40135619 M.Sc. report

MSc. Polymer Engineering

Project Report

SESSION 2014-2015

TITLE

Developing Polymer composite manhole cover using waste and recycled materials

Author Supervisor

Amit Kumar Rana Dr. Mike Barker

40135619

1

ACKNOWLEDGEMENTS

The writing of this dissertation has been one of the most significant academic

challenges I have ever had to face. Without the support, patience and guidance of

the following people, this study would not have been completed. It is to them that I

owe my deepest gratitude.

Foremost, I would like to express my sincere gratitude to my supervisor Dr. Mike

Barker for the continuous support of my M.Sc. project, for his patience, motivation,

enthusiasm, and immense knowledge. His guidance helped me in all the time of

research and writing of this dissertation. I could not have imagined having a better

supervisor and mentor for my M.Sc. project.

Besides my supervisor, I would like to thank the rest of my project members: Lynn

Chalmers, Professor Nick Christofi for their encouragement and insightful comments.

2

ABSTRACT

This work cover studies on manufacturing of manhole covers using recycled

polymeric waste materials such as glass fibre and rubber particles along with

thermoset epoxy resin used as matrix material. Surface treated rubber particles were

used which was done by using vinyltrimethoxysilane coupling agent. The mixture of

epoxy resin along with rubber particles and glass fibre was poured into moulds to

obtain mechanical test specimens. After curing of epoxy resin mechanical tests such

as tensile test, charpy impact test and 3-point bend test were performed and results

were analysed. Throughout the study, changes in mechanical properties were

observed on increasing the weight percentage of rubber particles and powdered

glass fibre. At starting, neat epoxy was not completely brittle and to find out that DSC

was also performed with no significant result; but upon adding recycled glass fibre

powder the sample cracked in a very brittle manner and also the tensile modulus

along with other tensile properties was drastically decreased. Therefore, particles of

recycled rubber was added to improve some ductility of prepared sample and the

results were impressive; tensile strength, impact toughness, and fracture toughness

all were increased to the approximate level of neat epoxy test values. With 10% 16

mesh size rubber particles and 30% powdered glass fibre, which was then kept in

compression moulding machine gave the best results among all the other

formulations. Similarly, with increasing the rubber content by 20% and lowering the

glass fibre content from 30% to 25% good results were obtained.

3

LIST OF SYMBOLS AND ABBREVIATIONS

GF glass fibre

CM compression moulding

HF heating off

HO heating on

R rubber

PMMA poly(methylmethacrylate)

PET poly(ethleneterephthalate)

t.s. Tensile strength

min. Minimum

PP Polypropylene

GRP Glass reinforced polymer

4

Table of Contents

1. INTRODUCTION.........................................................................................................................6

2. LITERATURE REVIEW.............................................................................................................8

2.1 Recycled rubber particles in concrete..............................................................................8

2.2 Recycled rubber particles in polymers.............................................................................9

2.3 Recycled glass fibre in polymers.....................................................................................10

3. EXPERIMENTAL......................................................................................................................11

3.1 Materials.................................................................................................................................11

3.2 Processing.............................................................................................................................12

3.3 Characterisation...................................................................................................................14

4. RESULTS..................................................................................................................................16

4.1 Tensile test.......................................................................................................................16

4.2 Charpy impact test.........................................................................................................18

4.3 3-point bend test.............................................................................................................19

5. DISCUSSION............................................................................................................................20

6. CONCLUSION..........................................................................................................................26

7. RECOMMENDATIONS............................................................................................................26

8. REFERENCES..........................................................................................................................27

9. BIBLIOGRAPHY.......................................................................................................................28

5

1. INTRODUCTION

Iron is used in most of the application due to its low price and abundant

availability in nature. Cast iron provides high durability and a strong product capable

to bear high load and severe impacts. But there is problem on using cast iron in open

environment, it get easily corroded, and also to maintain those high mechanical

properties product always becomes too heavy which causes problems to the

workers, as metal is a good electrical conductor it can be electrocuted which can

cause death in extreme conditions and also due to high resale value of cast iron it is

very attractive to thefts. To tackle these problems polymer composites can be used

instead of cast iron as these composites has either very low or zero scrap value.

Epoxy is one of the available thermoset polymer which can be used in place of cast

iron to prepare street furniture’s such as manhole covers, lamp posts, benches etc.

where it could last long in harsh environments very easily. As like cast iron there is a

problem with epoxies as well, that they are very brittle in nature; but this can be

substantially overcome by using recycled rubber particles which reduces the

brittleness of epoxy resin.

There are some studies that already have been carried out successfully with

positive results showing improvements in mechanical performances. In one study it

is mentioned that using homogenous and treated fine rubber particles improves

mechanical performance than using coarse and untreated rubber particles; and an

optimum concentration should be determined for the desired modifications because

using more than 25% volume treated rubber particles decreases the mechanical

performance of epoxy.

