共连续型高分子共混物性能预测模型的研究进展

共连续结构是不相容高分子共混物体系中的典型相结构。共连续共混物的机械性能、热性能、电性能以及阻隔性能等均由于两相的协同作用而得到显著改善。预测共连续共混物的性能无论是在工业生产还是在学术研究上都具有重要的意义。本文针对共连续共混物目前常用的性能预测模型进行了总结归纳,包括串并联模型、Kerner模型、Davies模型、...     

聚合物共混：Ⅰ.聚合物共混物的制备方法

本讲主要介绍聚合物共混物的制备方法,其中包括熔融共混、溶液共混、胶乳共混、冷冻干燥共混、接技共聚共混、互穿聚合物网络、就地反应型共混、分子共混等.     

填料对聚合物共混物相分离行为的影响

近年来,由于粒子填充聚合物共混物的广泛运用,复合材料的结构研究具有重要意义.除了研究粒子在聚合物中的分散外,关于粒子对聚合物共混物的相分离影响也做了大量工作.研究结果表明粒子的尺寸,粒子的表面处理以及粒子含量对聚合物共混物相分离热力学以及动力学有重要影响.由于粒子对聚合物组分的选择吸附、聚合物分子对粒子的润湿作用、填料对聚合物相区生长的阻碍导致了聚合物共混物-填料体系相行为的复杂性.本文扼要地综述了聚合物共混物-填料体系相分离的理论基础以及实验结果,介绍了粒子对相分离的影响因素,并展望了该领域的研究趋势和前景.     

Blends of poly(carbonate) with poly(styrene) and poly(methylmethacrylate): phase morphology,mechanical, and thermal properties

This paper is concerned with the dependence of mechanical and thermal properties of heterogeneous blends of poly(carbonate) (PC) with poly(methyl-methacrylate) (PMMA) and with poly(styrene) (PS) on the concentration of the components. PS displays a very weak phase coupling in blends with PC, whereas PMMA is characterized by a strong coupling to PC. Experimental results as well as predictions based on composite theories are reported. The general finding is that mechanical properties, such as the tensile modulus and the dynamic shear modulus, as well as thermal properties, such as thermal expansion, are (i) only weakly affected by the occurrence of a phase inversion and of a continuous phase morphology, (ii) vary continuously with the concentration of the components, and (iii) are rather insensitive to the strength of the phase coupling. The theoretical predictions on the concentration—property relationship for these properties, based on a self-consistent approach, agree very well with those observed experimentally. The elongation at break as well as the yield stress, on the other hand, are strongly influenced by the nature of the phase coupling: a discontinuous variation of these properties with the composition is observed for PS/PC blends but not for PMMA/PC blends. The general conclusion is that a set of mechanical and thermal properties of heterogeneous blends can satisfactorily be predicted on the basis of rather simple composite theories.     

聚合物共混物的相容性及相分离

综述了聚合物共混物相容性和相分离的研究现状。介绍了聚合物共混物的相容性理论,影响相容性的因素及改善和相容性的方法和表征相容性的手段。聚合物共混物的相分离机理制约着材料的性能,旋节分离和成核－增长相分离分别形成不同的形态结构。旋节分离和成核－增长相分离所对应的动力学过程是不同的,散射光强与相分离时间分别满足指数和幂指数关系。     

Co-continuous phase structure formed in melt processing inducing shear bands to prevent crack propagation: Significant improvement in impact toughness of PMMA

High toughened polymeric materials have a wide application in many fields. Poly(methyl methacrylate) (PMMA) is a typical brittle polymer and it has been difficult to prepare high toughened PMMA material for a long time. To work on this issue, co-continuous phase structure was devised in PMMA/chlorinated polyethylene (CPE) blends through controlling the interfacial tension and viscosity in this work, resulting in the pronounced enhancement of impact toughness. The notched impact strength of co-continuous blends with 40 wt% CPE was up to 28.5 kJ/m², increased by 26 times compared with pure PMMA. Selective extraction experiments, scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) showed that the CPE network was thin and weak when CPE addition was low, but became dense and strong once the content was more than 20 wt%. Two toughening mechanisms, i.e. cavitation and shear yielding, were put forward based on the micrographs of impact-fractured surfaces and double-notch four-point-bending test. This work may broaden the application prospects of PMMA and provide a new strategy to prepare high toughened polymeric materials through fabricating co-continuous in polymer blends.     

