【作者】 黄亚江；

【导师】 李光宪；

【作者基本信息】 四川大学 ， 材料加工工程， 2007， 博士

【摘要】 聚合物共混物研究与应用的核心目标是通过不同的手段（组分性质、加工参数等）来调控得到特定的共混物形态结构，以获得所需的材料性能。多相聚合物共混物的结构不仅与热力学因素有关，在外界流场和外界表面（例如基板、无机填料粒子）的存在条件下还能够呈现出丰富多彩的动力学响应。因此，研究复杂多因素耦合条件下聚合物共混物的相行为对于发展有效的加工成型方法、实现多组分材料性能的最优化和可控化具有重要的理论和实践意义。本论文首先借助剪切-显微装置在线研究了静态和简单剪切场下不相容聚合物共混物的分散结构和共连续结构的实时演变过程。以此为基本出发点，首次考察了粒子填充不相容体系的分散结构的在流场下的动力学响应。然后，研究了对两种具有不同粘弹特性的部分相容体系，即聚甲基丙烯酸甲酯/苯乙烯-丙烯腈共聚物（PMMA/SAN）和聚苯乙烯/聚甲基乙烯基醚（PS/PVME），在添加无机填料后的热力学稳定性，并将实验结果结合相应的粒子增容理论预测进行了相应的比较和讨论；考察了无机填料对具有粘弹反差的PS/PVME体系在粘弹相分离过程中结构演变的影响。最后，通过介观模拟技术考察了二元混合物在外界表面（填料、基板）和复杂温度条件下的结构生成。本论文的主要研究工作和结论如下：1．不相容聚合物共混物在剪切场下的结构演变a)以尼龙6（PA6）/PS和PS/高密度聚乙烯（HDPE）两种共混物为模型体系，对测定界面张力的三种实验方法进行了比较和讨论，开发了一套测定共混物界面张力的工具软件；并考察了变形液滴和纤维在高温下的形状稳定性及松弛过程；b)提出了利用平板剪切装置和光学显微镜来研究简单剪切场下分散相变形和取向的新方法，并测定了PA6分散相在不同剪切速率下的瞬态取向角；研究了剪切场下PA6分散相在经历破碎、凝聚之后的尺寸及其分布，从而确定了PA6/PS体系在230℃下的Elmendorp图；c)实验发现在剪切场下PS/HDPE共混体系可以形成核．壳液滴结构，并首次对核-壳结构粒子的变形、松弛和破碎行为进行了相应的观察，提出了剪切流场下核壳液滴的结构演变机理，为进一步在二元共混物体系中控制核-壳结构的生成、研究核壳粒子对共混物力学性能的影响提供了前期理论和实验支持；d)首次对简单剪切场下聚合物共混物在熔体共混早期分散相结构的演变进行了在线可视化研究，发现整个过程可以划分为薄膜的生成、孔洞生长、瞬态网络结构的生成以及网络结构的破碎等几个基本步骤。从实验角度估算了熔体薄膜的临界破碎厚度，确定了孔洞的线性扩张速率，并从解润湿的角度推导出相应的理论预测公式，发现孔洞扩张速率取决于共混物的界面张力和基体相的粘度。研究共混过程中熔体薄膜的形成和松弛过程为进一步了解共混物中组分的分散、共连续相结构的生成奠定了相应的理论和实验基础。2．填料对不相容聚合物共混物相结构的影响a)基于第2章的工作，本文进一步研究了微米级无机粒子对不相容的PA6/PS、PS/HDPE共混体系相结构的影响。发现SiO₂粒子使PA6分散相粒子在剪切场下更难变形，而且分散相在变形后的回缩动力学大大减慢。SiO₂的引入提高了纤维的临界断裂长径比，增强了PA6纤维的稳定性。通过液滴的回缩过程计算了SiO₂的引入对PA6分散相粘度的改变，并对填充分散相动力学减缓及形状稳定性提高的现象进行了解释；b)在低剪切速率下，填充SiO₂的PA6/PS体系分散相尺寸增长更快；SiO₂的加入对PA6分散相凝聚行为的改变可以归结于SiO₂提高了PA6分散相的熔体强度，使之在相同剪切速率下更难破碎；c)在剪切场下，SiO₂的填充使HDPE薄膜较难生成，而且SiO₂并不遵循理论预测迁移进入PS相中，而是可能分布在HDPE内部和两相的界面处；粒子对HDPE粘度的改变以及粒子在PS/HDPE界面铆接作用使孔洞生长速率明显减慢。3．填料对部分相容共混物体系相稳定性的影响a)对于动力学对称的PMMA/SAN部分相容体系，利用光学和流变学方法考察了微米级SiO₂填料粒子对其热力学稳定性的影响。发现选择性填料的引入提高了共混物相分离的温度，而利用Lipatov和Ginzburg提出的关于粒子增容的理论并不能解释填料对体系的热力学稳定性的改善；b)对于动力学不对称、强粘弹反差的PS/PVME部分相容体系，微米级SiO₂并没有对其热力学稳定性产生明显的影响，只影响着体系的粘弹相分离过程。PS/PVME体系的粘弹相分离过程受到体系组成和温度的影响；非临界的PS/PVME体系在发生逾渗．粒子转变（PDT）之后可以观察到明显的孔洞生长过程；粘弹相分离产生的孔洞在扩展过程中对周围的相区结构有强烈的取向效应；由于SiO₂对PVME的选择性吸附，粘弹相分离的孔洞更容易在粒子的表面产生。4．外界表面存在条件下二元共混物相行为的介观模拟a)本论文采用高效率的元胞动力学模型研究了外界表面（基板、填料）存在条件下二元共混物相分离的过程。基板和填料的引入改变了其表面附近的相结构，分别引发平行结构和环带结构。引发结构的生成与共混物体系的组成、体系初始组成波动幅度等因素有关。b)发现通过两步淬冷，临界组成和非临界组成的单纯二元共混物体系都可以形成层状相结构。相比一步深度淬冷而言，在两步淬冷过程中基板附近可以引发更加明显的平行结构，而在远离基板的区域，层状相依然存在。不可移动的填料粒子在两步淬冷时可以引发更加明显的环带组成波。填料粒子含量的增多导致本体层状相结构和组成波的消失。通过引入扩散限制聚集模型（DLA）产生的粒子束，模拟考察了粒子束对二元共混物相结构的影响，发现粒子束可以引发外围的轮廓结构，为研究实际情况下填料聚集体对共混物相结构的影响奠定了初步的理论基础。更多还原

