INTERPENETRATING POLYMER NETWORK OF POLYURETHANE AND UNSATURATED POLYESTER - MECHANICAL-PROPERTIES

Interpenetrating polymer networks (IPNs) of polyurethane (PU) and unsaturated polyester (UP) were prepared in this study. The mechanical properties of the IPNs were determined to relate to their structure. In order to improve the mechanical properties of the resultant IPNs, it was found that the -OH group present in the UP should be employed to react with some isocyanate-terminated PU prepolymer. Thus, the PU and UP were, in fact, interpenetrated with each other and chemically bonded through a grafting reaction to form the graft-IPN. The tensile strength of the IPNs was increased to a maximum value and then decreased as the PU content increased. The Izod impact strength and fracture energy of the IPNs increased more or less with an increase of the PU content, depending on the types, chain length of polyols used in the PU and the degree of the grafting reaction between PU and UP.