针对运行在温差较大、紫外辐射较强条件下的室温硫化硅橡胶(RTV),设计了高低温交变和紫外线辐射试验,采用静态接触角法研究了RTV的憎水性变化,并借助傅里叶变换红外光谱(FTIR)和差示扫描量热法(DSC)分别分析了RTV典型官能团和物化特性变化.结果表明:RTV试片在-20~120℃下进行高低温交变试验后,试片憎水性均优于未老化的RTV试片,且老化10天的试片接触角变化幅度较大,静置120 h后的接触角大于老化20天的试片.随着恢复时间的延长,接触角呈先减小后增大最后逐步趋于平稳的趋势,表面有微量Si-OH形成,且在试片中生成了耐热性差的副产物.RTV试片经UVA-340紫外辐射后,憎水性优于未老化试片,但紫外辐射20天的试片比辐射10天的试片憎水性差.随着恢复时间的延长,试片的憎水性呈先减弱后增强最后趋于平稳的趋势.在RTV表面,Si(CH3)3和O-H基团均有所下降,且耐热性差的成分减少.
Aiming at the room temperature vulcanized silicone rubber (RTV) operating in environment of large temperature difference and intensive ultraviolet radiation, a high-low temperature alternating experi-ment and an ultraviolet radiation experiment were designed. The hydrophobicity of RTV was investigated by static contact angle method. Besides, the variation of functional groups and physicochemical properties of RTV were studied via FTIR and DSC. The results show that the hydrophobicity of RTV after the high-low temperature alternating experiment under -20~120℃ is better than that of the un-aged sample, the contact angle of the sample aged for 10 days changes a lot, and its contact angle is larger than that of the sample aged for 20 days after standing for 120 h. With the extension of recovery time, the con-tact angle decreases at first then increases and finally tends to be stable. After the experiment, Si-OH group and by-products with poor thermal resistance are observed in the sample. After UVA-340 ultravio-let radiation experiment, the hydrophobicity of RTV sample is better than that of the un-aged sample, but the hydrophobicity of RTV aged for 20 days is worse than that aged for 10 days. With the exten-sion of recovery time, the hydrophobicity decreases at first then increases and finally tends to be stable.The content of Si(CH3)3 and O-H on the RTV surface decrease, and the poor thermal resistance composi-tions decrease also.
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