Interpenetrating polymer networks of polyurethane and unsaturated polyester
Polimery 2002, No 4, 242
Compositions consisting of mutually permeable semi-IPN type polymer networks were obtained, consisting of unsaturated polyester resin (UP) and polyurethane resin (PUR) (semi-IPN UP/PUR). Synthesis conditions of such systems were described, and a new method of PUR polyaddition in styrene (ST), which is also a UP component was presented. SEM allowed concluding that the investigated semi-IPN UP/PUR compositions are characterized by heterogeneous microstructure. Both PUR, as well as UP were able to form the dispersed phase, depending on chemical composition (Table 3); the matrix may be UP or a UP + PUR mix. DSC reported existence of three Tg values, corresportding to the hard and soft PUR and UP domains, indicated phase incompatibility. Static and dynamic mechanical properties (Figs. 3—8), je. tensile strength (σr), elongation at break (εr) and dynamic Young's elasticity module, are significantly affected by both PUR, as well as the ST present in the system. σr and εr values decrease with growing PUR content, but the effect ceases to be meaningful when PUR content in the composition exceeds 10% by weight. Increasing ST contents usually improve strength properties of samples. The dynamic elasticity modulus depends only on composition, with structure of the PUR used (Table 2) being irrelevant.
Keywords: polyurethanes, unsaturated polyester resin, interpenetrating polymer networks, microstructure, static and dynamic mechanical properties