【Abstract】 The main aim in the research and application field of polymer blend is to tailor the structure of multiphase materials by various means, such as component ratio and processing parameter. Besides the thermodynamics of system, the presence of an external flow field or an external surface will also contribute to the various kinetically behavior of polymer blends. Thus, to obtain better understanding about the phase behavior of multiphase under complex coupling conditions, and to find better optimum organization of structure is of significant importance both in theoretical research and industrial application.This dissertation focused on the structure formation of both immiscible and miscible blend in the presence of shear flow or external surface （including fillers and substrate）. Optical-Shear technique was utilized to study the structure evolution of two model immiscible polymer under shear and quiescence conditions. And then, the deformation and relaxation dynamics of filled dispersed phase in polymer blend were investigated for the first time. The thermodynamics stability of two partial miscible polymer blends with distinct viscoelastic characteristics was probed. Theoretical prediction accounting for the impact of inorganic fillers on the miscibility was compared and discussed with experimental result. Finally, mesoscopic simulation was performed to examine the pattern formation of binary blend in the presence of filler, substrate and complex temperature history. The main contents and conclusions are listed as follows: 1. The structure of immiscible polymer blends under shear flow. （a） Three methods for the measurement of interfacial tension were discussed and compared. Interfacial tension analysis software was developed and was utilized to obtain the interfacial tension of polyamide 6 （PA6）/polystyrene （PS） and PS/high density polyethylene （HDPE）. （b） A new method to measure the orientation angle of a deformation droplet on optical-shear setup was proposed. （c） Unique core-shell droplet was found in PS/HDPE dispersed blend. Systematical shear experiments were conducted to reveal the formation, relaxation and breakup behavior of core-shell droplets. The results were concluded as a dynamical morphology map. （d） The formation, breakup of HDPE melt film in PS matrix prior to the formation of co-continuous structure during the early stage of melt mixing was investigated in-situ. The development of hole on the film and the formation and disintegration of a melt network was visualized and discussed. A semiquantitative expression was derived to capture the physical nature of hole growth in a melt film immersed in another immiscible matrix.2. Morphology evolution of immiscible blends in the presence of fillers. （a） The incorporation of glass beads in the dispersed phase of PA6 made it difficult to deform under shear flow. Also, filled system shows slower relaxation dynamics. Upon the incorporation of SiO₂ particles, the critical break aspect ratio of PA6 at 230°C increased from 8.5 to 11. The results were discussed based on the increase in viscosity of PA6. （b）The SiO₂ particles accelerated the coalescence rate of dispersed phase in PA6/PS blend. The strong interaction between PA6 and SiO₂ particle was believed to be responsible for this change. （c） It was found that SiO₂-filled HDPE droplet was more difficult to form a melt film in PS matrix. The growth rate of hole in HDPE film was reduced greatly.3. Phase behavior of miscible blends with fillers. （a） The phase diagrams of a kinetically symmetric blend poly（methyl methacrylate） （PMMA） and poly（styrene-ran-acrylonitrile） （SAN） and a kinetically asymmetric polystyrene/poly（vinyl methyl ether） （PS/PVME）, were constructed with the aid of microscopy and rheology technique. The thermodynamics stability of PMMA/SAN was improved by selective fillers. The result was compared with the prediction of particle-compatibilizing theories based on modified Flory-Huggins equation, proposed by Lipatov et al. and Ginzburg. （b） The viscoelastic phase separation of PS/PVME blend showed distinct dependence on the component ratio and temperature. （c） SiO₂ particles with a diameter about 2.5μm did not change the phase diagram of PS/PVME. The wetting of PVME on SiO₂ particle initiated rapid hole growth near particle surface and destabilized the phase separating blend film.4. Simulation on the phase behavior of binary blend under the influence of complex thermal history and external surface. （a） By using cell dynamics system method, lamellar structure was found both in critical and off-critical blends which were subjected to a two-step quench. The formation of lamellar phase was ascribed to the existence of interface between two phases. （b） Parallel and target-like composition waves were initiated in the vicinity of a selective substrate and immobile fillers. The extent of composition wave was found to depend on the composition, temperature and initial composition fluctuation of system. （c） Under two-step quench conditions, the composition waves were more pronounced. Increasing the filler concentration suppressed the formation of lamellar structure in the bulk area and limited the range of composition wave near the filler surface. （d） Compositional waves were also formed in the vicinity of particle cluster produced by diffusion-limited aggregation （DLA） of fillers更多还原