Polylactic acid/Lignocellulosic residue composites compatibilized through a starch coating

The use of natural fiber residues as reinforcement in biodegradable composites has been performed; however, the incompatible interface limits the applications. In this work, the use of starch coating as a natural coupling agent was studied in three different natural residues: sugarcane bagasse, macaranduba, and pinus wastes, aiming biodegradable composites. The coating in bagasse showed low efficiency, with low thickness and failures, due to residue intrinsic higher surface area; while the wood residues showed shorter fibers with uniform starch deposition. These results affected the compatibility between filler and matrix; while the bagasse composite showed voids and decrease in the mechanical properties; however, the macaranduba and pinus showed an increase in the stiffness and strength. All the coated fiber composites showed stable thermal properties and an increase in the crystallinity in the coated samples. The addition of the natural filler resulted in a high water absorption with coated samples absorbing six times more water than neat PLA and without stabilization in a short time. This characteristic may favor the initial abiotic hydrolysis in the biodegradation, showing that the material could be an option to produce short-life packaging in dry environments.