Increasing strength and ductility of extruded polylactic acid matrix composites using short polyester and continuous carbon fibers

The application of polylactic acid (PLA) is limited by its relatively low ductility and strength capacity owing to a high level of crystallization. This study investigates the potential of introducing short polyester fibers in a PLA polymer matrix to address the limitations and enhance the structural flexibility of PLA. Virgin and treated polyester fibers (alkali-, silane-, and alkali–silane–treated) were tested, and at a fiber volume fraction of 40%, the tensile strength of the short polyester fiber/PLA composites was enhanced by 133.4%, 139.7%, 176.2%, and 260.6%, respectively. Similar tests were conducted with the additional inclusion of continuous carbon fibers, and the tensile strength of the resulting continuous carbon fiber–short polyester fiber (40%)/PLA matrix composite was enhanced by 35.1% (virgin), 37.7% (alkali-treated), 51.1% (silane-treated), and 63.8% (alkali–silane-treated). Continuous carbon fibers with a short polyester fiber/PLA matrix composite are compatible with the strength and stiffness of the plain continuous fiber-reinforced composite as well as commercial alternatives. This new type of composite meets the industrial requirements of clean production, high sustainability, low cost, and high-volume fabrication.