The Research On Bamboo Fiber Reinforced Polypropylene Composite

Bamboo fiber(BF)can be used as a reinforce material in thermoplastics because of its advantages of low density,high toughness,cheap and available.However,due to the problems existed dispersion,degradation and interfacial compatibility etc.in the mixed system,the production of BF-reinforced thermoplastic has not been commonly adopted.In this paper,BF was combined with polypropylene(PP)to make BF-reinforced polypropylene composite(BF/PP),and the microstructure of BF/PP was characterized by FTIR,XRD,SEM,TGA and DSC.The optimum conditions of injection molding,hot press molding and microbial modification were obtained through the studies on the relevant properties.The aging mechanism of BF/PP was tested by a UV accelerated aging experiment.Molding techniques of BF/PP composites were investigated.The effects of hot press molding and injection molding methods on the properties of BF/PP were studied respectively.3 MPa(unit pressure),190°C(hot pressing temperature)and 5 min(pressing time)was the optimum technical conditions of hot press molding,4~5 MPa(pressure),195°C(barrel temperature),10 s(holding time)was turn out to be the optimum technical conditions of injection molding.The tensile strength of BF/PP prepared by injection molding was 47%~95% higher and the bending strength was 59%~69% higher than those prepared by hot press molding.The effects of BF content on the performance of BF/PP were discussed under the optimum conditions of injection molding.BF was uniformly dispersed in PP when the BF content was 40 wt.%,and the tensile strength and bending strength of BF/PP were 19% and 49% higher than those of pure PP.The effects of microbial modification time on BF and BF/PP(with 30 wt.% and 40 wt.% BF)were studied under the optimum conditions of injection molding was discussed.The experimental results indicated that with the increasing of microbial modification time,the relative content and crystalline of cellulose in BF increased on the initial stage and then decreased,while the surface of BF became rougher.After treated for 21 days,the relative content of cellulose was increased by 25%,the polarity of BF was reduced.The obscure and highly compatible interface between modified BF and PP was observed,and the tensile and bending strength of BF/PP were increased more than 75% compared with BF/PP which made of untreated BF.Anti-aging performance of the composites was evaluated by 600 h UV accelerated aging test.The color of BF/PP was faded and surface integrity was destroyed after 600 h aging test.The retention rates of tensile strength and bending strength were 66.9% and 74.9%,respectively,when the BF content was 40 wt.%.The XPS and FTIR analyses of BF/PP before and after UV accelerated aging test showed that oxidation reaction of PP was enhanced which led to an increase of carbonyl and carboxyl groups on the surface.Meanwhile the quinone,carboxyl group and peroxyhydroxyl group,which caused to the color change of BF/PP.It was proved that both PP and BF had been photodegraded,which resulted in the decrease of mechanical properties of BF/PP.