Vorlesung 8 Processes WS2007 08(1)

1Dr. Klaus-Dieter Hungenberg, BASF AG Ludwigshafen Vorlesung Polymerisationstechnik, Universität Paderborn, WS 07/08 Polymer processes

Polymerisation Processes

Polymer Processes


Polymerisation Processes

Why look processes like as they do?


Polyethylene

• PE is industrially produced bay radical- and coordinative polymerization

• Polyethylene (PE) is semi-crystalline, non-polar thermoplastic material

• Most important standard plastics with highest production volume

Homo- und Copolymers of ethylene:

n


Polyethylene

LDPE LLDPE HDPE PP

structure

crystallinity [%]

Melting point [°C]

density [g/cm3]

Long- andShort chain-branching

Linear withshort chain-branches

Linear with fewshort chain-branches

Linear

50 - 55

106 - 120

0,91 - 0,93

55 - 60

125 - 130

0,91 - 0,93

70 - 80

128 - 136

0,93 - 0,96

~ 70

164 - 166

0,91


Polyethylene applications

• Films

• packaging material

• injection molding

• pipes

• electrical insulation material


Polyethylene densityDensity correlates with crystallinity and structure of PE:

amorphous PE: ρ = 860 kg/m³crystalline PE: ρ = 1000 kg/m³


Polyethylene melt flow index

Melt Flow Rate / Melt Flow Index= a measure for chain length / molecular weight

Amount of molten polymer [dg/min], that flows at defined conditions (pressure and temperature) through a defined capillary.

Standards: ASTM 1238 / ISO R1133

temperature 190 °C

weight 2,16 kg / 21,6 kg

geometry capillary:

D=2,095 mmL=8 mm High MFR = low molecular weight

Low MFR = high molecular weight


Polyethylen Processes

Reactions -mechanismradical coordinative

homogen

• bulk(LDPE high pressure process)

• solution • Suspension (3 Phase „Slurry“polymerization)

• Gas phase

• bimodal:slurry-slurryslurry-GPGP-GP

PEPE

processes

phaseshomogenous heterogenoushomogenous

phaseshomogenoushomogenous heterogenousheterogenoushomogenous


High Pressure Polyethylene Processes

High pressure process in one phase region

low pressure process in two phase region


High Pressure Polyethylene Processes

T = 200 - 300°CP = 2000 - 3000 bar

Tubular reactor

M

MGranules

Low pressureseparator

High pressureseparator

Low pressurecycle

High pressure cycle150-300 bar

Primary compressor

Hyper Compr.

Autoclave

alternative

Extruder


Side Reactions inHigh Pressure Polyethylene

R2CH2

CH2

CH2CH2

CH2CH2

CH2R3

R1CH2

CH2

CH2CH2

R1

CH2CH2

CH2CH3

R2CH2

CH2

CH2CH2

CH

CH2

CH2R3

CH2 CH2

R2CH2

CH2

CH2

CH2

CHCH2

CH2

R3

CH2

CH2

CH2

CH2

+ + n

Intermolecular transfer to polymer – long chain branching

Chain scission – unsaturated chains

R1 CH2 CH CH2 R2

R1 CH CH2 CH2 R2

CH2 CH R2 R1 CH2

++


Side Reactions inHigh Pressure Polyethylene

Intramolecular transfer to polymer – short chain branching

R1 CH2 CH2 CH

CH2

CH2

CH2

CH2

H

R1 CH2 CH2 CH

CH2

CH2

CH2

CH3

CH2 CH2

R1 CH2 CH2 CH

CH2

CH2

CH2

CH3

CH2 CH2 CH2 CH2 CH2

CH2 CH2

R1 CH2 CH2 CH

CH2

CH CH2 CH3

CH2

CH2

H

CH2 CH2

R1 CH2 CH2 CH

CH2

CH CH2 CH3

CH2

CH3

CH2 CH2 CH2R1 CH2 CH2 CH

CH2

CH3

CH CH2 CH2 CH2

CH2

CH3

n

n

n

Butyl side groups

Ethyl side groups


Activation energy and volumes in LDPE


Process parameters and properties - Trends


Different operation modes in LDPE reactors

I, M

I

300

200

100

I, M

I, MI, M

300

200

100

Multiple feed of monomer and initiatorSingle monomer feed of monomerMultiple initiator possible

Single initiator feed

double initiator feed


Coordinative Polyethylene Processes


Solution Coordinative Polyethylene Processes

Solution process:

