Effects of high‐temperature optimization and resin coating treatment on the mechanical, thermal, and morphological properties of natural kenaf fiber‐filled engineering plastic composites

In this study, kenaf natural fibers were coated with acetone‐thinned epoxy resin before compounding with high‐temperature polyethylene terephthalate (PET). Thus, composites of sodium hydroxide treated and epoxy‐resin coated kenaf fibers (KF) reinforced PET (CTKF‐PET) were manufactured using extrusion and compression molding techniques at an optimized 10 wt% constant fiber loading and processing temperatures of 240, 250, and 260°C, and were characterized for mechanical, thermal, and morphological performances. The obtained results showed an optimum processing temperature of 240°C with maximum mechanical and thermal properties with good interfaces between the coated fillers and the matrix, compared to those obtained at 250 and 260°C. Thermogravimetric analysis recorded maximum onset degradation and decomposition temperatures of 338.9 and 381°C with 9.5% and 13% improvements respectively after resin coating which positively impacted the constituent coated composites compared to the uncoated KF. Differential scanning calorimetry glass transition (Tg) and melting temperatures (Tm) for the CKF‐PET composites was maximum at 119.0 and 262.8°C with 2.18% and 2.8% improvements respectively compared to uncoated composites. The overall properties of all coated kenaf‐reinforced PET (CKF‐PET) and coated‐treated (CTKF‐PET) composites were higher with improved morphological properties irrespective of the processing temperature compared to the raw kenaf (KF‐PET) composites. Hence, natural fibers can be treated with resin coating to improve the thermal stabilities of natural fiber engineering plastic composites, and the interfacial adhesion between the coated‐KF and the engineering plastic matrix. The resultant composites are suitable for high‐temperature engineering applications such as the automotive and construction industries. High‐temperature and resin coating treatment processes of natural kenaf fiber‐filled engineering plastic composites.