temperature-dependency ofthe properties as well as the values obtained undershort-term stress must be taken into account. It isthese long-term properties that are improved bylong-fibre reinforcement compared with the unrein-forced or short-fibre-reinforced matrix materials.

4.2.2 Short-term stress

Reinforcement with long fibres improves in particularstrength and modulus of elasticity at elevated temper-atures and/or under long-term stress compared withshort-fibre reinforcement. Long-fibre reinforcementalso gives better impact strength.

This is shown in fig. 4.6 for some important applica-tion properties of Celstran PP with chemically coup-led glass fibres. The flexural strength and flexuralmodulus values of a Celstran PP-GF40 are almostdoubled compared with a PP with 30% by weightshort glass fibres. The value for Charpy notchedimpact strength is nearly three times higher. A corre-sponding picture emerges for PA, i.e. with PA66 asmatrix material, fig. 4.7.

21

4


Celstran® Compel®

The combination of high flexural modulus and hightensile strength, fig. 4.8, opens up particularly in the case of Celstran PA fields of application in whichlight metal castings have been used in the past. In thissubstitution the benefits of the high rigidity of theCelstran PA grades, especially compared with short-fibre-reinforced PA, are a clear advantage, fig. 4.9.

Reinforcement with long glass fibres also increasesthe tensile modulus and tensile strength when POMis used as the matrix material, as shown by the stress-strain diagram for Celstran POM-GF40, fig. 4.10.

Tensile modulus[MPa]

Tensile strength[MPa]

Charpy notchedimpact strength

[kJ/m2]Flexural strength

[MPa]

Flexural modulus[MPa]

Fibre content[%]

40

9

806,200

100

5,500

9,500

195

9,100 115

20

30

PPshort-fibrecompound

PP- long-fibre pellets,

cemicallycoupled

Fig. 4.6 · Improvement in some typical mechanical properties of glass-fibre-reinforced PP on switching from commercial short-fibre products

to commercial long-fibre products

5,000

10,000

15,000

20,000

Flex

ural

mod

ulus

E

MPa

Tensile strength �

MPa150 200 250 300

Celstran PA66

25%

30%

40%

40% 50%

60%

PA66 short fibres

Fig. 4.8 · Tensile strength and flexural modulus of some Celstran PA66 grades compared

with short-glass-fibre-reinforced PA66

conditioned

Stre

ss �

Strain ε

Celstran PA66-GF50

Celstran PA66-GF40

PA66-GV33short fibres

0 1 2 3 40.5 1.5 2.5 %0

50

100

150

200MPa

Fig. 4.9 · Stress-strain curves for Celstran PA grades and short-glass-fibre-reinforced PA66

Strain ε

Stre

ss �

00

40

80

MPa

120

0.4 0.8 1.2%

Fig. 4.10 · Stress-strain curve for Celstran POM-GF40

10,700

13,000

35

50

32

26017,000

405

15,000

210

305 13

Tensile modulus[MPa]

Tensile strength[MPa]

Charpy notchedimpact strength

[kJ/m2]Flexural strength

[MPa]

Flexural modulus[MPa]

Fibre content[%]

PAshort-fibrecompound

PA- long-fibre pellets,

freshlymoulded

Fig. 4.7 · Improvement in some typical mechanical properties of glass-fibre-reinforced PA66 on switching from commercial short-fibre

products to commercial long-fibre products

22

Celstran® Compel®


4.2.3 Creep properties

Designers have to know the creep properties of components subject to constant mechanical stress.Depending on the test conditions, these properties indicate how

- strain at constant stress increases with time(creep test to ISO 899 part 1)

- stress at constant strain decreases with time(stress relaxation test to DIN 53441).

The increase in strain under constant load, known as flow, shown in stress-strain curves is considerablyless in the case of Celstran PP than in the case of acomparable short-fibre-reinforced PP, fig. 4.11. Asthe diagram shows, the creep tendency is even less than that of short-fibre-reinforced PA66.

0.10

1

1 10 100 1,000

2

3

4

Stra

in �

Time th


PP-GV30short fibres

Celstran PP-GF50

%

CelstranPP-GF40

Fig. 4.11 · Creep curves for two Celstran PP grades(PP-GF40 and PP-GF50) compared with short-glass-fibre-reinforced PP (PP-GF30) and short-glass-fibre-

reinforced PA66 (tensile stress: 35 MPa)

In similar fashion to when PP is used as matrix material, the long glass fibres in PA66 reduce thecreep tendency substantially. This is evident particu-larly at high load with a tensile stress of 90 MPa, fig. 4.12.

Details of the creep properties of Celstran PA66-GF40 – measured in accordance with ISO 899part 1 – are given in figs. 4.13 and figs. 4.14. Thecorresponding details for Celstran PA66-GF60 are given in figs. 4.15 and figs. 4.16.

For stress at high temperature and very high load(120°C and 120 MPa) fig. 4.17 shows the creep properties of Celstran PP-GF40 characterized by the flexural creep modulus compared with a short-fibre-reinforced PP. In this accelerated test the long-fibre-reinforced material does not fail even after atime under load of 100 hours.

Celstran PA66-GF40


Time t

Stra

in �

0.5

1

1 10 100 1,000

2

%

0.1

1.5

2.5

h

Fig. 4.12 · Decrease in creep tendency of PA66 when reinforced with long fibres: comparison of

a short-glass-fibre-reinforced material and CelstranPA66-GF40 (tensile stress: 90 MPa) Time t

Stra

in �

0.03

0.1

0.3

1

3

%

Equivalent stress 10 MPa

30

5070

90100

100 10-1 101 102 103h

Fig. 4.13a · Characteristic values for the creep behaviour of Celstran PA66-GF40:

creep curves for various stress values

100 10-1 101 102 103

Equi

vale

nt s

tress

�0

300

100

30

10

MPa

strain 0.2%

0.4%

0.6%

0.8%1.0%

hTime t

Fig. 4.13b · Characteristic values for the creep behaviour of Celstran PA66-GF40: creep curves

for various strain values

23

4


Celstran® Compel®

00

25

50

75

MPa

100

0.4 0.8 1.2 % 1.6Strain �

Equi

vale

nt s

tress

�0

Time under stress T 0.1h1

10 102

103

104 (extrapolated)

0.4

10

0.50.6

0.3

0.2

Strain 0.1%

300

100

30

100 10-1 102 103hTime t 101

Equi

vale

nt s

tress

�0

MPa

15,000

10,000

5,000

0

Cre

ep m

odul

us E

c

MPa 2550

75

Equivalent stress 100 MPa

100 10-1 101 102 103hTime t

102

103

104

100

75

50

25

00 0.25 0.50 0.75 % 1

0.1h

1

10

(extrapolated)

Strain �

Equi

vale

nt s

tress

�0

MPaTime under stress T

0.3

0.03

1

0.1

100

90

70

50

30

Stra

in �

%

Equivalent stress MPa

100 10-1 101 102 103hTime t

Cre

ep m

odul

us E

c

25,000

20,000

15,000

75

50

25

Equivalent stress MPa

100 10-1 101 102 103hTime t

MPa

Fig. 4.14a · Characteristic values for the creep behaviour of Celstran PA66-GF40:

stress-strain curves for various times under stress

Fig. 4.14b · Characteristic values for the creep behaviour of Celstran PA66-GF40: creep modulus

as a function of time for various stress values

Fig. 4.15a · Characteristic values for the creep behaviour of Celstran PA66-GF60: creep curves

for various stress values

Fig. 4.15b · Characteristic values for the creep behaviour of Celstran PA66-GF60: creep curves

for various strain values

Fig. 4.16a · Characteristic values for the creep behaviour of Celstran PA66-GF60: stress-strain

curves for various times under stress

Fig. 4.16b · Characteristic values for the creep behaviour of Celstran PA66-GF60: creep modulus

as a function of time for various stress values

24

Celstran® Compel®


0.10

1,000

2,000

3,000

4,000

1 10 h 100

Celstran PP-GF40

failure

Time under stress t

Cre

ep m

odul

us E

c

MPa

PP-GV40short fibres

Fig. 4.17 · Flexural creep modulus of Celstran PP-GF40 as a function of time comparedwith a PP with 40% by weight short glass fibers [6]

(flexural stress: 120 MPa, temperature: 120°C)

