降解产物对聚苯乙烯薄膜光反应速率的影响

Neil A. Weir , Terence H. Milkie
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引用次数: 9

摘要

聚苯乙烯薄膜在25°C高真空条件下接受254 nm辐射。研究了新型紫外吸收发色团的时间演化特性;特别是,240 nm和400 nm处的吸收率增加。虽然这些吸光度的初始增长速度相对较快,但它们不能保持下去,并随着辐照的增加而逐渐下降。速率的下降归因于光学滤光效应,产物对254 nm辐射具有更高的消光系数,吸收了一些与聚合物直接竞争的入射辐射。根据模型对结果进行了分析,该模型允许适当降低聚合物的吸收率,并观察到实验数据与理论预测之间的良好相关性。讨论了其他可能有助于明显抑制发色团形成的因素,并评估了它们的影响。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
The effects of degradation products on the rates of photo-reactions in polystyrene films

Polystyrene films have been exposed to 254 nm radiation under high vacuum at 25°C. The time evolution characteristics of new ultraviolet-absorbing chromophores have been examined; in particular, increased absorptions at 240 nm and 400 nm have been measured. Whilst the initial rates of increase in these absorbances are relatively rapid, they are not maintained, and decline gradually with increasing irradiation. The fall-off in rates has been attributed to an optical filter effect, the products, which have higher extinction coefficients for 254 nm radiation, absorbing some of the incident radiation in direct competition with the polymer. The results were analysed in terms of a model which allowed for an appropriately reduced rate of absorption by the polymer, and a good correlation between experimental data and theoretical prediction was observed. Other factors which could contribute to the apparent inhibition of chromophore formation are discussed, and their effects assessed.

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