Suspension, bulk, and emulsion polymerization of vinyl chloride—mechanism, kinetics, and reactor modelling

Abstract

A review of relevant microscopic processes, both chemical and physical, which occur during suspension, bulk and emulsion polymerization (both before and after pressure drop) is given. The state of the art of kinetic modelling of monomer consumption rate, reactor pressure, molecular weight and short and long chain branching development and polymer chain microstructure is illustrated. The effects of diffusion-controlled termination and propagation reactions and the significant decrease in initiator efficiency and decomposition rate constant at high monomer conversions on the relative rates of various chemical reactions are discussed. The application of temperature programming and semibatch operation are emphasized. Finally, attempts to model polymer particle morphology are described.

Solution and aqueous miniemulsion polymerization of vinyl chloride mediated by a fluorinated xanthate

“…This is consistent with the results observed in conventional free-radical polymerization of VC. 37,38 In RAFT miniemulsion polymerization, the molecular weights and PDIs of PVCs are smaller than those of PVCs prepared by convention miniemulsion polymerization; the molecular weights of PVC increase with an increase in conversion. These results indicate that the X1-medidated RAFT miniemulsion polymerization of VC has the living nature.…”

PVC Manufacturing by Suspension Polymerization

“…The above physical picture was contradicted by several researchers, in the fi rst place by Xie and Hamielec [5,7,8] , who proposed a mechanism based on the precipitation and migration of living macroradicals to micropolymeric domains. The above physical picture was contradicted by several researchers, in the fi rst place by Xie and Hamielec [5,7,8] , who proposed a mechanism based on the precipitation and migration of living macroradicals to micropolymeric domains.…”

A model of the gel fraction of polymer in the vinyl chloride/divinyl monomers suspension copolymerization

“…(7), and converted into the sol radicals, which can termimaking an arrangement, give: nate by the chain transfer to monomers because the VC monomer chain transfer constant is very dN cr (b, a) high, up to Ç 10 03 . 24 In fact, our experimental…”

“…A gel is an As the termination reaction is diffusion-controlled infinite macromolecule, so its diffusion rate conin the polymer phase, the rate constant can be stant can be assumed to be zero. The gel macroformulated with 24 : molecules have to differ from the sol macromolecules in terms of the above assumption, so the (2) intercrosslinking reaction has to be divided into the following four kinds of reactions: (7) where:…”

“…An amount of the dry resin was backwashed in a The Parameters from VC Homo-polymerization Sohxlet extractor for 48 h with tetrahydrofuran Xie 24 has deeply studied VC homo-polymeriza-(THF) at 80ЊC under nitrogen. Then the extracted tion.…”