Development and mechanical characterization of composites based on unsaturated polyester reinforced with maleated high oleic sunflower oil‐treated cellulose fiber

This work studies the effect of surface functionalization of chopped cellulose fibers (CFs) on the mechanical properties of unsaturated polyester (UPE) matrix‐based composites. Surface functionalization of CFs was carried out by treating them with maleated high oleic sunflower oil (MHOSO) solutions at concentrations of 2.5, 5, and 10 vol.%. Untreated and MHOSO‐treated CFs were dispersed in UPE at 1, 2, and 3 wt% by mechanical mixing. Fourier transform infrared spectroscopy confirmed successful functionalization of CF with MHOSO. Scanning electron microscopy revealed that MHOSO‐treatment improved dispersion of the fibers in UPE. Tensile and compressive testing of the composites showed that MHOSO ‐treated CF improved the strength of the composites compared with untreated CF. This was attributed to better dispersion of the former cf. the latter. Increasing the extent of functionalization of CF with MHOSO resulted in increased strain to failure of the composites due to the MHOSO acting as a plasticizer. MHOSO ‐treated CF increased the hydrophobicity of the composites compared with untreated CF, thereby offering protection against moisture‐induced degradation.