Sisal fiber reinforced polyethylene terephthalate composites; Fabrication, characterization and possible application

The use of thermoplastics (TPs) for natural fiber composites is restricted to commodity ones like polypropylene and polyethylene However, using engineered TPs such as polyethylene terephthalate (PET) will benefit from its technical and economic advantages. The research aims to characterize injection molded PET composites reinforced with sisal fibers treated differently. Polyethylene terephthalate composites containing 40 wt.% of untreated, alkaline-treated, and alkali/acetylation treated sisal fibers were prepared using compounding and injection molding processes and then characterized. It has been found that production of sisal-PET composites by compounding and injection molding has been shown to be possible. Thermal damage to sisal fiber was noticed during composite production. Based on the thermogravimetric analysis analysis, a net weight loss (excluding water loss) of 11.1%–14.0% was observed at the operating temperatures of the two processes. The addition of 40 wt.% of sisal to the PET matrix improved the tensile modulus by 137%. Further improvement by 179% was observed when alkali-treated sisal fiber was used. The combined alkali/acetylation treatment of sisal yields more enhancement by 233%. This is a significant advancement because modulus is the most influential parameter during the design and service of an engineering product. Generally, compared to the raw sisal composite (RSC) the interfacial, mechanical, thermal, and water absorption properties of the alkali treated sisal composite (Al-SC) and alkali/acetylated sisal composite (Al-ASC) specimens recorded an improvement. Relative to the natural fiber reinforced thermoplastic composites that were commercialized in the automotive industry, the produced sisal–PET composites resulted in a considerable improvement of 66.6%–190% in flexural strength and by 110.5%–410.0% in flexural modulus, depending on sisal fiber treatment and the composite to be compared. Thus, the studied composites can be recommended for various parts of automobiles.