Novel Hierarchic Structures in Polymer Blends

We use computer simulations to investigate the dissolution and phase separation process in polymer blends. In particular, we take initial cylindrical and spherical structures and allow them to dissolve in the one phase region. Before the structure can completely dissolve, however, we thrust the system into the two-phase region. Phase separation then occurs such that hierarchic structures are formed both inside and outside the confines of the original structure. These novel hierarchic structures can be of significant technological importance.     

提高聚合物共混相容性的反应性聚合物

反应性聚合物作为聚合物共混的增容剂受到越来越广泛的重视。本文论述了该类反应性聚合物的制备，分类及研究开发现状，并结合实例讨论了其增容作用效果。     

聚合物共混物的原位成纤复合

综述了近年来原位成纤复合材料的研究成果，简要论述了原位成纤机理，介绍了原位复合材料的流变性能、力学性能、形态及形态分布、结晶熔融行为以及影响形态、性能的因素。     

共聚物在聚合物共混体系中的增容作用I.嵌段共聚物

随着高分子合金领域的研究发展，以共聚物作为增容剂对不相容的聚合物共混体系进行改性已得到了广泛的研究和应用。本文分为两篇，分别介绍利用嵌段共聚物、接枝共聚物和无规共聚物所做的增容改性研究。本篇着重讨论嵌段共聚物(包括两嵌段和三嵌段以及多嵌段共聚物)在聚合物共混体系中的增容作用和增容机理。     

Preferential Partition of Nanowires in Thin Films of Immiscible Polymer Blends

Summary: The preferential partition of silver nanowires in thin films of polystyrene/poly(vinyl pyrrolidone) (PS/PVP, with a 30/70 weight ratio) blends, that induces drastic blend morphology variation, is reported. The silver nanowires are fabricated with the anodic aluminum oxide templating method, and have a diameter of 300 nm and length of 10 µm. At a higher nanowire loading of 10 wt.‐%, the silver nanowires are entangled and selectively concentrate within the continuous PVP domain. If surface modified by thiols carrying hydrophobic tails, the silver nanowires become hydrophobic and prefer to stay within the discrete hydrophobic PS domains. At a lower nanowire loading of 5 wt.‐%, the nanowires are non‐entangled and concentrate at regions near the interfaces of the PS and PVP phases, which induces the formation of interconnected PS domains.

Preferential partition of silver nanowires in thin films of PS/PVP (30/70) blends at a casting temperature of −10 °C.     

显微镜图像分析研究非相容高密度聚乙烯/尼龙1010共混体系熔体动态过程中相结构的形成与发展

讨论了非相容高密度聚乙烯,尼龙1010共混体系在熔融混炼过程中相结构的形成与发展.应用在线连续采样方法,获得共混过程中体系不同时刻的样品,应用扫描电子显微镜观察并得到共混物相结构的显微图像.用图像处理和图估计方法求得了体系分散相平均粒径和粒径分布宽度,讨论了平均粒径和分布宽度随混炼时间的变化.结果表明,共混物相结构的变化主要发生在混炼初期,即混炼两分钟以前,之后平均粒径和分布宽度趋于平稳,保持在一定数值范围内.引入分性概念,应用测度法计算了体系的分形维数,表明体系相结构的变化具有自相似性,分形维数的变化与体系的均匀性有关.同时,研究了混炼温度和混炼设备的转速(剪切速率)与体系分散相平均粒径、分布宽度和分形维数等结构参数的关系.     