6

The main objective of this research is to find the possibilities of blending three

(epoxy, recycled rubber particles and powdered glass fibre) non-compatible

materials into a homogenous mixture while investigating the potential filler, and

developing the formulation so that it could exhibit the required properties which

needed to prepare manhole covers specifically. According to British standard BS EN

124-1994 manhole tops are divided into the following classes:

Group 1 (min. class A 15) – areas which can be used by pedestrians and

pedal cyclists.

Group 2 (min. class B 125) – footways, pedestrian areas and comparable

areas, car parks or car parking decks.

Group 3 (min. class C 250) – for manhole tops installed in the area of

kerbside channels of roads which when measured from the kerb edge, extend

a maximum of 0.5 m into the carriageway and a maximum of 0.2 m into the

footway.

Group 4 (min. class D 400) – carriageways of roads (including pedestrian

streets), hard shoulders and parking areas, for all types of road vehicles.

Group 5 (min. class E 600) – areas imposing high wheel loads, e.g. docks,

aircraft pavements.

Group 6 (class F 900) – areas imposing particularly high wheels loads, e.g.

aircraft pavements. (STANDARD, 1994)

7

2. LITERATURE REVIEW

2.1 Recycled rubber particles in concrete

Several researchers have worked on the recycling and reclamation methodologies of

waste rubber products to make them reusable for engineering applications. One

study has focussed on the use of shredded or ground rubber, without

devulcanization, in secondary products. Significant amount of work have been done

on the mixing of recycled rubber particles inside concrete, bitumen and asphalt to

make products appropriate for structural applications. The brittle nature of concrete

and its low loading toughness has initiated the use of rubber particles to remedy

these drawbacks. Several studies discussed the properties and performances of

concrete mixed with high volume of crumb rubber from scrap tires. All of them

demonstrated promising mechanical properties and enhanced performance by the

use of crumb rubberized concrete. Another common trend investigated by all of the

researchers was considerable deformation undergone by concrete before failure and

its capability to withstand post-failure loads. All of these studies reveal a dependence

of properties on the rubber particle size along with an increase in failure temperature.

The biggest common advantage depicted by all of these studies had been the ease

of fabricating crumb rubberized products for structural applications. In spite of all

these advantages, some drawbacks were also seen. Fattuhi et al. analysed the

properties of cement-based materials containing shredded scrap truck tire rubber

and got reduced compressive properties and densities of cement by the use of

rubber. Fenner et al. discussed the environmental and structural implications for the

reuse of tires in fluvial and marine construction. They showed that leaching of

different chemical compounds like zinc, cadmium and carbon black results in the

8

degradation of rubber tires and limits their use for marine applications, especially in

sea water and proposed one corrective measure for the same. In addition,

researchers found increased water permeability in the concrete mixtures by the

addition of rubber particles. (BHADRA, 2010)

2.2 Recycled rubber particles in polymers

Rubber particles have been found to be usable in polymeric matrix as well.

Elastic rubber particles are expected to absorb large impact energy through plastic

deformation of the particles. Rubber particles would also promote crack pinning and

crack bridging. These mechanism should lead to higher toughness in rubber

reinforced polymers. Researchers have observed that the processing method,

rubber particle size, and size distribution are important parameters in affecting

rubber–matrix adhesion and material properties. (BHADRA, 2010)

Using the resin transfer method, Structural Science Composite (SSC) said its

composite design produced covers which were “typically three to four times lighter

than an equivalent steel or reinforced concrete cover, yet still provides the long term

performance and mechanical properties required for this type of application”. The

group said this included very high load bearing capabilities to meet BS EN124:1994

Standards Group 4 Class D400, which specifies an access cover must be able to

cope with static loading from cars, vans, lorries and HGVs if installed on roads, hard

shoulders, factory sites or industrial estates. To pass BS EN124 Class D400 an

access cover or grating must withstand a 40 tonne test load. (staff, 2015)

9

2.3 Recycled glass fibre in polymers

Recycling of fibre reinforced polymers is an important area of research for

manufacturers to invest in. There are two types of FRP matrices: thermosetting and

thermoplastic. Thermoplastic resin matrixes are held together by weak Van-der-Waal

bonds which break when heated and “reconnect” when cooled. This section mainly

focuses on the recycling of FRP with a thermosetting matrix which presents a

problem when recycling because it cannot be melted and reformed. Thermosets

require a chemical reaction know as curing to convert liquid resin into a solid polymer

component. Curing involves a cross-linking process which occurs at a particular

temperature when a hardener initiates the cross-linking process. Cross-linking is the

reason thermosets cannot be melted and re-solidified to form new components.

Thermosetting resins are used as matrixes instead of thermoplastic resin matrixes

because the cross-linking process of the resin means that solid structures produced

are often stronger than any thermoplastic. They are also much better suited to higher

temperature applications because they do not soften or creep significantly when

heated. Thermosetting FRP are often specialist and require properties from the

thermoset that thermoplastics cannot match. Effective recycling of thermosetting

FRP is important so thermosetting composites can be continually used without a

huge impact on the environment. There are four main recycling techniques for

thermosetting FRP; size reduction, thermal degradation, chemical degradation and

energy recovery. Information on these four different recycling processes can be seen

in appendix 1. (Wait, 2010)

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3. EXPERIMENTAL

3.1 Materials

The epoxy resin used, was in liquid form provided by Gurit named SP106

(bisphenol-A-(epichlorhydrin) epoxy resin). The hardener used was slow hardener

also provided by Gurit, and no accelerator was used to decrease the curing time.

