Preparation and Characterization of Cellulose Dopes in NMMO€¦ · dissolved polymers above two shear stress steps (1) t = 0 t 0 between t 0 and t 2 and (2) t 0 t = 0 between t 2

Preparation and

Characterization of

Cellulose Dopes in NMMO

Frank Meister, Birgit Kosan

Thuringian Institute for Textile and Plastics Research,

Breitscheidstraße 97, 07407 Rudolstadt, Germany

[email protected]

1

TITK, F. Meister 15.04.2015 2

Thuringia

Germany

Rudolstadt

Where TITK is localised ?

District Saalfeld-

Rudolstadt

http://de.wikipedia.org/w/index.php?title=Datei:Locator_map_SLF_in_Germany.svg&filetimestamp=20090315115024

http://de.wikipedia.org/w/index.php?title=Datei:Wappen_Rudolstadt.svg&filetimestamp=20100906144636


1954 Prof. Dr. Böhringer constitutes the Institute for Textile Technology of man-made Fibres

(ITC) in fact and law independent from the man-made fibre mill Schwarza 1970 ITC looses its independence and becomes a part of the central textile research of the

man-made fibre mill (R&D activities on all fields of Textile Research; up to 480 employees

at the end of 1980’s) 1991 re-foundation of the TITK as a first private, non-profit R&D institute of Thuringia strong

linked to business interests of SME (55 employees) 1992 formation of the OMPG as a 100 % subsidiary of the TITK 1997 TITK/OMPG transferred together with Zimmer Corp. results of self-contained Lyocell

technology (ALCERU process) into pilot plant scale 300 t/y of textile staple fibres and 10

t/y textile filaments

2002 Competence centre for Polysaccharide Research Jena–Rudolstadt is founded.

2005 TITK becomes an “Associate Institute” at the Technical University of Ilmenau;

2006 1,000 t/a pilot plant for textile Lyocell staple fibres manufacturing is launched at Shanghai

by Chinese Partner and TITK

2009 TITK became a member European Centre of Excellence for Polysaccharide Research

(EPNOE), TITK is awarded with Thuringian R&D Price for Transfer of Lyocell fibres

2011 installation of centre of excellence for direct dissolution and dry-jet-wet technologies

named Hugo-Richard-Küttner Centre

2014 Smartpolymer Ltd. is launched as 100 % subsidiary of OMPG

A brief history

15.04.2015 4

- since 1991 the TITK has taken its textile expertise to become a

modern institute for materials research,

- whereby TITK's R&D activities are primarily focussed on studies

with natural and synthetic polymers.

The Research Departments:

The fields of expertise:

• Synthesis of polymers and functional additives

• Characterisation, forming and functionalisation of polysaccharides, particularly

cellulose and proteins

• Technical textiles

• Fibre-reinforced composites

• Polymer nano composites

• Polymer electronics,

• Polymer photovoltaic,

• Roll to roll coating,

• Materials modified by photo-chromic, thermo-chromic, electro-chromic and

solvato-chromic additives

• Native Polymers and Chemical Research

• Textile and Materials Research

• Plastics Research

• Functional Polymers Systems

http://www.titk.de/4/research/native-polymers-and-chemical-research/native-polymers-and-chemistry.html









http://www.titk.de/4/research/textile-and-material-research/textil.html







http://www.titk.de/4/research/plastics-research/plastic.html



http://www.titk.de/4/research/functional-polymers/funktionspolymersysteme.html





OMPG East Thuringian Material Testing

Company for Textiles and Plastics

(100 % subsidiary of TITK)

Employees: 31

analytical services (chemical, physical)

polymer and material testing

exclusive R&D orders

product commercialisation and technology

transfer

TITK Group

TITK Thuringian Institute for Textile and

Plastics Research

Employees: 125

Members: about 90

Research and development projects

on polymer materials, processing and

technologies (50 R&D projects each

year)

smartpolymer GmbH

(100 % subsidiary of OMPG)

