Examination of water uptake performance and mechanical properties of PLA/flax fiber biocomposites with the coupling agent

Abstract

The paper reports, the effect of water sorption on the microstructural and flexural properties of the flax fiber/ polylactic acid (PLA) biocomposites compared to the composites with maleic anhydride (MAH) as coupling agents and alkali treatment. In the current study, five different biocomposites which are 15 % wt. flax/PLA, 25 % wt. flax/PLA as control group and15 % wt. flax/PLA, 25 % wt. flax /PLA, and 35% wt. flax / PLA with 5 % wt. MAH was produced. Ten different soaking times were studied to understand the water absorption behavior of the biocomposites. To investigate mechanical properties of the biocomposites impact test was applied on the dry and 750 h, 1850 h water sorption composites. A three-point bending test was performed on the dry and 1850 h water sorption biocomposites to determine flexural properties. Short flax fiber-reinforced PLA matrix biocomposites were compounded using extrusion and manufactured by injection molding. Flax fiber surface was treated using sodium hydroxy solution to advance the interface interaction between fiber-matrix and surface performance of the fiber and matrix. According to the results, alkali treatment improved the water gain resistance of the composites since its enhancement of the interfacial bonding. Alkali-treated composites with maleic anhydride showed the better impact and flexural strength than composites without alkali-treated after 1850 h water sorption.