Diffused Reflection Performance of Microcellular Foamed Polyethylene Naphthalate

Due to the increasing demand for high-performance diffuse reflectors in applications including LCD displays and lighting, many studies on the manufacturing of high-performance reflectors have been conducted. Microcellular foamed plastics are characterized as having a structure with a cell size of 10 µm or less along with a cell density of at least 10⁹ cells/cm³. Since the structural characteristics of these materials were determined to result in diffused reflection, the use of polymers as diffuse reflectors has been studied. In this study, a diffuse reflector specimen was manufactured by applying a microcellular foaming process to polyethylene naphthalate (PEN). The optimum foaming conditions of PEN were determined through preliminary experiments using the Batch process and the specimen was manufactured using supercritical CO₂. Additionally, to improve the low productivity, which is one of the disadvantages of the Batch process, additional specimens were manufactured while varying the saturation conditions. Through observation of the cross-sections of the specimens, the cell morphology depending on the process conditions was confirmed and then, the diffusion reflectivity was measured.     

微孔塑料的研究开发进展

介绍微孔塑料的性能应用、常用制备方法及关键问题,并探讨了我国微孔塑料发展的方向。     

微孔塑料连续挤出加工技术

从发泡剂注入聚合物熔体、均相聚合物／发泡剂形成和微孔发泡三个方面综合评述了微孔塑料连续挤出加工技术的发展状况。     

泡沫塑料气泡膨胀过程的研究

从气泡膨胀过程的物理和数学模型出发,作者建立了描述气泡膨胀、传热、传质等过程的微分方程。通过对不同冷却条件下B_i数的分析,并发现采用无量纲数群来研究泡沫塑料气泡的膨胀过程比较有效。     

微孔塑料物理发泡的成核理论

研究了微孔塑料物理发泡的成核机理,给出了均相成核、非均相成核和空穴成核三种成核方式的临界成核半径、所需克服的吉布斯自由能及成核速率的计算公式;介绍了含有成核添加剂时的成核理论。     

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.     

国外微孔塑料物理发泡研究现状

本文综述了国际上微孔塑料物理发泡的最新进展,阐述了经典成核理论的应用况及存在的不足,同时介绍了气泡长大的物理模型及各种模型在实际研究中的应用。     

泡沫塑料在高层建筑中的应用前景

简介了国内外泡沫塑料在建筑业上应用的现状和发展趋势及其在住宅高层化和住宅产业现代化进程中占有的重要地位。     

超临界CO2发泡微孔塑料的研究进展

介绍了超临界CO2 的特性及作用,从微孔塑料成型过程中的气体溶解、气泡成核、气泡长大、泡孔定型4个阶段出发,阐述了超临界CO2发泡微孔塑料的机理。还综述了微孔塑料的间歇成型、挤出成型、注射成型等3种常用成型方法,重点讨论了温度、压力、时间及外力场对微孔塑料泡孔结构的影响,并对微孔塑料的未来发展趋势作出展望。     

泡沫塑料保温材料的研究进展

简述了国内外泡沫塑料保温材料的发展现状;介绍了聚氨酯泡沫塑料、聚苯乙烯泡沫塑料和酚醛泡沫塑料的研究进展;展望了泡沫塑料保温材料的应用前景和发展趋势。     

玻璃纤维/不饱和聚酯微孔复合材料的制备研究

用超饱和气体法制备了玻璃纤维/不饱和聚酯微孔复合材料。考察了保压时间对微孔复合材料泡孔直径及泡孔密度的影响,并对固化反应进行了动力学分析。结果表明:I阶段保压时间对泡孔直径及泡孔密度的影响大于II阶段保压时间;I、II阶段的最佳保压时间均为30min;在固化反应过程中,随着固化剂活性、固化剂浓度、不饱和聚酯分子中双键的浓度和反应温度的升高,固化反应速率升高。     

超临界CO_2/PS微孔塑料挤出成型中CO_2浓度对气泡成核影响的数值模拟

通过CFD软件对超临界CO_2/PS均相熔体在快速降压口模中流动状态的数值模拟,研究了CO_2浓度对CO_2/PS均相熔体气泡成核的影响。结果表明:当其他工艺条件不变时,在CO_2溶解度范围以内,增加CO_2浓度有利于提高成核率,从而产生更多的气泡,但不利于小尺寸泡孔的生成。     