Rubber particles of different sizes were provided by Recyclatech Group Limited of

different mesh sizes (2mesh, 6mesh, 8mesh, 12mesh, 16mesh) which was derived

from truck tyre buffing’s. For surface treatment of these recycled rubber particles

vinyltrimethoxysilane was used to enhance bonding in between rubber and epoxy

resin. Recycled Glass fibre which was used provided by Filon in powder form, having

a fibre lengths ranging from 18mm (shredded) to 1700 microns (M10) to 375 microns

(M40). Table 1 has the composition of different ingredients which were present in the

powdered recycled glass fibre.

Table 1. Composition of Filon GRP Filler

Product Name %

Glass Fibre ≥30

Aluminium Trihydrate ≥5

Polyester Resin ≥60

Polyester Film ≥0.2

Nylon ≥0.05

11

3.2 Processing

Casting is a manufacturing process by which a liquid material is usually

poured into a mould, which contains a hollow cavity of the desired shape, and then

allowed to solidify. The solidified part is also known as a casting, which is ejected or

broken out of the mould to complete the process. Casting materials are usually

metals or various cold setting materials that cure after mixing two or more

components together; examples are epoxy, concrete, plaster and clay. Casting is

most often used for making complex shapes that would be otherwise difficult or

uneconomical to make by other methods. (DeGarmo, 2003)

The mixing ratio of the epoxy and hardener was kept constant for all

experiments as 100:18 by weight respectively. To prepare neat epoxy sample, epoxy

and hardener was mixed in a plastic container made up off PP with the help of a pop

sickle stick and then the mixture was poured into a mould made up of metal. But

before that a PET film was placed onto the metal surface and Macwax named

releasing agent was sprayed onto that PET film and left for 2 minutes untouched, so

that the prepared sample would not stick to film and comes off easily from mould.

The whole system was hold together by the help of paper clips so that the mixture

does not flow outside from the mould. Then, another sample was prepared by using

8 mesh size recycled rubber particles along with epoxy to enhance the mechanical

properties of cured epoxy resin. This time mixing was done using an electric stirrer

having a propeller kind of attachment and mixing was followed by 2 minutes then the

mixture was poured into the metal mould. Similarly, another sample was casted but

this time instead of 8 mesh rubber 16 mesh size recycled rubber particles and

recycled powdered glass fibre were incorporated along with epoxy resin then this

mixture was poured into two different mould one was made up of metal and another

12

http://en.wikipedia.org/wiki/Clay

http://en.wikipedia.org/wiki/Plaster

http://en.wikipedia.org/wiki/Concrete

http://en.wikipedia.org/wiki/Epoxy

http://en.wikipedia.org/wiki/Curing_(chemistry)

http://en.wikipedia.org/wiki/Mold_(manufacturing)

http://en.wikipedia.org/wiki/Manufacturing

was made up of PMMA. The details of all different formulations with varying

components is discussed below in table 2. This whole processing was carried out at

room temperature (17-19oC). But at this very low temperature some problems came

into view which are discussed further in details in discussion section of report.

Therefore, to tackle these problems some changes were done at processing stage.

Firstly, the sample was placed onto the hot surface of oven hoping that it will

increase the temperature of the mould and problem could be overcome; but with no

luck, problem still persisted. Hence, for second time the sample was kept into

vacuum oven while the heating was off. But still no appropriate results were obtained

and for the third but not the last time sample was kept into vacuum oven with heating

maintained around 40oC. As these changes in processing conditions did not provided

desirable samples. Then at last, keeping the sample into the compression moulding

was decided under some pressure and temperature. Therefore, an another metal

plate was prepared having another PET film pasted onto the surface of metal and

each time Macwax named releasing agent was sprayed onto the whole mould

assembly so that no problems would have to face to release the prepared sample

from the mould. As the mixture was poured into the moulds another metal plate was

kept onto that and by keeping both casting samples upon each other, the whole

assembly was kept into the compression moulding machine; where the samples

were under high pressure (15KN) and normal temperature ranging from 33oC to

40oC.

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3.3 Characterisation

In this study, tension, impact and fracture toughness tests were performed in

order to determine the mechanical properties of rubber and glass fibre modified

epoxy resin. For tensile test, specimen with gauge length (55mm), width (3.58mm-

5.25mm) and thickness of 10.1mm were used. For charpy impact test, 2mm

notched bars were used having breadth (3.88mm-4.64mm) and width (8.08mm-

9.10mm). For 3-point bend test long bar like samples having breadth (3.58mm-

5.23mm) and width (9.48mm-10.92mm) were used. To perform these tests Zwick

Roell machines were used having load cells of 30KN and 50KN for tensile and 3-

point bend tests respectively; and for charpy impact test 5J hammer was used to

calculate the impact resistance of 2mm notched samples.

