振动力场下超微孔塑料发泡技术的研究

超微孔塑料是一种新型的高分子材料,与传统的泡沫塑料相比具有很多优异的性能.本文分析了影响超微孔塑料发泡挤出质量的因素,并从影响超微孔发泡挤出质量的动态因素出发,为了提高超微孔发泡挤出的质量,提出了一种超微孔塑料发泡挤出的新技术,即把振动力场引入到超微孔塑料发泡挤出的全过程的技术.     

微发泡弹性体材料的研究进展

微发泡弹性体材料是一种重要的高分子材料，它有其独特的微孔结构能够满足多方面的需要，因此也成为近来一段时间研究的热点。本文综述了其微孔成型机理及其制备微发泡弹性体材料的几个重要的方面即发泡剂的选择、发泡助剂的选择及交联过程和发泡过程的匹配，通过恰当的控制这几个方面，可以制得性能良好的微发泡弹性体材料。     

PET微孔发泡研究进展

聚对苯二甲酸乙二醇酯(PET0是一种常用的工程塑料,有许多优良的性能,微孔发泡后的PET材料性能得到显著改善.本文介绍了PET微孔发泡的研究进展,展望了PET微孔发泡材料的开发与应用前景.     

微孔发泡塑料的制备方法

微孔发泡塑料是采用特殊的制备方法加工的热塑性高分子材料，由于它减轻了材料的重量，赋予材料良好的力学性能等属于新型材料而迅速发展。综述了微孔发泡塑料的制备方法，讨论了各种制备方法的特点，展示了微孔发泡塑料的研究进展。     

高分子材料的微孔发泡方法

介绍了微孔发泡高分子材料的成型方法 ,成型原理和成型工艺及设备。     

不同聚丙烯材料共混的微孔发泡成型研究

聚丙烯(PP)熔体强度低,发泡性能差.将两种PP材料共混来改善PP的发泡性能,研究PP材料性质对共混体系微孔结构的影响.研究表明在各种发泡温度下使用纯PP材料很难制得泡孔结构好的微孔材料,而两种PP材料共混以后再进行微孔发泡,泡孔结构得到了改善.与两种相似熔点和黏度的PP共混材料相比,在高黏度的PP中混入少量的低熔点、低黏度PP时,可以制得泡孔结构更好的微孔材料.研究了共混比例对泡孔形态的影响,并从熔体黏弹性和结晶性能两方面分析了泡孔结构变化的机理.     

中国塑料专利

<正>专利名称:多用途高分子材料成型机专利申请号:CN200610108972.8公开日:2007.01.03本发明提供一种集RTM成型、SC-CO2辅助RTM成型、RIM成型、聚氨酯发泡成型、以SC-CO2为发泡剂的聚氨酯发泡和微孔发泡成型设备于一体的多用途高分子材料成型机。所述多用途高分子材料成型机由     

共混复合方式对PP/PP-g-MAH/MMT纳米复合微孔发泡材料力学性能及发泡质量的影响

采用双螺杆熔融共混法,以5种不同的共混复合方式制备聚丙烯/马来酸酐接枝聚丙烯/蒙脱土(PP/PP-g-MAH/MMT)纳米复合材料母粒.用化学发泡法注塑成型制备PP/PP-g-MAH/MMT纳米复合微孔发泡材料.探讨了不同共混复合方式对微孔发泡材料力学性能及发泡质量的影响.结果表明:不同的共混复合方式对纳米复合微孔发泡材料的力学性能和发泡质量均有影响.其中先将MMT和PP-g-MAH熔融共混,再与PP熔融共混制备的复合材料进行微孔发泡,其力学性能最优,发泡质量最好.     

微发泡塑料材料的应用概况

本文介绍了微孔发泡塑料材料的性能及应用现状，展望了微孔发泡塑料制品发展方向。     

微孔结构与本征韧性对微孔发泡聚丙烯冲击性能的影响

通过对不同本征韧性聚丙烯发泡和未发泡材料的冲击强度进行测试,系统研究聚丙烯本征韧性对微孔发泡材料冲击性能的影响.结果表明:发泡材料的冲击强度(ak)不仅与微孔的作用有关--包括裂纹扩展面上材料的有效截面积减少导致的冲击强度降低(αk1),以及微孔导致裂纹扩展阻力增加对冲击强度的贡献(αk2),而且材料的本征韧性对发泡材料的冲击强度也有影响(αk0),其微孔发泡材料的冲击强度可表述为:αk=αk0-αk1+αk2.     

微发泡聚合物材料的研究进展

微发泡聚合物材料是泡孔尺寸在微米级的一种新型高分子材料,因其独特的微孔结构能够改善制品的尺寸稳定性、收缩率等问题,已经成为近年来聚合物材料的研究热点。本文综述了微发泡成型研究机理,成型加工参数、纳米填料和发泡剂对微发泡聚合物材料结构与性能的影响,并对众多研究结果进行了分析,提出了未来微发泡聚合物材料的研究领域有待于进一步深入的研究方向,并对微发泡聚合物材料的研究及应用前景进行了展望,提出扩大工业应用的趋势是开发出微发泡聚合物母料来替代物理以及化学发泡。这些基础性的研究工作对于深入理解微发泡聚合物材料的形成机理及后续的应用研究具有非常重要的意义。     

