润湿脊发展动力学与聚合物薄膜黏弹性的关系研究

发布时间：2018-02-28 14:44

  本文关键词： wetting ridge 聚苯乙烯 薄膜 黏度 平台模量 黏流温度　出处：《浙江理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：聚合物薄膜黏弹性是其分子运动的宏观体现,对于聚合物纳米材料的性能调控及加工成型具有重要意义。由于纳米受限效应,聚合物薄膜具有与本体不同的黏弹响应行为。聚合物薄膜黏弹性的测量一直是学术界研究的焦点和难题之一。因此,开发聚合物薄膜黏弹性研究的新方法对于探究聚合物薄膜分子运动的微观机制以及完善受限高分子运动理论具有重要意义。本论文研究了聚苯乙烯(PS)薄膜的黏弹性与其表面wetting ridge的形成及发展过程的关系。所得结论如下:(1)通过研究wetting ridge的发展动力学开发了一种原位测量聚合物薄膜黏度的新方法。以550nm的聚苯乙烯(PS)膜为研究对象,研究了不同温度下在离子液体表面张力作用下产生的PS膜表面wetting ridge的形成及发展过程。发现wetting ridge高度随液滴作用时间逐渐增大,时间足够长时,wetting ridge高度随时间呈线性增长。研究了在不同温度下不同分子量PS膜表面wetting ridge高度与时间线性增长部分的斜率(k),并关联了线性斜率k与相对应的温度及分子量下PS的黏度(η)的关系,发现二者满足公式:η=0.37γsinθ/k。改变离子液体的表面张力,发现两种表面张力不同的离子液体所得的1/k与η均满足这一公式。这一结果表明通过监测wetting ridge形成及发展过程是一种研究聚合物膜黏度的有效方法。(2)利用上述方法研究了不同基底上PS薄膜黏度的厚度依赖性。结果发现,Si O2上PS薄膜的黏度随厚度的降低而降低,Si-H上PS薄膜黏度随厚度降低而升高,这是PS与基底之间的界面效应导致的,与文献报道相符;薄膜黏度产生厚度依赖性的临界厚度为10Rg,也与文献报道相符。结果说明这一新的方法可以敏感的反映薄膜厚度及基底性质对薄膜分子链整链运动的影响,是一种探测聚合物薄膜及超薄膜黏度的有效方法。(3)通过不同温度下wetting ridge的高度变化研究了聚苯乙烯(PS)膜力学性质与温度的关系,发展了研究聚合物膜平台模量及黏流温度的新方法。研究发现,wetting ridge高度与温度的关系曲线(h-T曲线)与聚合物的形变温度曲线类似。Wetting ridge的h-T曲线中存在平台区域,在这一区域内wetting ridge的高度保持恒定,不受温度、PS分子量的影响。利用Wetting ridge的平台高度可以估算PS的平台模量(~105.85Pa),其值与文献报道的模量值基本相同。同时,wetting ridge的平台区域结束的临界温度(T*)与PS的黏流温度(Tf)满足相同的分子量依赖性,并且满足Tf=T*+10℃的定量关系。T*随液滴作用时间增长而降低,二者关系满足Arrhenius方程,得到与T*相关的活化能,其值与PS的黏流活化能一致。该结果进一步证明T*与PS的黏流形变相关,与Tf具有相似物理意义。
[Abstract]:The viscoelasticity of polymer film is the macroscopical embodiment of its molecular motion, which is of great significance to the performance control and processing of polymer nanomaterials. The viscoelastic response behavior of polymer film is different from that of bulk film. The measurement of viscoelasticity of polymer film has always been one of the focuses and problems in academic research. It is important to develop a new method to study the viscoelasticity of polymer films. In this paper, the viscoelastic properties of PS / PS films are studied in order to explore the micro mechanism of molecular motion and improve the theory of confined polymer motion. The relationship between the properties and the formation and development of wetting ridge on the surface. The conclusions are as follows: 1) A new method for in-situ measurement of viscosity of polymer films has been developed by studying the development kinetics of wetting ridge. The formation and development of wetting ridge on the surface of PS film under the action of surface tension of ionic liquid at different temperatures were studied. It was found that the height of wetting ridge increased with the time of droplet action. When the time is long enough, the height of wetting ridge increases linearly with time. The slope of wetting ridge height and time linear increasing part of PS film surface with different molecular weight at different temperature is studied, and the linear slope k is correlated with the corresponding temperature. And the relationship between the viscosity (畏) of PS at molecular weight, It is found that both of them satisfy the formula: 畏 0. 37 纬 sin 胃 / k. change the surface tension of ionic liquids, It is found that 1 / k and 畏 of two ionic liquids with different surface tension satisfy this formula. The results show that monitoring the formation and development of wetting ridge is an effective method to study the viscosity of polymer membranes. The thickness dependence of PS film viscosity on different substrates was studied. The results show that the viscosity of PS films on Si-H substrate decreases with the decrease of thickness, and increases with the decrease of thickness. This is caused by the interfacial effect between PS and substrate, which is consistent with the literature. The critical thickness of thickness dependence on film viscosity is 10Rg, which is consistent with the reported results. The results show that the new method can reflect the effects of film thickness and substrate properties on the whole chain motion of the film molecule. It is an effective method to detect the viscosity of polymer films and ultrathin films. The relationship between the mechanical properties and temperature of polystyrene (PS) films has been studied by the height variation of wetting ridge at different temperatures. A new method for studying the modulus and viscous flow temperature of polymer membrane platform is developed. It is found that there exists a platform region in the h-T curve of wetting ridge height and temperature) and the deformation temperature curve of polymer is similar to that of ridge. The height of wetting ridge remains constant in this area. The platform modulus of PS can be estimated by using the platform height of Wetting ridge, which is basically the same as that reported in the literature. At the same time, the critical temperature at the end of the platform region of the wetting ridge can be estimated by the critical temperature of the end of the platform region and the viscosity flow of PS can be estimated by using the platform height of Wetting ridge. The temperature Tf) satisfies the same molecular weight dependence. The quantitative relationship of TfN and T* 10 鈩，

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