Mechanical, morphological and thermal analysis of unidirectional fabricated sisal/flax hybrid natural fiber composites

Abstract

We report the spectroscopic, thermal, and mechanical outcomes of epoxy reinforced sisal/flax (S/F) hybrid natural fiber composites. This work is intended to enhance the mechanical and thermal properties of the sisal fibers in addition to flax fibers. In recent years, natural fiber composites gained inclusive credit as a supernumerary to conventional synthetic composites for their superior ecological properties. Five different varieties of composite slabs i.e., 60% epoxy matrix and 40% of sisal/flax fibers were fabricated unidirectionally through a simple hand layout method by varying sisal and flax ratio as (40/0, 30/10, 20/20, 10/30, and 0/40) with a constant weight fraction as 0.4Wf. The x-ray diffraction analysis was performed on the 20 S/20 F specimen and the crystallinity index is calculated as 42.84%. The spectroscopic and thermal studies were conducted on the 20 S/20 F sample and the chemical imprint of the composite is revealed by the strong peaks of cellulose, hemicellulose, and lignin along with amorphous and crystalline content of the FTIR data and is confirmed through the XRD data. The addition of flax fibers to sisal fibers showed a constructive improvement of thermal stability which is shown by the TG/DTA graph. In a three-stage degradation of sample, a maximum is observed at 334 °C. The tensile, flexural, and impact tests of all the fabricated composite samples are performed and ultimate tensile strength of 165.2 N/mm2 for the 40 S/0 F composite with an elongation of 9.2% is noted. The ultimate flexural stress of 8.1 N mm−2 is observed in composite 10 S/30 F and composite 10 S/30 F has an excellent ability to absorb impact force of 1.2 J energy. Based on the above results the manufactured composites exhibited higher thermal and mechanical properties showing a unique characteristic for different concentrations of flax fibers. Thus, the developed composites can be used individually for various applications based on the requirement of the end-user.