15,000

10,000

5,000

00 10 20 30 40 50 70

Charpy impact strength �s

Flex

ural

mod

ulus

E

35%

25%

25%

35%

40%

30%

kJ/m2

PA-GVshort fibresconditioned

PP-GVshort fibres

20%

PA-GVshort fibresfreshly moulded

50% CelstranPP-GF

MPa

Fig. 4.19 · Flexural modulus as a function of Charpy impact strength of Celstran PP compared

with short-fibre-reinforced plastics

3,000

4,000

2,000

1,000

500

15 2010Deflection s

N

mm

Forc

e F

PP-GV40short fibres

CelstranPP-GF40

Fig. 4.20 · Force-deflection curve in the instrumented puncture test on Celstran PP-GF40 and a polypropylene with 40% short glass fibres

long fibreslong fibreslong fibres

short fibresshort fibres

Temperature [°C]

Izod

not

ched

impa

ct s

treng

th �

K*

-40 -30 -20 -10 0 20 °C0

200

400

600

800

J/m

Celstran PP-GF30

PA66-GV30 short fibres

PP-GV30 short fibres

*according to ASTM D 256

Celstran PP-GF50

Celstran PP-GF40

Fig. 4.18 · Improvement in low-temperature impactstrength by long-fibre reinforcement: comparison of

various Celstran PP grades with short-glass-fibre-rein-forced PP and with short-glass-fibre-reinforced PA66

Direct information on the behaviour under impactstress is provided by the multi-axial stress in thepenetration test. The results are shown in fig. 4.20 forCelstran PP and fig. 4.21 for Celstran PA. In bothcases the long-fibre reinforcement substantiallyincreases the maximum force and the fracture energy(this corresponds to the area beneath the curve).

Compel components have even better impact strengththan comparable Celstran components. The increasewith PP as matrix material is about 40% for theimpact-resistant formulation (Compel PP-GF30-05P25).

4.2.4 Toughness

Toughness is crucial to the behaviour of a componentunder impact stress. As already shown in figs. 4.6 forCelstran PP and 4.7 for Celstran PA, long-fibre rein-forcement brings an above-average increase in impactstrength.

This applies not only at room temperature but also tolow-temperature impact strength, fig. 4.18. With thecombination of high flexural modulus and very goodimpact strength, fig. 4.19, the long-fibre-reinforcedCelstran can be used in those cases in which thiscombination of properties is not adequate in short-fibre-reinforced plastics.

25

4


Celstran® Compel®

5,000

4,000

3,000

2,000

1,000

00 2 4 6 8mm

N


CelstranPA66-GF40

Deflection s

Forc

e F

Fig. 4.21 · Force-deflection curve in the instrumentedpuncture test on Celstran PA66-GF40 and a

polyamide with 40% by weight short glass fibres

Fig. 4.22 · Results of the tensile fatigue test on glass-fibre-reinforced polypropylene at elevated

temperature (70°C)

4.2.5 Fatigue

Components that are subject to fluctuating stressmust be dimensioned by means of the fatigue strength.

The long-fibre reinforcement substantially increases the fatigue strength at room temperature and espe-cially at elevated temperature and high load comparedwith short-fibre reinforcement, fig. 4.22.

The flexural fatigue strength*) of Celstran PP-GF40 compared with a short-fibre-reinforced PP is shown in fig. 4.23.

4.2.6 Surface properties

Celstran mouldings generally have a good surfacebecause of the good flowability of the melt. For partswith visible surfaces the following grades are highlysuitable:

- Celstran PP grades with modification 04(increased flowability)

- Celstran PA grades with modification 01(high gloss).

In each case graining of visible surfaces isrecommended.

Sliding properties: As with unreinforced plastics, an addition of PTFE improves the sliding properties of Celstran. A Celstran PA-GF50 modified withPTFE to suppress the stick-slip effect is obtainablefrom Lehmann & Voss & Co., Hamburg, Germany.

Wear: Like the sliding properties, wear is a characte-ristic of the system. Abrasion is dependent on varia-bles such as sliding partner, surface pressure, slidingspeed and lubrication. Under comparable conditionsCelstran PP and Celstran PA generally display lessabrasion than corresponding short-fibre-reinforcedmaterials, fig. 4.24: abrasion against steel of long- and short-fibre-reinforced PA66 (40% by weightglass fibres).

Stre

ss a

mpl

itude

�

A

70

50

40

30

20103

Number of cycles n

PP-GV30short glass fibres

104 105 106 107 108

MPa

Celstran PP-GF40

Fig. 4.23 · Flexural fatigue strength of Celstran PP-GF40 compared with PP reinforced

with 30% by weight short glass fibres

Stress amplitude Number of cycles until failure of

Celstran PP-GF40 PP-GV40MPa long fibres short fibres

80 14 1

60 300 66

50 871 182

*) Fatigue strength: Stress amplitude determined in a fatigue testthat a specimen withstands for a specific number of load cycleswithout fracture.

26

Celstran® Compel®


Rela

tive

abra

sion

8

4

6

2

0

PA66

-GV

40(4

0% b

y w

eigh

t sho

rt fib

res)

Test material

Taber abrasion method

Cel

stran

PA

66-G

F40

(40%

by

wei

ght

long

fibr

es)

Fig. 4.24 · Abrasion against steel of long- and short-fibre-reinforced PA66

(40% by weight glass fibres)

4.3 Thermal properties

4.3.1 Coefficient of expansion

Fibre reinforcement substantially reduces the coeffi-cient of linear thermal expansion of plastics. Becauseof the skeleton structure the differences in flow direc-tion and perpendicular to it are less than for compa-rable short-fibre-reinforced materials.

The coefficient of expansion of Celstran reaches values of 10 to 20 · 10–6 · °C–1 in the temperature range–30 to +30°C for the different test specimen geo-metries, fig. 4.25. It is thus in the same range as steel(12.1 · 10–6 · °C–1) and aluminium (22.5 · 10–6 · °C–1).

4.3.2 Specific heat, enthalpy

For designing the processing machines and mouldsand for dimensioning mouldings it is necessary toknow the amount of heat that has to be supplied formelting the long-fibre-reinforced thermoplastics andthen removed from the mould by cooling. Fig. 4.26shows by way of example the specific enthalpy curveof Celstran PP with 40% by weight long glass fibresas a function of temperature. The amount of heat tobe removed from the mould can be calculated fromthe melt temperature and the demoulding temperatu-re for Celstran PP with the values given in fig. 4.27 in accordance with the procedure in fig. 4.28.

00

100

200

300

400

J/g

600

50 100 150 200 250 °C 350Temperature �

Spec

ific

enth

alpy

Fig. 4.26 · Specific enthalpy (based on 20°C) as a function of temperature for Celstran PP-GF40

Fig. 4.25 · Coefficients of thermal expansion (range: –30 to +30°C)

of some frequently used Celstran grades

Material Coefficient of expansion (-30 to +30°C)

in perpendicularflow direction to flow direction

Celstran 10-6 · °C-1 10-6 · °C-1

PA66 unreinforced 90 not measurable

PA66-GF40 19 not measurablePA66-GF50 17 not measurablePA66-GF60 15 not measurable

PA66-CF40 13 not measurable

PP unreinforced 83 not measurable

PP-GF30 16 36PP-GF40 15 34PP-GF50 13 17

PET-GF40 16 72

PBT-GF40 19 75

PC/ABS-GF40 18 70

PPS-GF50 12 39

TPU-GF40 13 52TPU-GF50 10 50

TPU-CF40 18 64

Blends

PA66-SF6 66 74

ABS-SF6 64 96

PC-SF10 43 –

27

4


Celstran® Compel®

4.3.3 Thermal conductivity

Generally speaking, the reinforcing fibres have higherthermal conductivity than the matrix material.Therefore the thermal conductivity of fibre-reinfor-ced plastics rises slightly with the fibre content. Thethermal conductivity of Celstran PP-GF50 black (at30°C) is λ= 0.28 ± 0.01 W/(m·K).

4.4 Electrical properties

Reinforcement with electrically non-conductive glassfibres or aramid fibres has no appreciable influence on the electrical properties of the individual matrixmaterial. In particular the very good electrical insula-ting properties and good dielectric strength of theplastics remain virtually unchanged.

Of the Celstran grades with carbon fibre reinforce-ment PA66-CF40 has good conductivity and evensome shielding effect against electromagnetic radiati-on. Because of these properties this material is usede.g. for the housings of laptops. By adding a smallamount of stainless steel filaments the shielding effectand surface conductivity of plastics can be increasedspecifically. The Celstran SF masterbatches, which aredescribed in more detail in the offprint B182 d + e“Stainless steel fiber filled plastics – shielding compo-nents” (delivery upon request), were developed spe-cially to meet these requirements.

