Effects of ZnO nanoparticles, plasticizer, and emulsifier on PLA films properties and mechanical aging stability

Abstract

Polylactic acid is an environmentally friendly polymer that has the potential to be an alternative to petroleum-based materials in the food packaging industry. However, issues such as the fragility of the produced films, low thermal stability, etc. are obstacles to the widespread use of this type of film. In this work, films based on polylactic acid were produced with additives, namely zinc oxide nanoparticles (1 wt.% PLA), polyethylene glycol 400 (20 wt.% PLA), and tween 80 (0.25 wt.% solution). The purpose of adding additives was to improve the properties of the sample films. The results showed that the presence of plasticizer and emulsifier increases the hydrophilicity of the film and the water vapor permeability. The highest contact angle (85.33 [[EQUATION]] ±4.00) and the lowest water vapor permeability (0.074±0.002 g.mm/kPa.h.m 2 ) were related to neat PLA film. The effect of the added materials on the thickness of the films was not significant, and all the films had good transparency. The addition of nanoparticles, emulsifiers, and plasticizers increased the percentage of crystallinity. The highest crystallinity percentage was for film PLA/ZnO (7.7%). The effect of plasticizer and emulsifier on tensile strength and elastic modulus was more than nanoparticles. The effect of the type of film produced on the mechanical properties was significant, and the effect of their storage time was only significant on the elongation at break. These results can help to improve the physical, mechanical, and thermal properties of polylactic acid for food packaging on an industrial scale.