Crystal nucleating agent Bis (3, 4- dimethylbenzylidene) sorbitol (DMDBS) was used to tune the melt strength and microcellular foaming properties of isotactic polypropylene (iPP) in this study. Rheological testing results reveal that the introduction of DMDBS could enhance the storage modulus and complex viscosity of iPP, obviously increase its crystallization onset temperature, compared to its counterparts without DMDBS. The addition of DMDBS could also significantly increase the cell nucleating ability of iPP, due to its large surface, cooperating with a thermal history control treatment. Quite fine microcellular iPP/DMDBS foams were fabricated with relatively small average cell sizes of nano to several micrometers, and cell densities up to 1011∼1012 cells/cm3, using the synergy effect of DMDBS and iPP’s melt self-enhancement. Under a comparatively low re-saturation pressure of 8 to 12 MPa, ideal microcellular foams could be generated, at a temperature zone of 158 to 162°C, which is slightly below to iPP’s original pellets nominal melting point.

中文翻译：

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结晶成核剂和全同立构聚丙烯熔体自增强对其流变和微孔发泡性能的协同作用

在本研究中，结晶成核剂双 (3, 4-二甲基亚苄基) 山梨糖醇 (DMDBS) 用于调节全同聚丙烯 (iPP) 的熔体强度和微孔发泡性能。流变学测试结果表明，与不含 DMDBS 的对应物相比，DMDBS 的引入可以提高 iPP 的储能模量和复数粘度，显着提高其结晶开始温度。DMDBS 的添加还可以显着提高 iPP 的细胞成核能力，因为它的表面积很大，与热历史控制处理相配合。利用DMDBS和iPP熔体自增强的协同效应，制备了相当细的微孔iPP/DMDBS泡沫，其平均泡孔尺寸相对较小，从纳米到几微米，泡孔密度高达1011∼1012孔/cm3。