Fig. 4.28 · Procedure for calculating the amount of heat to be removed on solidification

Celstran PP-GF40:Cooling from 250°C to 72 °C

Enthalpy at 250°C 470 J/g- Enthalpy at 72°C 77 J/g

= heat to be removed 393 J/g

Fig. 4.27 Values for specific enthalpy of polypropylene, glass and Celstran PP grades, based on 20°C

Temperature Specific enthalpy in J/g, based on 20°C, of

°C PP Glass Celstran PP-GF30 Celstran PP-GF40 Celstran PP-GF50

20 0 0 0 0 0

50 55 24 46 43 40

72 100 42 82 77 71

100 160 64 131 122 112

115 200 76 163 150 138

150 310 104 248 228 207

170 400 120 316 288 260

172 445 122 348 316 283

200 525 144 411 373 334

250 660 184 517 470 422

300 795 224 624 567 510

28

Celstran® Compel®


4.5 Optical properties

Fibre-reinforced thermoplastics are not transparent and are translucent only if the wall thickness is low.

4.6 Acoustic properties

From the acoustic point of view components madefrom long-glass-fibre-reinforced Celstran PP offerthe following advantages:

- they have considerably better sound-deadeningproperties than components made from short-fibre-reinforced PA or metal

- noise emission is lower because of the highersound-deadening effect

- owing to their high rigidity the natural frequency ishigher, given otherwise unchanged conditions, andso additional ribs to increase the natural frequencyare not necessary

- they have lower oscillation amplitudes – with thesame design rigidity

- large-volume hollow components also attain highacoustic damping

- they permit a reduction in weight because of theiracoustic passivity.

The good acoustic damping is shown by oscillationmeasurements on cable trays for the electronic enginecontrol system of cars: because of its lower weight and higher rigidity the cable tray made from CelstranPP-GF40 has a higher natural frequency at a muchlower amplitude than a cable tray made from PA6with 30% by weight short glass fibres, fig. 4.29.

Because of their good acoustic damping propertiescomponents made from Celstran have good sound-deadening properties, fig. 4.30.

Fig. 4.29 · Frequency spectra on excitation with a rectangular impulse, measured on cable trays

made from Celstran PP-GF40

0.6

dB

0.4

0.3

0.2

0.1

0.0

0 200 400 600 Hz 1,000

Frequency

Am

plitu

de

PA6-GV30short glassfibres Celstran PP-GF40

292 Hz

306 Hz

0 s0

20

40

60

%

100

0.05 0.10 0.15 0.20

Time t

Rela

tive

ampl

itude

PA6-GV30 short fibres

Celstran PP-GF40

Fig. 4.30 · Decay curve on excitation with a rectangular impulse, measured on cable trays made from Celstran PP-GF40 and from a PA6

with 30% by weight short glass fibres

29

4


Celstran® Compel®

30

Temperature �

Shea

r m

odul

us G

16,000

8,000

4,000

00 100 °C 25015050-50

MPa

Celstran PA66-GF60-02Celstran PA66-GF50-02

Celstran PA66-GF40-02

Fig. 5.2 · Shear modulus of various Celstran PA grades as a function of temperature

5. Environmental Effects

5.1 Thermal properties

5.1.1 Heat deflection temperature

Because of the long-fibre reinforcement the heatdeflection temperature of all Celstran grades is signi-ficantly higher than that of the corresponding short-fibre-reinforced matrix materials.

The long-fibre reinforcement of Celstran PP-GF40accounts for the shear modulus up to a temperatureof 130°C being higher than that of short-glass-fibre-reinforced PA6 and PA66, fig. 5.1. Shear modulus of Celstran PA is plotted against temperature in fig.5.2. The long-fibre reinforcement furthermore sig-nificantly reduces the creep tendency compared withthat of corresponding short-fibre-reinforced plastics.This is shown by stress-strain curves of PP measuredat 120°C, fig. 5.3.

5.1.2 Heat ageing

The heat ageing of plastics is not a pure material pro-perty but is also dependent on environmental circum-stances, the loading condition and the natural colour of the material.

The base material used for Celstran PP is stabilizedeffectively against thermo-oxidative degradation andtherefore displays good ageing properties.

Because of their good heat ageing properties lightlystressed Celstran PP components are suitable for continuous service temperatures up to 130°C. Undershort-term stress – up to about 1,000 hours – tempe-ratures up to 150°C can be tolerated (medium: air).

In the flexural test based on ISO 178 the flexuralmodulus and flexural strength even rise slightly afterheat ageing, whereas the strain, normally highly sensitive to ageing, falls only slightly, fig. 5.4.

The base material of the heat-stabilized Celstran PA(modification -02) is stabilized against thermo-oxi-dative and hydrolytic degradation. Componentsmade from heat-stabilized Celstran PA are suitableunder low loading for continuous service tempera-tures up to 150°C and for short periods – up to about 1,000 hours – for temperatures of 170 to 200°C

1

0.5

%

0 500 1,000 h 1,500Time t

Stra

in

�

0

Celstran PP-GF40


Fig. 5.3 · Creep curves for Celstran PP-GF40 compared with a PP with 40% by weight

short glass fibres

5,000

2,000

1,000

500

200-50 0 50 °C 150

Temperature �

Shea

r m

odul

us G

MPa

Celstran PP-GF40

PA66-GV30 cond.short fibres

PA6-GV30 cond.short fibres

Fig. 5.1 · Shear modulus of Celstran PP-GF40 as a function of temperature compared with

conditioned PA6 and PA66, each with 30% by weight short glass fibres

Celstran® Compel®


(medium: air). At a temperature of 150°C even aftermore than 500 hours heat ageing Celstran PA66-GF40-02 has a flexural modulus of over 10,000 MPa, fig. 5.5, while Celstran PA66-GF50-02 has a flexuralmodulus of over 12,000 MPa, fig. 5.6.

Because of their good heat ageing properties theCelstran PA grades frequently replace light metals in the manufacture of complex castings. They usuallypermit considerably higher functional integration.

5.2 Flammability

The behaviour of numerous Celstran grades in theevent of fire has been tested and classified to UL 94.Fig. 5.7 shows an extract from these ratings, whichare constantly being updated.

Celstran PP-GF30 test specimens have withstoodexposure to edge and surface flame application inaccordance with DIN 4102 B2.

31

Flex

ural

mod

ulus

EFl

exur

al s

train

at b

reak

�Fl

exur

alstr

engt

h �

B

2.30

%

2.10

2.00

1.90

190

170

160

15010 100 h 1,000

Heat ageing time t

MPa

11,500

10,500

10,000

9,500

MPa 150°C

130°C

130°C

150°C

150°C

130°C

Fig. 5.4 · Heat ageing of Celstran PP-GF40-04-P10 black

Flex

ural

mod

ulus

EB

Stra

in �

Flex

ural

stren

gth

�B

2.2

%

2.0

1.8

330

300

270freshly

moulded500 h 1,000

Heat ageing time t

MPa

12,000

10,000

8,000

MPa

200100

Flex

ural

mod

ulus

EB

Fig. 5.5 · Heat ageing of Celstran PA-GF40-02-P10 black

Flex

ural

mod

ulus

EB

Stra

in �

Flex

ural

stren

gth

�B

2.0

%

1.8

1.6

450

350

250freshly

moulded500 h 1,000

Heat ageing time t

MPa

14,000

12,000

10,000

MPa

200100

Fig. 5.6 · Heat ageing of Celstran PA-GF50-02-P10 black

Fig. 5.7 · UL rating of flammability and relative temperature index (RTI) of some Celstran PP

and PA grades

Material Colour Thick- Flamm. Temperature indexness class elec. mechan.[mm] UL 94 with without

impact impact

PolypropylenePP-GF30 natural 1.57 HB 65 65 65PP-GF40 natural 1.57 HB 65 65 65PP-GF50 natural 1.57 HB 65 65 65

PolyamidePA66-GF40 natural 1.57 HB 65 65 65

black 3.17 HB 65 65 65PA66-GF50 natural 1.57 HB 65 65 65

black 3.17 HB 65 65 65PA66-GF50HG all 1.5 HB 65 65 65

3.0 HB 65 65 65PA66-GF60 natural 1.57 HB 65 65 65

black 3.17 HB 65 65 65PA6-CF35-10 black 1.2 V-0

5


Celstran® Compel®

In the flammability test to FMVSS 302 frequentlyused in the vehicle industry the following values wererecorded on 1-mm thick test specimens:

- Celstran PP-GF40 burning rate 1.61 inch/min,- Celstran PP-GF50 burning rate 1.63 inch/min.

Both materials thus qualify for a standard burningrate of less than 4 inch/min. Their burning rate isbelow the value of 2.37 inch/min measured on short-fibre-reinforced PP-GV30.

