Mechanical Properties and VOC Emission of Hemp Fibre Reinforced Polypropylene Composites: Natural Freezing-mechanical Treatment and Interface Modification

In this study, the effects of natural freezing-mechanical treatment and interface modification on the mechanical properties and VOC emissions of hemp fibre-reinforced polypropylene composites were investigated. To evaluate the influence of natural freezing-mechanical treatment on fibres and composites, several tests were performed. Natural freezing-mechanical treatment of HF enhanced the mechanical properties and reduced the VOC emissions of HF/PP composites compared with untreated composites. After the degumming treatment, HF was treated with urea and KH-550, and the mechanical properties of the modified composites were better than those of the unmodified composites. Compared with the tensile strength, flexural strength and impact strength of the unmodified composites, the mechanical properties of the urea-modified composites were enhanced by 16.45 %, 17.32 % and 13.23 %, respectively; the mechanical properties of the composites modified by the coupling agent KH-550 were increased by 19.53 %, 20.40 % and 11.19 %, respectively. The total VOC emissions of modified HF/PP composites were lower than those of the unmodified composites. The obtained results demonstrated that natural freezing-mechanical treatment is an effective fibre degumming method. Combined with interface modification, the composite has the characteristics of low VOC emissions, high strength, and good interface bonding.