Poly Merization Techniques

7/29/2019 Poly Merization Techniques

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TECHNIQUES IN POLYMERIZATION

SUBMITTED TO:

ENGR. MUBEEN AHMED

SUBMITTED BY:

TALHA SHAUKAT2009-NTU-1094

__________________________________________________________________

DEPARTMENT OF POLYMER ENGINEERING

NATIONAL TEXTILE UNIVERSITY

FAISALABAD - PAKISTAN

2009


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CONTENTS

EMULTION POLYMERIZATION 3

SOLUTION POLYMERIZATION. 5

BULK POLYMERIZATION... 7

PRECIPITATION POLYMERIZATION. 9

SUSPENSION POLYMERIZATION. 10


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EMULSION POLYMERIZATION

Emulsion polymerization is a type ofradical polymerization that

usually starts with an emulsion incorporating water, monomer, and surfactant. The most common

type of emulsion polymerization is an oil-in-water emulsion, in which droplets of monomer (the

oil) are emulsified (with surfactants) in a continuous phase of water. Emulsion polymerization isused to manufacture several commercially important polymers. Many of these polymers are used

as solid materials and must be isolated from the aqueous dispersion after polymerization. In other

cases the dispersion itself is the end product.

PROCESS

Emulsion polymerizations have been used in batch, semi-batch,

and continuousprocesses. The choice depends on the properties desired in the final polymer or

dispersion and on the economics of the product. Modern process control schemes have enabled

the development of complex reaction processes, with ingredients such as initiator, monomer, and

surfactant added at the beginning, during, or at the end of the reaction.

Schematic diagram of emulsion polymerization

By contrast, products sold as a dispersion are designed with a high degree of colloidal stability.

Colloidal properties such as particle size, particle size distribution, and viscosity are of critical

importance to the performance of these dispersions.
http://en.wikipedia.org/wiki/Radical_polymerizationhttp://en.wikipedia.org/wiki/Emulsionhttp://en.wikipedia.org/wiki/Monomerhttp://en.wikipedia.org/wiki/Surfactanthttp://en.wikipedia.org/wiki/Surfactanthttp://en.wikipedia.org/wiki/Batch_productionhttp://en.wikipedia.org/wiki/Continuous_productionhttp://en.wikipedia.org/wiki/Process_controlhttp://en.wikipedia.org/wiki/File:Emulsion_Polymerization_Cartoon_3.svghttp://en.wikipedia.org/wiki/Process_controlhttp://en.wikipedia.org/wiki/Continuous_productionhttp://en.wikipedia.org/wiki/Batch_productionhttp://en.wikipedia.org/wiki/Surfactanthttp://en.wikipedia.org/wiki/Surfactanthttp://en.wikipedia.org/wiki/Monomerhttp://en.wikipedia.org/wiki/Emulsionhttp://en.wikipedia.org/wiki/Radical_polymerization


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ADVANTAGES

High molecular weightpolymers can be made at fast polymerization rates.

The continuous water phase is an excellent conductorof heat and allows the heat to be

removed from the system, allowing many reaction methods to increase their rate.

Since polymermolecules are contained within the particles, viscosity remains close to that of

water and is not dependent on molecular weight.

The final product can be used as is and does not generally need to be altered or processed.

DISADVANTAGES

Surfactants and other polymerization adjuvants remain in the polymer or are difficult to

remove, For dry (isolated) polymers, water removal is an energy-intensive process

Emulsion polymerizations are usually designed to operate at high conversion of monomer to

polymer. This can result in significant chain transferto polymer. Can not be used for condensation, ionic or Ziegler-Natta polymerization, although some

exceptions are known.

APPLICATIONS

Polymers produced by emulsion polymerization can be divided into three rough categories.

Synthetic rubber.

Some grades ofstyrene-butadiene (SBR).

Some grades ofPolybutadiene.

Polychloroprene (Neoprene).

Nitrile rubber.

Plastics.

Some grades ofPVC. Some grades ofpolystyrene. Some grades ofPMMA. Acrylonitrile-butadiene-styrene terpolymer (ABS).