• broad range of comonomer types and densities possible

• pure products

• limitation: high molecular weight (high temperature, transfer to solvent)

• temperature well above melting point of PE

• commercial processes:• processes with very short residence time, e.g. 2 min:

• Nova Sclairtech / Advanced Sclairtech• Sabic / Stamicarbon Compact solution process

• processes with longer residence time e.g. 30 min:• Dowlex• Mitsui



Ethylen

Comonomer

solvent

Solvent recycleventing

Solvent purification

Additive HDPE-Granules

Additives

Flowsheet for solution polymerization (DSM)

solventTemperatureResidence timeSolid content

Hexane130°C~ 10 min< 10 %

adiabaticHigh space time yieldReactor volume 5 m3 for 5 t HDPE/h

Reactor Flash-Tank

Extruder

Absorber Mixer

Flash-Tank



Sclairtech Dowlex

temperature 200 - 300 °C 160 °C

pressure bis zu 100 bar 27 bar

solvent cyclohexane C8 / C9 paraffines

Residence time approx. 2 min approx. 30 min

heat removal: convective convective and conductive


Slurry Coordinative Polyethylene Processes

Slurry process:

• developed for HDPE

• Limitation: low density, low molecular weight: partial solubility of the polymer in the suspension media, fouling

• suitable for densities above 930 kg/m³ resp. 920 kg/m³ (with SSC)

• CSTR‘s or slurry-loop reactors used

• suspension media: paraffines, e.g. hexane, isobutane

• many commercial processes:• processes with loop reactor

• Phillips Loop• Solvay

• processes with stirred tank reactors• Hostalen• Mitsui CX


Slurry Coordinative– Phillips Loop

Flowsheet of the Phillips Loop process

a) Catalyst hopper and feed valve; b) Double loop reactor; c) Flash tank; d) Purge drier; e) Powder-fed extruder; f) Impeller; g) Sedimentation leg

Suspension media: isobutane

T = 85 – 100 C

p = 37 bar

residence time 30 – 60 min

solid content: up to 50 %

high specific surface

reactor completely filled


Fluidized Bed Polyethylene Processes

Fluidized-bed process

a) Catalyst hopper and feed valve; b) Fluidized-bed reactor; c) Cyclone; d) Filter; e) Polymer take-off system; f) Product recovery cyclone; g) Monomer recovery compressor; h) Purge hopper; i) Recycle compressor; j) Recycle gas cooler

T=80 – 100° C

P = 7 – 20 bars

RTD comparable to CSTR

Body widening in upper part of the reactor in order to reduce gas velocity

Partly condensation cooling („condensed mode“


Polypropylene applications

PP is versatile in application:

• packaging material (flexible films and rigid packings)

• fibers

• injection molding parts for automotive, electrical applications, consumer electronics

• Chemical equipment, piping

High growth rates for PP


Polypropylene structure

Isotactic PP

misinsertion

syndiotactic PP

atactic PP

Crystallinity correlates with stereo selectivity and melting point

Isotactic = crystalline

Atactic = amorphous


Types of Polypropylene

• homopolymers

• random-copolymers

with ethylene (1-8 wt.-%)

mit 1-butene

terpolymers

• heterophasic copolymers

at least two-stage processes,

in which a second,

elastomeric phase is generated


Polypropylene Processes – a variety

Slurry process in hydrocarbon slurry, tank or loop reactorsNovolen gas phase, vertical stirred powder bedInnovene gas phase, horizontal stirred powder bedUnipol fluidized bedSpheripol slurry loop reactors ( + gas phase copolymer)Mitsui slurry bulk + gas phaseBorstar liquid / scf proyplen (+gas phase copolymer)MZCR gas phasem, multi zone circulating reactor

1.ReactorPP homo-polymer

slurrygas

2. ReactorPP co-

polymergas

Cat, cocat.C3, H2,

Activepowder

C3, C2,

Extrusion


Spheripol Process

Spheripol process

a) Loop reactors; b) Primary cyclone; c) Copolymer fluidized bed; d) Secondary and copolymer cyclone; e) Deactivation; f) Purging

1. Stage:

Matrix homopolymer in bulkin loop-reactors

2. stage:

Impact-Copolymers in gas phas polymerization


BASF/ Novolen Gas Phase Process

BASF gas-phase Novolen process

a) Primary reactor; b) Copolymerizer; c) Compressors; d) Condensers; e) Liquid pump; f) Filters; g) Primary cyclone; h) Deactivation/purge


