Bulk or mass Polymerization

Bulk (or mass) polymerization of a liquid monomer such as MMA is relatively simple in the absence of oxygen and various vessels can be used as the reactors as long as the reaction heat can be released quickly enough. The volume of the final products is smaller than the original volume of the monomers because of the shrinkage during the formation of the polymers from the original monomers. 

Some improvements concerning the bulk polymerization have been proposed[14j. The heat dissipation and viscosity drawbacks can be circumvented by carrying out the polymerization to low conversion with separation and recycle of unreacted monomer. The polymerization can also be carried out in multi-stages in order to overcome the heat release problem. When reaction system becomes highly viscous because of the high conversion, the reaction is carried out in thin-film reactors which allow reaction heat to be released quickly. 

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Because PS is brittle with little impact resistance under normal operating conditions, early work was done to impart impact resistance. The best known material from this work is called HIPS, which is produced by dispersing small particles of BR in with the styrene monomer. Bulk or mass polymerization of the styrene is begun producing what is referred to as... 

Free radical polymerization of neat monomer in the absence of solvent and with only initiator present is called bulk or mass polymerization. Monomer in the liquid or vapor state is well mixed with initiator in a heated or cooled reactor as appropriate. The advantages of this method are that it is simple, and because of the few interacting components present, there is less possibility for contamination. However, vinyl-type polymerizations are highly exothermic so that control of the temperature of bulk polymerization may be difficult. Also, in the absence of a solvent viscosities may become very high toward the end of a polymerization, which could make stirring difficult, and add to the difficulty of heat removal from the system. The advantages of this system, however, are sufficiently attractive for this to be used commercially for the free radical polymerization of styrene, methyl methacrylate, vinyl chloride, and also for some of the polymerization processes of ethylene [7]. 

Free-radical polymerizations are carried out by a variety of processes that require different design considerations with respect to recipe of polymerization and physical conditions for the process and process equipment. Generally free-radical polymerizations are carried out by four different processes (a) bulk or mass polymerization, (b) solution polymerization, (c) suspension polymerization, and (d) emulsion polymerization. 

Free-radical polymerizations are commonly carried out by four different processes (a) bulk or mass polymerization, (b) solution polymerization, (c)... 

What is meant by bulk or mass polymerization Explain and discuss. 

Four general techniques are used for preparation of polymers by free-radical mechanism polymerization in bulk, in solution, in suspension and in emulsion. The bulk or mass polymerization is probably the simplest of the four methods. Only the monomer and the initiator are present in the reaction mixmre. It makes the reaction simple to carry out, though the exotherm of the reaction might... 

An older expression for bulk or mass polymerization. The adhesion between layers of plastic that may develop under pressure during storage or use. 

Bulk or Mass Polymerization — Bulk or mass polymerization is different from the foregoing processes in that no carrier liquid is used. Therefore, there is generally litde or no process wastewater associated with this process. 

The simplest and most direct method of converting monomer to polymer is known as bulk or mass polymerization. A typical charge might consist of monomer, a monomer-soluble initiator, and perhaps a charge-transfer agent. Simple rate and heat transfer problems due to reaction kinetics generally create problems with bulk polymerization. However, some polymers such as polystyrene are sometimes made in bulk. 

Bulk or mass polymerization" Gas-phase pol3mierization Precipitation polymerization Suspension polymerization Microsuspension polymerization Dispersion polymerization Emulsion polymerization Miniemulsion polymerization Microemulsion polymerization... 

Bulk Polymerization. Bulk or mass polymerization is conducted with undiluted monomers and prepolymers. It is most successful in reactions where the monomer, like styrene and methyl methacrylate, will dissolve its polymer. The major difficulty associated with bulk polymerization is dissipating the exotherm that accompanies the process. For example, conversion of a carbon-carbon double bond to a single bond evolves about 30 kilocalories/mole of double bond. For polystyrene this amounts to about 290 calories/g, enough energy to severely overheat the mass if a way is not provided to transfer this heat from the polymerizing bulk. 

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