FORMATION KINETICS AND VISCOELASTIC PROPERTIES OF SEMIINTERPENETRATING NETWORKS BASED ON CROSS-LINKED POLYURETHANE AND POLY(BUTYL METHACRYLATE)

The interconnection between the kinetics of semi-interpenetrating network (semi-IPN) formation, phase separation during the process and viscoelastic properties has been investigated. The semi-IPN based on crosslinked polyurethane (PU) and poly(butyl methacrylate) (PBMA) was synthesized in two ways: (1) by introducing PBMA into the reaction mixture for PU formation and (2) by simultaneously carrying out both the polyaddition reaction of PU formation and the polymerization of butyl methacrylate, the latter being produced using initiators and ultra-violet light. The kinetic constants, degrees of conversion at the onset of phase separation and viscoelastic properties have been estimated. It was shown that viscoelastic properties are changed essentially depending on the semi-IPN formation conditions, the degree of segregation (degree of phase sepration) being dependent on the kinetic conditions. The dependence of viscoelasticity on the kinetics is explained by various degrees of segregation fixed by crosslinking and by the formation of two phases of different composition.