反应注射成型聚氨酯互穿聚合物网络研究——刚性网络对于体系形态及性能的影响

用微型反应注射成型机制备了以聚氨酯(PU)为弹性相的两类同步互穿聚合物网络(SIN),其刚性相分别采用保留仲羟基的乙烯基酯树脂(VERH)以及封闭仲羟基的乙烯基酯树脂(VERA)。用傅里叶变换红外光谱在线跟踪了这类互穿网络的生成过程,发现刚性网络抑制了PU网络中硬段有序结构的形成,两个网络间有一定程度的互穿,而两个网络间的化学键作用进一步削弱氢键强度。自旋—自旋弛豫时间的测定进一步表明网络间存在一定的互穿以及刚性相对于PU硬段结晶的抑制作用。材料的力学性能与其SIN的形态有关。VERA网络对PU表现出明显的增强作用,而由VERH网络形成的SIN则由于体系相分离进程受到严重阻碍而使材料性能恶化。

Studies on Reaction Injection Moulded Polyurethane Interpenetrating Polymer Network: Effects of Rigid Phase upon Morphology and Property

The two kinds of simultaneously interpenetrating polymer networks (SINs) with polyurethane (PU) as the elastic phase were prepared through reaction injection moulding (RIM) process, the rigid phase of which was vinyl ester resin containing hydroxyl groups (VERH) or not possessing hydroxyl groups (VERA). The syntheses of SINs were monitored by using fourier transform, infrared spectroscopy to investigate the effect of the introduction of rigid phase upon the development of hydrogen bonding, and it was found that the rigid phase usually depressed the formation of ordered structure and crystallisation of the PU hard segments, suggesting that there were some degrees of interpenetration between the two networks. The formation of inter-component chemical binding between the two networks could further inhibit the hydrogen bonding process of the PU/VERH SIN systems. The results from the measurement of spin-spin relaxation time of these RIM SIN samples also supported the occurrence of interpenetration between the two networks and the restraint of rigid phase upon the crystallisation of PU hard segments. The mechanical properties could be correlated well with these morphological characteristics, i.e., the enhancement in tensile strength of PU network by the incorporation of VERA network was observed, while the PU/VERH SIN samples exhibited rather deteriorated properties for the severely inhibited process of the phase separation in the systems.