Enhancing the thermal and mechanical properties of epoxy resins by addition of a hyperbranched aromatic polyamide grown on microcrystalline cellulose fibers

In this study, microcrystalline cellulose fibers (MCFs) derived from sisal were treated with a hyperbranched aromatic polyamide (HBAP). The modified sisal fibers were used to produce composites with epoxy resins. Firstly the MCFs were treated with a silane coupling agent, then a HBAP was grown on the modified surface. The HBAP-MCFs were used to reinforce epoxy resins. The HBAP-MCF/epoxy composites were studied by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), thermal gravimetric analysis (TGA), dynamic mechanical analysis (DMA), and mechanical properties analysis. The results show that the HBAP-MCFs enhanced the thermal and mechanical properties of the epoxy resin. For instance, the impact strength, tensile strength, Young's modulus and toughness of the HBAP-MCF/epoxy composites with 2.0 wt% HBAP-MCFs were 32.1 kJ m−2, 59.4 MPa, 695 MPa, and 4.37 MJ m−3. These values represent improvements of 83.4%, 34.7%, 25%, and 178.3%, respectively, compared to a neat epoxy resin. Moreover, the addition of HBAP-MCFs produced composites with higher thermal degradation temperatures and glass transition temperatures. The HBAP-MCF swere effective in improving the thermal and mechanical properties due to a strong affinity between the fillers and the matrix.