热重分析
热重分析
降级(电信)
化学
X射线光电子能谱
傅里叶变换红外光谱
热稳定性
天然橡胶
化学分解
高分子化学
双键
水溶液
扫描电子显微镜
衰减全反射
核化学
红外光谱学
化学工程
材料科学
有机化学
复合材料
无机化学
分解
工程类
电信
计算机科学
作者
Susanta Mitra,Afshin Ghanbari‐Siahkali,Peter Kingshott,Søren Hvilsted,Kristoffer Almdal
摘要
Abstract The chemical degradation of an uncrosslinked pure fluoroelastomer (FKM; Viton A) in an alkaline environment (10% NaOH and 80 °C) was investigated. Scanning electron microscopy images showed that on a microscopic level, significant degradation substantially increased the surface roughness after prolonged exposure (e.g., 12 weeks). The molecular mechanisms of the chemical degradation processes at the surface were evaluated with X‐ray photoelectron spectroscopy and attenuated total reflectance/Fourier transform infrared spectroscopy. The results revealed that the early degradation proceeded primarily via dehydrofluorination reactions, creating double bonds in the rubber backbone. This further accelerated the degradation after longer exposure times. Furthermore, the resulting double bonds underwent nucleophilic attack by an aqueous NaOH solution to form several oxygenated species. All these species ultimately recombined to form crosslinks, as evidenced by the increase in the gel fraction and surface hardness (Shore A). The pronounced effect of chemical degradation through a reduction in the thermal stability of the pure FKM rubber upon exposure was also evident from thermogravimetric analysis and differential thermogravimetry. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 6216–6229, 2004
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