Changes of Mechanical and Chemical Properties of PP and PC Films Due to UV-Light-Induced Degradation.
Changes of Mechanical and Chemical Properties of PP and PC Films Due to UV-Light-Induced Degradation.
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紫外线引起的降解导致 PP 和 PC 薄膜的机械和化学性能发生变化。
DOI：
10.1299/kikaia.60.1450
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发表时间：
1994
期刊：
影响因子：
--
通讯作者：
T. Koizumi
中科院分区：
文献类型：
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作者：
M. Notomi;H. Kohda;K. Kishimoto;T. Koizumi
众所周知，太阳光诱导聚合物的紫外（UV）降解。本文研究了紫外光辐照对聚丙烯（PP）和聚碳酸酯（PC）薄膜力学性能变化的影响。在样品暴露于来自荧光UV设备的UV光之后，一些样品在暴露之后经受静载荷。进行了拉伸试验和动态粘弹性力学试验。此外，为了研究化学性质的变化，测量了红外光谱和分子量。(1)紫外光辐照导致的力学性能退化分为两个阶段，即：例如，降解潜伏期和降解发育期。在第一阶段，材料的破坏应变基本不变，随着紫外光辐照能量的增加，材料的破坏应变逐渐减小。辐照期间施加的应力有加速降解的趋势。(2)当暴露期间的温度大于玻璃化转变温度时，其对降解的影响相当大。(3)两种材料存在潜伏期的原因不同。PP本身不具有光诱导化学反应的活性基，因此引发主链断裂需要一定的时间。另一方面，PC具有活性碱基，但第二次缀合很强。因此，需要一定数量的主链断裂来降低破坏应变。
It is well known that sunlight induces the ultraviolet (UV) degradation of polymers. This paper describes the effects of UV irradiation on the change of mechanical properties of polypropylene (PP)and polycarbonate (PC) films. After the specimens were exposed to UV light from the fluorescent UV apparatus, some specimens were subjected to a dead load afterwards the exposures. Tensile tests and dynamic viscoelastic mechanical tests were conducted. In addition, infrared spectrum and molecular weight were measured in order to investigate changes in chemical properties. (1) The degradation of mechanical properties due to UV irradiation is divided into two periods, i. e., the degradation-incubation period and degradation-development period. The failure strain does not change in the first period, and gradually decreases with increase of the integrated UV irradiation energy. The applied stress during irradiation has a tendency to accelerate degradation. (2) The temperature during exposure influences degradation considerably when it is greater than the glass transition temperature. (3) The reason for the existence of the incubation period is different for two materials. PP has no active bases originally for light-induced chemical reaction, and thus a certain period is necessary to initiate scission of main chains. On the other hand, PC has active bases but the second conjugation is strong. Therefore a certain number of main chain scissions are required to decrease the failure strain.