剪切流动对共混物相行为影响的研究进展

介绍了国外８０年代以来开展的剪切流动对聚合物共混物相容性影响的研究概况，并着重介绍了采用最新的二维小角激光散射流变仪和光学显微流变仪对共混物体系在剪切应力作用下相行为的研究结果，反映了该前沿领域的最新进展。     

多组分聚合物体系中的相容和络合

在含可控特殊相互作用的多组分聚合物体系中，随着体系中的相互作用密度的增强，体系在本体中可经历由不相容到相容直至络合的不同物理状态。本文概述了相容、络合研究的进展，着重讨论了相容和络合的区别和联系，提出了含氢键相互作用的高分子共混体系中相容－络合转变存在的普遍性。     

聚合物共混相态形成过程及其理论研究进展

聚合物共混过程中相态的形成及变化规律是近年来研究热点问题,这一动态过程将决定静态材料的结构与性能.聚合物共混形态结构发展的机理有初期破碎、中期分散及后期归并等机理.在共混初期,分散相尺寸较大,以细化为主.随着混合时间的增加,分散相逐渐细化,尺寸越来越小,细化也越来越难,在应力场的作用下,分散相粒子可能因碰撞而发生归并,归并与细化将逐渐达到平衡而形成稳定的结构.在混炼后期,剪切力减小,粒子发生有效碰撞归并概率增大.     

共混聚合物辐射效应研究的进展

本文综述了近十几年来国内外共混聚合物辐射效应研究的进展情况.内容包括辐射交联理论在共混聚合物体系中的适用性、共混体系的相容性、相态结构对辐射效应的影响及共混组份间的辐射敏化及保护效应等.     

浸没凝胶相转化制备聚合物膜的孔结构及其形成机理

全面地综述了浸没凝胶相转化法制备的聚合物微孔膜的表面和膜中存在的各种孔的结构和形态,从制膜体系的热力学性质和成膜动力学角度解释了各种孔结构形态的形成和生长机理,即膜表面与膜中孔的结构形态由此时制膜体系发生的相分离类型决定,由此可推断出不同的膜层可能有不同的成膜机理。因此,只要掌握了各种膜孔结构形成的机理,通过改变膜的制备条件,控制体系的热力学性质与成膜时动力学扩散是可以实现相转化膜结构的控制。     

Effect of POSS on morphology and properties of poly(2,6-dimethyl-1,4-phenylene oxide)/polyamide 6 blends

Poly(2,6-dimethyl-1,4-phenylene oxide)/polyamide 6 (PPO/PA6) (50/50 w) blends filled with epoxycyclohexyl polyhedral oligomeric silsesquioxane (POSS) were prepared via melt-mixing. The reactions between POSS and PPO/PA6 blends were studied by Fourier transform infrared spectroscopy, end group and gel content tests. The morphology of PPO/PA6/POSS composites was observed by field emission scanning electron microscope and transmission electron microscope. As a chain extender and a crosslinking agent for PA6, POSS largely affected the morphology of the composites, which was mainly dependent on the melt-viscosity ratio and interfacial tension between the components. With increasing POSS content from 2 to 4 phr, the morphology of the composites transformed from droplet/matrix to co-continuous morphology. The PPO/PA6/POSS composites with co-continuous morphology had the better mechanical properties than those with droplet/matrix morphology. Dynamic mechanical thermal analysis showed that the addition of POSS increased the T_g of PA6.     

Preparation of Core‐Sheath Nanofibers from Conducting Polymer Blends

Summary: Core‐sheath nanofibers with conductive polyaniline as the core and an insulating polymer as the sheath were prepared by electrospinning of blends of polyaniline with either polystyrene or polycarbonate. These unique core‐sheath structures offer potential in a number of applications including nanoelectronics. When polyaniline was blended with poly(methyl methacrylate) and poly(ethylene oxide), only isolated domains of polyaniline in beadlike structures were formed. The phase morphology of electrospun fibers is thought to be dependent on the high‐surface tension of the solution and the molecular weight of the polymers. Incompatibility of the polymers and low molecular weight of compositions played a key role in the formation of core‐sheath structures, as opposed to co‐continuous morphologies.

TEM image of electrospun polyaniline/polystyrene nanofiber after staining by OsO₄. The dark regions are polyaniline.     

聚合物多相复合体系的结构和内耗行为特征

描述了聚合物共混物及纤维增强聚合物基复合体系的内耗研究现状，并着重分析了内耗行为与微观结构的相关性。目前迫切需要解决的问题包括对内耗微观机制的研究，建立起适当的模型，并赋予特征参数以明确的物理意义。