Fabrication And Property Investigation Of Hemp Fiber Reinforced Polypropylene Composite

In this paper, the method of surface modification of hemp fiber is graft, then use the hemp fiber blend with polypropylene to prepare flax fiber/polypropylene composites and their microstructure and properties were studied. The performance of samples with different fiber contents are investigated by comparing four kinds of composites whose fiber contents are 5%,10%,15%,20% when the fiber was chopped to approximately 5mm in length, and then the performance of samples with different fiber length are investigated by comparing four kinds of composites whose fiber length are 2mm,5mm,7mm,10mm when the fiber was approximately 10% in content, at the same time also study the different processing methods (alkali treatment and coupling agent) treatment of hemp fiber, and the performance was compared with the graft method of surface modification, Finally, make a comparative study of ramie and jute reinforced material's properties.The results show that:1.When the fiber with untreated blend with the polypropylene, the interface bonding conditions between fiber and matrix is not ideal, there are a lot of gaps between them.2.The fibers was treated by grafted, and was characterization by infrared spectroscopy (FTIR), scanning electron microscopy (SEM), TG, contact angle and the tension changes, then we can analysis and comparison of change before and after the graft treatment, the results show that the Graft was successful grafted onto the surface of ramie fiber, its surface has become rough, thermal become more stability, and increased in hydrophobic and the situation of the interfacial adhesion with the matrix of polypropylene was also improved.3.Before the treatment, when addition the matrix with the increase content fiber its tensile strength was only little increases, but with the increases of the fiber content, the flexural strength, tensile modulus, bending elasticity modulus, water absorption and heat distortion temperature of composite materials all was increased, impact strength and melt flow rate was decreased with the increase content of fiber, but after grafted the fiber-reinforced materials'performance in addition to outside the tensile strength was increased and impact strength went through a phase of first increases then decreases with the increase of fiber content, the other trend of performance is consistent to the untreated, and the performance of the grafted enhancing material is superior to the untreated.4.Later we do research on how the fiber length affect the properties of composite materials, the results show that, the effect of fiber length to mechanical properties of composite materials is the same to the fiber content, the trend is consistent, when compared with other treatment methods, the effect of grafting is the best. And under the same conditions ramie reinforced materials is superior to that of jute reinforced.5.General considering, for the grafted fiber when ramie fiber content was 10% and fiber length was 5mm, the mechanical properties of composite materials are more ideal, at this point the processing of melt is better, and the impact strength is near the peak, the other performance is also better, compared to the PP matrix, the tensile strength, bending strength, impact strength, tensile modulus and flexural modulus were increased by 10.5%, 17.31%, 6.6%, 104.6% and 93.83%.