| In the present work,the polyoxymethylene(POM)is chosen as the matrix material,while the Sep is chosen as the reinforced phase.Firstly,the Sep fibers is surface-modified with silane coupling agent(KH550).Secondly,Sep/POM and organic modified O-Sep/POM composites were prepared by extrusion and injection molding.The influence and its law of the reinforcing phase Sep fiber and O-Sep fiber on the mechanical and tribological properties of composites are inbestigated.Further,microscopic interface behavior of composites are analyzed by the First-principle calculations method based on density functional theory(DFT).The mechanical and tribological properties of composites are investigated on the law of Sep fiber and O-Sep fiber.The results show that the mechanical and tribological properties of the composites were improved with the increase of Sep fiber content.When O-Sep fiber content was 5.0wt%,the mechanical and tribological properties of the O-Sep/POM composites will reach the optimal state:tensile strength,flexural strength,flexural modulus,impact property increased by 28.6%、51.9%、79.1%and 8.76%,respectively.And the friction coefficient and wear loss of the composites reduced by 65.9%and 35.7%.But composites were dominated by adhesive wear.The micro-structure and physical properties of Sep fiber are studied by the First-principle calculations.The results show that the cell parameter of Sep crystal are in agreement with the experimental values.Sep fiber has a layer structure constructed of-ribbons of 2:1 phyllosilicate modules that are linked triple silicate chains that sandwich Mg-O octahedral strips.The ribbons are linked by inversion of the SiO4 tetrahedra through Si-O-Si bonds.Analysis of the electronic structures shows,the within Sep crystal,the Si-O bonding interactions are stronger than that of Mg-O.The Mg-O bonding and the Si-O bonding also exhibit a certain covalent bonding function in addition to the ionic bonding.In order to explore the interfacial bonding behavior between the Sep fiber and POM in Sep/POM and O-Sep/POM composites.The results show that the KH550 plays an important role in the interface performance between POM chain segment and Sep crystal.On the one hand,one end of the silanol(Si-OH)obtained by hydrolysis of KH550 is chemically bonded to the hydroxyl group on the surface of Sep(0 1 0).And on the other hand,the combination between POM and silanol is achieved through the other end of the silanol(N-H2)reacts with the aldehyde group on the POM to form an imine at a certain temperature. |
