Vibration damping characteristics of short hemp fibre thermoplastic composites

In this project, free vibration testing and dynamic mechanical analysis methods were used to study the damping properties of noil hemp fibre-reinforced polypropylene composites with varying fibre contents (0 to 60 wt%) and compatibilizers (maleic anhydride-grafted polypropylene and maleic anhydride-grafted polyethylene octane) under applied frequencies of 1 to 200 Hz. The storage modulus of the composites was increased by the increase in hemp fibre content. However, the maximum damping ratio was obtained from the composite with 30 wt% noil hemp fibre. The addition of coupling agents reduced the damping capacity of all composites. However, 30 wt% noil hemp fibre-reinforced polypropylene coupled with 2.5 wt% anhydride-grafted poly ethylene octane revealed the highest damping ratio among coupled composites. Damping properties of the composites were relatively constant over the frequency range, except at frequencies which the material–instrument system began to resonate and peaks were observed in the curves