Physio-mechanical and thermal characteristics of Mimosa pudica microfibers impregnated novel PLA biocomposite

The present work deals with the synthesis of compression-molded eco-friendly composites containing emerging biopolymer polylactic acid (PLA) impregnated with varying proportions (5, 10, and 15% by weight) of Mimosa pudica (MP) microfibers. Characteristics of the prepared composite variants were analyzed to figure out the influence of the novel fibers, derived by sodium hydroxide (NaOH) retting from the stem of the inedible plant with the common name—touch-me-not, which grows abundantly in tropical wastelands across the world. The physical attributes of the biocomposites accounted for in the study were density, void content, moisture content, and water absorption together with thickness swelling tendency. The maximum water absorption and thickness swelling of the composite samples, soaked in distilled water for 30 days, were recorded as 7.28% and 13.2%, respectively; both parameters increased with an increment in fibers loading in the composites. PLA composites with fiber content of 10% recorded the optimum tensile and flexural properties; tensile strength and modulus were 20 MPa and 6902 MPa and flexural strength and modulus were 28 MPa and 4758 MPa, respectively. The inclusion of MP fibers enhanced thermal stability of the PLA composites, indicated by thermogravimetric (TG) and derivative thermogravimetric (DTG) analyses, with a maximum degradation temperature of 293 °C for 15 wt% fiber loading. Biodegradability test results of the composites displayed appreciable weight loss at the end of 90 days, with the highest of 40.96% for the sample containing 15 wt% fiber, which was favorable for the end-of-life disposal and seamless assimilation by nature.

Graphical abstract