Enhanced Performance of Polylactide Film via Simultaneous Biaxial Stretching and Silane Coupling Agent as a Thermal Shrinkable Film

Abstract

Biaxial stretching technique has been known to improve the toughness of polylactide (PLA) film. Furthermore, blending with an additive is another way to control the mechanical properties of the product. The integrated effect of simultaneous biaxial stretching and blending with silane coupling agent on the properties of PLA film is examined in this study. The PLA pellets are melt compounded with various amounts of 3-aminopropyltriethoxy silane (APS). Then, the films are prepared by cast film extrusion and simultaneous biaxial stretching process with a stretching speed of 75 mm s–1. The relationships among the crystallinity, tensile properties, and thermal shrinkage of the prepared films are investigated. The crystallinity of PLA is significantly induced in the film by the stretching technique. An increase in the additive content also facilitates the polymeric crystallinity. The elongation at the break of the biaxially stretched film increases with the additive content, which corresponds with the PLA crystallinity. Compared to the pristine PLA film, the addition of 1% APS improves tensile strength in a transverse direction of the film about 10 times. The thermal shrinkage of the obtained films was evaluated to assess their applications as heat-shrinkable films. The prepared films show a thermal shrinkage of 45%, which are comparable to that of a commercial shrink film.