Amoco Gas Phase Process

Amoco – Chisso gas-phase process

a) Horizontal reactor; b) Fluidized-bed deactivation; c) Compressor; d) Condenser; e) Hold/separator tank


Unipol Fludized Bed Gas Phase Process

UCC/Shell – Unipol fluidized-bed process

a) Primary fluidized bed; b) Copolymer fluidized bed; c) Compressors; d) Coolers; e), f) Discharge cyclones; g) Purge


Borstar Process


processes with different reaction zones in one reactor:

C a t a l y s ti n l e t

D O W N E R

P r o d u c td i s c h a r g e

H e a te x c h a n g e r

B A R R I E R S E C T I O N

E t h y l e n es t r i p p i n gc o l u m n

P r o p y l e n ef e e d

P r o p y l e n eb a r r i e rs t r e a m

p a c k e d

( m o v i n gb e d

d o w n w a r d )( u p w a r d

t r a n s p o r t )

f l u i d i z a t i o nf a s t

R I S E R

M Z C R

G a sc i r c u l a t i n g

c o m p r e s s o r

C o n d e n s e r

Basell‘s spherizone® Draught tube reactor proposed byWeickert


Tailoring of mwd and comonomer distribution

:

• new property combinations

different approaches possible:

• multistage process

• reactors with different reaction zones

• multisite - catalysts

%

Molecular weight (= polymer chain length)

Reducedimpactstrength.

Migration, taste.

Smokeand odourduringextrusion

Processability,stiffness

Matrix

Mechanicalstrength

Meltstrengthduringextrusion

Bimodal

Conventional

ESCR and creep resistance


Melt flow dependent in mwd

HDPE 1

HDPE 2

HDPE 3

rel.

Häu

figke

it

Molmasse

100

10

10

10

1010 10 10 10 10

-1

-2

-3

-4

-5 -3 -1 1 3

norm

ierte

Vis

kosi

tät

η/η

o

Scherrate γ / s -1

melt flow behaviour of different HDPE at 190°C


Controlling mmd by different methods

Aternative processes for

bimodal PP

H2

M

t

H2


Controlling mmd by different methods

Mi

Wei

ght %

TiV

TiV

TiV

TiV


Bimodal properties by multi-site catalystunimodal process with multi-site catalysts:

• bimodal polymers can be produced with multi-site catalysts in single stage processes:

• lower investment costs compared to multireactor processes / processes with multizone reactors

• control of polymer structure more difficult / less flexible

• narrower product window compared to multistage processes

Kim, J. D., Soares, J. B. P., Journal of Polymer Science: Part A: Polymer Chemistry, 38, 1427-1432, (2000)


hydrogen response for Ziegler catalysts


Bimodal properties in a reactor cascade

MMPropylenehydrogen

catalyst Cocatalyst

1. Reactor 2. Reactor

Propylenehydrogen

Catalyst poisonSilo

1. Reactor 2. Reactorlow high

low high

800.000-1,5 Mio

50.000-200.000

Temperatur[°C]

H2-concentration

Mw

Catalyst poisoncontrols fraction in 2. reactor


Bimodal properties in an oscillating reactor

MPropylenWasserstoff

Katalysator Cokatalysator

1. Reaktor


Styrenic PolymersPS- transparent- stiff- brittle

P[S/a-MS]P[a-MS/AN]-heat resistant

α-MeS Acrylnitril

PSAN-environmental stress resistant

Polybutadiene-rubber

HIPS- tough- opaque- low weather

resistance

Polybutadien-rubber

ABS- tough- opaque- low weather

resistance

Polyacrylate-rubber

ASA- tough- opaque- weather

resistance

MMAMMA

MBS, MABS- tough- transparent

S/Bu (block-)copolymers- tough- translucent- low weather

resistance

Bu


Styrenic Polymers – thermal initiation

H

.H

CHCH3

*

+

+

Pn*

+ Pn

**

** * *

* *

*


Styrenic Polymers – processes over the years

IG Farben, 1936 Union Carbide, 1943 Dow, 1952 BASF 1965


Styrenic Polymers –process and mwd

2000 4000 6000 8000

dmdP10-2

Styrene / EB50-80% conv.130-170°C


Degassing polymer solutions / melts

Extruder

Short diffusion paths

Renewal of melt surface

Falling strand devolatiizer

Long diffusion

Falling strangs

´tubular / pipe degassing

Heating during evaporation

Separation melt/gasin tubes

Thin film evaporatorExtremely thin films

Short diffusion ways

Vacuum

Vacuum

Vacuum

Heating during evaporation

Adiabatic flash

VacuumHeatexchanger

Non-isothermal flash

Nearly isothermal flashNearly isothermal flash


Degassing of polystyrene

Residual concentration of styrene deviates from equilibrium:mass transfer limitationsdegradation of polystyrene to monomer, dimers, trimers

