3.2 添加
填料
PU胶中添加合适的填料可以降低
收缩应力和热应力，从而提高其耐热性。由于聚氨酯中有机和无机部分相互作用形成独特的界面效应和协同作用，使得这种材料具有更高的热和氧稳定性。按有机相和无机相的相互作用关系可[30]将混合聚氨酯分为2类 ：第1类是有机与无机相通过弱键如氢键、范德华力和静电力相互作用，另一类则是有机相和无机相通过共价键结合。常用的填料有
纤维（如
玻璃纤维、
云母等）、粉末（如纤维素、二氧化硅、三氧化二
铝等）、片状材料（如滑石）、块状材料（如重晶石）及纳米粒子或功能纳米粒子。[31]
Sebastian Clauβ等 在单组分PU胶中加入体积分数30%的白垩，胶接接头的热稳定性明显提高。B. S. Kim等[32]分别用疏水和
亲水性基团改性的2种纳米二氧化硅增强UV固化聚氨酯乳液，发现随着纳米二氧化硅加入量的增[33]加，聚氨酯降解温度尤其是硬段降解温度增加。Lee等 研究了水性聚氨酯/粘土纳米复合材料，也发现体系中含有粘土越多其耐热性就越高。
4 结束语
在聚氨酯胶粘剂的制备和使用过程中应充分了解其结构与性能的关系，根据使用的目的和要求合理进行设计。目前，开发新型耐热聚氨酯胶粘剂，研发新的合成技术、新的添加材料以及相应机理研究已成为聚氨酯研究的重点。
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