Effect of PLA Molecular Weight on Mechanical and Morphological Properties of PVA/PLA Biomaterial Blown Films

This study investigates the influences of polylactic acid (PLA) molecular weight on mechanical behaviors and morphological property of polyvinyl alcohol (PVA)/PLA biomaterial blown films. Three commercial PLAs (L105, L130, and L175) with distinct molecular weights are individually blended with PVA at a fixed ratio of 50 wt%. Glycerol (20 phr) is employed as a plasticizer to enhance film processability. Films are fabricated via twin-screw extrusion followed by film blowing. Morphological observations confirm that interfacial adhesion and phase distribution are dependent on both PLA molecular weight and content. Mechanical analysis demonstrates that biomaterial PVA blown film with PLA L175 exhibit superior tensile strength and ductility due to improved interfacial entanglement. These findings highlight the critical role of interfacial interactions in tuning the structure–property relationship of PVA/PLA biomaterial systems, supporting their development as flexible, biodegradable films for advanced packaging applications.