Dispersions (i.e. polymers sold as aqueous dispersions).

Styrene-butadiene

Latexacrylic paint

Polyvinyl acetate copolymers
http://en.wikipedia.org/wiki/Molecular_weighthttp://en.wikipedia.org/wiki/Heat_conductionhttp://en.wikipedia.org/wiki/Polymerhttp://en.wikipedia.org/wiki/Moleculeshttp://en.wikipedia.org/wiki/Viscosityhttp://en.wikipedia.org/wiki/Molecular_weighthttp://en.wikipedia.org/wiki/Adjuvantshttp://en.wikipedia.org/wiki/Chain_Transferhttp://en.wikipedia.org/wiki/Styrene-butadiene_rubberhttp://en.wikipedia.org/wiki/Polybutadienehttp://en.wikipedia.org/wiki/Polybutadienehttp://en.wikipedia.org/wiki/Polychloroprenehttp://en.wikipedia.org/wiki/Neoprenehttp://en.wikipedia.org/wiki/Nitrile_rubberhttp://en.wikipedia.org/wiki/Nitrile_rubberhttp://en.wikipedia.org/wiki/Plasticshttp://en.wikipedia.org/wiki/PVChttp://en.wikipedia.org/wiki/Polystyrenehttp://en.wikipedia.org/wiki/PMMAhttp://en.wikipedia.org/wiki/Acrylic_painthttp://en.wikipedia.org/wiki/Acrylic_painthttp://en.wikipedia.org/wiki/Acrylic_painthttp://en.wikipedia.org/wiki/PMMAhttp://en.wikipedia.org/wiki/Polystyrenehttp://en.wikipedia.org/wiki/PVChttp://en.wikipedia.org/wiki/Plasticshttp://en.wikipedia.org/wiki/Nitrile_rubberhttp://en.wikipedia.org/wiki/Neoprenehttp://en.wikipedia.org/wiki/Polychloroprenehttp://en.wikipedia.org/wiki/Polybutadienehttp://en.wikipedia.org/wiki/Styrene-butadiene_rubberhttp://en.wikipedia.org/wiki/Chain_Transferhttp://en.wikipedia.org/wiki/Adjuvantshttp://en.wikipedia.org/wiki/Molecular_weighthttp://en.wikipedia.org/wiki/Viscosityhttp://en.wikipedia.org/wiki/Moleculeshttp://en.wikipedia.org/wiki/Polymerhttp://en.wikipedia.org/wiki/Heat_conductionhttp://en.wikipedia.org/wiki/Molecular_weight


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SOLUTION POLYMERIZATION

Solution polymerization is a method of industrial polymerization. In

this procedure, a monomeris dissolved in a non-reactive solvent that contains a catalyst.

The heat released by the reaction is absorbed by the solvent, and so the reaction rate is reduced.

PROCESSA process for the solution polymerization of olefins with improved on-stream time is

provided. The solution polymerization process of the current invention comprises a method for

the on-line removal of foulant material from one or more heat exchangers downstream of a

polymerization reactor. Removal of foulant material is accomplished by deliberately applying a

positive pressure differential across a heat exchanger. In the process of the current invention,

reactor shut down is not required for the purpose of cleaning foulant material from a heat

exchanger.

POLYHEME

Polyheme utilizes human hemoglobin as the oxygen carrying molecule in solution, and the

extraction and filtration of this hemoglobin from red blood cells is the first step in production.

Then, using a multi-step polymerization process illustrated below, the purified hemoglobin is

associated into tetramers and, as the final step, is incorporated into an electrolyte solution.
http://en.wikipedia.org/wiki/Polymerizationhttp://en.wikipedia.org/wiki/Monomerhttp://en.wikipedia.org/wiki/Solventhttp://en.wikipedia.org/wiki/Catalysthttp://en.wikipedia.org/wiki/Heathttp://en.wikipedia.org/wiki/Solventhttp://en.wikipedia.org/wiki/Reaction_ratehttp://en.wikipedia.org/wiki/Reaction_ratehttp://en.wikipedia.org/wiki/Solventhttp://en.wikipedia.org/wiki/Heathttp://en.wikipedia.org/wiki/Catalysthttp://en.wikipedia.org/wiki/Solventhttp://en.wikipedia.org/wiki/Monomerhttp://en.wikipedia.org/wiki/Polymerization


