PLA composites formulated recycling residuals of the winery industry

Particulate composites with polylactide (PLA) as a matrix and wastes deriving from the wine production have been formulated at different compositions. The microstructure and the mechanical properties of the composites, as well as the thermal stability and water uptake have been evaluated. The results showed that the wine waste residue does not compromise the thermal stability of the matrix while improves the impact strength and influences tensile properties. Specifically, tensile strength progressively decreases on addition of the winery waste, while the elastic modulus slightly increases. This behavior was attributed to the inhomogeneity of the filler particle size and morphology, which can partially induce a discontinuous interface at high filler loading and affect the water uptake. An increase in the value of the water contact angle is obtained below a 10% wt content and the mechanism of water uptake is not modified below the 20 wt% of filler. In any case, up to a content of 15 weight percent, winery wastes can be used in the plain matrix as an extender. Since simple and low cost operations are requested to obtain suitable fillers, an overall decrease in the material cost can be envisaged thus partially solving the drawbacks of PLA exploitation in the packaging industry, and leading to cost-effective application. Moreover, the conversion of lignocellulosic wastes as filler in biocomposites would be in favor of waste reduction while adding value to the agro-food chain.