In order to obtain these samples, different formulations were used by varying mainly

the rubber and glass fibre loading percentage and all these formulations were

followed by a mixing time of at least 2 min and maximum of 5 min according to mix-

ability of rubber and glass fibre into epoxy resin and those different formulations are

mentioned below in table 2.

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Table 2. Description of the Formulations used

Epoxy

Resin

(g)

Slow

Hardener

(g)

Rubber

(g)

Vinyltrimethoxy-

-silane

(g)

Glass

fibre

(g)

Formulation 1 45.8 10 3 (8 mesh) 1.2 0

Formulation 2 45.9 10.1 0 0 14

Formulation 3 53.4 11.7 3.5 (16 mesh) 1.4 0


Formulation 5 50.5 11.1 3.5 (16 mesh) 1.4 3.5



Formulation 8 33.3 7.3 7 (16 mesh) 1.4 21


Formulation 10 30.4 6.7 14 (16 mesh) 1.4 17.5


15

4. RESULTS

4.1 Tensile test

Tensile properties of recycled rubber and glass fibre modified epoxy are

presented in Table 3 as tensile modulus, tensile yield, tensile strength, elongation at

t.s., stress at break and strain at break. This SP106 epoxy has ductile nature,

because during tensile testing it gave yield point which was a strange behaviour, as

epoxies are generally brittle in nature and does not give yield points. Similarly,

strange behaviour can be seen with increasing powdered recycled glass fibre

concentration and keeping rubber content constant at 5 percent. These all differently

behaving properties are further discussed in details in discussion section of report.

Materialcomposites

Tensile modulus

MPa

Tensile Yield

MPa

Tensile strength

MPa

Elongation at T.S. %

Stress at break MPa

Strain at break %

Width

mm

Thickness

mm

Area

mm2

Epoxy 711 52.5 52.5 9.9 40.8 11.8 3.58 10.1 36.16Epoxy+5%R 296 21.2 21.2 8.9 15.1 11.0 3.91 10.1 39.44Epoxy+5%R+5%GF

499 25.5 5.9 24.9 5.9 4.538 10.1 45.83

Epoxy+5%R+10%GF

383 19.7 4.8 19.6 4.8 4.018 10.1 40.58

Epoxy+5%R+20%GF

273 13.9 13.9 7.8 11.8 13.1 4.1 10.1 41.41

Epoxy+5%R+30%GF+hf

303 13.1 4.5 12.8 4.5 5.25 10.1 53.03

Epoxy+5%R+30%GF+ho

468 13.5 3.1 13.2 3.1 4.293 10.1 43.35

Epoxy+10%R+30%GF+CM

625 21.3 3.8 21.2 3.8 4.07 10.1 41.11

Epoxy+15%R+30%GF+CM

546 17.3 3.9 17.2 3.9 4.13 10.1 41.71

Epoxy+20%R+25%GF+

393 15.6 4.4 15.2 4.4 4.045 10.1 40.85

16

CMEpoxy+15%R

242 13.4 13.4 7.0 12.2 7.6 4.073 10.1 41.14

Table 3. Tensile test results

4.2 Charpy impact test

Charpy impact test results are presented in Table 4 as impact resistance values.

On considering the obtained results, it is shown clearly that upon adding rubber

particles into epoxy resin during processing increases the impact resistance of epoxy

resin. Whereas, addition of powdered glass fibre decreases impact resistance.

Table 4. Charpy impact test results

Material composite bmm

hmm

I.R.KJ/m2

Epoxy 4.15 8.13 6.97Epoxy+5%R 4.59 8.20 3.03

Epoxy+5%R+5%GF 4.64 9.10 1.53

Epoxy+5%R+10%GF 4.24 8.95 1.73

Epoxy+5%R+30%GF+hf 4.56 8.14 1.8

Epoxy+5%R+30%GF+ho 4.31 8.78 1.55

17

Epoxy+10%R+30%GF+CM 3.91 8.44 5.18

Epoxy+15%R+30%GF+CM 3.88 8.08 50.45

Epoxy+20%R+25%GF+CM 4.1 8.16 217.83

Epoxy+15%R 4.55 8.11 241.57

4.3 3-point bend test

The results for 3-point bend test are presented in table 5 and these results are

much similar to impact test results. On addition of more recycled rubber particles the

sample became more flexible and upon adding powdered recycled glass fibre the

sample becomes stiffer and gave very low force bearing values.

