高分子科技英语第四节.pdf

高分子材料工程专业英语(2) 李文 材料科学与工程学院高分子材料系 2014年12月9 日，第四周 Schedule of the Lecture Unit 25. Thermal Properties of Polymers ? Article Interpretation ? Introduction of Scientific Articles (Structure, Finding Reading) Unit 25: Thermal Properties of Polymers 1st-2nd paragraph The heat stability is closely related to the transition and decomposition temperature, i. e. to intrinsic properties. By heat stability is exclusively understood the stability (or retention) of properties (weight, strength, insulating capacity, etc.) under the influence of heat. The melting point or the decomposition temperature invariably form the upper limit; the “use temperature” may be appreciably lower. 倒装强调句 The way in which a polymer degrades under the influence of thermal energy in an inert atmosphere is determined, on the one hand, by the chemical structure of the polymer itself, on the other hand, by the presence of traces of unstable structures. (聚合物)的热稳定性与转变和分解温度紧密相关，也就是说，与(聚合物)固有的性质有关。通 过热稳定性可以完全理解诸如重量，强度以及绝缘能力等在热作用下的稳定性(或保留率)。熔 点或分解温度一定是上限，使用温度明显的可以更低。 在惰性气氛中，热能影响下，聚合物降解取决于两方面，一方面是其本身的化学结构，另一方 面，所存在的少量不稳定结构。 1. Be closely related to … 与…密切相关 Be associated with… Be bound up with… 2.on the one hand, …, on the other hand…一方面….另一方面…. Unit 25: Thermal Properties of Polymers 3rd-4th paragraph Thermal degradation does not occur until the temperature is so high that primary chemical bonds are separated. For many polymers thermal degradation is characterized by the breaking of the weakest bond and is consequently determined by a bond dissociation energy. Since the change in entropy is of the same order of magnitude （数 量级） in almost all dissociation reactions, it may be assumed that also the