Investigating the influence of alkali treated hemp fibre on the mechanical properties of diverse rubber composites

This study investigates the effect of natural hemp fibre and alkali modification on the properties of rubber compounds. The effect of adding hemp fibre from alkali modified natural fibres to three different rubber compounds was studied. The results revealed a decrease in curing times with the addition of fibres, a decrease that was further increased by alkali modification, shifting the environment to a basic environment. As the fibre content increased, the cross-link density and compound hardness also increased. Alkali modification reduced fibre hardness, resulting in lower compound hardness and viscosity compared to untreated fibre. Tensile strength showed improvement with fibre reinforcement among different rubber types. We observed an increase in tensile strength of up to 70%. The presence of fibres significantly increased the tear resistance. Nitrile butadiene rubber showed an improvement of 137% with untreated fibre and 209% with treated fibre. In contrast, epoxy modified natural rubber showed an improvement of 165% with treated fibre. These findings are promising for the improvement of mechanical properties of rubber compounds through natural fibre reinforcement, especially with alkali modification. However, deformation properties deteriorate after 10% strain, highlighting the need for further optimisation of fibre/polymer interactions for improved performance.