Employees: 30

product commercialisation and technology transfer


Cell SolutionTM protection

Smartpolymer GmbH

Cell SolutionTM skin care

Cell SolutionTM hygienic

Cell SolutionTM ceramic

Cell SolutionTM bioactive

Cell SolutionTM filaments

Cell SolutionTM clima


Outline

1. Pulp characterisation and impact of pulp impurities

1.1. General view

1.2. Effects of pulp impurities

2. Dope characterisation

2.1. Dope inhomogeneities

2.2. Rheological measurements of dope characteristics

3. Fibres spinning

4. Conclusions


Fibres and spinning procedures

Fibres are materials, what: - possess a huge length to thickness ratio

- molecules are preferentially oriented into MD

animal, like silks, wools or hairs

mineral, like asbestos

vegetable, like cotton or bast fibres

natural

Fibres

man-made

modified natural synthetics,

like PP, PA, PET, PAN, PVC, PU

inorganic, like carbon, glass, metal,

basalt organic, like cellulose CV, CLY, CUP, CA, CAB, CC


Varieties of fibres spinning processes

spinnability - is the capability to form mechanical stable liquid filaments

cooling, consolidating,

drafting, crimping

Solution spinning

polymer pellets

molten mass

melt spinning

Melt spinning

fibres, filaments

polymer powder

spinning dope

dry spinning wet spinning dry-wet spinning

cooling, consolidating

drafting, coagulating

drafting, crimping

washing, crimping

fibres, filaments

solvent h0 = 80 - 20,000 Pa s

200 - 2,000 mm hole diameter,

50 - 6,000 m/min take-up speed

10 – 60,000 spinning holes 40 - 250 mm

hole diameter,

80 - 120 m/min

take-up speed,

2,000 up to

200,000

spinning holes

h0 = 20 - 20,000 Pas


Dissolving Pulp

(enzymatically activated)

N-methylmorpholine-

N-oxide solution

Pre-dope

preparation

Dissolving

Spinning

After-treatment

washing, bleaching,

finishing, drying

Shaped bodies,

like fibres, filaments, MB-non-woven, films

Textile

processing

Textile use

Biodegradation

© holz.bayern.de

recycled solvent

and process water

What is the Lyocell Process cycle ?


Analytical methods for pulp characterisation at TITK

Determination of ash content, Fe, Cu, Mn, Cr, Ni, Na, K, Mg and Ca

= important for process safety in the case of NMMO and the

contamination of spinning bathes because of solvent recovery

Determination of Cuoxam-DP by capillary viscometry

= average degree of polymerisation for estimation of usable

cellulose concentration for dissolution tests, evaluation of cellulose degradation at dissolution and shaping processes

Molecular weight distribution (MWD) by size exclusion

chromatography (SEC)

= MWD of the pulp influences the solution properties, the spinning behaviour and attainable fibre properties

Content of carbonyl and carboxyl groups

= influenced by pulp cooking processes and MWD of the pulp

a-cellulose content

= important for solution properties and attainable fibre properties

http://www.malvern.com/labger/products/viscotek/viscotek_dsv/viscotek_dsv.htm

http://www.malvern.de/images/content/520x320/viscotek-tda-max.jpg

http://en.wikipedia.org/wiki/File:GPC_instrument.jpg


Main solvent degradation effects in the system cellulose /

N-methylmorpholine-N-oxide (NMMO)

References: Lukanoff, B., Philip, B., Schleicher, H.: Acta Polymerica 35, (1984), 339-343

Taeger, E., Franz, H., Mertel, H.: Formeln, Fasern, Fertigware 4, (1985), 14-22

Buijtenhuijs, F.A., Abbas, M., Witteveen, A.J.; Papier 12, (1986), 615-619

Rosenau, T., Potthast, A., Sixta, H., Kosma, P. Prog. Polym. Sci. 26, (2001), 1763-1837

Hydrogen bond system

between cellulose and NMMO

O

OH

OH

HOCell-O

O-Cell

ON

O

O

OH

OH

HOCell-O

O-Cell

temperature

and

pressure

O

OH

OH

HO

OH

O

OH NO

O

Cell-O

+

NO

OHOCell-

HO

OH

OH

Thermal degradation

Oxidation of cellulose, deoxygenation of NMMO

Radical reaction

Polonovski type reaction

NO

OAA

NO

O-Acyl

NOB

CH2 + O-Acyl H-B+

OH-

NO CH2OH

NO H

+ HCHO

AA = acylating agent

B = Base

NO

O

Fe(II)+ +.

