In Situ Constructing Highly Aligned Ribbon-like PHBV Lamellae in PBAT: Towards Strong, Ductile and High-Barrier PBAT/PHBV Films

This study presents a facile approach to fabricate PBAT/PHBV films with superior mechanical and barrier properties by in situ forming ribbon-like lamellae, achieving a PHBV platelet-reinforced PBAT films. The fabrication involves melt blending of PBAT and PHBV, where styrene–methyl methacrylate–glycidyl methacrylate copolymer as a multifunctional reactive compatibilizer (RC) regulates PHBV domain size by forming a branched/cross-linked PBAT-B-PHBV structure. The introduction of a compatibilizer into the PBAT/PHBV system can reduce domain size and improve interfacial adhesion, thereby elevating PBAT’s storage modulus and complex viscosity for optimized blow-molding processability. During blow-molding, biaxial stretching with rapid cooling transforms PHBV sea–island structures into well-aligned ribbon-like lamellae. Notably, when PHBV content is ≤30 wt.%, lamellae form in the PBAT matrix, significantly enhancing both mechanical and barrier properties. The addition of RC reduces the lateral dimensions of PHBV lamellae while increasing PHBV number density. The introduction of 0.2 wt.% RC optimizes lamellar dimensions and density to maximize permeation pathway tortuosity. Ultimately, the lamellae in the PBAT matrix yield remarkable property enhancements: yield strength increased by >600%, elastic modulus by >200%, and water vapor/oxygen transmission rate reduced by ~81% and ~85%, respectively.