Film Performance of Poly(lactic acid) Blends for Packaging Applications

Abstract

Poly(lactic acid) (PLA), a biodegradable thermoplastic derived from renewable resources, stands out as a substitute to petroleum-based plastics. PLA based films for food packaging has been an area of both commercial and research interest within the context of sustainability. In spite of its high strength, packaging applications have been limited because PLA is more brittle than traditional oil-based plastics. Because of this, films display low tear and impact resistance and produce a loud crackling sound when manipulated. Although many studies address the toughening of PLA in the bulk, little attention has been placed on the film performance. The present study is aimed at providing a survey of binary PLA based blends with other biodegradable and non-biodegradable plastics. Acrylic impact modifier (AIM, 5 wt. %), ethylene vinyl acetate (EVA, 20 wt.%), polyhydroxyalkanoate (PHA, 10 wt.%), polycaprolactone (PCL, 30 wt.%), polybutylene succinate (PBS, 20 wt.%) and polypropylene carbonate (PPC, 30 wt.%) were each blended with PLA through single-screw extrusion and converted into films via the blown-film process. Tear and impact resistance, heat seal strength, and noise level were measured. EVA, PHA, PCL, and PBS improved the tear resistance with EVA having the highest effect (>2x). Similarly AIM, EVA and PPC improved the resistance of the film to impact-puncture penetration. Heat seal strength was significantly improved by the PHA and moderately increased by AIM (2x) and EVA. Additionally, we proposed a method to quantify the annoyance of the noise made by the films upon manipulation. PCL and PBS significantly reduced the annoyance level of the films.