PDMS在大振幅剪切流动中的壁面滑移  

Wall Slip of Polydimethylsiloxane in Large Amplitude Oscillatory Shear

作　　者：廖华勇[1] 范毓润[1] 

机构地区：[1]浙江大学流体传动及控制国家重点实验室

出　　处：《材料科学与工程学报》2008年第3期375-379,共5页Journal of Materials Science and Engineering

基　　金：国家自然科学基金资助项目(10472105);教育部博士点专项基金资助项目(20050335050)

摘　　要：本文采用旋转流变仪研究了聚二甲基硅氧烷(PDMS)在两平行板间的大振幅剪切流动,其中的关键参数是应变幅值和角频率。随应变幅值增加,依次观察到没有波形畸变→明显的波形畸变→波形畸变减弱直至消失,对应着熔体与壁面之间的粘附→弱滑移→粘附/滑移→强滑移。同时角频率增加,样品的非线性增加,滑移也增强。从应力的间距依赖性和波形畸变等力学响应角度讨论了大振幅剪切流中的壁面滑移现象,同时使用应力分解的方法对大振幅剪切流中样品的非线性强弱进行了度量,提出了PDMS在大振幅剪切流中的动力学图谱。Large Amplitude Oscillatory Shear（LAOS） of the melt of polydimethylsiloxane （PDMS） was studied experimentally by using a rotational rheometer with parallel plates fixtures. As the strain amplitude increased, no→obvious→ decreasing even obsolescent wave form distortion in sequence were observed, which showed that stick→weak slip→stick/slip →strong/full slip even unsteady flow occurred between the melt and the wall. As angular frequency increases, both nonlinear viscoelasticity and slip increases. Wall slip phenomenon was studied by investigating the gap-dependence of the shear stress and the wave form distortion. At the same time the nonlinear viscoelasticity in LAOS was measured by using the stress decomposing method proposed by Cho et al. ＇s. A dynamic spectrum concerning two key parameters of the strain amplitude and angular frequency was shown to predict the flow behavior in LAOS. It was found that the higher the angular frequency was, the earlier and more severe wall slip occurred.

关 键 词：大振幅剪切流 壁面滑移 波形畸变 动力学图谱 

分 类 号：O373[理学—流体力学]