Influence of chemical treatment on the tensile properties of kenaf fiber reinforced thermoplastic polyurethane composite

In this study, the effect of polymeric Methylene Diphenyl Diisocyanate (pMDI) chemical treatment on kenaf (Hibiscus cannabinus) reinforced thermoplastic polyurethane (TPU/KF) was examined using two different procedures. The first consisted of treating the fibers with 4% pMDI, and the second involved 2% NaOH + 4% pMDI. The composites were characterized according to their tensile properties, Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). The treatment of the composite with 4% pMDI did not significantly affect its tensile properties, but the treatment with 2% NaOH + 4% pMDI significantly increased the tensile properties of the composite (i.e., 30 and 42% increases in the tensile strength and modulus, respectively). FTIR also showed that treatment with 2% NaOH + 4% pMDI led to the strongest H-bonding. Additionally, the surface morphology of specimens after tensile fracture confirmed that the composite treated with 2% NaOH + 4% pMDI had the best adhesion and wettability.