6 polymzn process (251050)

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By Dr. Walaiporn Prissanaroon-Ouajai

411317 Polymer chemistry (2-2552)

411317 by Dr. Walaiporn Prissanaroon-Ouajai (IC-KMUTNB)

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Polymerization ProcessPolymerization Process

Polymerization ReactionPolymerization Reaction

1. Chain-Growth Polymerization

2. Step-Growth Polymerization

( Methods or Techniques of Polymerization


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1. Bulk Polymerization

2. Solution Polymerization

3. Suspension Polymerization

4. Emulsion Polymerization

Techniques of PolymerizationTechniques of Polymerization


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1. Organic Substance1. Organic Substance* Toxicity

Acryonitrile

Styrene-Acryronitrile Copolymer (SAN)

Maximal Concentration : 20 ppm for 8 hr-Exposure

Design CriteriaDesign Criteria

CHCH22=CH=CH

CNCN

Polyacryonitrile-CH2-CH-

CNn

-CH2-CH-CH2-CH-

CNn


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Design Criteria1. Organic Substance

Ziegler Catalyst (Complex of TiCl3-AlR3)

Acrylate Monomer Ester

*

Flammability

* Odor

Ex. CH3

H2C=C

O=C-O-CH3

Methylmethacrylate (MMA)


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Monomer + Initiator + Solvent + Catalyst

PolymerizationPolymerization

Polymer + Starting Material DistillationDistillation

ExtractionExtractionCrystallizationCrystallization

2. Polymer Product2. Polymer Product* Purity



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Exothermic Reaction

3. Reaction3. Reaction* Heat of Polymerization


CH2=CHX -CH2-CHX-n

--HHpp


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-Hp of Various Polymers


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--HHpp

RepeatingUnit

Monomer

16.7 kcal/mol16.7 kcal/mol

-CH2-CH-

Styrene


CH3

-CH2-CH-

-methyl styrene


CH3

-CH2-CH-

CH3

Isobutylene

-CH2-CH-

CH3

Propylene


High Pendent Group

SterricSterric ReplusionReplusion Difficult to occurDifficult to occurPolymerizationPolymerization

Lower -Hp


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Problems of Heat

--HHpp = 10 kcal/mol= 10 kcal/mol

ExampleExample

MonomerMonomer PolymerPolymer MW = 100MW = 100Specific Heat = 0.5Specific Heat = 0.5 cal/cal/ooCC--gg

H = CH = CppTT

= 200= 200 ooCC

T =T = H = 10,000 cal/molH = 10,000 cal/molCCpp 0.50.5 cal/cal/o

oCC--gg

T = 10,000 cal/molT = 10,000 cal/mol

0.5 x 100 cal/0.5 x 100 cal/oo

CC

--molmol

MW decrease


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PolymerizationPolymerization

IncreasingViscosity

Design Criteria3. Reaction

* Viscosity

Auto-accelerationor Trommsdroff Effect


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Rpincrease

PropagationPropagation

kkpp constantconstant

A + A*

TerminationTermination A* + A*

kktt decreasedecrease

MWincrease


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Types of Polymerization ProcessesTypes of Polymerization Processes


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Types of Polymerization ProcessesTypes of Polymerization Processes

Homogeneous reactions

Heterogeneous reactions


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1. Bulk Polymerization1. Bulk Polymerization(Mass or Block Polymerization)

MonomerMonomer ++ InitiatorInitiator

Polymer Unreacted Monomer

Unreacted Initiator

++ImpurityImpurity

CriteriaCriteria

%% Initiator and Polymer must be able to dissolveInitiator and Polymer must be able to dissolvein Monomer.in Monomer.


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AdvantageAdvantage Polymer with very high purity

DisadvantageDisadvantage High Conversion High Viscosity

\ Difficult to release heatHigh MWD

Hard to control reaction rate

Low MW

\ Auto-acceleration(from high viscosity)

High MW


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Applications

[ Chain-Growth Polymerization

[ Step-Growth Polymerization

Only Clear Products (PE/PS/PMMA/PC)

Most



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1.1 Quiescent Bulk Polymerization

Monomer CastingMonomer Casting Ex. Phenol-formaldehyde Polymer

PMMA Sheet

High MW Product Tough Polymer

Monomer + Initiator

Advantages

Shaped Product


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1.1 Quiescent Bulk Polymerization

Mold Mold filled with Mor casting syrup

Mold sealedand clamped

Mold placed in oventime and temp. dependon sheet thickness,type of M

Sheetsremovedand cooled

Cast sheetsannealed andpreshrunk at > 145oC

Molds cooled anddisassembled


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Major ProblemsMajor Problems

1. Heat Removal

2. Conversion

3. Shrinkage (~21%)

Solution

Add low MW polymer (Syrup)10-30%


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1.2 Stirred Bulk Polymerization

PMMA & PS Continuous Stirred Tank Reactor(CSTR)

CSTRCSTR

Heat Removal

Melt Polymer

MoldingMonomer

Initiator

Polymer < 70% conversion


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1.2 Stirred Bulk Polymerization

Nylon 66

High MW Polymer

Die HeadDie Head :: SpinneretSpinneret


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2. Solution Polymerization2. Solution Polymerization

MonomerMonomer++ InitiatorInitiator++SolventSolvent

Q Release Heat of Reaction

Q Reduce Viscosity Avoid Autoacceleration Effect

Problems of SolventProblems of Solvent

Purity

Chain Transfer Reaction by Solvent


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4 Types of Solution Polymerization4 Types of Solution Polymerization

ComponentsComponentsTypeType

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SolubleSolubleSolubleSoluble

