Effects of poly(vinyl acetate) suspending agents on suspension polymerisation of vinyl chloride monomer

When partially hydrolysed poly(vinyl acetate) (PVAc) is used as a suspending agent in the suspension polymerisation of vinyl chloride monomer, it has significant effects on the morphology of the resulting poly(vinyl chloride) (PVC) particles. At the initial step of polymerisation, PVC molecules are grafted onto the molecules of the suspending agent forming a PVC–PVAc membrane. The properties of this membrane depend on the type of suspending agent, the polymerisation temperature, the mixing efficiency, and other factors. The morphology of the growing PVC particles and the properties of the PVC resin obtained depend in turn on the characteristics of the membrane. A model has been developed relating to the connection between the polymerisation conditions and the characteristics of the suspending agent on one hand, and on the PVC properties on the other hand. The model is based on an analysis of the characteristics of the PVC–PVAc membrane and their effect on PVC properties.