Table 5. 3-point bend test results

Material

compostites

Fmax

N

dL at

Fmax

mm

Fbreak

N

dL at

break

mm

a0

mm

b0

mm

S0

mm

flexural

stress

KN/mm2

maximum

strain

Epoxy 153 6.97 124.45 10.09 4.17 9.48 39.57 12.80821 0.09679

Epoxy+5%R 110.56 6.03 109.63 6.4 4.58 9.77 44.21 10.9796 0.086298

Epoxy+5%R+5%G

F

108 8 106 8.3 4.85 11.25 54.56 7.819779 0.131836

Epoxy+5%R+10%

GF

49.2 10.5 47.7 11.9 3.58 10.82 38.73 11.45259 0.166421

18

Epoxy+5%R+30%

GF+hf

66.3 5 63.7 5.1 5.23 10.52 55.08 8.292931 0.077051

Epoxy+5%R+30%

GF+ho

43.6 4 42.2 4.1 4.29 10.53 45.18 10.09084 0.061699

Epoxy+10%R+30

%GF+CM

62.23 3.13 61.78 3.18 4 9.94 39.77 12.14531 0.045575

Epoxy+15%R+30

%GF+CM

58.07 2.93 58.02 2.95 3.95 9.78 38.66 12.70476 0.041976

Epoxy+20%R+25

%GF+CM

66.67 3.43 65.02 3.48 4.08 10.92 44.25 9.865879 0.054867

Epoxy+15%R 86.03 6.16 17.28 12.79 4.8 10.93 52.47 8.370659 0.098626

5. DISCUSSION

There has been a lot of difficulties were faced during the processing of epoxy

resin. The main problem was with the air bubbles and to avoid them various

improvements in processing techniques were done such as keeping samples over

hot oven surface, into vacuum ovens and compression moulding machine. The air

bubbles persisted after all these amendments done during the processing, until the

sample was kept into compression moulding machine. As the sample was kept into

vacuum oven while the heating was off the surface of sample became very rough

and all the air bubbles were trapped onto upper surface generating stress

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concentrators all over of the sample; even when the heating was switched on air

bubbles remained in samples. As like the PET film was kept on lower surface during

casting; similarly another PET film was kept onto the upper surface. This time there

were no air bubbles in sample but all the rubber particle came onto the upper surface

and also keeping the PET film on upper surface was very difficult because air was

trapping in between and were creating big air bubbles instead of smaller ones.

Therefore, at last compression moulding machine was used at some elevated

temperature (40oC) than the room temperature. The curing time of epoxy was 4

hours because slow hardener was used instead of fast as slow hardener diminishes

the creep properties of epoxy, and also high temperature could not be used as well

because this would have decreased the viscosity and all the rubber particles might

be migrated to lower surface leaving very bad dispersion and distribution of the

particles. But high pressure was used so that obtained sample would have been very

compact, having high density. When 8 mesh size recycled rubber particles were

used the dispersion and distribution of the rubber particles was not very good and

also did not possess any significant improvement in mechanical properties of

modified epoxy resin. Therefore, in all formulations smaller particles i.e. 16 mesh

size recycled rubber crumbs were used. The critical point for mixing of rubber

particles and glass fibre with epoxy resin while making a composite was 15% and

30% respectively. If there is any need to increase the rubber loading percentage

then the glass fibre loading percentage will decrease for obtaining appropriate

dispersion and distribution of the particles into the mixture. Otherwise, there will be a

problem in mixing all three components into each other and then spreading the

prepared mixture into mould for casting.

20

On comparing the tensile modulus values of virgin epoxy with modified epoxy

there is a drastic decrease in that as epoxy is brittle material and upon adding rubber

into that it becomes less brittle hence the stiffness of epoxy decreases.

Chart 1. Tensile modulus

But other properties were changing in a positive aspect such as impact toughness,

flexural stress and flexural strain.

Similarly, on comparing tensile strength results there is decrement in strength on

increasing the glass fibre content because it makes the product more brittle.

Ep o x y

Ep o x y +5 %R

Ep o x y +5 %R +5 %

G F

Ep o x y +5 %R +1 0 %

G F

Ep o x y +5 %R +2 0 %

G F

Ep o x y +5 %R +3 0 %

G F+h f

Ep o x y +5 %R +3 0 %

G F+h o

Ep o x y +1 0 %R +3 0 %

G F +C M

Ep o x y +1 5 %R +3 0 %

G F +C M

Ep o x y +2 0 %R +2 5 %

G F +C M

Ep o x y +1 5 %R

52.5

21.2 25

.5

19.7

13.9

13.1

13.5 21

.3

17.3

15.6

13.4

tensile test resulttensile strength

Chart 2. Tensile strength

Hence more vulnerable to failure. As the rubber content in the composite reaches a

level of 10% from 5% tensile strength was increased by approximately 8MPa, but

21

upon adding more rubber than this does not make any significance improvement in

tensile strength.

As like other tensile properties stress at break is also related with the loading

percentage of recycled glass fibre and recycled rubber particles.

Ep o x y

Ep o x y +5 %R

Ep o x y +5 %R +5 %

G F

Ep o x y +5 %R +1 0 %

G F

Ep o x y +5 %R +2 0 %

G F

Ep o x y +5 %R +3 0 %

G F+h f

Ep o x y +5 %R +3 0 %

G F+h o

Ep o x y +1 0 %R +3 0 %

G F +C M

Ep o x y +1 5 %R +3 0 %

G F +C M

Ep o x y +2 0 %R +2 5 %

G F +C M

Ep o x y +1 5 %R

40.8

15.1

24.9

19.6

11.8

12.8

13.2

21.2

17.2

15.2

12.2

tensile test resultstress at break

Chart 3. Stress at break

At breaking point maximum bearable stress of 40.8 MPa was given by neat

epoxy resin which was not achieved by any another composite. However, more than

50% stress bearing capability was achieved by 15% rubber & 30% glass fibre and

5% of each rubber & glass fibre contained composites. Whereas, other samples

were able to withstand only 11-15 MPa of stress.