Meister, Platt, Ind. Eng. Chem. Res., 28(1989)1662Scheirs, Modern Styrenic Polymers

monomerVle S über PS


Brittle and tough materials

Area= energy

elongation, ε

stre

ss, s

trai

n, σ

elongation, ε

stre

ss, s

trai

n, σ

brittle, hard tough, hard

Tear resistance at elongation at

tear

Tensile strength

Pure thermoplastic polymer, Tg>TuseThermoplastic polymer + rubber, Tg<<Tuse


HIPS, High impact polystyrene / solution/mass ABS

Dissolve PBu rubber in styrene and start polymerization of styrene in the presence of rubberRubber particles are formed, which toughen the brittle polystyrene


HIPS, solution/mass ABS - principles

Course of reactionRubber ( PBu) dissolved in Styrene

(/ Ethyl benzene)Polymerization of styrene, homo-PS and grafted PBuPhase separation ( PBu/S and PS/S) Phase inversionParticle formationEnd of reaction

A

BD

C


HIPS grafting and phase inversionPBu in S PS in S

Phase separation Phase inversion

S SSS SS

SSSS

SS

BB

BBB

BB

BB

BB

BBB

BBB

BB

S SSS SS

S SSS SS

Graft copolymers needed for stabilization of morphology


HIPS – phase inversion in first 2 reactors

Reactor 1 Reactor 2

Polybutadiene in styrenePolystyrene in styrene

HomogeneLösung

Viscosity

conversion

in inout out

Phase inversion whenvolume ratio = 1:1 ofdisperse : continuous phase

Stabilization of particles bygraft polymers formed in 1. reactor


HIPS – phase inversion in first 2 reactors

Viscosity

Conversion


HIPS – various continuous processes


HIPS – process with static mixers

solvent

monomer

comonomer

additives

Recycle solvent

additiveswater

water


Specific heat removal capacity for different reactors

1 – SMR, 2- static mixers, 3- empty tube, 4 – stirred tank, 5 extruder


SAN copolymers


SAN copolymerization behaviour

W-%

AN

in p

olym

erconversion

65% AN

30% AN

10% AN

24% AN

0.0

0.2

0.4

0.6

0.8

1.0

0 0.2 0.4 0.6 0.8 1x_Styrol

X_St

yrol

rS=0.34rAN=0.05

Copolymerisationsdiagramm für Styrol / Acrylnitril


SAN copolymers by….

Suspension polymerizationonly azeotropic compositionwater- solubility of AN

Emulsion polymerzationsemi- batch, starved feedshows some haze

Continuous solution polymerization in CSTRall compositions available


SAN copolymers in CSTR

Multiple degassing unit:toxic ANhigh temperatures give yellow polymer

To flaredegassing

continousSAN-Polymerisation

SAN-meltTo Extruder

SAN-Granulat

M

PRC

SAN,EB


Rubber modification of SAN –> ABS rubber from emulsion or solution process

1µm1µm

Emulsion polymerization

•High glance of surface•Yellowish colour•waste water•Separate polymerization of SAN (solution polymerization) and rubber (in emulsion)

Solution polymerisation

Mat surfaceWhiteNo waste waterSolution polymerization of SAN in the presence of rubber as for HIPS


