共查询到19条相似文献,搜索用时 203 毫秒
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采用磷酸三甲酚酯(TCP)对聚碳酸酯(PC)片材进行增塑,并采用模压法对所增塑的PC片材进行微孔发泡,探讨了加工参数和TCP用量对PC片材泡孔结构的影响。结果表明:TCP对PC具有良好的增塑效果,制得的微孔塑料具有理想泡孔结构,且拓宽了发泡温度范围;增塑PC片材的泡孔结构随发泡压力、发泡时间、发泡温度的变化趋势与未增塑PC片材的变化趋势保持一致,只是泡孔尺寸、泡孔密度发生了一定程度的变化;随TCP含量的增加,泡孔尺寸先减小后增大,泡孔密度的变化趋势则相反。 相似文献
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采用化学交联模压法制备了丙烯腈-苯乙烯-丁二烯共聚物(ABS)微孔发泡材料,研究了发泡温度、发泡压力及发泡时间对ABS微孔发泡材料气体的扩散行为及泡孔结构的影响,结果表明:气体吸收量随着发泡温度、发泡压力和发泡时间的增加,先增大后减小;随着气体吸收量的增加,制品的泡孔尺寸逐渐减小,泡孔密度逐渐增大,增加气体吸收量有利于提高发泡效果。当发泡温度为170℃、发泡压力为10 MPa、发泡时间为12min时,泡孔密度约为2.87×108个/cm3,可满足工业上微孔发泡材料泡孔密度的要求。 相似文献
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使用超临界CO2流体作为发泡剂在不同条件下制得一系列微孔聚碳酸酯(PC)。通过扫描电子显微镜观察分析了各种制备工艺参数对微孔PC泡孔结构和分布的影响。结果表明,饱和阶段的时间超过3.5 h时,试样中的CO2基本达到饱和;饱和阶段压力的增加会使泡孔直径减小,泡孔密度增大;而发泡温度的增加和发泡时间的延长则会使泡孔直径增大,泡孔密度减小。当完全发泡时,试样的泡孔结构在厚度方向上有明显区别:试样表皮部分未发泡,有致密的表皮结构;试样表层附近泡孔直径较小,泡孔密度较大;试样中心处的泡孔直径较大,泡孔密度较小。 相似文献
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采用自制的微孔发泡模拟机研究了温度和压力以及气体饱和时间对微孔聚碳酸酯(PC)泡孔结构的影响。结果表明,对于微孔PC泡沫塑料的成型存在一个最佳温度值;随着饱和压力升高,泡孔直径变小,泡孔的密度增大;气体饱和时间对PC泡沫塑料泡孔结构的影响不是很明显,在一定的饱和时间范围内,延长PC发泡时间有利于得到更均匀的泡孔结构。 相似文献
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发泡工艺对超临界CO_2/PLA微孔发泡泡孔形态的影响 总被引:1,自引:0,他引:1
研究了超临界CO2/PLA微孔发泡过程中,发泡温度、饱和压力、剪切速率对聚合物PLA泡孔形态的影响。结果表明,发泡温度对泡孔形态影响很大,温度降低,熔体强度增加,泡孔塌陷和合并减少,发泡材料的泡孔密度增大,泡孔尺寸减小,但温度太低时,熔体黏度和表面张力增加,发泡样品泡孔密度较低,泡孔壁较厚;压力对发泡形态的影响也是很显著的,压力太低,CO2的溶解度小,泡孔壁厚,泡孔分布不均匀。随着压力升高,CO2的溶解度增加,发泡样品的泡孔密度增加,泡孔更加均匀;随着转子转速增加,泡孔尺寸减小,气泡成核密度增大。但是转子转速过快,泡孔沿剪切的方向被拉长,泡孔取向严重,泡体质量变差。 相似文献
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采用化学交联模压法制备了丙烯腈-苯乙烯-丁二烯共聚物(ABS)微孔发泡材料,研究了发泡温度、发泡压力、发泡时间等加工参数对泡孔性能的影响,采用力学测试方法、扫描电子显微镜(SEM)研究了ABS微孔发泡材料的力学性能和泡孔形态。研究结果表明,当发泡温度为170℃、发泡压力为10 MPa、发泡时间为12 min时,制得的ABS微孔发泡材料泡孔尺寸、泡孔密度适中,表观密度最小,同时具有较好的冲击强度。在此模压工艺参数下,材料的平均泡孔直径约为50μm,泡孔密度约为3.2×108个/cm3,满足工业上微孔发泡材料泡孔密度的要求。 相似文献
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加工参数对PP/木粉复合材料结构和性能的影响 总被引:3,自引:0,他引:3
将聚丙烯(PP)与处理木粉混合,经双螺秆挤出机适粒后·混入微扎发泡母粒,经单螺杆挤出机塑化和片材口模成型PP/木粉复合微孔片材试样.通过改变挤出温度、螺杆转速、口模压力降以及冷却定型条件,测定试样拉伸性能、密度、孔隙率,扫描电镜(SEM)观察试样断面形貌,研究加工参数与PP/木粉复合微孔片材结构和性能的关系.结果发现,在挤出温度180℃,螺杆转速50 r/min,高的挤出压力时,泡孔尺寸小而均匀.对片材坯料给予的冷却定型可以固定泡孔结构防止泡孔合并和过度生长及塌陷. 相似文献
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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 相似文献
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To obtain cellular with small cell diameter, to control cell structure and to improve impact strength of foaming materials, the quick-heating method was applied for foaming polystyrene (PS) using supercritical CO2 (Sc-CO2) as physical blowing agent. Then, changes of cell structure and impact strength in microcellular foamed PS materials under constrained conditions were studied. The effects of foaming processing parameters, such as foaming temperature, saturation pressure and foaming time on the cell structure and impact strength of foamed PS in the constrained conditions were studied. The results showed that the Sc-CO2 solubility and nucleation density in the constrained conditions were not influenced compared with those under free foaming conditions. However, cells in constrained foaming process are mostly circular and independent with thick cell walls; the phenomenon of cell coalescence and collapse was effectively eliminated under constrained conditions. In addition, cell diameters in constrained foaming process decrease with increase in foaming temperature and increase with increase in the foaming time. Compared with that in free foaming conditions, the cell growth was restrained dramatically under constrained conditions which resulted in smaller cell diameter. Moreover, higher impact strength could be obtained for foamed PS as foaming time was prolonged, foaming temperature was increased or saturation pressure was enhanced. 相似文献
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发泡工艺对超临界CO2/PP微孔发泡泡孔形态的影响 总被引:1,自引:0,他引:1
研究了超临界CO2/PP微孔发泡过程中发泡温度和饱和压力对结晶性聚合物PP泡孔形态的影响。结果表明,温度对泡孔形态影响很大,温度升高,熔体黏度和表面张力降低,泡孔变大,泡孔密度减小。与发泡温度相比,CO2饱和压力对泡孔结构的影响较小。压力太低,CO2的溶解度小,泡孔壁太厚,泡孔分布不均匀。随着压力升高,CO2的溶解度增加,熔体黏度减小,所以泡孔直径和泡孔密度都增加,泡孔壁变薄。 相似文献
