Alojz Anžlovar,* Majda Žigon
National Institute of Chemistry, Hajdrihova 19, SI-1000, Ljubljana, Slovenia, E-mail: alojz.anzlovar@ki.si

Abstract
The morphology and mechanical properties of grafted semi-interpenetrating polymer networks (SIPNs), based on ester-urethane (PU) prepolymers and methacrylate (PM) prepolymers were studied with regard to the PU and PM mass ratio and with regard to the concentration of functional groups. The SEM micrographs, glass transition temperature shifts of the individual constituents and mechanical properties of the studied SIPNs show that their miscibility is enhanced by the interaction of complementary functional groups which also stabilize the mixture at elevated temperatures. However, enhanced miscibility was observed only in SIPNs with PU component in excess, while in SIPNs with the PM component in excess miscibility was poor. Enhanced miscibility in the SIPN with functional groups having a PU/PM mass ratio of 0.5/0.5 was ascribed to the most intense interaction between functional groups at this PU/PM ratio. Mechanical properties (Young’s modulus and tensile strength) of SIPN films were defined by the polymer component forming the matrix. They were significantly influenced by the interaction between functional groups.

Key words: semi-interpenetrating polymer networks, functionalization of polymers, morphology, mechanical properties, DSC, electron microscopy