Bimodal Cellular Structure Evolution in PBAT Foams Incorporated by Carbon Nanotubes and Graphene Nanosheets

Due to extensive concerns of tremendous environment pollutions, particularly microplastic as an emerging pollutant, the development and investigate on biodegradable polymer foams raised growing interest and revealed promising application prospects. In this work, carbon nanotubes (CNTs) and graphene nanosheets (GNPs) were introduced into poly (butylene adipate-co-terephthalate) (PBAT) foams to develop micro-nano bimodal cellular structure (BCS) using a supercritical CO2 foaming approach. CNTs and GNPs (CG) network structures were formed in PBAT/CNTs/GNPs nanocomposites by the gradual addition of CG, which made a significant enhancement on their melt viscoelasticity. Systematically, the effect of CG content and foaming temperature on the PBAT cellular structure were investigated. As the CG content increased, BCS was steadily formed in the PBAT/CG foams, meanwhile, their cell size decreased. At last, the generation mechanism of BCS in different PBAT/CG foams was explored.