淀粉基复合泡沫塑料制备工艺研究进展

阐述了淀粉基复合泡沫塑料的研究现状,在概述淀粉材料发泡原理的基础上,综述了国内外淀粉基可降解泡沫塑料的成型方法,主要包括挤出发泡、烘培发泡、模压发泡和超临界流体挤出发泡工艺的研究进展,并就淀粉基泡沫塑料的应用现状提出了其未来发展对策。     

Effect of processing parameters on cell morphology of polycarbonate foam

Abstract

The purpose of this research is to investigate the effect of processing parameters on the cell morphology of polycarbonate (PC) foam. In this study, foamed PC was prepared using a dynamic simulation foaming set-up. The cell morphology was compared at different temperatures, pressures, gas saturation times, pressure drop rates and shear rates. The cell morphology of foamed samples was characterised using SEM. It was found that foamed samples with better morphology could be obtained by varying mechanical properties, such as pressure, pressure drop rate and gas saturation time. Optimum temperature and shear rate for microcellular foaming of PC are presented.     

软质聚氨酯泡沫塑料生产过程中自燃故障的原因及预防

对软质聚氨酯泡沫塑料生产过程中自燃故障产生的原因及其影响因素进行了分析，并介绍了预防自燃的措施。     

聚乙烯醇缩甲醛/二氧化硅复合泡沫材料的制备及热性能研究

以正硅酸乙酯(TEOS)为前驱体,采用溶胶凝胶法,对聚乙烯醇缩甲醛（PVF）泡沫材料进行改性,制备了PVF/二氧化硅复合泡沫材料,探讨了TEOS用量对材料性能的影响,采用傅里叶变换红外光谱（FTIR）、热失重分析法（TG）对材料进行了分析。结果表明,二氧化硅含量为15 %时,材料的初始热分解温度为322.5 ℃,比改性前提高了约94 ℃,TEOS的加入明显改善了PVF泡沫材料的拉伸强度和耐热性。     

微孔塑料成型技术及关键步骤

微孔塑料的成型方法主要包括间歇成型法、连续挤出成型法、注射成型法和相分离法等,并且各有优缺点.其中,连续挤出成型法及注射成型法适合工业化生产.微孔塑料的成型过程包括聚合物 /气体均相体系的形成、气泡成核和气泡长大及定型高的三个步骤,与常规泡沫塑料相比较,其加工过程的要求非常高,必须有高的气体浓度、高的成核速率、成核密度和短的长大定型时间.     

The Effect of Control Factors and the Effect of CaCO3 on the Microcellular Foam Morphology

Abstract

Microcellular foamed plastics by injection molder draw attraction due to light weight, less warp, reduced cycle time, less sink mark, and so on, because of cells nucleated in the polymer matrix during the injection. Although foamed plastics by injection molder have many merits as listed above, there are few studies which factors are influencing on the foam morphology that characterize the quality of foamed plastics due to the complexity of injection molding. We studied the effect of control factors of injection molding and the effect of CaCO₃ as an additive for nucleation on the cell morphology according to the design of experiments. We analyzed the effects of each factor by using SEM images of foamed plastics through Minitab software using main effect plot, interaction plot, and ANOVA.     

关于建筑层面防水隔热新材料——聚氨酯硬泡推广使用的探讨

对聚氨酯硬泡用于建筑屋面防水隔热这一新领域从材料性能 ,设计施工规范 ,综合经济效益分析及推广应用前景作了较为全面的探讨和阐述。     

Effects of Repeated Microcellular Foaming Process on Cell Morphology and Foaming Ratio of Microcellular Plastics

Microcellular plastics (MCPs) are manufactured through a batch process comprised of saturation and foaming stages. In the saturation process, gas molecules are dissolved into plastic in a high-pressure vessel. Following the saturation process, micro-cells are formed inside the plastic as the gas-dissolved plastic sample undergoes the foaming process. In this paper, we investigate the effects of repeating the batch process on the formation of MCPs. Because the plastic sample after the first batch process has developed microcells, these pre-existing cells are expected to affect the second round of the batch process. Of particular interest is the effect of repeated saturation at different saturation pressures. Experiments show that repeating the batch process can lead to favorable outcomes in terms of foaming ratio and cell morphology, which are otherwise unattainable particularly with a single batch process.