5.3 Chemical resistance

The chemical resistance is influenced essentially bythe base material. Celstran PP and Celstran PA areresistant to glycol-water mixtures (engine cooling incars) up to 135°C. The changes with time of themechanical properties at 132°C are shown in fig. 5.8,fig. 5.9, fig. 5.10 and fig. 5.11.

5.4 Weathering and UV resistance

Celstran PP and Celstran PA can be supplied onrequest with highly effective light stabilization.

32

Flex

ural

stre

ngth

�B

750 h 1,000Immersion time t

400

200

100

00

MPa

250 500

Celstran PA66-GF40-02P10 black


Celstran PP-GF50-04P10 black

Fig. 5.8 · Effect of heat ageing at 132°C in a glycol-water mixture on the flexural strength of

various Celstran grades

Cha

rpy

impa

ct s

treng

th a


100

60

40

00

kJ/m2

250 500



Celstran PP-GF50-04P10 black20

Fig. 5.9 · Effect of heat ageing at 132°C in a glycol-water mixture on the Charpy impact strength

of various Celstran grades

Tens

ile s

treng

th �

Z


250

150

100

00

MPa

250 500



Celstran PP-GF50-04P10 black50

Fig. 5.10 · Effect of heat ageing at 132°C in a glycol-water mixture on the tensile strength of

various Celstran gradesTe

nsile

stra

in a

t bre

ak �


3

2

1

00

%

250 500



Celstran PP-GF50-04P10 black

0.5

1.5

Fig. 5.11 · Effect of heat ageing at 132°C in a glycol-water mixture on the elongation at break

of various Celstran grades

Celstran® Compel®


6. Processing

Celstran is intended for injection moulding, blowmoulding and extrusion. Compel is suitable for plasticizing/compression moulding. In processing allCelstran and Compel grades care should be taken toensure that fibre breakage is kept to a minimum. Thelonger the glass fibres in the component, the betterare its mechanical properties.

6.1 Preparation

The pellets should be stored in a dry place in closedcontainers until they are processed so as to preventcontamination and moisture absorption (including condensation).

Celstran PP and Compel PP: drying is not normallyrequired before processing. Should the material havebecome damp owing to incorrect storage, it must bedried for 2 hours at 80°C.

Celstran PA: drying in a dehumidifying dryer for 4 hours at 80°C is recommended in principle beforeprocessing.

Other Celstran grades: drying in a dehumidifyingdryer is in principle recommended before processing.The drying conditions are given in the product datasheet – see fig. 6.5.

33

6.2 Injection moulding of Celstranincluding mould making

Celstran can be processed by the various injectionmoulding methods commonly used for thermopla-stics. For the gentlest possible melting it is generallyrecommended that screw speed, injection speed andback pressure should be kept as low as possible.

6.2.1 Machine requirements

All Celstran grades can be processed on commercialinjection moulding machines. For optimum care ofthe reinforcing fibres and to prevent feed problemsbecause of the relatively long pellets, fairly large pla-sticizing machines should be used, preferably with ascrew diameter of more than 40 mm.

Pellets 7 mm long are available for processing glass-fibre-reinforced Celstran PA66 grades on smallermachines. Three-zone screws are recommended, fig. 6.1, if possible with a deep-flighted feed zone,low compression ratio and a three-piece annular non-return valve of large cross-section to ensure smootheven flow, fig. 6.2. Plasticizing units with mixingzones are in principle not suitable.

Fig. 6.1 · Metering Screw for Celstran Materials Fig. 6.2 · Three Piece Screw Tip Ring Valve

total length

generously dimensioned slotsfor gentle melt throughput

precision-ground mating surfacesfor good seal

highly polished

effective screw length

outside diameter

flight depth,metering zone

non-return valve

screw tip

met

erin

g zo

ne

com

pres

sion

zone

feed

zon

e

shaf

t len

gth

flight depth,feed zone

5

6


Celstran® Compel®

6.2.2 Processing conditions

Celstran can be injection-moulded without anyproblems. Machine settings that result in optimumfinished parts are dependent on the moulded partgeometry, the injection mould and the injectionmoulding machine used. Settings that have provedsuccessful are given in

- fig. 6.4 for Celstran PP and Celstran PA,- fig. 6.5 for other Celstran grades.

Plasticizing and cylinder temperatures

Gentle plasticizing is necessary to keep fibre lengthreduction during melting to a minimum. The requi-red melt temperature is achieved firstly by cylinderheating (heat supply from outside by heat conduc-tion) and secondly by friction (heat supply throughinternal and external friction, produced by back pressure and screw speed).

The melt shear occurring on melting may shorten thelong reinforcing fibres. It is therefore particularlyimportant to maintain very low back pressure oreven to plasticize without back pressure, but at thesame time to ensure uniform metering and adequatemelt homogeneity. It is recommended that the screwspeed should be as low as possible so that about 90%of the cooling time can be utilized for metering. Inorder for a maximum amount of heat to be suppliedvia the cylinder heating, the pellets should meltrapidly in the feed zone. For this material, therefore,a somewhat higher temperature profile should bechosen than for processing corresponding short-fibrecompounds.

Mould wall temperatures

The recommended mould wall temperatures are governed by the matrix material. Details are given infigs. 6.4 and 6.5. For Celstran PP mould wall tempe-ratures of 40 to 50°C have proved successful.Mouldings with a very good surface are obtained ifthe mould wall temperature is raised to 70°C. Themould wall temperatures for Celstran PA are nor-mally 90°C.

Since all Celstran grades contain reinforcing fibres, itis necessary for the plasticizing unit to be wear-resi-stant. Depending on the matrix material, additionalcorrosion protection may be necessary, e.g. for PA66or PPS.

Details of recommended machine equipment aregiven in fig. 6.3. Pneumatic conveying equipment hasproved successful for automatic material supply. Thediameter of the conveying lines should be at least 40 mm. Low air speeds (up to about 16 m/s) shouldpreferably be used. Suction tubes cut at an angle haveproved successful for feeding the product.

Gravimetric metering equipment is recommended forproducing blends with a fairly low fibre content.

The conveying and metering equipment used in pro-ducing conductive blends of Celstran with stainlesssteel filaments must not have any magnetic compo-nents. These blends can also be processed on machi-nes with smaller screws (diameter 20 mm and above)owing to the good stability of the stainless steel fila-ments.

34

Fig. 6.3 · Recommended equipment and parameters for injection moulding machines for

processing Celstran PP and Celstran PA

Celstran PP Celstran PA

Machine size preferably fairly large machines

Screw standard 3-zone screw,screw diameter preferably ≥ 40mm

Non-return valve streamlined non-return valve for good flow,with large cross-section

L/D 18 : 1 to 22 : 1 18 : 1 to 22 : 1

Compression ratio 1 : 1.8 to 1 : 2.5 1 : 1.8 to 1 : 2.5

Functional feed 50 to 60%zone ratios compression 20 to 30%

metering 20%

Flight depth feed zone preferably ≥ 4.5mm

Steel quality wear-resistant wear-resistantsteels and corrosion-HRC ≥ 56 resistant steels

HRC ≥ 56

Shot weight 30 to 60% of machine capacity

Nozzle open, diameter ≥ 4mm, preferably ≥ 6mm,own temperature control for the nozzle

Gating if possible central sprue gate, diameter ≥ 4 mm, preferably ≥ 6mm, all flow channels streamlinedfor good flow, gate diameter ≥ 3mm, if possible

no pin or film gates

Predrying 4h at 80°Cdehumidifying dryer

Celstran® Compel®


35

Celstran PP Celstran PAheat stabilized = 02 high-gloss = 01

PP-GF30 PP-GF40 PP-GF50 PA66-GF40 PA66-GF50 PA66-GF60 PA66-GF40 PA66-GF50 PA66-GF60

Temperature [°C] 230 to 270 250 to 290 250 to 290 275 to 310 280 to 315 285 to 320 270 to 305 270 to 305 275 to 310cylinder

Temperature [°C] 240 to 270 260 to 290 280 to 290 305 to 315 310 to 320 315 to 325 290 to 305 295 to 305 295 to 310nozzle and melt

Temperature [°C] 30 to 70 40 to 70 40 to 70 80 to 120 80 to 120 80 to 120 70 to 110 70 to 110 70 to 110mould pref. 90 pref. 90 pref. 90 pref. 90 pref. 90 pref. 90

Injection [mm/sec] 40 to 60 40 to 60 40 to 60 40 to 75 40 to 75 40 to 75speed

Screw speed [min-1] 40 to 60 40 to 60 40 to 60 40 to 60 40 to 60 40 to 60

Holding pressure [bar] 400 to 800 400 to 800 400 to 800 500 to 800 500 to 800 500 to 800

