【作者】 崔周波；

【导师】 刘涛；

【作者基本信息】 华东理工大学 ， 化学工程， 2011， 硕士

【摘要】 聚对苯二甲酸乙二醇酯(PET)的发泡材料由于其较高的性价比与特殊的性能而具有良好的应用前景。本文通过挤出改性制备了适合发泡的高熔体强度PET,优化其微孔注塑成型过程,探索了提高微孔注塑成型制品结晶度的途径。以MA为改性剂对PET进行挤出改性,结果表明MA添加量为0.5%时,改性PET (M-PET)具有较高的粘度和良好的流动性,较未改性PET更适于发泡。正交实验结果表明各操作参数对M-PET微孔发泡制品拉伸性能影响的大小顺序依次为：熔胶量>射胶速率>SCF含量>熔体温度>模具温度。高的熔胶量,适中的发泡剂含量和熔体温度,以及较低的射胶速率与模具温度有利于提高该制品的拉伸强度。M-PET微孔发泡制品的拉伸与弯曲强度均随着减重量的增加而线性下降,比拉伸与比弯曲强度基本保持不变,冲击强度和比冲击强度均有增强。通过在M-PET中添加适量的成核剂不仅提高制品的结晶度,增大聚合物的表观粘度,同时也改变了微孔注塑成型制品的特点。结果表明结晶度的提高使发泡制品的硬度增强,但损失了韧性,并且成型过程中所形成的晶体结构对泡孔形态产生了不利影响。更多还原

【Abstract】 Polyethylene terephthalate (PET) foams have a wide range of applications due to its excellent performance-to-price ratio and special performance. The PET with high melt strength for foaming was prepared by using reactive extrusion. Microcellular injection molding process for the PET was optimized, and the ways how to improve the crystallinity of the molding specimens were also explored.The results showed that the modification PET (M-PET) was prepared with high viscosity and good fluidity when the content of MA was 0.5%. The results of a design of experiments matrices indicated that the influence order of the operating parameters on the tensile strength was:shot size> injection speed> SCF content> melting temperature> mold temperature. The large shot size, moderate SCF content and melt temperature, and low injection speed and mold temperature were favorable to produce tensile specimens with high tensile strength. The dependence of tensile strength and bending strength on weight reduction was linear. The impact strength and its specific strength of microcellular specimen both increased in comparison with those of specimen without foaming.The viscosity could be enhanced and the properties of the microcellular injection molding specimens could be changed by adding appropriate amount of nucleating agent. The results showed that the rigidity was enhanced with the improvement of the crystallinity, while some toughness was lost at the same time. It was demonstrated that the crystal structure generated during the forming process had adverse effect on cell morphologies.更多还原