Effective reinforcement of epoxy composites with hyperbranched liquid crystals grafted on microcrystalline cellulose fibers

Interface design plays a crucial role in developing superior mechanical performance of nature fibers/polymer composites (NPC). Herein, microcrystalline cellulose fibers (MCFs), extracted from sisal fibers, were modified by function end-group hyperbranched liquid crystals (HLP) with respect to improve the wettability and interactions between the MCFs and epoxy resin (EP). The HLP that modified MCFs (HLP-MCFs) were studied by Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and polarizing microscope. The results showed that the MCFs can be successfully modified by the HLP, which would provide strong MCFs/matrix interfacial adhesion. Therefore, the addition of HLP-MCFs was found to produce significant enhancements in the mechanical and thermal properties of EP. In particular, at 1.0 wt% filler loading, the flexural strength, tensile strength, impact strength, and flexural modulus of the HLP-MCFs/EP composites increased by 60, 69, 130, and 192 %, respectively, as well as the glass transition temperature increased by a notable 42.9 °C. It is anticipated that our current work would inform ongoing efforts to exploit more efficient method to overcome the poor nature fiber/polymer adhesion in the interface region and broad implications for the development of the NPC for engineering applications.