聚氨酯/环氧树脂互穿网络硬质泡沫塑料反应过程和微观结构

聚氨酯／环氧树脂互穿网络(PU／EPIPN)硬泡中异氰酸根的消耗速度较纯PU硬泡高，是由于环氧树脂的固化荆同时也是异氰酸根反应的催化荆。而PU／EP IPN硬泡中环氧基的反应速度和反应程度均较纯EP网络低，归因于互穿网络对基团扩散的阻碍。在互穿网络硬泡形成过程中，存在环氧开环中所新产生的羟基与异氰酸根的反应、大分子多元醇中羟基与环氧基的反应以及异氰酸根与环氧基形成嗯唑烷酮的反应三种形成网络间的化学键的途径。同时由于PU／EPIPN硬泡高度的交联，使得IPN硬泡中两个网络具有良好的相容性。动态力学性能表明所有IPN样品都只有一个玻璃化温度。透射电镜表明IPN样品无明显的相界面。

Reaction Process and Morphology of the Rigid Foams Made from Interpenetrating Polymer Network of Poylurrethane/Epoxy Resin

The reaction rate of NCO groups by producing polyurethane/epoxy resin IPN foams was faster than that by producing pure PU foam, which was attributed to that the curing agents of epoxy resin were also acted as the catalysts for the reaction of NCO groups. The epoxy groups, however, show lower reaction rate and conversion by producing IPN foams than that by producing pure epoxy resin. The reason might be owed to that the epoxy groups are diluted and restricted by the PU network. There are three kinds of reactions between the PU and EP networks: the reaction between the OH groups formed by ring opening of epoxy groups with NCO groups, the reaction between the OH groups on polyol and epoxy groups and the reaction between the NCO groups and epoxy groups to form oxazolidinone. Because of high degree of crosslinking in PU/EP IPN rigid foams and chemical bonds between the PU and EP networks, the PU and EP resin are miscible. Only one glass transitions temperature ( Tg ) was observed in PU/EP IPN rigid foam by dynamic mechanical thermal analysis (DMTA). There is no obvious interphase surface between the PU and epoxy resin observed in IPN foams with transmission electron microscopy (TEM).