SolubleSoluble

22

SolubleSolubleInsolubleInsoluble

SolubleSoluble

33

SolubleSolubleInsolubleInsoluble

InsolubleInsoluble

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SolubleSoluble

SolubleSoluble

InsolubleInsoluble

Monomer andMonomer and

solventsolvent

InitiatorInitiator

PolymerPolymer


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2.2 Insoluble Initiator2.2 Insoluble Initiator

Initiator = Solid

Ex. Cr-SiO2-AlO3 Catalyst

Isooctane (liq)Ethylene (g)

Catalyst

bed

Separator

Polymer

Recycle


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2.3 Insoluble Initiator & Polymer2.3 Insoluble Initiator & Polymer2. Solution Polymerization

Heterogeneous Reaction

monomer + solvent initiator

solution

polymerization

polymer

cooling

suspension

separatorUnreactedmonomer

Isooctane

Ethylene

Polymer

T < 150 oC

Catalyst

liquid

Cooling coil

Unreacted ethylene

(gas)

Separatorsuspension


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2.4 Insoluble Polymer2.4 Insoluble Polymer


Interfacial PolymerizationO O

Cl-C-(CH2)8-C-Cl

in CCl4

H2N-(CH2)6NH2

in H2O

+O O

-C-(CH2)8-C-HN-(CH2)6NH-

amide bond

insoluble polymer


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3. Suspension Polymerization3. Suspension Polymerization

MonomerMonomer ++ InitiatorInitiator ++ HH22OO

Suspension

+ Suspending Agent+ Suspending Agent

Medium forheat removal

Polymz in suspended beads

Stirred

Suspended beads of polymer O 0.01-0.5 cm

Initiator must be soluble in Monomer

Heterogeneous Polymerization

[ Ex. PVAL &Gelatin


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Mechanism : Bulk Polyzn

Rate : Faster than Bulk

O 0.01-0.5 cm

Stirring Rate

Suspending Agent

Size of beads ordroplets of polymer


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Polymer Suspend in H2O

If Tg of Polymer > Troom

Temp

glassy state

rubbery

state

Tg

Solid

If Tg of Polymer < Troom Rubber

Glue

Dried Granules

Application

PSPMMAPAN

Clear solid(Amorphous)


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4. Emulsion Polymerization4. Emulsion Polymerization

MonomerMonomer ++InitiatorInitiator++ HH22OO

+ Emulsifier-Stabilize colloid system

-Form Micelle

Heterogeneous Polymerization

Suspension

Micelle Polyzn in Micelle

Polymer in Latex form Direct Application

K Paint & coating agent


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Comparison btw Emulsion & Suspension Polyzs

Composition

Initiator

Product

Product size

Emulsion

M + I + H2O + EM

soluble in H2O

Latex

0.05-5 m

Suspension

M + I + H2O + SA

soluble in M

Suspended droplets

0.01-0.5 cm


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Mechanism of Emulsion Polymerization

Emulsifier : Surfactant R-COO

-

Na+

-----R---COO-

Hydrophobicsegment Hydrophilicsegment

CMC

in H2O

Micell~ 50-100 molecules

H2O

Polymerization

CMC = critical micell conc.

surface

tension

viscosity

[surfactant]

[CMC]


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Polymerization SystemPolymerization System

Monomer droplet (non-polar)

stabilized by surfactant (1-10 m)

I soluble in H2O

surfactant

micelle after CMC (10-3-10-4 m)

I and M diffuse into micelle

polyzn in micelle

M droplet decrease in size

Swollen micelleboth polymer &unreacted monomer

Zero when 50-80% conversion

No monomer in micelle

Rp decrease

Latexcolloid of polymerin H2O

(0.05-5 m)(monomer-polymer particle)


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Kinetic of Emulsion Polymerization

v polymerization in micelle

Rp = kp [M][M*]

unreacted monomer

propagating molecule

%conversion < 70%

[M] ~ constantH2O

M


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[M*] = conc. of propagating chain (with active species)

Rate of Initiator diffusioninto micelle ~ 10 sec/radical

[M*] = Np2

No. of swollen micelle

in swollen micelle

swollen micellewith active radical

with inactive radical

H2O

M


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Rp = kp [M] Np

2

Emulsion polymerization

Degree of polymerization

DP = 2 = 2 Rp

Ri

const.Rp Np [EM]

Ri = 2fkd[I]

DP = kp [M] Np2fkd [I]DP Np

[I]

Kinetic of Emulsion Polyzn


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Comparison btw Emulsion & Bulk Polyzs

Kinetic of Emulsion Polyzn

Emulsion

Bulk

Rp Np [EM] DP Np[I]

Rp [M] [I]1/2 DP [M]

[I]1/2

[I] increase

Emulsion

Rp & DPBulk

Rp const. & DP

If High MW is wanted ?411317 by Dr. Walaiporn Prissanaroon-Ouajai (IC-KMUTNB)

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Advantage of Emulsion polymerization

Obtain High Rp and High MW in the same time byincreasing [EM]

Seeded Polymerization

Complete Latex Dilute

I + M

High MW Latex


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Comparison of 4 types Polymerization Process

System

Mechanism

Temp Control

Product

Purity

MW

Bulk

M+I

difficult

Shaped product

Very High

High MWD

Solution

M+I+solt

easier

Any

High

Lower

Rp [M] [I]1/2

DP [M]/[I]1/2

suitable for step polyzn

Suspension

M+I+solt+SA

easy

granule

Lower

High

Emulsion

M+I+solt+EM

easy

colloid or Latex

Lower

High

suitable for chain polyzn

Rp Np [EM]DP Np/[I]

6 polymzn process (251050)

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