Study On Preparation And Properties Of Waste Denim Fibers Reinforced Polypropylene Composites

With the improvement of people’s living standard,the consumption of textiles is increasing,and more and more waste textiles are produced.At present,the disposal of waste textiles is mainly incineration and burial,which leads to the waste of resources and environmental pollution.Therefore,the recycling of waste textiles is an effective means to reduce environmental pollution and material waste.In the waste textiles,waste cotton textiles account for 24% of the total,which can be used to make natural fiber reinforced thermoplastic composites.Moreover,natural fiber reinforced thermoplastic composites have been paid more and more attention because of their low cost,convenient recycling and environmental friendliness.However,due to the poor dispersity of natural fibers in the matrix and the poor interfacial compatibility with the matrix,the strengthening effect is limited.In order to solve the above problems,this thesis used waste denim fibers,which were loosened from used jeans,and then combines it with polypropylene(PP)fiber to prepare the waste denim fibers/PP composites through three-dimensional needling process and molding.The optimum preparation parameters,interfacial properties,mechanical properties,water resistance and formaldehyde content of the waste denim fibers/PP composites were studied.In addition,silane coupling agent and flame retardant agent were used to modify the waste denim fiber to improve the interfacial properties and flame retardant properties of the waste denim fibers/PP composites,so as to prepare the composites with excellent performance and low cost which can be used in the fields of furniture,automobile interior and construction.The conclusions of this thesis are as follows:(1)The optimal process parameters of the waste denim fiber/PP composites were obtained by surface response method.The fiber content was 58.38%,the molding time was 5.29 min,and the molding temperature was 194.66 ℃.(2)Compared with the cotton fiber/PP composites,the residual dyes and the pretreatment process before dyeing improved the mechanical properties and interfacial properties of the waste denim fiber/PP composites,and the bending strength,peel strength and shear strength of the waste denim fiber/PP composites were increased by 18.6%,21.8% and 20.2%,respectively.Compared with high density fiberboard,the bending strength,bending modulus,peeling strength and water resistance of the waste denim fiber/PP composites were increased by 91.1%,10.5%,104.4% and 90.0%,respectively.And there is no formaldehyde in the waste denim fiber/PP composites.The results indicate that the waste denim fiber/PP composites can be used in furniture,automobile interior and architecture instead of high density fiberboard.(3)Using silane coupling agent to treat the waste denim fiber can improve the interfacial properties of the waste denim fiber/PP composites.At the same time,the mechanical properties and water resistance were improved by 25.45% and 41.6%,respectively.The optimum concentration of silane coupling agent was 1%.(4)The use of ammonium polyphosphate flame retardant to treat the waste denim fiber/PP composites can improve its flame retardant performance,so that it can be better used in furniture,automotive interior,construction and other fields.This paper contains 20 figures,8 tables and 116 references.