扩链剂对水性聚氨酯脲与聚甲基丙烯酸甲酯复合体系结构和性能的影响

分别用乙二胺 (EDA)和水作为扩链剂制备了聚氨酯脲 聚甲基丙烯酸甲酯 (PUA)水分散液 .借助DSC、DMA、FTIR研究了扩链剂对PUA的结构和性能的影响 .结果表明在EDA扩链体系中 ,虽然聚甲基丙烯酸甲酯 (PMMA)和聚酯软段以及扩链剂与异氰酸酯生成的硬段均有一定程度的相容性 ,但由此合成的PUA仍具有多相结构 ;水扩链体系只有一个较宽的二级转变区 ,各相之间有较大程度的混合 .由EDA扩链合成的PUA在耐溶剂、耐水性及拉伸强度等方面优于水扩链体系 .两种扩链剂体系所得PUA的性能差异 ,主要与二者和异氰酸酯反应生成的脲键密度不同 ,导致不同的微相结构有关

INFLUENCE OF CHAIN EXTENDERS ON THE STRUCTURE AND PHYSICAL PROPERTIES OF WATER-BORNE POLYURETHANEUREA-POLYMETHYLMETHACRYLATE

Ethylenediamine(EDA) and water were used respectively as the chain extender in the preparation of polyurethaneurea|polymethylmethacrylate(PUA) hybrid aqueous dispersions.The relationship between the structures and physical properties for dried films of these water|borne PUAs was studied by means of DSC,DMA and FTIR.The testing results of DSC and DMA show that there is only one broad glass transition peak in the PUA prepared with water as extender exhibiting a compatible system while there are two glass transition temperatures in the film made with EDA as extender giving rise to phase separated morpholygy.Furthermore,as consistent with the DSC scan results and DMA measurements,the experimental results of FTIR indicate that there are stronger hydrogen bonding effect and much higher urea bond density in the EDA system than in the water system.In this case,the different morphologies for these two multi|component systems should be expected.A yield phenomenon appeared in the stress|strain curve of PUA prepared with water as extender while it was not observed in the EDA counterpart.The PUA synthesized with EDA as extender is superior to the water counterpart in solvent and water resistance as well as tensile strength,which could be related with the morphologies for such two extender systems studied in this paper.