| Epoxy/anhydride system,with low viscosity,long application period,minimal exothermic reaction,high mechanical and thermal properties,was an ideal resin matrix material for liquid forming technology for large composites such as large ship and offshore fan blade composites.However,there were some problems in the traditional epoxy/anhydride system,such as low curing reactivity,brittleness of cured resin and intolerance to hygrothermal aging due to ester groups in the cross-linking network.Therefore,it is necessary to carry out the research on improving the reactivity of epoxy/anhydride system and its hygrothermal aging resistance properties.In this paper,a novel polyether-polyester semi-interpenetrating structure with high epoxy/anhydride molar ratio catalyzed by a highly efficient composite catalyst was designed and prepared.The use of composite catalysts can synergistically catalyze the rapid opening of epoxy and significantly improve the reaction activity.High epoxy/anhydride molar ratio can effectively improve the content of ether bond and reduce the content of ester group in the resin matrix.The polyether-polyester semi-interpenetrating cross-linking structure can reduce the attack of water molecules on the resin matrix and improve the hygrothermal aging resistance properties of the resin matrix.In this paper,the catalytic curing reaction and the hygrothermal aging resistance properties of traditional resin system with epoxy/anhydride molar ratio of 1.0:1.0 and epoxy/anhydride molar ratio 1.4:1.0 resin system with semi-interpenetrating cross-linking structure of polyether-polyester were studied using FT-IR,DSC,XRD,XPS and DMA.The experimental results showed that the composite catalyst could significantly improve the curing reactivity.The resin system with epoxy/anhydride molar ratio of 1.0:1.0 and 1.4:1.0 had similar apparent activation energy.It was found that the coordination catalyst Salen Co in the composite catalyst could promote the formation of ether bonds,while the anionic catalyst BDMA could promote the epoxy ringopening reaction.The resin system with high epoxy/anhydride molar ratio had higher ether bond content and shorter molecular chain spacing.Compared with the traditional epoxy/anhydride resin system,it had lower and wider glass transition,indicating the formation of semi-interpenetrating cross-linking structure of polyether-polyester.The flexural strength retentions of epoxy/anhydride resin system with high molar ratio were 93.3% and 88.4%,after 28 days of hygrothermal aging at NaCl/60°C and NaOH/60°C,and the glass transition temperature was only reduced by 2.9% and 3.9%.The mechanical properties,thermal stability and chemical structure stability of resin system with high epoxy/anhydride molar ratio were all better than those of resin system with epoxy/anhydride molar ratio of 1.0:1.0.Compared with the traditional epoxy/anhydride system,the novel epoxy/anhydride system with polyether-polyester semi-interpenetrating structure had better hygrothermal aging resistance. |
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