微孔及纳米孔发泡材料研究进展

对聚合物微孔发泡基本过程、机理、聚合物微孔发泡的实施等进行了介绍,同时指出通过嵌段共聚物为载体可以制备纳米孔发泡材料。     

开孔型聚合物微发泡材料研究进展

通过回顾目前几种微孔材料成型的主要方法,介绍了微发泡成型技术用于制备开孔型微孔材料的必要性。讨论了关于开孔型聚合物微发泡材料制备技术及研究方法的几种思路,分别是不相容聚合物共混、泡孔合并模型、熔融挤出发泡、开孔剂法和气体浓度阈(值)等方法,这些方法的微孔成型机理各不相同,所制备的材料微观结构也各有特点。文献分析表明:微发泡成型方法用于开孔型微孔材料的制备是一种非常有前景的技术。     

Bubble Nucleation and Growth in Microcellular Injection Molding Processes

Bubble nucleation and growth are the key steps in polymer foam generation processes. The mechanical properties of foamed polymer are closely related to the size of bubbles created inside the material. Thus, it is necessary to study how to improve mechanical strength by producing extremely fine bubbles inside polymer resin. We developed a theoretical framework to help produce uniformly distributed microcellular bubbles and experimentally verified the theoretical analysis results using an injection molding machine modified to make microcellular foaming products.     

Changes in the Reflectivity and Color Characteristics of Microcellular Foamed Plastics

As the use of plastics has increased in various industries, research on microcellular plastics has increased as well. The microcellular foaming process helps produce lighter plastic and reduces material consumption. This process also affects the optical properties. The primary purpose of this study is to measure the visible changes occurring in polymer samples by comparing changes in the samples before and after the microcellular foaming process. To measure the changes in color characteristics, colored PC samples were utilized for the experiments. Changes in the color characteristics were indicated using the Munsell color system.     

Cell morphology and property relationships of microcellular foamed pvc/wood-fiber composites

Wood-fiber composites make use of cellulose fibers as a reinforcing filler in the polymer matrix and are known to have a lower material cost and a higher stiffness than neat polymers. However, the lower material cost and enhanced stiffness of wood-fiber composites are achieved at the expense of other properties such as the ductility and impact strength. Since microcellular plastics exhibit a higher impact strength, higher toughness, and increased fatigue life compared to unfoamed plastics, microcellular foaming of wood-fiber composites will improve the mechanical properties of the composites and therefore increase the usefulness of the materials. In this paper, microcellular foamed PVC/wood-fiber composites with unique cell morphology and material composition are characterized. Microcellular structures are produced in PVC/wood-fiber composites by first saturating the composite samples with CO₂ under high pressure followed by rapidly decreasing the solubility of gas in the samples. The void fraction of the microcellular foamed PVC/wood-fiber composites is controlled by tailoring the composition of materials and the foaming process parameters. The results indicate that tensile and impact properties of microcellular foamed PVC/wood-fiber composites are most sensitive to changes in the cell morphology and the surface modification of fibers.     

微孔塑料的成型原理、制备和最新发展

主要介绍微孔塑料的概念、发泡原理、发展简史和热诱导相分离法、单体聚合反应法、超饱和气体法、压缩流体反溶剂沉淀法四种常用的制备技术,并详细综述了国外在微孔复合材料、微孔生物医学材料、微孔橡胶材料和其它方面的最新发展动态及应用。     

振动力场对含有成核剂的微孔塑料泡孔结构的影响

在微孔塑料成型加工过程中,成核剂的加入可以增加泡孔成核点数量,从而增加泡孔密度,改善泡孔的结构,但如果纳米级成核剂在发泡过程中分散性不好,会使泡孔分布不均匀,影响泡孔质量。在实验中,对含有成核剂(纳米碳酸钙)的发泡材料(聚苯乙烯)施加振动场,通过比较发现,施加振动后,纳米级成核剂的分散效果明显改善,颗粒分布变得更均匀,从而使得泡孔分布更均匀,改善了泡孔的结构,提高了微孔塑料泡孔结构质量。     

Mathematical modeling and numerical simulation of cell growth in injection molding of microcellular plastics

A mathematical formulation and numerical simulation for non‐isothermal cell growth during the post‐filling stage of microcellular injection molding have been developed. The numerical implementation solves the energy equation, the continuity equation, and a group of equations that describe the mass diffusion of dissolved gas and growth of micro‐cells in a microcellular injection molded part. The “unit‐cell” model employed in this study takes into account the effects of injection and packing pressures, melt and mold temperatures, and super‐critical fluid content on the material properties of the polymer‐gas solution and the cell growth. The material system studied is a microcellular injection molded polyamide 6 (PA‐6) resin. Two Arrhenius‐type equations are used to estimate the coefficients of mass diffusion and solubility for the polymer‐gas solution as functions of temperature. The dependence of the surface tension on the temperature is also included in this study. The numerical results in terms of cell size across the sprue diameter agree fairly well with the experimental observation. The predicted pressure profile at the sprue location has also been found to be in good agreement with the dynamics of the cell growth. Whereas for conventional injection molding the pressure of the system tends to decay monotonously, the pressure profile in microcellular injection molding exhibits an initial decay resulting from cooling and the absence of packing followed by an increase due to cell growth that expands the polymer‐gas solution and helps to pack out the mold uniformly. Polym. Eng. Sci. 44:2274–2287, 2004. © 2004 Society of Plastics Engineers.