Interface Structure And Mechanical Properties Control Of Waste Textile Fiber Reinforced Polyethylene Composites

The recycling and high-value utilization of waste textile fibers and plastics have become the focus of academia and industry.The waste textile fibers was used to strengthen and modify waste plastics which can obtain composite materials with excellent properties such as light weight,high strength and corrosion resistance.It is one of the effective ways to solve "fabric pollution" and "white pollution" along with broad application prospects.The properties of composites depend on the inherent properties and interfacial bonding effects of the composites each component.Good interfacial adhesion is one of the key factors to ensure the excellent properties of composites.However,its structural characterization and its performance regulation are still the main challenges in the development of high-performance composites,as the interfacial structure of textile fiber/polymer composites is very complex and difficult to observe and analyze.Therefore,two kinds of waste textile fibers with different structures(polyester fiber,PET-fiber,the largest consumption;ultra-high molecular weight polyethylene fiber,UHMWPE-fiber,new high-performance fiber)was utilized as reinforcement materials in the paper.A wide range of low-density polyethylene(LDPE)was used as the matrix,and the interface structure and performance regulation of the two composite materials were systematically studied by combining experiments and finite element simulation methods.The main research contents and conclusions are as follows:Firstly,LDPE/PET-fiber composites and LDPE/UHMWPE-fiber were prepared by a mold with independent property rights(patent name: A mold suitable for preparing single/single bundle fiber composite polymer materials by thermoforming,patent number:ZL202120525488.5).The structure insight into the interfacial behavior of composites were performed by using mechanical testing,experimental characterization and finite element methods.The results show that the average interfacial shear strength(IFSS)of the LDPEU/HMWPE-fiber composites is 3.59 MPa,which is 3 times that of the LDPE/PET-fiber composites(1.18 MPa).Obviously,this difference in mechanical properties is due to the co-crystallization phenomenon at the interface between LDPE matrix and UHMWPE-fiber,which makes the interface between LDPE matrix and UHMWPE-fiber produce greater adhesion.However,LDPE and PET-fiber do not have this phenomenon at the interface,so the interface between LDPE and PET-fiber is dominated by friction(the composites is under the action of external force).Secondly,LDPE/UHMWPE-fiber composites were prepared by injection molding and compression molding,respectively,which for UHMWPE-fiber and LDPE materials with co-crystallization ability.The influence of molding method on the structure of UHMWPE-fiber and the mechanical properties of composites was discussed,and the effect of annealing treatment on the structure and properties of composites prepared by compression molding was further studied.The results show that the mechanical strength of annealed LDPE/UHMWPE-fiber composites is higher than that of unannealed composites under the same mass of UHMWPE-fiber.In addition,there are obvious interfacial transition regions in both annealed and unannealed composites,and the crystallinity of each component phase of annealed composites is higher than that of unannealed composites.Thirdly,the PE-g-MAH compatibilizer was used to improve the compatibility of LDPE and PET-fiber regarding the weak interface of LDPE/PET-fiber composites,and LDPE/PET-fiber composites and LDPE/fiber composites were prepared by injection molding.The mechanical properties and interfacial structure of LDPE/PET-fiber composites and LDPE/PET-fiber/PE compatibilizer composites were discussed.The results show that the mechanical strength of LDPE/PET-fiber/AT1870E(compatibilizer)composites is higher than that of LDPE/PET-fiber composites with the same mass fraction of PET-fiber.In addition,there are no obviously interfacial transition regions for LDPE/PET-fiber/AT1870 E composites and LDPE/PET-fiber composites.Finally,based on the experimental results of LDPE/PET-fiber composites,Digimat and ANSYS finite element software were used to simulate PET-fiber reinforced polymer composites,afterwards,the reliability and accuracy of the finite element simulation was analyzed by comparing the experimental results and the simulation results.The results show that both Digimat and ANSYS finite element simulations have fairly reliable accuracy in predicting the final properties of composite materials,which can predict the stress-strain behavior of composite materials with geometric structures.It provides a new idea for the development and performance prediction of high-performance textile fiber-reinforced polymer composites.