A systematic study was done to screen for the polydimethylsiloxane (PDMS) with molecular weight (Mw) from 770 g/mol to 17,000 g/mol to optimize the supercritical CO₂ foaming process of semi-crystalline polypropylene (PP). The solubility and diffusion measurements demonstrated that the high solubility and slow desorption rate of CO₂ were achieved in PP/PDMS blends via incorporating PDMS. Rheology results showed the viscosity of PP/PDMS blends increased with the increase of Mw of PDMS. The crystallization behaviors of PP and PP/PDMS blends were thoroughly investigated in the presence of CO₂. PDMS with Mw from 4000 g/mol to 9000 g/mol enhanced the crystallization of the blend evidently. Since PDMS with medium Mw could work as a CO₂-philic additive and crystallization nucleating agent in PP, the resultant foams exhibited a more uniform cellular morphology with smaller cell size (decreased from 23 to 13 μm) and higher cell density compared with that of PP foam.

进行了系统的研究，以筛选分子量（Mw）为770 g / mol至17,000 g / mol的聚二甲基硅氧烷（PDMS），以优化半结晶聚丙烯（PP）的超临界CO ₂发泡工艺。溶解度和扩散测量表明，通过掺入PDMS，在PP / PDMS共混物中实现了CO ₂的高溶解度和缓慢解吸速率。流变学结果表明，PP / PDMS共混物的粘度随PDMS分子量的增加而增加。在CO ₂存在下，对PP和PP / PDMS共混物的结晶行为进行了彻底研究。Mw从4000g / mol至9000g / mol的PDMS明显增强了共混物的结晶。由于中等分子量的PDMS可以作为CO ₂起作用-PP中的亲液添加剂和结晶成核剂，与PP泡沫相比，所得泡沫具有更均匀的泡孔形态，泡孔尺寸更小（从23至13μm减小）和泡孔密度更高。