Study On The Co Curing Properties Of Aramid Fiber/Epoxy Composites And EPDM

The solid rocket engine is indispensable factor in aerospace industry.The preparation of solid rocket engine shield through co-curing method is a urgent problem.The main focus of this system is aramid fibers reinforced epoxy resin and EPDM composite.Through the design of curing system of epoxy resin and the depth research of EPDM,a co-curing method is established to improve EPDM crosslink density and improve the properties of solid rocket engine shield as a final consequence.In this thesis,different concentrations of phosphoric acid solutions are prepared,and then the fiber surface is treated by the acid solutions obtained above.Given the data from X-ray photoelectron spectroscopy?XPS?test,a large number of polar groups were introduced into the fiber surface.At the same time,the change of morphology of the fiber surface because of the etching effect of phosphoric acid,can be observed by SEM and AFM.The monofilament pull-out test shows that the interfacial properties of the treated aramid fiber were significantly improved.After treatment,the mechanical properties of the epoxy resin composite reinforced by aramid fiber were improved.The bending strength of this fiber increases from 485 MPa to 512 MPa,and the ILSS of this composite increase from 40.23 MPa to 50.19 MPa after treatment.In terms of the results above,we think the best optimal concentration of phosphoric acid solution to treat aramid fiber is 20 %.Co-curing method can not only accomplish the combination of epoxy resin composite material and EPDM rubber,but also achieve the desired properties by adjusting the curing system of the curing system.In this paper,epoxy resin curing system,EPDM rubber vulcanization process,and co-curing system were characterized by different analysis methods.Finally,the mass ratio between epoxy resin and curing agent is 100:34,and the amount of DCP added into EPDM is 3.5 g,and the best curing mechanism for the co-curing system is 90?/2 h+120?/2 h+150?/2 h+170?/1 h.Through analysis and characterization of the co-curing system,the final peel strength is 2.274 N/mm,which shows that the interface between EPDM and aramid fiber/epoxy composite has good adhesion properties.The results of hydrogen nuclear magnetic resonance show that the cross-link density of propylene rubber is 3.879(10^-5mol/cm³).The thermal stability of the co-curing system can be obtained by TG analysis.The ILSS test determined that the optimal amount of aramid fiber in the co-curing system is 65%.Compared with the composite curing in a traditional method,the mechanical properties of the co-cured system have not decreased.It can be seen that during the co-curing process,the interface properties of the composite material have not changed.