紫外辐照下透明聚氨酯胶片老化机理

针对高端夹层玻璃的老化问题,选用荧光紫外灯,对其主要粘结材料——透明聚氨酯胶片分别进行0/200/300/500 h的照射,借助紫外/可见光分光光度计、傅里叶红外光谱仪、扫描电镜等设备,研究照射过程中材料颜色、结构、微观形貌的变化。扫描电镜显示照射时间延长到500 h,材料表面出现龟裂。实验发现胶片的老化起始于硬段及软段部位与N,O相连的α位置的碳原子,在紫外光及氧气的联合作用下产生氢过氧化物;该过氧化合物一部分继续氧化成CO,一部分通过β分裂,使C—N,C—O键断裂,致使材料龟裂。

Degradation Mechanisms of Transparent Polyurethane Interlayer under UV Irradiation

According to the ageing problem of laminated transparency, the trasparent polyurethane film used as interlayer had been irra-diated by fluorescent ultraviolet lamp for 0 h, 200 h, 300 h, and 500 h respectively. With the aid of ultraviolet / visible spectropho-tometer, FTIR and SEM etc. , the color, structure and morphology of the materials were studied. SEM shows that when the irradiation time is increased to 500 h, the film surface cracks. The UV degradation mechanisms are that —CH2— of the position connecting the O and N from hard segment and the soft segment are easy to oxidize and produce hydrogen peroxide under UV and oxygen, which is furtherly oxidized to C—O, and some part of the C—O and C—N bonds is cracked throughβscission, and then the materials are fractured.