Study On Epoxy Composites Reinforced By Co-deposition Modified Polyester, Cotton And Polyester-cotton Waste Fabric

35 million tons of textile fiber are consumed in China every year,and 20 million tons of waste textiles are generated per year,among which polyester,cotton and polyester/cotton account for more than 90%.Due to the lack of recycling technology and so on,the recovery rate of waste textiles has been always less than 20%.Inspired by biomimetic chemistry of mussels,the co-deposition technology of polyethyleneimine（PEI）and catechol（CCh）provides a new idea for the recycling waste textiles because of its low cost,simple operation,universal adhesion and easy functionalization.Based on this,this paper proposes a strategy of non-destructive recovery of polyester,cotton and polyester/cotton waste textiles based on PEI and CCh co-deposition technology,mainly focusing on the in-situ reconstruction and mechanism of waste textiles’surface,the construction and propeties of waste textiles’fiber/epoxy interface,the preparation and performance of waste textiles reinforced epoxy composites,and the interlayer toughening and mechanism of waste textiles toughened composites.The specific research contents are as follows:Based on PEI and CCh co-deposition technology,interfaces between fiber and co-deposition layers were constructed on the surface of polyester,cotton and polyester/cotton.The influence of preparation conditions on surface reconstruction was systematically studied.When PEI/CCh ratio is 2:1,3:1 and 1:1,the maximun amine content on fiber surface of polyester,cotton and polyester/cotton is obtained at 4.45%,4.10%and 5.32%,respectively.FTIR,SEM and XPS analysis indicated that the codeposition modified layer formed on the fabric surface was more complete under the optimized conditions,besides,the amine groups were introduced and distributed along the fiber surface.The polarity component of surface energy on polyester and polyester/cotton fiber surface increased from 4.1 m J.m^-2and 5.2 m J.m^-2 to 19.2 m J.m^-2and 14 m J.m^-2,respectively.The effect of co-deposition modification on interfacial bonding properties of fiber/epoxy was studied by yarn pull-out experiment.It was found that interfacial bonding strength of polyester/epoxy and polyester-cotton/epoxy was increased by 55.26%and 32.25%,respectively,while that of cotton/epoxy was decreased.The increase of interfacial bonding strength is linearly correlated with the content of amine group,and primary amines contribution to interfacial bonding strength is better than secondary amines.The finite element simulation of yarn pull-out test shows that the interfacial axial shear stress experiences four stages:generation,growth,reaching peak and decline to satble value,corresponding to the crack generation,expansion,beginning of debonding and stable pulling out of interface failure.The simulation results are basically consistent with the experimental results.Fiber reinforced epoxy composites with light weight and good mechanical properties were prepared using polyester,cotton and polyester/cotton as reinforcement.It was found that the introduction of amine groups on the surface significantly improved the tensile properties and interlayer shear properties of the composites,especially the interlayer shear strengths of polyester and polyester/cotton,which increased by 72.47%and 39.71%,respectively.Primary amines can improve the mechanical properties of composites better than secondary amines.Based on the fact that the co-deposition layer can form an excellent interface with epoxy resin,a modified polyester,cotton,polyester/cotton toughened glass fiber and carbon fiber reinforced epoxy composite was constructed based on the co-deposition method,and the interlayer toughness of the composite was improved.It is found that the type I and type II critical energy release rate and maximum bridge stress of polyester and polyester/cotton composites are increased,while that of cotton is slightly decreased by double cantilever beam experiment and end notch flexural experiment.Combined with finite element simulation,it is found that the interlayer matrix cracking and fiber/matrix interface debonding mainly occur in type I,while type II shows a large number of serrated sections.