Interfacial And Mechanical Properties Of Oxygen Plasma-Modified UHMWPE Reinforced Composites

To explore the effect of oxygen plasma treatment on the surface modification of UHMWPE fiber reinforcement,the three parameters of plasma gas flow rate,treatment time and discharge power were controlled to modify the UHMWPE fiber.The water contact angle,AFM,DSC and XRD technology were used to modify the UHMWPE fiber.UHMWPE fiber before and after modification was characterized and analyzed.The results show that the surface wettability of the modified fiber is significantly improved,the surface roughness is increased,a large number of oxygen-containing functional groups are introduced on the fiber surface and intermolecular hydrogen bonds are generated,which can provide more polar sites for the interface layer of the composite material.The fiber extraction experiment was used to test the interface bond strength of UHMWPE/vinyl ester resin composites.The results showed that the interface bond strength of the modified composite material increased to 62.99 MPa,an increase of 90.99% compared with that before the modification.UHMWPE/vinyl ester resin composites were prepared by vacuum assisted resin infusion molding(VARI),and their tensile,bending,interlaminar fracture toughness and multiple impact resistance were tested.The interface and mechanical properties of plasma modified UHMWPE fiber/vinyl ester resin composites were investigated.The acoustic emission technology was used to monitor the damage process in the mechanical testing of composite materials in real time.It was proved that the interface toughening of composite materials could improve the damage threshold of each property testing.Plasma modification enhance the interfacial transfer and blocking effect by improving the interface toughness strength of the composites,and the tensile strength of the composites is increased by 10.67% compared with that without modification.In the impact resistance test,the damaged area and pit depth of the modified composite can be reduced by 51.93%and 24% respectively,and the main energy dissipation mode of the modified composite is changed from deformation and interlaminar delamination to fiber fracture mode.In this study,response surface method was used to optimize the above tests.The discharge power range of 150-180 W,the modification time range of 120-150 s,and the gas flow rate of8 sccm is the optimal conditions for plasma treatment.To explore the influence of fabric structure on plasma modification effect and composite sheet properties,three fabric structures of oxygen plasma-modified UHMWPE/vinyl ester composite laminates were prepared with plain,2/2 twill and 5/3weft satin weave UHMWPE fabrics as reinforcements.The mode Ⅰ / Ⅱ interlaminar fracture toughness and impact resistance of the composite laminates were tested.The results showed that the interlacing zone of fabric is stronger before modification,the toughness and stiffness of plain weave structure are larger,the impact strength of plain weave structure composite sheet is lower than that of twill weave and satin weave structure composite sheet,the energy absorption capacity of the sheet is stronger,the elastic recovery energy is poorer,and the impact energy is consumed mainly by the internal structure damage.After oxygen plasma modification,the fiber bridging effect formed in the longer zone of structural float line can provide better toughening effect,and the interlaminar fracture toughness strength of satin and twill structure composite is obviously improved,and more fiber bridging and fiber pulling effect can consume the fracture energy of resisting delamination.The maximum impact strength and elastic energy of UHMWPE composites increase by more than 10%,which can protect the structural stability of composite laminated-plate.The impact resistance of plain weave structure has the most obvious improvement effect.The mechanical and impact resistance of UHMWPE composites are synergistically affected by the microstructure and plasma modification.