Injection pressure [bar] 600 to 1200 600 to 1200 600 to 1200 1200 to 1500 1200 to 1500 1200 to 1500

Back pressure as low as possible as low as possible

Fig. 6.5 · Drying and processing conditions for other Celstran grades

Drying Processing Processing Injection Back Screwtemperatures [±10°C] temperatures [±10°C] speed pressure speed

Time Temp Cylinder temperatures Nozzle Melt Mould Commentsat at

Product [h] [°C] hopper centre nozzle [bar] [min-1]

Polybutylene terephthalatePBT-GF40-01P10 4 120 255 260 265 260 265 90 medium 0 to 3 30 to 50 Predry to 0.015%PBT-GF50-01P10 4 120 260 265 270 265 270 90 medium 0 to 3 30 to 50 moisture content

Polycarbonate blendPC/ABS-GF25-02P10 4 90 265 270 275 275 275 80 medium 0 to 3 30 to 50PC/ABS-GF40-02P10 4 90 270 275 280 280 280 80 medium 0 to 3 30 to 50

PolyethylenePE-HD-GF60-03P10 2 90 230 240 250 240 250 70 medium 0 to 3 40 to 60

Polyethylene terephthalatePET-GF40-01P10 4 150 265 270 275 270 275 150 medium 0 to 3 30 to 50 Predry to 0.015%PET-GF50-01P10 4 150 270 275 285 280 285 150 medium 0 to 3 30 to 50 moisture content

Polyphenylene sulphidePPS-GF50-01P10 4 130 305 315 320 310 320 150 medium 0 to 2 30 to 50 Predry to 0.02%

moisture content

Polyoxymethylene (Polyacetal)POM-GF40-01P10 3 80 195 200 205 205 205 80 medium 0 to 3 30 to 50 Melt < 230°C

Thermoplastic polyurethaneTPU-GF30-01P10 4 80 240 245 250 245 250 70 medium 0 to 3 30 to 50 Predry to 0.02%TPU-GF40-01P10 4 80 245 250 255 250 255 70 medium 0 to 3 30 to 50 moisture contentTPU-GF50-01P10 4 80 250 255 260 255 260 70 medium 0 to 3 30 to 50 Melt < 275°CTPU-GF60-01P10 4 80 255 260 265 260 265 70 medium 0 to 3 30 to 50

With aramid fibresPA66-AF35-02P10 4 80 295 310 315 310 315 90 medium 0 to 3 30 to 50POM-AF30-01P06 3 80 200 205 210 210 210 70 medium 0 to 3 30 to 50PPS-AF35-01P06 4 130 315 320 320 320 320 150 medium 0 to 3 30 to 50

With carbon fibresPA66-CF40-01P10 4 80 300 305 310 310 310 90 medium 0 to 3 30 to 50PPS-CF40-01P10 4 130 305 310 315 315 315 150 medium 0 to 3 30 to 50TPU-CF40-01P10 4 80 245 250 255 255 255 70 medium 0 to 3 30 to 50

Fig. 6.4 · Processing conditions for Celstran PP and PA

6


Celstran® Compel®

Injection and holding pressure

High shear can also occur in the melt in the injectionoperation and shorten the fibres. Therefore low injec-tion speeds are recommended. Injection and holdingpressure should be adapted to the moulded part geo-metry. A holding pressure of 60 to 100% of the injec-tion pressure is recommended. To ensure as constanta moulded part quality as possible, an adequate hol-ding pressure time must be ensured. This is achievedwhen the moulded part weight remains constantdespite a lengthy holding pressure time with a con-stant total cycle time.

Regrind addition

When Celstran is processed, it is possible to addcoarsely ground production waste to virgin materialof the same grade. Additions of up to 10% have vir-tually no adverse effect on moulded part properties[3], fig. 6.6.

6.2.3 Flow properties and flow path lengths

In the spiral flow test under simulated service con-ditions the Celstran PP grades reach flow path lengths up to 550 mm for 2 mm wall thickness at aninjection pressure of 1,000 bar and a melt temperatureof 245°C, fig. 6.7. Raising the melt temperature by 45 K to 290°C increases the flow path length byabout 15%, fig. 6.8. Thus, despite reinforcement withlong glass fibres the flowability of Celstran PP is better than that of standard PP compounds with acomparable short glass fibre content, fig. 6.9.

Similarly, the Celstran PA grades too have betterflowability than corresponding short-fibre com-pounds. Even the heat-stabilized grades reach flowpath lengths up to 300 mm in the spiral flow test atan injection pressure of 1,000 bar and a melt tempera-ture of 305°C, fig. 6.10. Raising the melt temperatureby only 15 K to 320°C increases the flow path lengthby over 20%, fig. 6.11.

6.2.4 Shrinkage

Shrinkage has a major influence on the dimensional stability and warpage of a moulding. It is governed not only by the fibre content but also to a consider-able extent by the fibre orientation and the processingconditions, and so shrinkage data can be no morethan guide values.

Despite reinforcement with long glass fibres the anisotropy of shrinkage, i.e. the ratio of longitudinalto transverse shrinkage, is fairly low and generallymore favourable than that of short-fibre-reinforcedplastics. The average shrinkage measured on test barsis 0.25% in flow direction and 0.3% in transversedirection. Owing to the low anisotropy of shrinkagethe warpage tendency of Celstran components issimilarly low.

Additional information on the dimensional accuracyof Celstran components can be derived from the ratio of the flexural modulus in flow direction to thatin transverse direction. This anisotropy is muchlower in Celstran PP components than in identicalcomponents made from a corresponding short-fibre compound, as shown by tests on an injection-moulded air intake pipe for a car engine, fig. 6.12.

00

5 10 15 20 25 30 % 40

20

40

60

%

100

Regrind content

Rela

tive

chan

ge

Tensile strengthin accordance with ISO 527-1,2,initial value 115 MPa

Charpy notched impact strengthin accordance with ISO 179/1eA,initial value 20 kJ/m2

Fig. 6.6 · Change in tensile strength and Charpy notched impact strength as a result of

regrind addition

36

Celstran® Compel®


800300

1,000 1,600

400

500

600

mm

800

Injection pressure

Flow

leng

th

700

1,200 1,400 bar

Celstran PP-GF30-04

Celstran PP-GF40-04

Celstran PP-GF50-04

Celstran PP-GF30-03

Celstran PP-GF40-03

Fig. 6.7 · Flow lengths of the commercial Celstran PP grades

300

400

500

600

mm

800

Injection pressure

Flow

leng

th

700

Celstran PP-GF50-04

Tm = 290°C

Tm = 245°C

800 1,000 1,6001,200 1,400 bar

Fig. 6.8 · Influence of melt temperature Tm

on the flow length of Celstran PP-GF50-04

200900

400

500

mm

Injection pressure

Flow

leng

th

1,100 1,300 bar700

300

Celstran PA66-GF40

Tm = 320°C

Tm = 305°C

Fig. 6.11 · Influence of the melt temperature Tm

on the flow length of Celstran PA66-GF40-02

200900

400

500

mm

Injection pressure

Flow

leng

th

1,100 1,300 bar700

300

Celstran PA66-GF40

Celstran PA66-GF50

Fig. 6.10 · Flow lengths of Celstran PA66-GF40 and PA66-GF50

37

800300

1,000 1,600

400

500

600

mm

800

Injection pressure

Flow

leng

th

700

1,200 1,400 bar

Celstran PP-GF30-04

PP-GV30short fibres, easy flowing

Celstran PP-GV30-03


Fig. 6.9 · Flow lengths of Celstran PP-GF30 compared with PP with 30% by weight

short glass fibres

100.75

1.00

1.25

1.50

2.00

Fibre content

Ani

sotro

py

1.75

%15 20 30 40 30

long glass fibres

short glass fibres

Fig. 6.12 · Component anisotropy, determined from the ratio of the flexural modulus measured in

flow direction and transversely to it

6


Celstran® Compel®

6.2.6 Special methods

The usual special methods can be used for injectionmoulding Celstran. For example, the gas injectionmethod has proved successful for a gear lever, fig. 6.14.

Decorative effects can be achieved with two-colourinjection moulding. When multicomponent injectionmoulding is used, for example for producing combi-nations of hard and soft materials, the compatibilityand bond strength between matrix material and softcomponent must be borne in mind. Practical experi-ence has shown that Celstran PP can also be pro-cessed without any problems by foam injectionmoulding, fig. 6.15.

