Preparation of Micro/NanoCeliular Polypropylene Foam With Crystal Nucleating Agents

摘要

Open-cell, porous microcellular foams with nanofibril-lated structures were prepared from high tacticity isotactic polypropylene (i-PP) with a crystal nucleating and gelling agent. The 1,3:2,4 bis-0-(4-methylbenzyli-dene)-D-sorbitol gelling agent (Gel-all MD) was used as the crystal nucleating and gelling agent, which enhanced the crystallization and gelation of i-PP with a three-dimensional network of highly connected nanofi-brils. The core-back foam injection molding technique was employed to foam the i-PP with nitrogen (N2) at a high expansion ratio, where the crystal nucleating agent induced bubble nucleation and bubble growth in the inter-lamella region and opened the cell walls with a nanoscale-fibrillated structure. The effects of the nucleating agent on the open cell content (OCC), density and crystallinity were thoroughly investigated. We prepared open-cell microanocellular foams with an average cell size of microscale voids of < 5 μm. Nanometer-scale fibrillated structures were formed on the cell wall of the microscale void, the expansion ratio was five-fold and the open cell content was over 90%.