22

Maximum impact resistance were obtained with 15 percent rubber content into

epoxy resin which is quiet acceptable as rubber particles toughen the epoxy by crack

deflection and crack bridging methods of toughening mechanism in composites.

Ep o x y

Ep o x y +5 %R

Ep o x y +5 %R +5 %

G F

Ep o x y +5 %R +1 0 %

G F

Ep o x y +5 %R +3 0 %

G F+h f

Ep o x y +5 %R +3 0 %

G F+h o

Ep o x y +1 0 %R +3 0 %

G F +C M

Ep o x y +1 5 %R +3 0 %

G F +C M

Ep o x y +2 0 %R +2 5 %

G F +C M

Ep o x y +1 5 %R

6.97

3.03

1.53

1.73

1.8

1.55

5.18

50.4

5

217.

83

241.

57

Impact ResistanceImpact Resistance

Chart 4. Impact resistance

But with 20% rubber and 25% glass fibre content results were very good too, by

providing approximately same impact toughness value as with only 15% rubber

content. This happened because of the glass fibre concentration as it was making

the specimen more susceptible to impact failure.

23

Maximum force bearing strength was shown by neat epoxy on comparing all the 3-

point bend test results. There had been a drastic decrease in force bearing ability of

epoxy in all other composites. During testing the composites having 20% and 15%

rubber were cracked but did not split apart showing some positive significance of

added rubber particles. If the deflection at maximum force is also considered then

there is no hierarchy is present in results. But as like tensile test having 10% rubber

and 30% glass fibre gave pretty good result for flexural stress much more close to

neat epoxy values.

Ep o x y

Ep o x y +5 %R

Ep o x y +5 %R +5 %

G F

Ep o x y +5 %R +1 0 %

G F

Ep o x y +5 %R +3 0 %

G F+h f

Ep o x y +5 %R +3 0 %

G F+h o

Ep o x y +1 0 %R +3 0 %

G F +C M

Ep o x y +1 5 %R +3 0 %

G F +C M

Ep o x y +2 0 %R +2 5 %

G F +C M

Ep o x y +1 5 %R

153

110.

56

108

49.2 66

.3

43.6 62

.23

58.0

7

66.6

7 86.0

3

3-point bend test resultFmax

Chart 5. Fmax

24

6. CONCLUSION

After tension, impact resistance and flexural tests studies of modified epoxy with

treated rubber particles and glass fibre, the following conclusions can be drawn:

a) For improved mechanical behaviour the size of rubber particles is very

important; because large size particles do not disperse and distribute very

well as small size particles do.

b) Increasing glass fibre content increases the brittleness of epoxy matrix

causing drastically decreases in mechanical properties but there is a need to

incorporate glass fibre into the epoxy because presence of rubber particles

makes epoxy matrix very flexible having low tensile properties. Therefore, a

considerable amount of both rubber and glass fibre need to add to obtain

desired properties.

7. RECOMMENDATIONS

The further recommendations for this work is to observe the different cracked

sample surfaces under optical microscope so that dispersion of glass fibre

particles, rubber particles and type of cracks can be observed. There is a need to

take the work upon next level by preparing a prototype for which the work has

been carried out to investigate the proper ratio of all materials. The formulation

having 10% rubber and 30% glass fibre content would be a great choice for

further work and also there will be a need to study the mechanical properties of

the prepared prototype in real life scenarios.

25

8. REFERENCES

B.J.P. Jansen, K. T. H. M. P. L., 1999. Preparation of thermoset rubbery epoxy particles as novel toughening modifiers for glassy epoxy resins. Polymer, Volume 40, pp. 5601-5607.

BHADRA, A., 2010. MICROSTRUCTURE–MECHANICAL PROPERTY RELATIONSHIP OF CRUMB RUBBER–POLYURETHANE FOAM COMPOSITES, Oklahoma: s.n.

Cengiz Celikbilek, G. A. C. K., 2004. Modification of Epoxy by a Liquid Elastomer and Solid Rubber Particles. PoIymer BuIIetin, Volume 51, pp. 429-435.

Cevdet Kaynak, C. C. G. A., 2003. Use of silane coupling agents to improve epoxy–rubber interface. European Polymer Journal, Volume 39, pp. 1125-1132.

E. Paul DeGarmo, J. T. B. R. A. K., 2003. MATERIALS AND PROCESS IN MANUFACTURING. 9th ed. s.l.:John Wiley & Sons, Inc.

E. Sipahi-Saglam, C. K. G. A. M. Y. N. A., 2001. Studies on Epoxy Modified With Recycled Rubber. Polymer Engineering And Science , Volume 41, pp. 514-521.