Virgin and recycled polyolefines are often processedinto complex large components by special methodssuch as transfer moulding, low-pressure injectionmoulding or intrusion. In such applications the effect of Celstran or Compel is to improve properties; anaddition of as little as 10 to 40% by weight givesthese components the required rigidity and strength.In addition, the stable parts are easier to demould,and so shorter cycle times are possible.

6.2.5 Gate and mould design

As with the injection unit, care must be taken toensure minimal shortening of the reinforcing fibres indesigning moulds. For this reason the diameters andradii of curvature of runners in flow direction and thecross-sections of gates must be dimensioned as largeas possible.

For Celstran PP and Celstran PA a central sprue gatehaving a diameter of at least 4 mm, better 6 mm, withall runners designed to promote smooth even flowhas proved successful. The diameter of the gateshould if possible be greater than 3 mm. Smallercross-sections (down to 1 mm diameter) can be cho-sen for blends with Celstran SF (stainless steel fibres).Pinpoint and film gates can be used with good resultsprovided they have adequately large cross-sections.

Hot runner technology for sprueless processing ofCelstran can readily be used provided open hot run-ner nozzles are used. If the recommendations forplasticizing and mould design are observed, a mould-ing is obtained with a fibre length distribution inwhich a high proportion of fibres are above the criti-cal length [7] (see section 1.3), i.e. with optimum reinforcing effect, fig. 6.13.

1Fibre length

Wei

ght c

onte

nt

5 10mm

Critical fibrelengthrange

3 mm0.8

Moulding

0

Fig. 6.13 · Indication of fibre length distribution of Celstran components: correctly produced moulding, critical fibre length range

drawn diagrammatically [7]

38

Celstran® Compel®


39

Fig. 6.14 · Gear lever made from Celstran PP-GF40 by gas injection moulding (manu-

facturer: Möller Plast GmbH, Bielefeld, Germany)

Fig. 6.15 · Pallet for the “Stecon”, returnable collapsible container made by foam injection moulding of Celstran PP-GF40, side walls and

cover compression moulded with Compel PP-GF30

6.3 Blow moulding of Celstran

Fundamental tests carried out by a machine manu-facturer have shown that long-glass-fibre-reinforcedplastics can be blow-moulded if a conventional blowmoulding machine is equipped with a special screwwith a gentle action for melting the pellets [8].

The long-glass-fibre-reinforced materials used for blow moulding normally have fibre contents bet-ween 5 and 30% [8]. To achieve these low contents acorresponding amount of Celstran with a higher fibre content is added to the unreinforced matrixmaterial by means of a metering unit.

6.3.1 Materials

The most important matrix material in blow mould-ing is PE-HD. For low fibre contents the blowmoulding grade normally employed for the unrein-forced blow-moulded part is used. Celstran PE-HD-GF60-01P10 is added to this material.

For higher fibre contents a PE-HD with a lower vis-cosity, i.e. with higher MFI, must be employed foruniform, gentle incorporation of the long-fibre mate-rial. In this case it is particularly important to ensurehomogeneous distribution in the melt of the fibrescontained in the added Celstran. This can be achievedby adapting the extruder temperatures. The long glassfibres give the melt the elasticity necessary for blowmoulding. With PP as matrix material blow-mouldedparts are obtained that withstand higher service tem-peratures.

As with PE-HD, Celstran PP-GF50 is added to a PPwith low melt viscosity via a metering and mixingunit so as to achieve the desired content of long glassfibres in the moulding.

Blow-moulded PP parts with long glass fibres aresuitable for applications in the engine compartmentof vehicles. Since they do not exhibit environmental stress cracking, they can also be used for mouldings in contact with fuel, lubricants or cooling water.

Because of their good strength even at elevated tem-peratures they are suitable for service temperatures up to 130°C under low load.

In the case of both PE-HD and PP the achievableblow-up ratio is lower with reinforced plastics thanwith standard blow moulding materials [8].

6


Celstran® Compel®

40

Coextrusion enables mouldings with an unreinforcedinner and outer layer to be produced by blow mould-ing. As a result the surface quality can be influencedwithin wide limits. Materials with a high glass fibrecontent can also be processed by this method [8].

6.3.2 Machine requirements

Celstran can be processed on commercial blowmoulding machines with single-screw extruders. Inselecting machine and screw care must be taken toensure that

- the material is melted gently so as to minimize fibredamage and

- the fibres remain uniformly distributed in the melt.

The screw must not have any shear elements, in particular no Maddock shear elements. Barrier-typescrews are also unsuitable because they cause con-siderable fibre breakage. Other mixing elementsshould also be avoided if possible. If it is necessary to use them, they should have an adequately largefree cross-section for the melt flow.

The screw diameter must be matched to the requiredthroughput; it should be at least 40 mm. In principlelarge screw diameters, low compression and lowspeeds should be employed so as to minimize shearenergy. The feed zone of the screw should be deep-flighted.

The compression ratio must not exceed 2:1.

The energy required for melting the pellets should ifpossible be provided solely via the barrel heating.Shear must be avoided. The extruder must not haveany screens or strainer plates because these can beblocked by the fibres.

6.3.3 Parison die

Celstran can be processed with continuous parisondies and with accumulator heads. The glass fibres give the parison increased rigidity in longitudinal and transverse direction. As a result the parison stretches less severely than in the case of unreinforcedPE-HD or PP.

The long glass fibres give the melt high rigidity. The diameter of the extruded parison should be aslarge as possible so as to minimize the blow-up ratio.The long glass fibres reduce parison swell markedly.

Fibre orientation in the component is influenced by the design of the flow channels in the parison die.The fibres are aligned in flow direction by means ofspider legs. This results in weld lines, which shouldbe located in component areas subject to low stress.Narrow flow channels also cause strong fibre orienta-tion in longitudinal direction. Layers with differentlyoriented fibres often form in the parison. In melt layers flowing near the wall the fibres are oriented inlongitudinal direction, whereas in the middle layerthey are oriented in circumferential direction.

6.3.4 Temperatures

The processing temperatures are governed by the plasticizing and homogenizing characteristics of themachine. Normally the material can readily be pro-cessed with a temperature profile similar to that forunreinforced PE-HD. Should poorly dispersed fibrebundles still be visible in the melt, the temperaturesmust be raised. In so doing, temperatures up to 50 Kabove those for unreinforced PE-HD are possible forthe rear extruder zones.

In the case of PP to which Celstran PP has beenadded it is advisable to use the temperature profilecommonly employed for unreinforced PP. The temperatures should be 240°C at the heating zone,230 and 220°C at the following zones and 210°C atthe extruder tip.

Celstran® Compel®


Fig. 6.16 · Drawing of a plasticizing/compressionmoulding machine, consisting of screw plasticizing

unit, vertical press and positive mould, for processing Compel [10]

Fig. 6.17 · Processing conditions for the plasticizing/compression moulding of Compel PP

6.4 Extrusion of Celstran

Extruded sheets and profiles can be obtained fromEnsinger GmbH, Nufringen, Germany. Coextrudedprofiles with a Celstran core and unreinforced innerand outer layers are supplied under the trade nameVHME (very high modulus extrudate) by IntekWeatherseal Product Inc., Hastings, Minnesota, USA.

6.5 Processing of Compel

6.5.1 Plasticizing/compression moulding

Because of its typical fibre length of 25 mm Compel is processed mainly by a gentle combination ofplasticizing and compression moulding [9]. A suitablemachine is shown in fig. 6.16 [10].

Procedure

Plasticizing/compression moulding comprises the following steps [10]:

1. The pellets are conveyed to the hopper and fed tothe plasticizing unit.

2. A deep-flighted screw plasticizes the materialgently. The screw then retracts and places the pre-pared melt in the enclosed space in front of it.

3. The plasticizing unit enters the opened mould.

4. The closure device at the plasticizing unit opens,the screw pushes the melt out and places it in theform of a strand in the mould.

5. The closure device at the plasticizing unit cuts offthe melt strand and the unit retracts from themould.

6. The press closes and the melt is distributed underfairly low pressure (typically 30 to 50 bar) andunder low shear stress in the cavity between thetop and bottom of the mould.

7. At the end of the cooling time the press opens.Parallel to this the plasticizing unit has preparedfresh melt.

8. The finished moulding is demoulded automaticallyor manually. With the placement of melt in themould the production cycle for the next mouldingbegins.

41

Melt temperature200 to 280°C, depending on the moulding

Mould temperatureup to 80°C

Closing speedas high as possible to prevent premature cooling

Compression speed≥ 5 mm/s, depending on the moulding

Specific cavity pressuredepending on the moulding

Cooling timenormally 15 s for 2 mm wall thickness,depending on the moulding

6


Celstran® Compel®

Machine and mould technology

The gentle plasticizing of Compel requires special plasticizing units with a screw diameter of at least 80 mm. Reductions in cross-section caused e.g. by inserts, nozzles or deflectors should be avoided.

