Efficient fabrication of PLA/PHB composites with enhanced mechanical properties, excellent thermal stability, fast crystallization ability, and degradation rate via the synergistic of weak shear field and melt quenching technique

Abstract

Melt blending is an attractive strategy for the industrial fabrication of high-performance Polylactic acid (PLA), nevertheless, the damage of traditionally strong shear-based melt plasticization process on PLA molecular chains reduces its comprehensive mechanical properties, thereby revealing defects such as low modulus, low heat deflection temperature, slow crystallization rate, and narrow thermal processing window. In this work, a synergistic strategy involving a weak shear of elongational rheology technique and a melt quenching process was utilized to fabricate high-performance PLA/Polyhydroxybutyrate (PHB) composites. While the weak shear force minimizes the molecular weight (Mw) destruction during the thermal processing and the PHB in-situ fibrillates promote the interfacial bonding, thus maintaining a high Mw, favorable thermal stability, and optimal mechanical properties. In addition, the melt quenching process enabled not only the original fibrillation structure of PHB to be well-reserved, but also significantly enlarged the crystallization rate of the PLA phase, resulting in high-crystallinity PLA/PHB. Encouragingly, the superior fabrication process achieved a considerable enhancement in the PLA degradation rate, yielding a 90.9 % weight loss over 10 days of degradation in an alkaline solution. As expected, high-performance PLA composites are acquired by weak shear melt-plasticization and melt-quenching processes. The proposed method demonstrates promising applications in biomedical, agricultural engineering, and food packaging fields.