3.2 添加
填料
PU膠中添加合適的填料可以降低
收縮應力和熱應力，從而提高其耐熱性。由于聚氨酯中有機和無機部分相互作用形成獨特的界面效應和協(xié)同作用，使得這種材料具有更高的熱和氧穩(wěn)定性。按有機相和無機相的相互作用關系可[30]將混合聚氨酯分為2類 ：第1類是有機與無機相通過弱鍵如氫鍵、范德華力和靜電力相互作用，另一類則是有機相和無機相通過共價鍵結合。常用的填料有
纖維（如
玻璃纖維、
云母等）、粉末（如纖維素、二氧化硅、三氧化二
鋁等）、片狀材料（如滑石）、塊狀材料（如重晶石）及納米粒子或功能納米粒子。[31]
Sebastian Clauβ等 在單組分PU膠中加入體積分數(shù)30%的白堊，膠接接頭的熱穩(wěn)定性明顯提高。B. S. Kim等[32]分別用疏水和
親水性基團改性的2種納米二氧化硅增強UV固化聚氨酯乳液，發(fā)現(xiàn)隨著納米二氧化硅加入量的增[33]加，聚氨酯降解溫度尤其是硬段降解溫度增加。Lee等 研究了水性聚氨酯/粘土納米復合材料，也發(fā)現(xiàn)體系中含有粘土越多其耐熱性就越高。
4 結束語
在聚氨酯膠粘劑的制備和使用過程中應充分了解其結構與性能的關系，根據使用的目的和要求合理進行設計。目前，開發(fā)新型耐熱聚氨酯膠粘劑，研發(fā)新的合成技術、新的添加材料以及相應機理研究已成為聚氨酯研究的重點。
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