CHEMICAL-TRANSFORMATIONS AND PHASE-TRANSITIONS IN POLYMER RHEOLOGY AND TECHNOLOGY

Fundamental rheokinetic effects observed in processes of linear polyme rization and three-dimensional oligomer curing are discussed.It was sh own that changes in rheological properties during linear polymerizatio n can be described by relationships based on treating a reactive mass as a polymer solution, if a newly formed polymer is soluble in reactiv e medium. Phase separation limits this approach and leads to some new rheological consequences such as change in the rate of viscosity growt h (in some cases viscosity can even decrease in the course of polymeri zation). Shearing influences temperature of a phase transition and kin etics of chemical reaction if it proceeds in heterogeneous conditions. The same phenomena were also observed for oligomer curing which can o ccur in heterogeneous manner with microgelation and formation of collo id particles of a new phase before the gelation of a system as a whole .