【作者】 张洪吉；

【导师】 何亚东； 信春玲；

【作者基本信息】 北京化工大学 ， 机械设计及理论， 2010， 硕士

【摘要】 聚苯乙烯(PS)是无定形、非极性线性高聚物,具有优良的绝热、绝缘和发泡成型性；CO2在PS中的溶解度较小,并且扩散系数较大,所以制备低密度的PS发泡制品有较大的挑战性。超临界二氧化碳(SC-CO2)具有无污染、化学稳定、低成本等优点,并且临界点(临界温度31.5℃,临界压力7.3MPa)容易获取,已经被应用于工业化生产中。本文研究了共混PMMA后对PS发泡的影响,讨论温度、压力以及PMMA含量对发泡的影响,并确定了实验工艺区域内获得较好发泡效果的工艺条件。PMMA的加入增加了CO2在体系中的吸附量,并且提高了CO2在其中的稳定性。PS/PMMA体系发泡得到最低表观密度为0.042g／cm3,泡孔直径为11.196μm,泡孔密度最大值为9.23×109个／cm3,其发泡性能优于纯PS体系。本文还研究了乙醇／CO2复合发泡剂对PS发泡的影响。吸附实验表明：乙醇／CO2复合发泡剂在PS中的溶解度明显高于单纯CO2在PS中的溶解度,能显著降低PS发泡制品的表观密度,所获得发泡样品的表观密度最小为0.042g／cm3。随发泡剂吸附量增大,发泡剂在PS中的扩散系数增大；乙醇含量过大,得到发泡制品收缩严重,且表观密度增大。本文最后研究了机头结构对PS发泡过程的影响。机头入口角度对PS发泡有较大影响,机头入口角不同时,发泡样品的宽度和厚度也不同。经过实验获得最佳发泡机头入口角为90°。更多还原

【Abstract】 Polystyrene (PS) are amorphous, non-polar linear polymer with excellent thermal insulation, insulation, and foamability. Solubility of CO2 in the PS is small and with large diffusion coefficient, the density of the PS foam products prepared by a greater challenge. Supercritical carbon dioxide (SC-CO2) has the advantage of clean, chemical stability and low cost, and the critical point (critical temperature 31.5℃, the critical pressure of 7.3MPa) could be obtained easily. SC-CO2 has been used in the industrial production.We studied the impact of PS foam after blending with PMMA. Discuss the temperature, pressure and the content of PMMA on the foam’s impact and to identify the experimental process in the region to obtain better foaming effect of processing conditions. The addition of PMMA increased CO2 absorption capacity in the system, and improve the stability of CO2 in it. PS/PMMA system have the lowest apparent density foam 0.042 g/cm3, the cell diameter 11.196μm, the maximum cell density was 9.23×109/cm3. The foamability of this system is superior to pure PS system.We also studied ethanol/CO2 blowing agent on the impact of PS foam. Adsorption experiments showed that:ethanol/CO2 blowing agent solubility in the PS was significantly higher than the solubility of CO2. The apparent density of PS foam can significantly reduce, we obtained a minimum apparent density is 0.042g/cm3. With the adsorption capacity of blowing agent increased, the diffusion coefficient of blowing agent in the PS becomes larger. The content of alcohol was too large, the apparent density of PS foam was larger and with serious foam shrinkage.Finally, we studied the structure of the die impact of the PS foam process. Entrance angle of the die o has great influence n the PS foam. The width and thickness of the foam samples are different with different entrance angle of the die. After the experiment, we obtained the optimal foam with the die angle of 90°.更多还原