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采用化学发泡注塑成型技术,在二次开模条件下制备微发泡聚丙烯(PP)材料;通过热力学分析法研究了二次开模距离对PP微发泡材料发泡行为的影响。结果表明:二次开模距离能有效地控制PP材料的发泡过程,二次开模距离越小,体系的发泡过程越容易自发进行。当二次开模距离L=5.3 mm时,体系中的吉布斯自由能小于零,发泡过程不可能自发进行;二次开模距离L=4.3 mm时,PP体系的发泡质量最理想,泡孔平均直径为21.6 m,泡孔密度为5.63×106个/cm3,能够获得泡孔细小、均匀的微发泡PP材料。
The foamed polypropylene (PP) was prepared by chemical foaming injection molding under the condition of secondary mold opening. The influence of secondary mold opening distance on the foaming behavior of PP micro foaming material was studied by thermodynamic analysis. The results show that the secondary mold opening distance can effectively control the foaming process of PP materials. The smaller the secondary mold opening distance, the easier foaming process of the system spontaneously. When the second mold opening distance L = 5.3 mm, the Gibbs free energy in the system is less than zero and the foaming process can not spontaneously proceed. When the second mold opening distance L = 4.3 mm, the foaming quality of PP system is the best , The average cell diameter of 21.6 m, the cell density of 5.63 × 106 / cm3, to obtain a small cell foam, uniform micro-foaming PP material.