Emulsion Rubbers for impact modification of SAN

SAN matrix

Crosslinkedrubber

SAN graft

lowhighLow temperature impact resistanceHigh-Weather resistance-40°C-80°CTg

-ManyDouble bonds

Acrylic ester+ bifunctionalmonomer

PolybutadieneRubber typeASAABSProduct

100-250nm


ABS, ASA via emulsion rubber and solution SAN

M

PRCS

M

MM M M

Base rubber

SAN grafting

Storage tank

precipitation

De-watering

extruder

ABS

Vacuumvapor

SAN-melt

M

MM

M

PRC


PMMA – Polymethyl methacrylate

Some special features

Strong gel effect

Low ceiling temperature

Tendency to depolymerization

High shrinkage

Termination by combination and disproportionation


PMMA – gel an glass effect effect

50 100 150 200T/°C

conv

ersi

on

Due to glass effect

Due to Ceiling temperature

100%


PMMA – weak links

C*O

O

CH3

O O

OO2

From combination

O

O

O

O

C*O

O

CH3

CH2

O

O

+ *

From disproportionationStarting point for depolymerization

Comonomers stop unzipping

MMMMMMMMMMMMMMMMMXMMMMMM* MMMMMMMMMMMMMMMMMX* + M


PMMA – continuous bulk process


PMMA – process for plates and sheets


PVC – suspension process

0ppks H=

χ=0.98

22220

1

1 )1ln(ln Φ+Φ+Φ−=⎟⎟⎠

⎞⎜⎜⎝

⎛χ

pp

p=const- = separate monomer phase


PVC – suspension process


PVC – bulk process

Prepolymerization up to 10%

Post polymerization up to 85-90%


PVC – bulk process, post reactorsHigh solidParticle size 0.08-0.2 mm


PVC – bulk process, particle size and stirring


The Nylon revolution 1945

(CH2)6NH

NH

CO

CO

n(CH2)6


Polyamides – basic structures

PA 6: Perlon PA6.6: Nylon

PA 6: Caprolactam

PA 11: Undecanlactam

PA 12: Laurinlactam

PA 6.6: Hexamethylendiamine+ Adipic acid

PA 6.10: Hexamethylendiamien+ Sebacic acid

PA 4.6: Butandiamine+ Adipic acid

CH2 C

O

NH (5 n

) NHCH2NH (6

) C

O

CH2(4) C

O

n


Polyamides – base materials

ε-Caprolactam: OH OHH

O N�H

Phenol Cyclohexanol Cyclohexanon Cyclohexanon-oxim

Benzene Cyclohexan

COH2C

H2C

NHCH2H2C

H2C

+6H

(Ni)

+H2NOH

- H2O

+6H

(Ni)

-2H

+CINO

- HCI

ε-Caprolactam:

(H2SO4)

Hexamethylene diamine:H2C = CH – CH = CH2

+Cl2 +2NaCN

- 2NaClH2C = CH – CH = CH2

Cl Cl

+2H

(Ni)H2C – CH = CH – CH2

CN CN

NC – (CH2)4 – CN H2N – (CH2)6 – NH2+8H

(Ni, NH3)

Adiponitrile Hexamethylendiamin

Adipic acid:H2C

H2C

H2C CH2

CH2

CHOH

H2C

H2C

H2C CH2

CH2

C = O (CH2)4

COOH

COOHCyclohexanol Cyclohexanone Adipic acid


PA6 – basic reactions

(CH2)5

3. Polycondensation

2. Polyaddition

1. Ring opening

NH (CH2)5 CO + H2O H NH COOH

NH CO + H NH CO OHn

H NH CO OHn+1

NH CO NH CO OHm

H NH CO OH + H2On+mH OH + H

n

(CH2)5

(CH2)5 (CH2)5

(CH2)5 (CH2)5 (CH2)5


Polyamide 6 - VK column

M

Vacuum(1 mbar)

ε-Caprolactame

melting80°C

Melt filter

water

preparation Pre condensation250°C, 40 bar

granulation

Extractor95°C

silo

Water

VK-column270°C

Granules

280°C

Mean residence time VK columnthroughput:

≈ 15 - 30 h≈ 2000 moto

dryer 80°C


PA6-process – modelling of each process unit

Schmelzepolymerisation im VK - Rohr

PA 6 - Granules

N2

Trocknung/Temperung

N2

-H2O

-O2

Caprolactam(+Kettenregler) + 0,5% H 2O

Granulation

Extraktion

Water

Bedingungen:

T : 95 - 120 °C τ : 17 - 30 h

Bedingungen:

T : 135 - 180 °C τ : 20 - 40 h

Bedingungen:

T : 250 - 280 °C p : 0 - 0,3 bar

τ : 9 - 17 h

Extractt-water

Polyamide 6air

nitorgen

Caprolactam(+chain regulator + H2O)

Melt polymerizationExtraction of oligomers Drying,

solid state polymerization


PA6-process – modelling of melt process

0

20

40

60

80

100

120

140

160

180

235 240 245 250 255 260 265 270 275 280te mpera ture in top of VK-Rohr

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Extract, %, CL, H2O, OligomersNH2-end groupsdegree of polymerizationdimer, %

simulation results taking into account exp. binary VLE date

Model input:

Kinetic scheme and parameters

Non-ideal phase behavior using NRTL model

Model output:

Molecular weight

end groups

Residual monomer

Oligomer concentration


PA6-process – modelling of extraction

Model assumptions:

Nernst law at phase boundaries

Nernst coefficient dependent on monomer concentration

Fick diffusion in polymer phase and liquid boundary layer

Model output:

Concentration profile of residual monomer and oligomer in polymer and liquid phase

2 4 6 8 10 12

2468

10

Top bottom

% extractable

2 4 6 8 10 12

0.20.40.60.8

1

Top bottom

% dimer in granules


PA6-process – modelling of solid state condensation

Model assumptions:

Polymer end groups, water, monomer und oligomere only in amorphous phase

reaction kinetics as in melt

diffusion coefficients dependent on degree of crystallinity

surface is free of water

Isothermal spherical particle

Model output

Pn, monomer and oligomerconcentration

re a c tio n t im e [h ]0 1 0 2 0 3 0 4 0 5 0

num

ber-

aver

age

chai

n le

ngth

1 0 0

1 5 0

2 0 0

2 5 0

3 0 0

3 5 0

4 0 0

4 5 0

T = 1 2 5 °CT = 1 4 5 °CT = 1 6 5 °CT = 1 8 0 °CT = 1 9 0 °Cm o d e l

r e a c t io n t im e [h ]0 1 0 2 0 3 0 4 0 5 0

mas

s fr

actio

n of

cap

rola

ctam

[%

]

0 .0 0

0 .0 2

0 .0 4

0 .0 6

0 .0 8

0 .1 0

0 .1 2

0 .1 4

0 .1 6

0 .1 8

0 .2 0

T = 1 4 5 ° CT = 1 6 5 ° CT = 1 9 0 ° Cm o d e l


PA66- basic reactions

Adipic acid Hexamethylene diamine

– H2O

+

+ H2O

AH-salt solution

Polycondensation

HO C OHO

CO

(CH2)4H2N NH2CH(CH2)6

HO C NHO

CO

(CH2)4 HNH(CH2)6


Polyamide 66 - tank process


Polyamide 66 – continous tubular process

H2O-Steam

tube reactor Devolatilisatione.g. Extruder

Separator

Pump

Post-condensation

PolymerMelt

Pump

40-60%AH-Salt Solution

High energy consumptionEvt. loss of volatiles in vapor


Polyamide 66 – countercurrent process – reactive distillation

Molten diacidfeed (bb)

Gaseous diaminefeed (aa)Polymer(aabb)

Steam

Reactive distillation

Pressureatmospheric

typically

Temperatureconventional

Product Mn9000

typically86Dr. Klaus-Dieter Hungenberg, BASF AG Ludwigshafen Vorlesung Polymerisationstechnik, Universität Paderborn, WS 07/08 Polymer processes

Polyethylen(butylen)terephtalat, PET, PBT

Side reactions: acetaldehyde, THF from butane diol (PBT)

Pre-condensationPost-condensation

Terephtalic acid ester Diol Terephtalic acid

transesterification esterfication

CH3 O O CH3CO

CO

x=2: PETx=4: PBT

n

HO OHCO

CO

HO (CH2)x OH

HO (CH2)x O OCO

CO

(CH2)x OH

HO OCO

CO

(CH2)x O H


Some processes – PET, PBT from DMT

CH3 O O CH3CO

CO


Rotating disc reactor for PET, PBT

To force conversion from 0.95 to 0.99 –0.995 ( or Pn>100), water removal more important than for polyamides, because of low equilibrium constants


Polyoxymethylene – anionic polymerization of CH2O

Formaldehyde(water solution.)

R Hexane

Acetic anhydride

Purification, drying

Formaldehyde(Gas)

Suspensions polymerization

End group stabilization by chemical modification

CH2O

CH2O

CH2R O O CH2 O O CH3n

O

CH2R O O CH2 On


Polyoxymethylene – anionic polymerization of CH2O


Polyoxymethylene – end group stabilization


Polyoxymethylene – cationic bulk process –‘Schalenkreis’

Heat Stabilizier

Antioxidant

PolymerizedMaterial

Milling

Vacuum

Additives


Polyoxymethylene – cationic kneader process

Vorlesung 8 Processes WS2007 08(1)

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Transcript of Vorlesung 8 Processes WS2007 08(1)