Reactive toughening of injection-molded polylactide pieces using maleinized hemp seed oil (original) (raw)

2018, European Polymer Journal

The present study describes the effect of maleinized hemp seed oil (MHO) on the physical performance of polylactide (PLA) pieces. To this end, PLA pieces with varying MHO contents in the 0-10 wt% range were manufactured by twin-screw extrusion (TSE) followed by injection molding. The resultant pieces were characterized in terms of their mechanical, thermal, and thermomechanical properties. The obtained properties suggested that, unlike typical plasticizers, MHO does not only induce an increment in elongation at break and impact strength but it also enhances both elastic modulus and tensile strength. In addition, it was observed a moderate decrease in the glass transition temperature (Tg). This was ascribed to a linear chain extension and/or branching phenomenon due to the reaction of the multiple maleic anhydride (MAH) groups present in MHO with the hydroxyl groups of the PLA terminal chains. Furthermore, morphology characterization revealed that, though certain phase separation occurred at its highest content, MHO was finely dispersed as submicron droplets within the PLA matrix contributing to improving toughness. The use of multi-functionalized reactive oils thus represents a highly sustainable solution to reduce the intrinsic brittleness of PLA materials without compromising their mechanical resistance and the toughened biopolymer pieces described herein can find interesting applications in, for instance, rigid packaging.