Improving The Interfacial Properties Of UHMWPE Fiber/epoxy Composites Via Multi-scale Methods

Ultra high molecular weight polyethylene(UHWMPE)fiber is an ideal choice for the preparation of a new generation of bullet-proof equipment due to its outstandig mechanical properties,e.g.,light weight,high modulus and impact resistance.However,when it is subjected to high speed impact resistance of the bullet,the composite reinforced by UHMWPE fiber is susceptible to cracking,due to the poor adhesion properties between UHMWPE fiber and matrix,resulting from smooth surface and few polar group of UHMWPE fiber.Ballistic Protection is not ideal because of poor energy dissipation,which seriously impaired the performance of bullet-proof.Therefore,it is necessary to develop a new and efficient approach for improving the interfacial properties of composites reinforced by UHMWPE fiber without impairing the mechanical properties of the modified fibers.This is of great significance for the preparation of a new generation of light weight and safety personal protective equipment with good anti-elasticity.In the paper,we utilized multi-scale hybrid methods of the interfacial properties to prepare UHMWPE fiber/epoxy composites,aiming to improve the interface properties of composites.The effects of those methods on the surface of resulting composites were investigated.The results indicated that those methods could effectively improve the interfacial properties of composites.Furthermore,it was found that the UHMWPE/amino-reactive graphene oxide(KH550-GO)reinforcement was more effective in improving the interfacial properties.Furthermore,this method maked it easier controlled the surface topography of the coating.The main research in this paper is shown as follows:(1)Firstly,the synergistic multi-scale method was used to improve the interfacial property of UHMWPE fiber/epoxy composite.Polydopamine(PDA)particles functionalized by epoxy groups were coated on the surface of UHMWPE fiber.Meanwhile,reactive GO(M2070-GO)were used to modify epoxy.The results indicated that the interfacial adhension of UHMWPE fiber/epoxy composites was significantly enhanced due to improvement of the wettability,mechanical interlocking and chemical bonding between UHMWPE fiber coated by PDA(M-UHMWPE)and resin modified by M2070-GO.Among all the samples,the interface shear strength(IFSS)of M-UHMWPE fiber/0.6 wt% M2070-GO/epoxy composites was the highest,from 2.69 MPa to 12.86 MPa with an increase of 382%.Among all of the factors improved IFSS,The chemical bonding of PDA-g-M2070-GO played a key role in improving IFSS of composite,and the interaction between PDA and UHMWPE fibers determined the limit of interface strength.(2)UHMWPE fibers were pretreated by the oxygen plasma,then grafted reactive GO(KH550-GO)via γ-(2,3-epoxypropoxy)propyltrimethoxysilane as bridge and to prepare UHMWPE fiber/KH550-GO reinforcement.The KH550-GO layers improved both the surface roughness of the UHMWPE fibers and the mechanical interlocking between the fiber and the epoxy.Moreover,the reactive groups introduced onto the fibers surface improved the compatibility between UHMWPE fibers and epoxy.However,these effects were secondary to the improvement of the interfacial properties of UHMWPE fiber/epoxy composites.The chemical bonding between the KH550-GO layers and the epoxy played a key role in the interfacial properties of the composite.After modification,the IFSS of the composite was improved from 2.72 MPa to 21.97 MPa with an increase of 707.7%.When the UHMWPE fiber/KH550-GO multi-scale reinforcement/epoxy composites took place microdebond,the ductile fracture of epoxy at interface was found.It meant that the KH550-GO hybrid layer could effectively improve the interfacail toughness of composite.