Construction of rigid polylactic acid/soft polytetrafluoroethylene dual nanofibers in poly(butylene adipate-co-terephthalate) to fabrication of PBAT microcellular foams with superior compression strength, anti-shrinkage and resilience.

Polybutylene adipate-co-terephthalate (PBAT) is attractive as a biodegradable polymer foam owing to its light weight, resilience, high flexibility and low price. However, modifying PBAT foam to improve its strength and reduce its shrinkage while maintaining its resilience has been a challenge. In this study, we used in situ fibrillation to incorporate a dual nanofiber network of rigid polylactic acid (PLA) and soft polytetrafluoroethylene (PTFE) in a branched PBAT (CEPBAT) foam. The nucleation and enhanced viscosity effect of the PLA/PTFE dual nanofiber structure induced the formation of microcellular PBAT foams with a cell size of 13 μm and an expansion ratio of 13.1. Moreover, the formation of the PTFE nanofibers enhanced the viscosity of the matrix, which increased the aspect ratio of the PLA nanofibers. The rigid PLA nanofibers were dispersed in the cell walls of the CEPBAT foam, which evenly distributed the applied forces and enhanced the overall compressive strength and flexibility of the composite. Compared to a CEPBAT foam, the CEPBAT/PLA/PTFE composite foam demonstrated a 257 % increase in compressive strength and 200 % reduction in shrinkage while maintaining comparable resilience. The construction of a rigid/soft dual nanofiber network is an innovative and practical approach for preparing high-performance PBAT microcellular foams.