Preparation and performance evaluation of 3D printed Poly Lactic Acid composites reinforced with silane functionalized walnut shell for food packaging applications

The main goal of this work is to develop silane-grafted Poly Lactic Acid (PLA) bio-composites reinforced by various compositions of 0, 5, 10, and 15 wt% Walnut shell (WAL) particles and 3D printed by Fused Filament Fabrication (FFF) technique. The composite filaments are extruded by filament extrusion technique, and the 3D printed Walnut shell/PLA (WAL/PLA) bio-composite samples are evaluated for various mechanical, water absorption and biodegradation properties. The effect of silane grafting increases the crystallinity index value of 61.2% for the silane-grafted WAL particles. The mechanical property results reveal that using WAL particles reduces the strength value and improves the modulus of both untreated and silane-treated WAL/PLA composites. The silane grafted 15% WAL/PLA samples show the highest shore hardness value of 71 MPa and the heat deflection temperature of 63.79 ℃. The biodegradation test results reveal that the untreated 15% WAL/PLA composites have a higher mass loss of 6.4% and 19.1% for 30 and 60 days, respectively. Fractographical results of silane-treated 10% WAL/PLA composites exhibit a uniform distribution of WAL particles with minimum particle pull-out from the polymeric matrix. The findings of this study affirm the potential of WAL/PLA bio-composites as a viable and sustainable material for application in food storage and service.