Jute–polypropylene composites using m-TMI-grafted-polypropylene as a coupling agent

Jute fiber filled polypropylene composites were prepared using m-isopropenyl-α-α-dimethylbenzyl-isocyanate (m-TMI)-grafted-polypropylene as the coupling agent. The effect of filler concentration and coupling agent on mechanical properties (tensile, flexural, impact strengths and tensile modulus) of the composites were investigated. Fourier transform infra red (FTIR) spectroscopy of the coupling agent and composites revealed effective coupling between jute fibers and polypropylene. The coupling agent was found to be effective in improving the strength and stiffness properties of the composites. Thus, at 50 wt% jute content, the tensile strength exhibited 87% increase and flexural strengths exhibited about 95% increase over virgin polypropylene. The tensile modulus of the composite with 50 wt% jute content was nearly five times of virgin polypropylene (6.7 GPa vs. 1.4 GPa). The improvement in properties indicated reinforcement of polypropylene matrix by the jute fibers with an effective transfer of load from matrix to fibers. Significantly without coupling agent, the strength properties did not exhibit any improvement with increasing filler content. However, only the tensile modulus exhibited an increasing trend with filler content. The elongation at break and the unnotched impact strength of the composites decreased whereas the notched impact strength increased with increasing filler content. The moisture absorption in composites without the coupling agent, measured over 600 h, was two to three folds higher as compared to composites with the coupling agent.