Development and characterization of PLA/nanoclay biocomposites reinforced with Mimosa pudica microfibers for enhanced mechanical and thermal performance

Abstract

The purpose of the present work is to investigate the physical, mechanical, and thermal properties of a novel Mimosa pudica (MP) microfiber-reinforced polylactic acid (PLA) green nanocomposite for biomedical and packaging applications. Calcium sulfate (CaSO₄) has been chosen as a filler, which is a by-product of PLA production. In addition, different weight % (2, 3, and 4) of organically modified montmorillonite (o-MMT) nanoclay, as the reinforcing filler, have been mixed with PLA by twin-screw extrusion to obtain three polymer samples. The biocomposite variants were prepared by stacking a layer of 10 wt.% MP microfibers between two layers of nano PLA matrix mix in a compression molding machine. Characterization of the molded composites has been done through the investigation of density, water absorption, mechanical properties, morphology, and biodegradability tests, along with thermal analysis. Results indicate that the MP microfibers reinforced biocomposite containing 3 wt.% nanoclay exhibited the highest tensile strength, 22.98 MPa, whereas the biocomposite containing 4 wt.% nanoclay exhibited the highest impact strength of 162.52 J/m, flexural strength of 32 MPa, and hardness of 19.4 HV. PLA/MP composites with 4% nanoclay recorded the highest thermal resistance at 359°C for 80% weight loss. The addition of MMT nanoclay improved water resistance, mechanical properties, and thermal stability across the variants, with a marginal decrease in biodegradability.