The effect of the soft segment of prepolymers on properties of poly(urethane-ester) and its biodegradability

The influence of soft-segment prepolymers prepared through the polymerization of delta-valerolactone (VL) and 2,2-dimethyl-1,3-propandiol (DP) monomers on the structure and properties of poly(urethane-ester) as well as its biodegradability were investigated. Poly(urethane-ester) was prepared in two steps. The first step was the preparation of prepolymers with various chain lengths by polymerizing VL and DP monomers in the presence of a distannoxane catalyst at 100 degrees C under nitrogen atmosphere. The second step was the preparation of poly(urethane-ester) by polymerizing 4,4'-methylene-bis(phenyl isocyanate) (MDI) and prepolymers with various chain lengths in the absence of catalysts. The poly(urethane-ester) was characterized through an analysis of functional groups (FTIR), thermal properties (differential thermal analysis/TGA), mechanical properties (tensile tester), crystallinity (XRD) and biodegradability. An increased chain length of the prepolymer used in polymerization with MDI leads to an increase in the thermal properties and crystallinity of poly(urethane-ester). However, the maximum biodegradability in the activated sludge was observed in the poly(urethane-ester) prepared by polymerizing MDI and prepolymers with a molar VL/DP ratio of 20/1. The amorphous parts of polymers were more easily decomposed by microorganism enzymes than were the crystalline parts after an incubation period of 30 days. (C) 2011 Society of Chemical Industry