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。     

PVC微孔塑料的研究进展

阐述化学发泡剂、物理发泡剂和添加剂对PVC微孔发泡的影响,综述了PVC微孔发泡成型方法的研究进展,包括间歇成型法、连续挤出成型法和电磁动态挤出成型法。将振动力场引入到微孔发泡过程为PVC微孔塑料连续挤出成型提供了新的思路和研究方向。     

微孔发泡聚合物材料断裂性能研究

对室温下呈脆性的聚丙烯(PP)和呈韧性的高密度聚乙烯(HDPE)进行化学微孔发泡。系统测试了微孔发泡和未发泡的PP和HDPE的缺口冲击强度。结果发现,微孔使试样芯部基体材料的应力状态改变,易于在冲击载荷下产生塑性变形或在脆断条件下裂纹尖端钝化阻止裂纹扩展,导致微孔对脆性、韧性聚合物冲击性能的影响机制不同。对于脆性聚合物,断裂过程主要是裂纹扩展,微孔起到了阻隔裂纹扩展的效果,使冲击性能提高;而对于韧性聚合物,断裂过程主要是塑变撕裂,微孔的引入减小了材料的有效承载面积,反而使冲击性能降低。     

云母粉对聚丙烯微孔发泡行为和力学性能的影响

将云母粉加入到聚丙烯(PP)中,在二次开模条件下制备微孔发泡PP/云母粉复合材料,分析了不同含量的云母粉对微孔发泡复合材料发泡行为及力学性能的影响。结果表明,当云母粉质量分数为6%时微孔发泡复合材料的泡孔尺寸最小,泡孔密度最大;随着云母粉加入量的增大微孔发泡复合材料的缺口冲击强度略有降低,拉伸强度基本保持不变。     

间歇式超临界流体微孔发泡的成核机理研究

采用间歇式超临界流体微孔发泡技术制备出一系列的聚碳酸酯(PC)微孔泡沫塑料,通过扫描电子显微镜研究了间歇式超临界流体微孔发泡的成核机理。结果表明,间歇式超临界流体微孔发泡其泡核的成核位置是由外部开始,逐渐向内部扩散,最终形成了微孔泡沫塑料,这与传统发泡其泡核初始位置存在明显的不同。同时,在间歇式超临界流体微孔发泡过程中,PC微孔泡沫塑料的结构由初期的多层结构转变为最终的层芯结构。     

低密度聚乙烯/聚苯乙烯合金材料的发泡行为

通过共混挤出制备低密度聚乙烯/聚苯乙烯合金材料,在二次开模条件下制备微孔发泡LDPE/PS合金材料,分析了不同含量的PS对微孔发泡合金材料发泡行为的影响规律。实验结果表明:PS的添加量影响合金材料的发泡行为。当PS质量分数为15%时,微孔发泡合金材料的密度最小,泡孔分布均匀且孔径较小。     

微孔发泡注塑技术研究进展

介绍了微孔发泡塑料的定义及优点,阐述并对比了物理微孔发泡和化学微孔发泡等2种微孔发泡注塑成型工艺;详细介绍了近年来微孔发泡注塑技术在工艺优化、开模二次发泡、表面质量改善和力学性能预估等方面的最新研究进展;最后,对微孔发泡注塑技术未来的研究方向进行了展望。     

超临界CO2发泡制备聚氯乙烯微孔材料研究进展

阐述了超临界CO2发泡制备聚氯乙烯（PVC）微孔塑料不同工艺过程及其关键影响因素。介绍了CO2在PVC中的溶解扩散行为及CO2对PVC的增塑作用;分别论述了应用间歇升温发泡法、间歇降压发泡法和连续挤出发泡法制备PVC微孔材料的情况,分析了不同发泡工艺过程的优缺点,并总结了各发泡工艺过程中影响因素和PVC配方组成对发泡样品泡孔形貌和力学性能的影响;最后展望了超临界CO2发泡制备PVC微孔材料的工业化应用前景。     

超临界CO_2微孔发泡影响因素研究进展

对超临界CO2在聚合物基体内微孔发泡成型过程中材料特性参数与加工工艺条件等影响因素的研究进展进行了综述。     

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。     

微孔发泡注射成型设备及技术研究进展

简要介绍微孔发泡注射成型技术的机理,重点介绍微孔发泡注射成型设备的发展历程和微孔发泡注射成型技术的研究现状,展望了微孔发泡注射成型技术的发展前景.     

改性剂和增塑剂对PVC微孔泡沫塑料形态影响

以超临界CO2为发泡剂,用自制的动态模拟发泡装置研究了聚氯乙烯(PVC)配方中改性剂丙烯酸酯类高分子聚合物(ACR)含量和增塑剂邻苯二甲酸二辛酯(DOP)含量对PVC微孔塑料泡孔形态的影响.结果表明,在其他工艺条件和配方相同的情况下,ACR为4份时得到的PVC微孔泡沫塑料泡孔密度最大,泡孔粒径最小,DOP为2～6份时比较适合PVC微孔发泡,并且振动力场的引入有利于得到细小均匀的微孔结构.     