Fe(III)NO2 H+

- H2O

O

NO HNO H2O+

_

+NO 1/3 1/3 1/32/3 + + CO2

NMMO

labile oxidant

Cellulose end groups

sugar acids

radicals

Impurities especially iron

or copper ions

Properties of

additives

pH value,

proton

donating

groups like

carboxyl, or

amino,

pore size,

particle size ,

porosity

O

OO

O

OO

RO

HO

OH

OR

OR

OH

OH

HO

O

N

CH3

O

HO

H

O HO

H

H

OH

OH

OH

HORO

O

H

OH

ON

CH3

O


Dope preparation tests in laboratory scale 3

by preparation of about 250 g cellulose solution it will be possible to test most suitable dissolution conditions, to characterise solution properties and to realise a first laboratory spinning test

modified laboratory kneading system, Haake Rheocord 900


Protocol for cellulose dope characterisation 4

Refractive index: determination of water contents in solvents and in cellulose dopes with known cellulose content, important for the completion of the water removing in the case of NMMO monohydrate

Solids content: precipitation, washing, drying and weighing of the cellulose from a definite dope sample

DP and MWD: determination of the cellulose DP in cuoxam solution and molecular weight distribution of precipitated cellulose from dopes or fibres

Microscopy: monitoring of fibre residuals in cellulose dopes by polarising microscope

Particle analysis: particle content in dopes, particle size distribution between 0.5 and 175 μm by laser diffraction

Rheometry: zero shear viscosity, storage and lost moduli, master curves and mean relaxation time of cellulose dopes

Helos Particle Analyser

Haake Rheostress RS 100


Polarising microscopy 5

visualisation of discrete particles with diameters greater than 10 μm

(not perfect dissolved fibre residuals, pulp or solvent impurities)

incomplete dissolving state a few fibre residuals of 10 to

30 μm

dope without visible particles


Particle analysis by laser diffraction

detection of particle sizes between 0.5 and 175 μm; particle content is based

on basic calibration using spherical particles

verification of gel particles with minor differences in the refraction index by

means of Fraunhofer diffraction

measurements only possible at low particle contents

Helium-Neon laser working with wave length at 632 nm

temperature controlled measuring cell

0

20

40

60

80

100 Q

3(x

) / %

0

20

40

60

80

100

120

de

nsity q

3*(

x)

/ %

0.5 1 5 10 50 100 particle size / µm


Rheological evaluation of polymer solutions 7

1. Determination of zero shear viscosity h0 by means of creep and creep recovery

is one of the most important rheological parameter in polymer industry

it permits to give relative information for change of molecular weight

may be determined (a) by rotation test at controlled shear stress (90 Pa) or (b) frequency sweep (oscillation test) from h*, if angular velocity w 0

2. Characterisation of the viscoelastic flow behaviour and stress relaxation

oscillation tests (frequency sweeps between 0.046 and 14.7 Hz) at

different temperatures for calculation of master curves (storage and loss

moduli as well as the complex viscosity depending on frequency

respectively angular rate, referring to a reference temperature, i.e. 85 or

95 °C)

determination of the cross over between storage and loss modulus and

the plateau moduli (plateau value of the storage modulus)

calculation of the weighted relaxation spectra (relaxation time lm,

information on the molecular mass distribution of the polymers which

are involved in the solution state by rheological methods


Rheometric evaluation of polymer dopes is realised by 2 different

experimental approaches: 1. Creep (and creep recovery trial) - shear stress steps

determination of the linear viscoelastic behaviour of meltable or of dissolved polymers above two shear stress steps (1) t = 0 t0 between t0 and t2 and (2) t0 t = 0 between t2 and t4

