One step production from the monomer of poly(L‐lactide)/flax biocomposites by thermoplastic resin transfer molding: Mechanical properties and aging

Abstract

AbstractDevelopment of biocomposites is becoming a necessity due to environmental concerns. Polylactide is a matrix of choice, regarding its bio‐sourced and compostable nature along with its mechanical properties. In this study, poly(L‐lactide)/flax biocomposites were produced using thermoplastic resin transfer molding (TP‐RTM) in one step process from the monomer, affording sustainable and fully compostable composite materials. The polymerization of L‐lactide (L‐LA) monomer was promoted by tin octoate, affording poly(L‐lactide) (PLLA) matrices displaying monomer conversions superior to 96% and mass‐average molar masses above 140,000 g/mol. Flax fibers were used as received without any functionalization which is usually conducted to prevent the hydroxyl groups to conduct side reactions. Mechanical testing revealed bending modulus of 9.3 GPa and bending strength of 177 MPa comparable to existing literature values for PLLA/flax composites produced by other techniques. Digital microscopy analysis provided insights into impregnation quality and void characterization within the composites. In addition, the durability of these biocomposites was also evaluated via accelerated aging tests.Highlights PLLA/flax biocomposites were produced by TP‐RTM for the first time. In situ polymerization of the PLLA matrix associated with non‐functionalized flax fabrics was conducted. Bending properties were found in line with those of PLLA/flax composites produced by compression molding. Aging tests under UV at 50°C of PLLA/flax biocomposites were conducted.