Effect of carbon black and chain extender on thermal, rheological and mechanical properties of fully biodegradable poly(butylene adipate‐co‐terephthalate)/poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate) blends

Abstract Different carbon black (CB) contents in poly(butylene adipate‐ co ‐terephthalate) (PBAT)/poly(3‐hydroxybutyrate‐ co ‐4‐hydroxybutyrate) (P34HB) blends were prepared by melt blending using chain extender multifunctional styrene‐acrylic‐ epoxy random oligomer (ADR), as a compatibilizer. PBAT and P34HB were immiscible, and ADR could react with PBAT and P34HB to improve interfacial adhesion force and molecular entanglement. CB fillers were uniformly and selectively located in the PBAT matrix and could act as a nucleating agent to promote the nucleation of PBAT crystallization. At a CB content of 5 wt%, a percolation network structure of CB was formed. The most interesting result in the work was the achievement of composites with improved rheological and mechanical properties under the synergistic effect of chain extender and CB fillers. The viscoelasticity of the system was markedly improved and a transition from liquid‐like to solid‐like behavior was observed. Young's modulus and yield strength of chain extender modified PBAT/P34HB/CB composite with 10 wt% CB increased by 502% and 69% compared to neat PBAT, and by 89% and 43% compared to PBAT/P34HB binary blend. The combination of improved melt viscoelasticity and mechanical properties will further broaden the practical application of biodegradable polymers. © 2024 Society of Industrial Chemistry.