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The polymerization of the hemoglobin represents the critical step in this process because, as

demonstrated by failed attempts at blood substitutes, when hemoglobin remains disassociated, it

tends to take up nitric oxide, causing vasoconstriction. Also, free hemoglobin can be taken up bythe kidney causing liver dysfunction and failure.

ADVANTAGES

Products sometimes are directly usable.

Controlled heat is released.

Depending on concentration of monomer the solution does not increase in viscosity.

DISADVANTAGES

Contamination with solvent.

Chain transfer to the solvent.

Recycling of solvent.

APPLICATIONS

Acrylic coating.

Fiber spinning.

Film casting.


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BULK POLYMERIZATIONThe polymerization of a monomer in the absence of any medium other

than a catalyst or accelerator. The monomers are usually liquids, but the term also applies to the

polymerization of gases and solids in the absence of solvents. Also known as MASS

POLYMERIZATION. Polymerization of the undiluted monomer. Viscosity increasesdramatically during conversion.

PROCESS

The bulk polymerization of monomers which produce polymer insoluble in the

monomers, in which the polymerization is carried out in an autoclave mounted on a horizontal

axis and provided with stirring means formed of at least two half-frames arranged symmetrically

of the axis of the autoclave and fixed at each end to a rotatable stub shaft axially mounted in theautoclave, each half-frame having a peripheral member serving as a blade which, on rotation of

the half-frames, passes in close proximity to the interior surface of the autoclave, and bracing

means interconnecting the peripheral members of the half-frames

Bulk polymerization reactor


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A bulk polymerization reactor takes the form of a vertical, cylindrical vat of a jacket construction

defining a reaction chamber which a rotary drive shaft having an off-center longitudinal section

with perforated discs and shearing blades extends vertically through. Successful preclusion of

abnormal stagnation of the liquid phase in the reaction chamber during polymerization avoids

undesirable coloring in the product while assuring stable polymerization and high yield.

ADVANTAGES

The system is simple and does not require thermal inulation.

The polymer obtained is pure.

Very high molecular weights are obtained.

Large castings may be prepared directly.

Polymers having higher glass transition temperatures and higher heat distortiontemperatures to be produced with greater economy.

DISADVANTAGES

Heat transfer and mixing become difficult as the viscosity of reaction mass increases

The problem of heat transfer is compounded by the highly exothermic nature of free

radical addition polymerization.

The polymerization is obtained with a broad molecular weight distribution due the the

high viscosity and lack of good heat transfer.

APPLICATIONS

Polymers through step reactions (nylon 6).

PMMA-plates.

In manufacturing of polydienes.
http://en.wikipedia.org/wiki/Exothermichttp://en.wikipedia.org/wiki/Molecular_weight_distributionhttp://en.wikipedia.org/wiki/Viscosityhttp://en.wikipedia.org/wiki/Viscosityhttp://en.wikipedia.org/wiki/Molecular_weight_distributionhttp://en.wikipedia.org/wiki/Exothermic


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PRECIPITATION POLYMERIZATION

A polymerization reaction in which the polymer being formed is insoluble in

its own monomer or in a particular monomer-solvent combination and thus precipitates out as itis formed. This invention relates to the polymerization of a monomer capable of forming a

precipitate of polymerized particles which comprises reacting in the liquid phase said monomer

in the presence of a high temperature, free radical initiator at a temperature within a critical rangeof between about 110 and 150 C.

PROCESS

The process envolves essentialy catalyst prepration step and polymerization at pressure usually

less then 50 atm and low temperatures(less then 100oC).the resultant polymer which is

precipitated as fine flocks, forms a slurry consisting of about 20% polymer suspended in the

liquid hydrocarbon employed as solvent.the polymer is recovered by stripping off the solvent,

washing off the catalyst, and if necessary extracting any undesirable polymer components.