F.G. Smith l, E. D. A. T., 1995. Testing and evaluating commercial applications of new surface-treated rubber technology utilizing waste tires. resources, conservation and recycling, Volume 15, pp. 133-144.

R. BAGHERI, M. A. W. R. A. P., 1997. Use of Surface Modified Recycled Rubber Particles for Toughening of Epoxy Polymers. POLYMER ENGINEERING AND SCIENCE, Volume 37, pp. 245-251.

Song Aiteng, Y. Y., 1990. CTBN-toughened epoxy resins effect of curing mechanism on network structure of the rubber phase. Chinese Journal of Polymer Science, Volume 8, pp. 183-187.

staff, P., 2015. Composites do a good cover-up job. [Online] Available at: http://www.prw.com/subscriber/headlines2.html?id=6281[Accessed 25 04 2015].

STANDARD, B., 1994. Gully tops and manhole tops for vehicular and pedestrian areas - Design requirements, type testing, marking, quality control. Brussels: CEN.

Wait, C. F., 2010. The Reuse and Recycling of Glass Fibre Waste, Birmingham: s.n.

26

9. BIBLIOGRAPHY

B.J.P. Jansen, K. T. H. M. P. L., 1999. Preparation of thermoset rubbery epoxy particles as novel toughening modifiers for glassy epoxy resins. Polymer, Volume 40, pp. 5601-5607.

BHADRA, A., 2010. MICROSTRUCTURE–MECHANICAL PROPERTY RELATIONSHIP OF CRUMB RUBBER–POLYURETHANE FOAM COMPOSITES, Oklahoma: s.n.

Cengiz Celikbilek, G. A. C. K., 2004. Modification of Epoxy by a Liquid Elastomer and Solid Rubber Particles. PoIymer BuIIetin, Volume 51, pp. 429-435.

Cevdet Kaynak, C. C. G. A., 2003. Use of silane coupling agents to improve epoxy–rubber interface. European Polymer Journal, Volume 39, pp. 1125-1132.

E. Paul DeGarmo, J. T. B. R. A. K., 2003. MATERIALS AND PROCESS IN MANUFACTURING. 9th ed. s.l.:John Wiley & Sons, Inc.

E. Sipahi-Saglam, C. K. G. A. M. Y. N. A., 2001. Studies on Epoxy Modified With Recycled Rubber. Polymer Engineering And Science , Volume 41, pp. 514-521.

F.G. Smith l, E. D. A. T., 1995. Testing and evaluating commercial applications of new surface-treated rubber technology utilizing waste tires. resources, conservation and recycling, Volume 15, pp. 133-144.

R. BAGHERI, M. A. W. R. A. P., 1997. Use of Surface Modified Recycled Rubber Particles for Toughening of Epoxy Polymers. POLYMER ENGINEERING AND SCIENCE, Volume 37, pp. 245-251.

Song Aiteng, Y. Y., 1990. CTBN-toughened epoxy resins effect of curing mechanism on network structure of the rubber phase. Chinese Journal of Polymer Science, Volume 8, pp. 183-187.

staff, P., 2015. Composites do a good cover-up job. [Online] Available at: http://www.prw.com/subscriber/headlines2.html?id=6281[Accessed 25 04 2015].

STANDARD, B., 1994. Gully tops and manhole tops for vehicular and pedestrian areas - Design requirements, type testing, marking, quality control. Brussels: CEN.

Wait, C. F., 2010. The Reuse and Recycling of Glass Fibre Waste, Birmingham: s.n.

27

Appendix-1

There is high demand to recycle thermoset materials and mainly there are four main

techniques to recycle thermosetting FRP; chemical degradation, thermal degradation

size reduction and energy recovery.

Chemical degradation – chemical degradation involves the use of chemical

solvents at different temperature which when added to FRP composite cause the

thermosetting matrix to degrade and breakdown so fibres can be recovered.

Chemical recycling requires the use of a chemical solvent to break strong cross-

linking bonds in thermosetting resin. In some cases the organic compound produced

from dissolution of the polymer can be a used for the formulation of new resins.

Dang et al. found bisphenol-F epoxy resin cured with 1, 8-p-menthanediamine would

completely decompose in a nitric acid solution. They used the products obtained

from the chemical decomposition and repolymerized them with an epoxy resin and

curing agent to prepare a recycled resin. Liu et al. used a nitric acid solution at 90 °C

to decompose a bisphenol-A epoxy resin matrix with curing agent IPDA and recover

carbon fibres. Under optimum conditions, epoxy resin was found to decompose

rapidly and it was reported that the fibre appeared unharmed and retained most of

the strength. A urethane-based matrix of scrap end-of-life vehicles with reinforcing

carbon fibres was found to completely degrade using a triethylene glycol/water

solution at temperatures ~240°C and carbon fibres could be recovered. However,

the same treatment was not successful in decomposing an epoxy-based substrate.

Another work completed by Jiang et al. investigated using supercritical n-propanol to

breakdown C-O-C and C-N-C bonds of epoxy resin and obtain long-recycled carbon

fibres maintaining the advantages of continuous structure resulting in high strength.

