Degradation of a mechanically recycled polylactide/halloysite nanocomposite in an ethanolic food simulant

Abstract

This work aims to study the effect of immersion in a ethanolic food simulant in mechanically recycled poly(lactic acid) (PLAR) and its nanocomposites reinforced with halloysite nanotubes (HNT). PLAR was obtained by subjecting PLA to an accelerated ageing process, which includes photochemical, thermal and hydrothermal ageing steps, followed by a final demanding washing step. PLAR was further reinforced with 4 %wt. HNT to improve the properties of the PLAR films. The materials were melt compounded by melt extrusion and processed into films by compression molding. The resulting films were exposed to food simulant D1 (50 %vol. ethanol solution) for 10 days at 40 °C. The intrinsic viscosity, crystallization behavior, thermal stability as well as the mechanical performance were analyzed before and after the contact with the food simulant. The swelling, plasticizing and hydrolyzing effect of the food simulant led to an important decrease of the intrinsic viscosity of all the samples, along with a significant increase of the crystallinity. Thermal stability was negatively affected by the decrease of the molecular weight, while the high crystallinity values resulted in materials with higher Vickers hardness values after the immersion in the food simulant.

Keywords

• poly(lactic acid)
• halloysite
• nanocomposites
• mechanical recycling
• food simulant