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Low Concentrations for Significant Improvements in Thermal and Thermomechanical Properties of Poly(Lactic Acid)–Keratin Biocomposites Obtained by Extrusion and 3D Printing

ABSTRACT Polymer composites of polylactic acid (PLA) reinforced with rachis obtained from chicken feathers (0.5–1.0 wt %, 5–10 wt%) were developed by extrusion and additive manufacturing. Rachis was incorporated into the polymer after milling, and it was also milled and modified with sodium hydroxide (NaOH). Thermomechanical properties evaluated by dynamical mechanical analysis revealed significant increments with treated ground rachis at 1 wt%, which produced the greatest increase in E´ with respect to PLA (195%). The scanning electron microscopy images show a clear difference between the fracture surface of the compounds obtained by 3D printing according to the type and concentration of reinforcement used. In addition, the 3D printing composites show different thermal conductivities than PLA with the addition of keratin. Thus, natural composites obtained by 3D printing technology with very low concentrations of keratin show significant changes in thermal and thermomechanical properties of PLA matrix.