Strong and thermally insulating polylactic acid/glass fiber composite foam fabricated by supercritical carbon dioxide foaming

Environmental friendly and non-toxic polylactic acid (PLA) foam exhibits a promising perspective in many areas. However, PLA shows very poor foaming ability. Herein, silane-modified glass fiber (GF) was compounded with PLA to improve its foaming ability. Thanks to the increased melt viscoelasticity and melt strength, and the enhanced crystallization by adding GF, PLA/GF composites show dramatically improved foaming ability, characterized by widened processing window, increased expansion ratio, and improved cellular uniformity. Compared with pure PLA foam, PLA/GF composite foam shows dramatically enhanced mechanical properties in compressive strength and modulus. For foams with the same expansion ratio of 20-fold, the incorporation of 10 wt% GF led to increased compressive strength and modulus by 44.8% and 92.0%, respectively. The PLA/GF composite foam with an expansion ratio of 24.2-fold has a low thermal conductivity of 31.4 mW/m·K, which is comparable with the excellent thermal insulation performance of commercial polymer foams.