Comparative Studies on the Mechanical and Thermo-Mechanical Performance of Flax Fiber Reinforced Polyester and Polyester-Biopolymer Blend Resins

摘要

Bio-composites made of biopolymer and natural fibers provide good alternative to traditional fiber reinforced composites made of synthetic fibers and non-biodegradable polymers. In order for biocomposites to attain widespread applications and acceptance, compatibility between natural fibers and biopolymers in terms of good interfacial load transfer should be established which could be obtained through fiber surface treatment. Hence, current investigations were focused on the surface treatment of fiber and study its influence on the adhesion between fiber and polymer matrix. Initially, dew retted flax fibers were treated with alkali by varying concentration keeping temperature and time constant. The fibers were treated with 2.5, 5, and 7% of alkali at room temperature for one hour. 2.5% treated fiber showed comparatively better properties than higher concentration. Hence, for further studies, all flax fibers were treated with 2.5% solution of alkali at different temperatures. In the next phase of study, biocomposites were prepared by immersing fiber mats in resin bath and compression molded using a hot press. Two polymers: Polyester and a polyester-biopolymer blend, ENVIREZ? 1807 were used as matrix. Moisture absorption, mechanical and thermomechanical tests were conducted on the composites. It was determined that treated composites showed reduction in moisture uptake compared to untreated. Alkali treated composites showed an increase in flexural properties as well as storage modulus. The improvement of composites properties is attributed to the chemical treatment. Composites made using ENVIREZ 1807 which has about 18% of natural polymer blend showed comparable properties with those of polyester resin system with potential to reduce amount of styrene used in fabrication.