The processing conditions for Compel PP are sum-marized in fig. 6.17. The rod-shaped pellets should be melted without compression. The back pressureshould be as low as possible. Cylinder temperaturesof 220 to 280°C can be used, depending on themoulded part geometry. The mould temperaturesshould be between 50 and 80°C.

The mould for shaping the parts must be designed as a positive mould, as in conventional compressionmoulding. The same design guidelines apply to ribs,drafts etc. as for Celstran. Components of complexgeometry, for example mountings and fascia panel supports for cars, can be made from Compel withoutany problems.

A vertical hydraulic press, if possible with synchro-nization control, is required to hold the mould and produce the locking force. Because of the relatively low cavity pressure locking forces of 8,000 to 30,000 kN are sufficient even for large mouldings.

Recycling

After compression moulding of Compel, waste frompunching operations is produced when openings arecut out in mouldings. This waste can amount to asmuch as 30% of the component weight. It can berecycled immediately in plasticizing/compressionmoulding provided it is granulated correctly: the finescontent in the granulated material must be low. Ourown investigations show that up to 30% waste frompunching operations can be added to a component,depending on the stress to which it will subsequentlybe subjected.

This and other facts of importance for recycling long-fibre-reinforced plastics are investigated in the project“Material recycling of long- and continuous-fibre-reinforced thermoplastics into high-quality, long-fibre-reinforced flow-moulded components” by the“Deutsche Bundesstiftung Umwelt”, Osnabrück,Germany. This project is a cooperative venture in-volving, among others, the “Institut für Aufbereitung(IFA)”, Aachen, the “Institut für VerbundwerkstoffeGmbH (IVW)”, Kaiserslautern, and the “Institut fürKraftfahrwesen Aachen (ika)”.

Further information on the processing of Compel isobtainable from Ticona.

6.5.2 Other methods

Apart from plasticizing/compression moulding, injection stamping is also suitable for processingCompel. Here too, gentle melting of the pellets by an adequately dimensioned screw (diameter at least80 mm) without a non-return valve and with lowback pressure must be ensured.

When the melt is injected into the still partly openedpositive mould, a low injection speed is essential forprotecting the fibres from damage.

6.6 Safety notes

Long-fibre-reinforced plastics, like many organicsubstances, are flammable (exceptions: Celstran PPSis not flammable, the Celstran PA6-CF30 andCelstran PC/ABS-GF40 grades are flame-retardantand reach UL 94 rating V-0).

It is in the interest of the processor when storing,processing or fabricating the material to take thenecessary fire prevention measures. Certain end products and fields of application may be subject to special fire prevention requirements.

The statutory safety regulations vary from one country to another. In each case the local regulationsare mandatory. It is the responsibility of the pro-cessor to ascertain and observe such requirements.Important information is given in safety data sheets,which are available from Ticona on request.

Due to danger of thermooxidative degradation notprocessed plastificates must always be cooled downcompletely in a water basin.

42

Celstran® Compel®


7. Finishing

7.1 Machining

The two most important methods of processing plas-tics, namely injection moulding and blow moulding,produce moulded parts that normally do not requireany finishing if the moulds are correctly designed.

Compression-moulded parts may require deflashingbecause material is unavoidably squeezed out of themould. In many cases the flash is removed with cut-ting tools.

Generally speaking, the high reinforcing fibre con-tent must be taken into account in milling, drilling orturning Celstran, Compel or Fiberod parts. In prin-ciple, tools with hard metal or diamond cutters arerecommended in order to achieve high-quality surfa-ces and long service life.

7.2 Assembly

7.2.1 Welding

Of the assembly techniques for plastic mouldings thevarious welding methods have achieved outstandingimportance.

Mouldings made from long-fibre-reinforced plasticscan be welded to each other or to parts made fromunreinforced or short-fibre-reinforced plastics. Thetype and quantity of reinforcing fibres must howeverbe taken into account in designing the weld area andin selecting the welding parameters.

In the case of glass-fibre-reinforced Celstran PP,regardless of the fibre content, heated tool weldingyields the highest values for weld strength. Themajor variables are given in fig. 7.1. The weldstrength achieved with Celstran PP is

- values between 25 and 40 MPa in heated tool buttwelding with the parameters given in fig. 7.2

- a tensile shear strength of about 15 MPa in heated tool lap welding under the conditions givenin fig. 7.3.

These values show that the weld strength is determi-ned basically by the matrix material.

43

Fig. 7.1 · Major variables on heated tool welding

Fig. 7.2 · Heated tool butt welding of Celstran PP

Material

· Density (type of fillerand content)

· Shear modulus (if possiblehigh and constant overtemperatureprofile)

· Viscosity(too low canlead to thematrix beingsqueezed outof the weldingzone)

Weldingparameter

· Surface temperature ofthe heated tool

· Heating pressure

· Heating time

· Welding pressure

· Welding time

Moulding

· Moulding rigidity

· Radius design(to avoid stress cracking> 5 mm)

· Weld geometry

Injectiongeometry

· Surface defects (voids)

· Dimensionalvariations(shrinkage,warpage)

· Processingdefects(demixing,decomposition)

· Internal stresses

· Moulding contamination(e.g. releaseagents)

F F

4

Weld strength: 25 to 40 MPa(depending on the glass fibre content, welding parameters,

moulding geometry, injection moulding)

orfor PTFE-coated

heated tool

Temperature of the heated tool: 260°C

Heating time: 10 to 20 s

Heating pressure: 0.5 to 0.6 MPa

Welding pressure: 0.5 to 0.6 MPa

for uncoatedheated tool


Heating time: 5 to 10 s

Heating pressure: 0.4 to 0.5 MPa

Welding pressure:0.4 to 0.5 MPa

Process variables

Recommended welding parameters

6

7


Celstran® Compel®

Vibration welding also gives good values for weldstrength. Values up to 25 MPa are achieved withCelstran PP under the conditions given in fig. 7.4.The weld strength is largely independent of the wel-ding depth, fig. 7.5.

In line with the higher strength of the matrix materialthe weld strength of Celstran PA rises to 45 to 55 MPa, fig. 7.6. Ultrasonic spot welding can be usedinstead of riveting. The characteristic welding para-meters and the achievable tensile shear forces areshown in fig. 7.7.

44

Fig. 7.3 · Heated tool lap welding of Celstran PP

FF4

415

Tensile shear strength: 15 MPa(depending on the glass fibre content, welding parameters,

moulding geometry, injection moulding)

for PTFE-coated heated tool


Heating time: about 20 s

Welding pressure: about 0.3 MPa

Fig. 7.4 · Vibration welding of Celstran PP

Linear movement

100

4

Weld strength achieved with

Celstran PP-GF40-04: about 21 MPaCelstran PP-GF50-04: about 17 MPa

00

0.5 4

10

20

30

Welding depth

Wel

d str

engt

h

mm

MPa

32.521.51

Celstran PP-GF40-04

Celstran PP-GF50-04

Fig. 7.5 · Weld strength as a function of welding depth of Celstran PP

0 0.5 3Welding depth

Wel

d str

engt

h

mm

MPa

21.510

20

40

60

Celstran PA66-GF50

Fig. 7.6 · Weld strength as a function of welding depth of Celstran PA


for Celstran PP, modification 04

Welding pressure: 1 MPa

Welding time: 5 s

Welding depth: about 2.0 mm


Celstran® Compel®

7.2.2 Adhesive bonding

In adhesive bonding of components made fromCelstran or Compel the matrix material is of crucialimportance. For instance, pretreatment of CelstranPP is necessary to lower the surface tension (coronadischarge, flame application) so as to obtain bondedjoints with adequate strength.

Bonded joints are simpler to produce with CelstranPA. Two-pack adhesives based on polyurethane andone-pack adhesives based on cyanoacrylate give goodresults.


45

Fig. 7.7 · Ultrasonic spot welding of Celstran PP


1.5 s

3 s

1.5

s

s

Sonotrode diameter: 4 mm

Amplitude: 0.05 mm

Ultrasonic exposure time: 1.2 s

Welding pressure: 0.25 MPa

Holding time: 3 s

Number of Tensile shear force in N wherewelding points s = 3 mm s = 4 mm

1 2800 3400

2 4500 5200

3 6200 8200

7


Celstran® Compel®

46

8. Recycling

Recycling of Celstran production waste (sprues, re-jects) is described in section 6.2.2 “Processing con-ditions”.

