OXIDATIVE DAMAGE AND RECOVERY OF SILICONE-RUBBER SURFACES .1. X-RAY PHOTOELECTRON SPECTROSCOPIC STUDY
OXIDATIVE DAMAGE AND RECOVERY OF SILICONE-RUBBER SURFACES .1. X-RAY PHOTOELECTRON SPECTROSCOPIC STUDY
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DOI：
10.1002/app.1994.070520914
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发表时间：
1994-05-31
影响因子：
3
通讯作者：
SZAPLONCZAY, P
中科院分区：
文献类型：
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作者：
TOTH, A;BERTOTI, I;SZAPLONCZAY, P
采用x射线光电子能谱（XPS或ESCA）研究了射频或电晕放电获得的空气等离子体中硅橡胶表面的氧化降解和随后的恢复过程。使用相对较短的处理时间（5分钟），发现表面氧含量增加，碳含量减少。在1天内观察到对原始成分的一些恢复，但远未完全恢复。与角度相关的测量显示，最上层几乎完全恢复。溶剂萃取样品的表面降解程度远高于非萃取样品，而其回收率远小于非萃取样品的相应特征。根据GC和GC- ms分析，提取物含有环状和少量线性二甲基硅氧烷低聚物的混合物。基于上述结果，对硅橡胶表面的氧化损伤和随后的恢复过程提出了以下步骤：首先，去除大部分表面甲基，出现含有与3或4个氧结合的Si原子的氧化层。由于低分子量组分从体块中迁移，表面随后被一层非常薄（2-3纳米厚）的“硅油”层覆盖。这种扩散控制的迁移步骤在恢复过程中比新形成的极性基团最终从表面向体重新定向发挥更重要的作用。结合已发表的数据对所提出的模型进行了讨论。(C) 1994 John Wiley & Sons, Inc。
The oxidative degradation of silicone rubber surfaces in air plasmas obtained by RF or corona discharges and the subsequent recovery process were studied by X-ray photoelectron spectroscopy (XPS or ESCA). Using relatively short treatment times (5 min), the surface oxygen content was found to increase and that of carbon to decrease. Within 1 day some recovery toward the original composition was observed, but it was far from being complete. Angle-dependent measurements have shown an almost total recovery in the topmost layer. The degree of surface degradation of a solvent-extracted sample was much higher while its recovery was much smaller than the corresponding features of the nonextracted sample. According to GC and GC-MS analyses the extract contained a mixture of cyclic, and, in a minor quantity, linear dimethylsiloxane oligomers. Based on the above results the following steps were proposed for the oxidative damage and the subsequent recovery processes on silicone rubber surfaces: first the majority of surface methyl groups is removed and an oxidized layer containing Si atoms bound to 3 or 4 oxygens appears. The surface is later covered by a very thin (2-3 nm thick) ''silicone oil'' layer due to migration of low-molecular-weight components from the bulk. This diffusion-controlled migration step plays a more important role in the recovery process than the eventual reorientation of the newly formed polar groups from the surface toward the bulk. The proposed model is discussed in the light of published data. (C) 1994 John Wiley & Sons, Inc.