High biomass filled biodegradable plastic in engineering sustainable composites

The production of single-use, non-renewable plastic has persistently impacted the environment through non-biodegradable plastic accumulation. Injection-moulded biodegradable polymer blend [poly(butylene succinate-co-butylene-adipate) (PBSA) and poly(butylene adipate-co-terephthalate) (PBAT)] with an inexpensive filler, walnut shell powder (WSP), enables an appropriate melt flow behaviour after incorporating compatibilizer as confirmed by rheological analysis. The sustainable composites with 60 wt% WSP showed a decrement of 68.4% in tensile strength as compared to PBSA/PBAT blend. However, the inclusion of a 5% compatibilizer in PBSA/PBAT/60wt%WSP composite increased tensile strength by 48.7%, indicating improved interfacial adhesion. Further, the improvements in tensile (694%) and flexural moduli (461%) of PBSA/PBAT blend were observed with the addition of 60% WSP in presence of 7% compatibilizer due to fibrillar morphology of filler. Thus, signifying enhanced stiffness with increased filler, leading to a composite suitable for rigid packaging. Scanning electron microscopy (SEM) confirmed an improved adhesion between matrix and filler interfaces with the addition of a compatibilizer as gaps decreased, subsequently leading to increased mechanical properties. The novelty of this work establishes a high loading of filler can be incorporated with biodegradable polymers and improved properties in presence of compatibilizer makes it more suitable for injection moulding applications to produce a low-cost biocomposite capable of being used as a single-use plastic alternative in rigid packaging.