Finally, the polymer is compounded with additives and stabalizer and the granulated.the

suspension of the polymers plocs in the solvent produces a physical system of low viscocity that

is easy to stir. However, problems may arise due to settling of the polymer and the formation of

deposits on the stirrer and reactor walls. Most industrial transition-metal catalysts are insoluble,

and cosequently polymerization accurs in a multiphase system and may be controlled by mass

transfer. Therefore, the type of catalyst employed exerts a larger influence on parameters and

reactor geometry.

ADVANTAGES

Physical state of system permits easy agitation.

Relatively low temperatures employed.

DISADVANTAGES

Separation of product is difficult and expensive.

Ctalyst systems are special and need careful preparation.

Moleculer weight distribution depends on type of catalyst.


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SUSPENSION POLYMERIZATION

(also known as pearl polymerization, bead

polymerization and granular polymerization) is a polymerizationprocess that uses mechanical

agitation to mix the monomeror mixture of monomers in a liquid phase such as

water,polymerizing the monomer droplets while they are dispersed by continuous agitation.

PROCESS

Water insoluble monomers are dispersed in water.Initiator dissolved in

monomer.Stabilization of droplets/polymer particles with non-micelle forming emulsifiers

like polyvinyl alcohol or Na-carboxymethylcellulose. Equivalent to bulk polymerization,

small droplets dispersed in water. Product can easily be separated, particles 0.01-1mm.Pore

sizes can be controlled by adding a combination of solvent (swelling agent) and non-solvent.

Viscosity does not change much.

This process is used in the production of most PVC, a widely used plastic, as well as Sodium

poly acrylate.
http://en.wikipedia.org/wiki/Polymerizationhttp://en.wikipedia.org/w/index.php?title=Mechanical_agitation&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Mechanical_agitation&action=edit&redlink=1http://en.wikipedia.org/wiki/Monomerhttp://en.wikipedia.org/wiki/Liquid_phasehttp://en.wikipedia.org/wiki/Polymerizehttp://en.wikipedia.org/wiki/PVChttp://en.wikipedia.org/wiki/Sodium_polyacrylatehttp://en.wikipedia.org/wiki/Sodium_polyacrylatehttp://en.wikipedia.org/wiki/Sodium_polyacrylatehttp://en.wikipedia.org/wiki/Sodium_polyacrylatehttp://en.wikipedia.org/wiki/PVChttp://en.wikipedia.org/wiki/Polymerizehttp://en.wikipedia.org/wiki/Liquid_phasehttp://en.wikipedia.org/wiki/Monomerhttp://en.wikipedia.org/w/index.php?title=Mechanical_agitation&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Mechanical_agitation&action=edit&redlink=1http://en.wikipedia.org/wiki/Polymerization


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ADVANTAGES

Efficient heat transfer. Low viscosity even at high solid content.

High monomer conversion. High rates of polymerization. High molecular weights can be achieved. Direct application of the final product. High surface area of particles.

DISADVANTAGES

Contamination of product with additives, e.g., surfactant. Not easy to control in the case of hydrophilic monomers.

APPLICATIONS

Ion-exchange resins.

polystyrene foam.

PVC.

REFERENCES

www.wikipedia.com.

www.books.goolge.com.

Gilbert, R. G. Emulsion Polymerization: a Mechanistic Approach Academic Press, London, 1996.

German patent 250690 (Sept. 12, 1909).

Colloid chemistry, lecture 11.pdf.

Heterogeneous_Polymerization.pdf.

http://www.faqs.org/patents/app/20090048407#ixzz0gnQFOPH9 .
http://www.wikipedia.com/http://www.books.goolge.com/http://www.faqs.org/patents/app/20090048407#ixzz0gnQFOPH9http://www.faqs.org/patents/app/20090048407#ixzz0gnQFOPH9http://www.faqs.org/patents/app/20090048407#ixzz0gnQFOPH9http://www.books.goolge.com/http://www.wikipedia.com/

Poly Merization Techniques

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