Fabrication of Poly(butylene succinate) phosphorus-containing ionomers microcellular foams with significantly improved thermal conductivity and compressive strength

Abstract

Biodegradable microcellular foams with high comprehensive performances were highly desired for many applications. Differed from previous researches, poly(butylene succinate) ionomer (PBSI) foams fabricated by supercritical CO2 were promising for yielding high thermal conductivity and compressive feature. Novel PBSIs microcellular foams with different phosphorus-containing ionic group (PCIG) content (FPBSIs-K) were fabricated in the study. Then, the relationships between the structure and properties, including thermal conductivity, compressive strength and thermal safety of FPBSIs-K were investigated. Strikingly, owing to the physical cross linking by PCIG aggregation, the significant increases in the melt strength generated stronger surface tension and orientation force. Consequently, FPBSI7.5-K (7.5 wt% PCIG content) achieved about 100% closed cell structure, and high orientation for cells. Compared with those of PBS foams, FPBSI7.5-K achieved 10-folds, 9-folds and 5-folds increases in char yield, thermal conductivity and compressive strength, and their values were 15.4%, 315 mW/mk and 3.5 MPa, respectively. The mechanism for FPBSIs-K with significant improvements in thermal conductivity and compressive strength were proposed. Moreover, the incorporation of PCIG promoted FPBSIs-K to form a stable char layer and inhibit the release of combustible gaseous pyrolysis products. This work inspired to develop high-performances biodegradable microcellular foams for environment protection, lightweight structural materials and fire safety.