Supercritical n-propanol was used in a semi-continuous flow reactor with a pressure

28

of 5.2 MPa at 310 °C. Recycled carbon fibre cleaned in an ultrasonic bath of

acetone, followed by a fresh acetone rinse. Resulting carbon fibres had similar

tensile strength and Modulus to as-received carbon fibres with the main difference in

reduction of interfacial bonding strength when recycled fibres were added to epoxy

resin to produce a new composite.

A major disadvantage of using this process is different chemicals and solutions

required to degrade different types of polymer matrix due to different chemical bonds

they can break. Also recovered fibres require washing to remove residual chemicals

and solvents from the surface. There is a large amount of chemical waste produced

during this process making it less environmental friendly. However, this technique

does enable recovery of fibres in continuous form therefore composites produced

using these fibres could potentially achieve higher strengths due to continuous fibres

reducing crack propagation through a composite component. (Wait, 2010)

Thermal degradation - Thermal degradation of FRP matrix is achieved by pyrolysis.

Pyrolysis is the removal of thermosetting resin by thermally degrading the matrix

component of the composite. Pyrolysis involves heating a composite sample to a

moderate temperature in an oxygen-free environment until the volatile organic part

(polymer matrix) decomposes into gases and oils and the inorganic part remains

unchanged (fibres, fillers and char). These can then be recycled back into new

polymeric products with little changes made to the acquired components. Oil and gas

are separated via cooling where they can be collected and fibres are trapped in a

mesh and extracted for use. Oil produced could be added to petroleum or used

directly as a fuel it is also an important source of chemicals which can be used in

other applications. Cunliffe & Williams found oil produced could be used as a viable

fuel when blended with suitable oils to increase the flash point to meet UK and US

29

health and safety legislation. Gas produced could be burnt to power the pyrolysis

system because emissions generated from the combustion of the gas lack toxicity

and hazards that are associated with normal incineration emissions. Recovered

fibres are often covered in char and can require further heating to remove any solid

residue left on the fibres. Fillers such as calcium carbonate can be used again as

fillers in other composites. A study by Torres et al. showed the optimum temperature

for pyrolysis is between 400 ˚C and 500 ˚C. At temperatures above this there was

degradation of the CaCO3 filler and deterioration in properties obtained from fibres

recovered. Temperatures below 400 ˚C resulted in only partial decomposition of the

thermosetting matrix and fibres could not be removed. Torres et al. found the sample

only had to be held at final pyrolysis temperature for 30 minutes. After this time no

more pyrolysis products were produced. Average recovery achieved during the

pyrolysis process is approximately 98% therefore is an efficient recycling technique

especially if gas produced is used to power the process, this would reduce recycling

cost for the manufacturer. Kennerley et al. found that using a fluidized bed pyrolysis

process (hot bed of sand to heat up composite) at 450 °C minimizes the degradation

of recovered glass fibres. However at this temperature the polymer did not

completely combust, so a secondary higher temperature heating process is required.

After processing, around 60% weight of fibres recovered was the filler. But washing

of fibres demonstrated little contamination or filler remained on fibres indicating that

this process effectively removes the polymer and leaves the fibres “clean”. (Wait,

2010)

30

Size reduction - Size reduction is a process by which a composite component

(uncured prepregs) undergoes a series of cutting and milling processes into a

recyclate which can be of different sizes. This can then be reused as a filler with

virgin constitutes in a new FRP component. The disadvantages are the fibres

become damaged and are reduced in size so lose their continuous structure. Astrom

found during grinding fibre length is shortened and there is a decrease in the

molecular weight of the resin. They also found a reduction in the interfacial bonding

between fibre and resin. Pannkoke et al. ground uncured prepreg tapes and fabric

waste and manufactured composites by pressing, autoclave pressing or scale cut

recyclates (two layered laminates). They found tensile modulus of the ground

material was nearly independent of manufacturing process and was three times that

of just epoxy resin. Superior stiffness was found in the scale cut material to the mill

cut materials used for the pressing. This demonstrates that modulus depends on the

scale size. Broken fibres in the components produced form recycled fibres might

make them unsuitable for structural applications due to broken fibres acting as

notches which increase crack initiation at lower loads thus failure could occur at

lower tensile strength than predicted if using the rule of mixtures. However, bending

strength of the ground recyclate composite was better than tensile strength and

suggested that it might be useful for use in sandwich structures. (Wait, 2010)

31

Incineration with energy recovery - Incineration with energy recovery and

composting should only be considered if all alternatives are deemed inappropriate

because toxic fumes generated contribute to global warming and damaging the

environment. Given that polymers are made from oil, it would make since that they

produce a good fuel sources when burnt. FRPs have a high calorific value therefore

incineration with energy recovery is a viable option. Incinerator operators will usually

charge more for FRP waste because of the high calorific content and toxic emissions

given off during incineration. Electricity can be produced from energy recovery but

this is not the primary concern of the incinerators. (Wait, 2010)

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