Prepartion And Performance Of Bamboo Fiber/Polypropylene Composites

As known as the “kingdom of bamboo”,China is rich in bamboo resources.Owing to fast growth,strong regeneration,early mature,high yield,high strength and low cost compared with other species,bamboo,as a supplement to timber,has gained increasing attention to use in housing,furniture,packaging,transportation and other fields.However,the comprehensive utilization rate of bamboo is less than 40% due to its special structure of thin and knobby hollow wall.A large number of bamboo waste in processing were only used as boiler fuel,which wastes resources and causes environmental pollution.As an effective way to solve above problem,using the bamboo waste to prepare bamboo-plastic composites(BPCs)can save resources,protect the environment,improve the added value of bamboo waste,and realize the efficient utilization of bamboo resources.So this research has important scientific significance and broad application prospect.Bamboo waste,common wood waste and different parts of bamboo were used to prepare polypropylene(PP)matrix composites in this paper.The effects of composition and structure on fiber morphology and properties of composites were revealed.It provides a theoretical basis for the preparation of high-performance BPCs.Bamboo waste were modified by heat treatment and the economic feasibility of it was comprehensively evaluatedand.The influence of heat treatment process and maleic anhydride grafted polypropylene on the properties of BPCs were explored.This provided theoretical guidance for the practical production of BPCs by heat treatment.The main research contents and results of this paper are as follows:(1)Five omposites of bamboo/PP,poplar/PP,eucalyptus/PP,Chinese fir/PP and pterocarpus tinctorius/PP were systematically studied.Due to the low content of extract,low ash content and high crystallinity,poplar and eucalyptus flour have large aspect ratio and its composites have high tensile and bending strength.The good thermal stability of chinese fir and the highest modulus of it composites were because of the highest lignin content.However,the highest content of small particles inhibited the PP crystallization and degraded the processing properties of its composites.The content of pterocarpus tinctoriusreducing the interfacial bond strength,thus resulted in the low crystallinity and strength of its composites.But the lubricating effect of the extractive improved the processing properties of its composite.The content of hemicellulose is as high as 22.63% and the content of cellulose is only 34.70%,which resulted in the worst thermal stability and the lowest aspect ratio(2.07)of bamboo flour.And bamboo/PP exhibited the worst mechanical properties.In general,the properties of composites prepared by bamboo waste are slightly lower than those traditional wood-plastic composites,thus BPCs has the potential of wide application and has the value of further research.(2)Six types of bamboo particles made from bamboo culm,bamboo green,bamboo timber,bamboo yellow,bamboo node,and bamboo waste were compounded with PP to prepare BPCs.The composition and structure of bamboo,morphology of particles and properties of BPCs were investigated.The results show that the crushing mechanism of different parts bamboo is different because of the difference in anatomical structure and chemical composition.Thus,different morphology and size of prepared bamboo particles led to the difference performance of BPCs.The BG,which possessed the densest distribution of VBs mainly consisting of sclerenchyma fibers and exhibited the highest crystallinity,was split into slender long fibers with the largest length(996 ?m)and L/D(6.20)and the smallest diameter(191 ?m),respectively.BG/PP had the highest modulus,the higher strength and the highest creep resistance.Due to the highest content of brittle parenchyma cells,the highest hemicellulose content,and the lowest crystallinity,BY was fragmentized into shortest(419 ?m)fibers with the lowest aspect ratio(2.14),which resulted into the the lowest strength and modulus,and the worst processing properties of BY/PP.BN have the roughest surface,the largest diameter(249 ?m),the highest ductility and toughness because of the crisscrossed VBs.Thus,its composites exhibited the highest loss factor,creep strain,elongation at break,and the higher impact strength.(3)Bamboo particles were modified by heat treatment using a self-developed multi-functional plant fiber powder dryer.The effects of the processing temperature,time,and the addition of maleic anhydride grafted polypropyleneon on the properties of BPCs were evaluated.The results show that 25?30wt.% bamboo extract was extracted from bamboo waste during the heat treatment process,and the purification rate of bamboo extract was 98.0?99.2wt.%.Compared with untreated BPCs,the comprehensive production cost of BPCs prepared by heat treated bamboo fiber was greatly reduced,and its mechanical properties and mildew resistance were improved.Therefore,modification of bamboo fiber by heat treatment is an economically feasible modification technology.The treatment technology of 160 ? for 3 hours have the highest comprehensive benefit.The tensile and flexural strength of its composites have hardly improved,but the impact strength of its composites was increased by 39% and the mildew control efficiency was about 9.4% at a lower treatment cost.With the addition of maleic anhyde-grafted polypropylene,the tensile strength,flexural strength,tensile modulu,flexural modulus and dimensional stability of BPCs were increased by 118%,82%,78%,33% and 25%,respectively.The elongation at break was reduced by 40% and the mildew control efficiency was up to 38%,but the notch impact strength was reduced by 41%.