calculation of zero shear viscosity h0 and molecular weight M (h0 M3.4); at begin of the trial a constant shear stress t0 is impressed until the end of reading

h0 = t0 / tan b = t0 / [g3 / (t2 – t1)] = t0 / g 0

t

t

t0

t2 t4 t0 t0 t1 t2 t3 t4 t

g

g3

g2

g1

ge

gv


2. Relaxation trial - deformation steps

- by dynamic-mechanical measurements (deformation steps) complex material characteristics like complex viscosity 𝜼∗(𝝎)

storage modulus G’(w) and

loss modulus G”(w)

are detected at exactly allowed shearing amplitudes (amplitude sweep) or frequencies (frequency sweep) and temperatures (commonly 85 °C)


Dope 1: 11.8 % cotton linters in NMMO Cuoxam-DP pulp: 584 DPL: 570 h0 (85°C): 8,211 Pas h0 could also be calculated

from the plateau value of the complex viscosity

cross over 2.9 rad/s // 4,255 Pa

plateau modulus 31,700 Pa

G’’

G’

h*

100

1,000

10,000

100,000

0,01 0,1 1 10 100 1,000

w [rad/s]

Sto

rage

/ L

oss

Mo

du

lus

[Pa]

10

100

1,000

10,000

Co

mp

lex

Vis

cosi

ty [

Pas

]

storage modulus loss modulus complex viscosity

WLF = Williams, Landel, Ferry


Dope 2:

12.1 % spruce pulp dissolved in NMMO

DP pulp: 615

DPL: 564

h0 (85°C): 12,760 Pas

Plateau Modulus

27200 Pa

Cross over

1.3 rad/s // 2390 Pa

G’

G’’

h*

Master curve of spruce pulp in NMMO

(reference temperature: 85°C)

100

1000

10000

100000

0,01 0,1 1 10 100 1000

w [rad/s]

Sto

rag

e / L

os

s M

od

ulu

s [

Pa

]

10

100

1000

10000

Co

mp

lex

Vis

co

sit

y [

Pa

s]

12.1 % SP - Storage modulus 12.1 % SP - Loss Modulus 12.1 % SP - Complex Viscosity


0

500

1000

1500

2000

2500

3000

0,001 0,01 0,1 1 10 100 1000

Relaxation time l [s]

H(l

) *

l [

Pa

s]

11.8% CL in NMMO

12.1% SP in NMMO

Shear stress relaxation relaxation is a specific material function and controls time-dependent deformation and

back-deformation of polymer fractions of defined molecular weight and molecule

structure

such specific functions aren’t directly detectable, but could be calculated by means

of linear viscoelastic (LVE) theory - generalised Maxwell model

relaxation = f(h*(w), G(t)) (1), because validity of Boltzmann super positioning principle

at LVE region t(t) = 𝝉𝒊 𝒕 = 𝜸𝟎 ⋅ 𝑮𝒊 𝒊 ⋅𝒊 exp (-t / li) (2)

t(t) = tmax , if t = 0, t(l) = 0.368 ⋅tmax , if t = l and t(t) = tmax 1/e = 0, if t = (3)

H(l)l ...

- represents the collectivity of similar

molecules of a polymer

- indicates the frequency of

occurrence of macro molecules

exhibiting a low or a high relaxation

time l


complex viscosity at cross over :h

wco Mw (as lower wco as higher Mw, if PDI (Uh) is more or less identic )

Gco‘ PDI (as lower Gco‘ as higher PDI (broader MWD), if DP=const.)

lm important value for spinning safety (viscoelastic dope behaviour)

(as higher lm as higher safety of use of a longer air gap)

h0 Mw (as higher h0 as higher Mw, h0 Mw3.4)

References (German language, only):

Schrempf, Ch.; Schild, G.; Rüf, H.: „Pulp-NMMO-Dopes and their Flow Behaviour“ Das Papier 12/1995, 748-757

Michels, Ch. et al.: About Determination of Molecular Mass Distribution in Cellulose from Rheometric Data,

