Impact of Surface Modification of Hemp Fibers Using a Coupling Agent in Solvent on the Properties of Polyethylene Composites

This study investigates the grafting of a coupling agent, maleic anhydride-grafted polyethylene (MAPE), onto hemp fibers in a 1,2,4-trichlorobenzene (TCB) solution, followed by an evaluation of the morphological, rheological, and mechanical properties of the resulting polyethylene composites containing 30% hemp. SEM analysis revealed the formation of a thin layer of MAPE on the surface of the modified fibers. This was further confirmed by the appearance of a MAPE degradation peak at 448 °C, observed in the modified fibers but absent in the unmodified counterparts. Composites made with unmodified hemp fibers (UT30) showed a significant increase in modulus but not in tensile strength. In contrast, the modification of hemp in solution significantly enhanced the tensile strength of the composites (UTE3S) without significantly affecting the modulus. Increasing the amount of coupling agent (in UTE6S and UTE9S) reinforced this trend, indicating that the thin polymer layer on the surface of the modified hemp fibers notably improved interfacial bonding, with minimal impact on the tensile modulus of the composites.