| Composites have played a very important role in the development of modern science by virtue of many advantages,such as light weight,high strength,nonmagnetic,corrosion resistance,strong designability and low price.Resin matrix composite are the most widely used and most mature composites.Resin matrix composites have the advantages of low density,high strength,good molding process performance,good corrosion resistance and so on.It has gradually replaced metal alloys and other materials which are widely used in aerospace,automotive,construction,marine and other fields.In recent years,it has developed rapidly.As an internationally recognized highly corrosion-resistant resin,epoxy vinyl ester resin has similar mechanical properties to that of epoxy resin,and has fast curing speed.It can be cured at room temperature and has good molding and processing properties,which can meet the production requirements of automotive parts and marine structures.Therefore,carbon fiber reinforced epoxy vinyl ester resin(CF/ VE)composite has a broad application prospect in lightweighting.However,the interface bonding strength of the CF/VE composite is low,which affects the overall performance of the composite.So,it is necessary to modify epoxy vinyl ester resin.In this paper,from the perspective of resin modification,the resin is modified by the introduction of epoxy resin through blending method.This paper chooses two different types of epoxy resin are as modifier.First of all,the curing process of resin was preliminarily determined by comparing the changes of DSC curve before and after adding epoxy resin to epoxy vinyl ester resin,and then determines the optimal formula of the modified resin by studying the effect of the amount of epoxy resin added on the overall mechanical properties of the resin and the change in molecular structure;Finally,the formula with the addition amount of TDE85 epoxy resin at 20% was determined as the best formula.At this time,the tensile strength,compressive strength and flexural strength of the resin casting increased by 26.9%,25.5% and 34% respectively,compared with that before modification,and the compression modulus increased by 21.8%,elongation at break increased by 42.1%.Secondly,the curing process of the mixed resin was further optimized according to the DSC curves at different heating rates of the optimal modified resin formulation.The final optimized process was: room temperature/2h+70℃/2h+120℃/2h+150℃ /2h+180 ℃ /2h.Comparing the strength of the cured resin before and after optimization,it was found that the compression and tensile properties of the resin did not change much;the bending strength was increased by 5.78% compared with that before optimization.Through the DSC curve of the mixed resin,this paper also studies the curing kinetic parameters of the modified resin.Finally,this article uses Materials Studio software to conduct a molecular dynamics simulation of the interface between the epoxy vinyl ester resin and carbon fiber.By comparing the molecular concentration distribution and the interaction between the interfaces in different models,it was found that the IPN-20 system had the best infiltration performance for carbon fiber.Based on the resin matrix formula,the composite laminate samples before and after modification were prepared and tested for mechanical properties.It was found that the mechanical properties of the modified composite materials were significantly improved,including tensile strength,compressive strength,bending strength and interlaminar shear strength were increased by 47.2%,172.6%,145.2% and 102.5%,respectively.The fracture morphology of the laminates was investigated,and it was found that the interface of the composites was improved obviously after modification. |
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