Das Papier 1/1998, 3-8

Haake Mars II rheometer

Rheometric parameter and its structural relevance

Rheological dopes data: 11.8% CL (584)

in NMMO

12.1% SP (615)

in NMMO

zero shear viscosity (85°C) Pas 8,211 12,760

angular rate w at cross over rad/s 2.9 1.3

storage modulus G' at cross over Pa 4,255 2,390

plateau modulus Pa 31,700 27,200

rheological polydispersity Uh 3.0 3.7

relaxation time lm at H(l)m s 2.4 11.6

: rheological poly-

dispersity 𝑈𝜂 =

𝜂0

𝜂+# - 1,


Final examination: Laboratory spinning tests 13

dry-wet spinning tests for preparation staple fibres using available

laboratory spinning equipment

testing of suitable spinning parameters (temperature, air gap length,

take-up velocity, conditioned air gap clima, …)

detection of textile-physical values of the prepared fibres using

defined ambient atmosphere (fineness, elongation, tenacity, loop

tenacity, fibrillation behaviour, modulus)


Continuous dry-wet spinning testing plant at TITK

bobbin

winding-up

filament

dryer

filament

washing

dope

preparation

dry-jet-wet

spinning bar

fibre

staples

cutter

fibre after-

treatment

and fibre

finishing

fibres dryer

and

baling press


Conclusion - air-gap spinning of cellulose is among solution spinning and needs a lot

of additional knowledge toward polymer properties in dissolved state

- analytical protocol of pulp and dope characterisation is a very suitable instrument to guarantee save and optimal solvation and spinning procedures

- rheological properties of polymer solutions are influenced by: properties of the polymer (DP, MWD, a-cellulose content) chemical -physical behaviour of the solvent (NMMO, different ILs) polymer concentration dissolving state

- dope characteristics are important criteria for most secure air-gap spinning procedure adjustment of intended fibre properties (fineness, tenacity,

elongation, …)

- all the properties of pulp and cellulose dopes have always to be adapted for the shaping process, shaped product and intended application


Contact:

Thuringian Institute for Textile and Plastics Research

Chemical Research Department

Breitscheidstraße 97, 07407 Rudolstadt

Phone: +49(0)3672 37 92 00 Fax: +49(0)3672 37 93 79

E-mail: [email protected], [email protected] http://www.titk.de

Thank you very much for your kind attention !

Comments or any questions ?

Acknowledgement

Research activities presented

were financial supported by the

Federal Ministry of Economy

and Energy and the Thu-

ringian Ministry of Economy,

Labour and Development.

We also wish to express our

thanks to company partners for

cooperation and support and

textile research institutes

(STFI, HIT, TITV) for

processing and application

studies complementing the

TITK‘s R&D-activities.

mailto:[email protected]

mailto:[email protected]

http://www.bmwi.de/


Agenda 04/08/2015 at TITK

14.15 Arrival of participants at TITK, walk to IUK 14.20 – 14.50 Presentation „Preparation and Characterization of Cellulose Dopes in NMMO“, Dr. Meister 14.55 – 16.20 Activity centres for explanation and demonstration in following topics

1. Characterisation of cellulose dopes in NMMO Dr Meister 2. Dry-jet-wet (air-gap) sping of cellulose dopes at laboratory scale Mrs Dr Kosan 3. Demonstration electrospinning Mrs Dr Römhild

Three groups (about 10 persons) are guided by TITK staff. Group 1 begins at Station 1 and ends up at Station 3, Dr. Schaller Group 2 begins at Station 2 and ends up at Station 1, Dr. Schulze Group 3 begins at Station 3 and ends up at Station 2, Hr. Schmuck

about 16.20 every group immediately adjourns to the bus 16.25 Trip to the smartpolymer pilot plant at Prof.-Hermann-Klare-Straße 23 16.30 Round tour through the pilot plant, Dr. Meister 17.00 End of the course at TITK, return to Jena, Dr. Koschella

Documents

Preparation and Characterization of Cellulose Dopes in NMMO€¦ · dissolved polymers above two shear stress steps (1) t = 0 t 0 between t 0 and t 2 and (2) t 0 t = 0 between t 2