After use Celstran mouldings can be recycled. Themost important requirement is to segregate Celstranfrom other polymers. Celstran PP recyclate can beblended with other PP recyclates. An addition ofCelstran PP recyclate to unreinforced PP generallyimproves the latter’s properties because of the glassfibre reinforcement. The same applies to Celstran PA66 and PA66 recyclates. Further shortening of thefibres is likely in recycling, and so mouldings madefrom pure Celstran recyclates have poorer values thanvirgin Celstran material especially in impact strength.

Celstran® Compel®


47

Assembled Frontend for AUDI, Compel PP-GF40

Battery Tray for Opel Astra, Celstran PP-GF40

9. Photo supplement showingtypical applications

8

9


Celstran® Compel®

48

Lever for Electrical Cabinet,Celstran PA66-GF50

Housing Part for Seat Belt Mechanism,Celstran PA66-GF40

Celstran® Compel®


49

Mirror Bracket and Housing made fromCelstran PP-GF50 and Hostalen PPU

DEU Housing for Board Communicationin Airplanes, Celstran PPS-SF20

9


Celstran® Compel®

50

Tilt Tray Mechanism, Celstran PP-GF40 (company: WPK, Radevormwald)

Celstran® Compel®


10. Subject Index

abrasion, relative 27acoustic properties 29adhesive bonding 45anisotropy (shrinkage) 36

back pressure 35, 36blow-up ratio 39blow moulding 39, 40bonding 45burning-off (resin matrix) 6

chemical resistance 32coefficient of thermal expansion 27coloration 9colour masterbatches 9content of reinforcing material 10 – 19, 22continuous service temperatures 30, 39creep modulus 23 – 25creep properties 23, 25creep tendency 5, 23, 30

density 10 – 19, 21dielectric strength 28drilling 43drying 33 – 35

electrical insulation 28electrical properties 28electromagnetic shielding 28elongation at break 10 – 19, 31, 32enthalpy 27, 28environmental effects 30 – 32extrusion (Celstran) 41

fatigue strength 26fibre length 5, 6fibre skeleton 6, 20film gate 38finishing 43flammability 31flexural fatigue strength 26flexural modulus 10 – 19, 20, 22, 25, 31flexural strength 10 – 19, 31, 32flow path length 36flow properties 36fluctuating stress 26foam injection moulding 38form supplied 9fracture energy in puncture test 10 – 19, 25, 26

51

gas injection method 38gate design 38GMT compression moulding 6

heat ageing 30, 31heat deflection temperature 10 – 19, 30heated tool welding 43, 44hot runner technology 38hybrid reinforcement 9

impact strength 6, 10 – 19, 25, 32in-house coloration 9injection moulding 33 – 38injection moulding machines, equipment for 34injection pressure 36injection speed 35intrusion 38

literature 53long-fibre pellet 4, 6low-pressure injection moulding 38

material data 10 – 19matrix, thermoplastic 4mechanical properties 10 – 19, 21 – 27melt temperature (injection moulding) 34 – 37metering screw 33milling 43mould design (injection moulding) 38mould temperature (injection moulding) 34 – 36

nomenclature 8non-return valve 33notched impact strength 5, 10 – 19, 20, 25, 36

optical properties 28outer fibre strain 8 – 17overview of grades 5

parison die 40puncture test 10 – 19, 25, 26pinpoint gate 38plasticizing (Celstran) 34plasticizing/compression moulding 6, 41, 42preparation (processing) 33processing 33 – 42processing conditions (Celstran) 34 – 36

9

10


Celstran® Compel®

processing conditions (Compel) 41, 42processing temperatures (Celstran) 35processing temperatures (Compel) 42properties, acoustic 28,

electrical 28mechanical 10 – 19, 21 – 27optical 29physical 20 – 29thermal 27, 28

pultrusion process 4

quality management 5

recycling (Celstran) 46recycling (Compel) 43regrind, addition 36

safety data sheets 42safety notes 42screws (blow moulding) 40screws (injection moulding) 33screw speed (injection moulding) 34 – 36shear modulus 30short-fibre pellet 4short-term stress 21, 22shrinkage 36, 38shut-off nozzles 38sliding properties 26sound deadening 29special methods (injection moulding) 38specific strength 20specific heat 27spiral test 36sprue gate 38strand sheating 4stress-strain curves 23, 30stress-strain diagrams 22surface properties 26

temperatures (blow moulding) 40temperatures (injection moulding) 34 – 36tensile modulus 10 – 19, 20, 22tensile strength 10 – 19, 20, 22, 36thermal conductivity 28thermal properties 27, 28thermoplastic matrix 4toughness 25, 26, 30transfer moulding (Celstran) 38transfer moulding (Compel) 42turning 43two-colour injection moulding 38

UL rating 31ultrasonic welding 43, 44

vibration welding 43, 44volume price 21

warpage tendency 36water absorption 10 – 19wear 26, 27wear resistance 33welding 43, 44weld strength 43, 44

52

Celstran® Compel®


11. Literature

[1] Lücke, A.: Thermoplaste mit Rückgrat.Kunststoffe 87 (1997) 3, p. 279 – 283

[2] Lücke, A.: Eigenschaften und Anwendungenvon langfaserverstärkten Thermoplasten. In: Zepf, H.-P. et al.: Faserverbundwerkstoffemit thermoplastischer Matrix. Reihe Kontakt & Studium, vol. 529, Expert-Verlag, Eßlingen 1997

[3] Lücke, A.: Long Fiber ReinforcedThermoplastics in Cars. In: Handbuch zur 18th SAMPE EuropeInternational Conference, Paris 1997

[4] Pfeiffer, B.: Konstruktionswerkstoffe mitEdelstahlfasern gefüllt. In: Handbuch zum 7. SymposiumElektrisch leitende Kunststoffe, TechnischeAkademie Eßlingen 1997

[5] Pfeiffer, B.: EMI-Shielding mit Edelstahl-filamenten.Plastverarbeiter (1997)

[6] Dr. Edward M. Silverman: “Creep and ImpactResistance of Reinforced Thermoplastic:Long Fibers vs. Short Fibers”SPI/RPC 1985

[7] Wolf, H. J.: Personal communication from theDKI, Darmstadt

[8] Thielen, M.: Starke Hohlkörper. Kunststoffe 84(1994) 10, p. 1406 – 1412

[9] Thomas, G.: Entwicklung kostengünstiger,serientauglicher Plastifizier- und Preßver-fahren zur Herstellung von Strukturbauteilenaus anwendungsspezifisch entwickelten,unidirektional langfaserverstärktenThermoplast-Granulaten.Abschlußbericht der Hoechst AG zumBMFT-Projekt 03 M 1055, Frankfurt 1996

[10] Plastifizier-/Preßanlage – Verarbeitung thermoplastischer Kunststoffe im Strang-ablegeverfahren.Firmenschrift der Kannegießer KMHKunststofftechnik GmbH, Minden 1997

53

10

11


Celstran® Compel®

Important: Properties of molded parts can be influ-enced by a wide variety of factors involving materialselection, further additives, part design, processingconditions and environmental exposure. It is the obligation of the customer to determine whether aparticular material and part design is suitable for aparticular application. The customer is responsiblefor evaluating the performance of all parts containingplastics prior to their commercialization. Our pro-ducts are not intended for use in medical or dentalimplants. Unless provided otherwise, values shown

54

merely serve as an orientation; such values alone donot represent a sufficient basis for any part design.Our processing and other instructions must be fol-lowed. We do not hereby promise or guarantee spe-cific properties of our products. Any existing indu-strial property rights must be observed.

© Copyright by Ticona GmbH

Published in December 2000

Cel

stra

n® C

om

pel

® L

ong-

fibre

-rei

nfor

ced

ther

mop

last

ics (

LFT

)

B 34

1 E

BR-1

2.20

00

Ticona GmbHCustomer Service EuropeD-65926 Frankfurt am MainTel.: +49 (0) 69-3 05-8 47 32Fax: +49 (0) 69-3 05-8 47 35

Hostaform® POM

Celcon® POM

Duracon® POM

Celanex® PBT

Impet® PET

Vandar® Thermoplastic polyester blends

Riteflex® TPE-E

Vectra® LCP

Fortron® PPS

Topas® COC

Celstran® LFT

Compel® LFT

GUR® PE-UHMW

Ticona90 Morris AvenueSummit, NJ 07901USA

Technical InformationTel.: +1-8 00-6 33-48 22

Customer ServiceTel.: +1-8 00-6 33-48 22

Documents

Celstran - Hi Polymers brochure... · 1.2 Quality Management Celstran is a unit of Ticona, ... model of the European Quality Award (EQA) of the European Foundation of Quality Management