Research On Mechanical Properties Of Fiber Reinforced Vinyl Ester Resin Composites After Thermal Cycling

Fiber reinforced polymer composites(FRP)areexpected to be used as fastener materials in marine engineering in cryogenics,due to their light weight,high strength,anti-fatigue,corrosion resistance and wear resistance.However,FRP composites are affected by temperature and corrosion and other factors in marine engineering,resulting in decreased mechanical properties.In this paper,the different kinds of fiber reinforced vinyl ester resin composites were prepared.The mechanical properties of basalt fiber reinforced vinyl ester resin composites(BFRP)and carbon fiber reinforced vinyl ester resin composites(CFRP)were studied after room low temperature cycling(25 oC~-196 oC)and extreme thermal cycling(150 oC~-196 oC).Moreover,the wear resistance of short carbon fiber(SCFRP)compositesin cryogenics was studied by self-developed friction and wear equipment.Finally,BFRP and SCFRP composites were laminated and the B/CFRP composites were prepared and their mechanical properties were evaluated.Otherwise,the microstructure of fracture of different fiber reinforced vinyl ester resin composites was observed by SEM to analyze the intrinsic relationship between microstructure and mechanical properties which reveals the damage mechanism of composites.In addition,the corrosion resistance of different fiber reinforced vinyl ester resin composites was evaluated by immersion method.The possibility of application of fiber reinforced vinyl ester resin composites in marine environment was explored.Firstly,the wear resistance of SCFRP composites in cryogenics was studied.The results showed that the SCFRP composites with the content of 20% ultra short carbon fiber and the fiber content of 1.5%,the fiber length of 5mm have the best wear resistance in the SCFRP composites,and the wear resistance of SCFRP composites in cryogenics is better than in room temperature.The surface morphology of SCFRP compositeswas observed by SEM,and the resultsindicated that theadhesive wearat room temperature and abrasive wear in cryogenics.Simultaneously,SCFRP composites exhibitedexcellent acid and alkali resistance.Then,the mechanical properties of BFRP and CFRP composites were investigated after the thermal cycling consisting of room low temperature cycling and extreme thermal cycling.It was demonstrated that the tensile strength and flexural strength of BFRP composites were increased by 78.12% and 58.85%,reached to 407.98 MPa and 363.84 MPa after room low temperature cycling respectively.The tensile strength and flexural strength of BFRP composites were increased by 101% and 94.75%,reached to 460.40 MPa and 447.72 MPa after extreme thermal cyclingrespectively.The impact strength of BFRP composites was decreased by 15.74% to 127.22 MPa after room low temperature cycling,and decreased by 9.85% to 136.11 MPa after extreme thermal cycling.50% CF composites have the best comprehensive mechanical properties,and their tensile strength and flexural strengthwere increased by 9.78% and 26.58%,reached to 502.60 MPa and 472.11 MPa after room low temperature cycling respectively.The tensile strength and flexural strength of 50% CF composites wereincreased by 48.42% and 53.94%,reached to 460.40 MPa and 574.14 MPa after extreme thermal cycling respectively.The impact strength of 50% CF composites was decreased by 29.49% to 70.09 MPa after room low temperature cycling,and decreased by 38.25% to 61.39 MPa after extreme thermal cycling.Otherwise,the fracture form of the BFRP composites is resin matrix breakage and fiber tearing.The fracture form of CFRP composites is the delaminating of carbon fiber and matrix resin.The corrosion failure of BFRP and CFRP composites is mainly due to the interfacial swelling and destruction of permeable media.Finally,the mechanical properties of B/CFRP composites were examined after room low temperature cycling and extreme thermal cycling.It was showed that the tensile strength and flexural strength of B/CFRP composites were increased by 118% and 52.30%,reached to 309.04 MPa and 380.71 MPa after room low temperature cycling.And the tensile strength and flexural strength of B/CFRP composites were increased by 117% and 61.12%,reached to 307.70 MPa and 402.75 MPa after extreme thermal cycling respectively.The impact strength of B/CFRP composites was decreased by 19.75% to 147.29 MPa after room low temperature cycling,and decreased by 5.28% to 116.50 MPa after extreme thermal cycling.The fracture is originated from the damage of resin matrix and the delaminating of carbon fiber and matrix resin.The corrosion failure of B/CFRP composites is mainlyascribed to the interfacial swelling and destruction of permeable media.The results showed that the mechanical properties of B/CFRP composites were considerably improved after thethermal cycling.