Preparation of microcellular poly(ethylene terephthalate) and its properties

Engineering plastics poly(ethylene terephthalate) (PET) is relatively difficult to process microcellularly compared to general thermal plastics because of its low melting viscosity. A new method was developed to microcellularly process PET in this study with a general hydraulic press above PET's crystallization temperature and below its melting temperature within times of a few minutes. A processing window existed in which to prepare microcellular PET under certain foaming time, pressure, temperature, and foaming reagent content scope. The effects of foaming time, temperature, pressure, and foaming reagent content on the thermal, mechanical, and dynamic mechanical thermal properties of microcellular PET foam were investigated. Differential scanning calorimetry (DSC) analysis showed that the transition temperature and crystallinity of microcellular PET had small changes with increasing foaming time. Under some processing conditions used in this study, the tensile strength and breaking extension of microcellular PET foam were both increased at the same time, indicating strengthening and toughening effects. The variation of storage modulus, loss modulus, and tan δ under dynamic mechanical thermal analysis was in accord with DSC analysis and mechanical measurements. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1956–1962, 2003     

汽车仪表板骨架微孔发泡塑件的综合性能

为了研究微孔发泡在大型塑件中的应用问题,以汽车仪表板骨架塑件为例,利用Moldflow软件模拟分析微孔发泡注塑和传统注塑成型。结果表明,微孔发泡注射成型在注塑时间、注塑压力、体积收缩和翘曲变形等方面均好于传统注塑成型。通过对塑件泡孔形貌、密度、孔隙率、力学强度、表面粗糙度等性能的检测,研究微孔发泡实际应用问题。检测结果表明,微孔发泡能够有效实现产品减重,且产品力学性能优于传统注塑,但表面粗糙度较传统注塑差,汽车外观零件如采用微孔发泡成型须经过表面处理来改善表面缺陷。     

Open‐celled microcellular thermoplastic foam

A theoritical model of the production of open‐cell microcellular foam is presented. This model allows the prediction of the conditions necessary to produce these materials. Experiments verify the model quite well. The results of the batch processing experiments indicate the processing parameters that promote the development of open‐celled microcellular polystryene foam. A saturation pressure of 17.2 MPa (2500 psig) provides the nucleation density necessary to form an impinged structure with microcellular bubble density. A foaming temperature of 200°C promotes the formation of both internal and surface porosity. A scaled time between 1 and 2.7 seconds develops a foam structure that intrudes a large volume. Samples foamed at 200°C for 1 and 2 seconds possess pores less than 1 μm in diameter. These samples represent scaled times of 1 and 2 seconds. Therefore, to produce open‐celled microcellular polystyrene foam with batch processing, samples should be saturated at approximately 17.2 MPa (2500 psig) and foamed for a scaled time between 1 and 2 seconds.     

Preparation and characterization of microcellular thin polycarbonate sheets

A new method was developed for the microcellular processing of polycarbonate (PC) thin sheets by compression molding above PC's glass‐transition temperature and below its melting temperature within a few minutes. The effects of the foaming time, foaming pressure, foaming temperature, and foaming agent active ratio on the cell size, cell density, and relative density were studied. The structures of the microcellular PC foam were controlled in the foaming process by carefully choosing the foaming parameters. In addition, the thermal, dynamic mechanical thermal, and electrical properties of the microcellular PC foam were investigated. A differential scanning calorimetry analysis showed that the microcellularly processed PC may have a plastication effect. The variation of the storage modulus, loss modulus, and tan δ under dynamic mechanical thermal analysis was in accord with the calorimetry analysis. The measurement of the electrical property demonstrated that the insulation ability of the microcellular PC thin sheet was obviously enhanced and the dielectric strength of the microcellular PC foam was decreased compared to the unfoamed PC. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1760–1766, 2006     

微孔泡沫塑料成型研究进展

介绍了微孔泡沫塑料的性能、成型原理和成型技术的研究进展。     

本征特性对聚苯乙烯及聚丙烯发泡行为的影响

以化学发泡注塑成型技术为主线,在二次开模条件下制备微发泡聚苯乙烯（PS）及微发泡聚丙烯（PP）;通过流变性、加工性分析了树脂本征特性对PS及PP发泡行为的影响。结果表明：本征特性对气泡的长大和定型过程、气体扩散具有明显的影响;熔体强度越高的材料,阻碍泡孔长大的趋势越明显,所得到的泡孔越细小而均匀;PS具有合适的熔体强度和熔体流动速率（MFR）,发泡质量较理想,泡孔直径和泡孔密度分别为41.4μm、8.7×106个/cm3;PP（K9026）熔体强度较低,而熔体流动速率过大,发泡质量明显降低,泡孔直径和泡孔密度分别为65.94μm、5.82×105个/cm3。     

微孔泡沫注射成型技术

介绍了微孔泡沫成型工艺的技术特点。对其应用和发展前景作了分析。认为这一技术内含巨大的发展优势和效益。