Structure and property relationship of semi-interpenetrating polymer networks of polyurethane and poly (vinyl chloride)

Abstract

Semi-Interpenetrating polymer networks (semi-IPN)of poly (vinyl chloride) (PVC) disperse phase and acontinuous matrix crosslinked polyurethane (PU) basedon polycaprolactone glycol (PCL), triethanolamine (TEA)and modified methylene diisocyanate (MMDI) was preparedusing either one-shot or prepolymer process. The lattergave completely phase compatibility while the formerincompatibility. The compatibility could be observedfrom the optically transparent, a homogeneous phase asobserved by SEM technique and a sharp T(,g) peak asobserved by DMA technique. It is attributed to thehydrogen-bonding between PVC hydrogen with PUprepolymer carbonyl and with PCL carbonyl. The value of T(,g) of PU (the equivalent ratios ofNCO/OH = 1.05 and of PCL:MMDI:TEA = 1:3:2) is reportedto be -7.0 degree C while that of the compatibleSemi-IPN be in the ranges of -4.0 degree C to 8.6degree C, dependent upon the amount of PVC presented. The mechanical properties including tensilestrength, elongation at break and hardness of PU andSemi-IPN prepared by those two processes were alsomeasured. In general the partially uncompatibledispersed phase PVC with the continuous matrix PU gavepoor mechanical properties than the completelycompatible Semi-IPN. The values of tensile strength,elongation at break and hardness (shore A) of theSemi-IPN are reported respectively in these studies inthe ranges of 3.46-6.10 N/mm('2), 385.4-557.3 %, and59.6-64.3, dependent upon the amount of PVC presented.In general, the larger the amount of PVC gave thebetter those mechanical properties except the hardnessof the materials was not significantly different eventhe variation of amount of PVC from 5 to 30 % byweight