肼单体对聚氨酯-聚丙烯酸酯乳胶膜力学性能及热降解性的影响

Effect of Hydrazine Monomer on the Thermal Decomposition and Mechanical Property of Polyurethane-Polyacrylate

以甲基丙烯酸乙酰乙酸乙酯(AAEM)为酮单体,己二酰肼(ADH)、碳酸二酰肼、草酸二酰肼和丁二酸二酰肼为肼单体,采用原位聚合法制备了系列阴离子酮肼交联改性聚氨酯-聚丙烯酸酯(PUA)分散液。通过透射电镜和动态光散射研究了乳胶粒的尺寸和微观形貌;系统分析了不同肼单体对乳胶膜的力学性能、断面微观形貌、耐水性和热性能的影响。研究结果表明,肼单体的引入可综合提高乳胶膜的吸水性、交联密度、力学性能和热性能,乳胶膜断裂由脆性断裂转变为韧性断裂。采用不同肼单体所制PUA分散液的粒径及其分布随着肼单体亲水性的增加而降低。4种肼单体中碳酸二酰肼的反应活性最高,己二酰肼的反应活性最低。采用碳酸二酰肼所制PUA乳胶膜的力学性能、耐水性和热性能最佳,其热分解活化能最高。而采用己二酰肼所制PUA乳胶膜的综合性能较差。

A series of polyurethane-polyacrylate(PUA)dispersions were obtained through in-situ emulsion polymerization,using acetoacetoxy ethyl methacrylate(AAEM)as ketone monomer,adipic dihydrazide(ADH),carbohydrazide,oxalylhydrazide and succinohydrazide as hydrazine monomer.The particle size and micromorphology of PUA colloidal particles were characterized by transmission electron microscopy and dynamic light scattering.The effects of hydrazine monomers on the mechanical property,cross-section morphology,water resistance and thermal properties of PUA films were investigated.Meanwhile,decomposition kinetic was characterized with activation parameters through Kissinger method.It is found that the water resistance,crosslinking density,mechanical property and thermal stability can be improved with the introduction of hydrazine monomers.The film fracture transfers from brittle fracture to ductile fracture.The particle size and distribution decrease with increasing the hydrophility of hydrazine monomers.Among four hydrazine monomers,carbohydrazide displays the highest reactivity,while the reactivity of ADH is the lowest.The PUA film prepared with carbohydrazide is endowed with better mechanical property,water resistance and thermal property,as well as higher thermal decomposition activation energy.While the PUA film made from ADH displays poor performance.