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Jian-Min Feng Wei-Kang Wang Bang-Hu Xie Ming-Bo Yang 《Polymer-Plastics Technology and Engineering》2013,52(10):1027-1034
Polypropylene (PP) sheets obtained through a two-step process (masterbatch method) were crosslinked by electron beam irradiation. The crosslinked PP sheets were foamed in an oven under different processing conditions. The effects of foaming temperature and time on the mechanical properties and cell structure of PP foams were studied. With the foaming temperature increasing and foaming time lengthening, both the compression modulus and compression strength dropped. Scanning electron microscope (SEM) was employed to study the morphology and cell structure of different samples and the related morphology parameters were acquired. The results showed there was an optimum temperature and time that produced the maximum expansion ratio or the minimum foam density. As foaming temperature or time increased, the cell size increased and the cell density decreased regularly. Excessively high foaming temperature and overly long foaming time caused the coalescence and even the collapse of the cells. 相似文献
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The production of microcellular plastic was studied in the polymethyl metacrylate (PMMA)-supercritical carbon dioxide and
polycarbonate (PC)-supercritical carbon dioxide systems. The test pieces of PMMA and PC were put into a saturation vessel
of which temperature and pressure were kept constant. Supercritical carbon dioxide at temperature between 303K and 393K and
pressure between 100 bar and 250 bar was used as a foaming agent. After saturation of carbon dioxide, the pressure was quickly
released to atmospheric pressure. The samples were immediately taken out from the vessel and heated in an oil bath. The fractured
part of the sample was used for microstructure analysis with SEM. The effect of the saturation temperature, pressure of sorption
and the foaming time on the cell mean size and cell density of the foam was investigated by considering the solubility of
carbon dioxide in PMMA and PC. The foam morphologies of the foamed plastics were affected by solubility of carbon dioxide,
which was directly related to saturation temperature and pressure. The cell density increased and, consequently, the cell
size decreased with the solubility of carbon dioxide. The foaming time can be used a controlling factor to obtain the desired
foam structure and the volume expansion ratio. 相似文献
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《塑料、橡胶和复合材料》2013,42(9):457-464
AbstractThe 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. 相似文献
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A new process was used to prepare microcellular foams with supercritical carbon dioxide as the physical foaming agent in a batch. The foaming temperature range of the new process was about five times broader than that of the conventional one. Characterization of the cellular structure of the original polypropylene (PP) and PP/nano‐CaCO3 (nanocomposites) foams was conducted to reveal the effects of the blend composition and processing conditions. The results show that the cellular structure of the PP foams was more sensitive to the foaming temperature and saturation pressure variations than that of the nanocomposite foams. Uniform cells of PP foams are achieved only at a temperature of 154°C. Also, the low pressure of 20 MPa led to very small cells and a low cell density. The competition between the cell growth and cell nucleation played important role in the foam density and was directly related to the foaming temperature. Decreasing the infiltration temperature depressed the initial foaming temperature, and this resulted in significantly larger cells and a lower cell density. A short foaming time led to a skin–core structure; this indicated that a decrease in the cell size was found from skin to core, but the skin–core structure gradually disappeared with increasing foaming time. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 相似文献