Abstract:
Vitrimer can undergo plastic deformation while maintaining a cross-linked state, which means that traditional thermosetting resins have the ability to undergo secondary thermal processing and molding, which will effectively reduce scrap rates and reduce waste from the beginning. The plastic deformation of vitrimer can also endow item self-healing ability and extended its service life, and so contribute to environmental protection and emission reduction. In the paper stannous iso-octanoate as a catalyst and phenolic resin as a modifier was used to prepare anhydride cured epoxy vitrimer materials. The research results indicate that the increase in catalyst content could make the system cure more completely, so there is a certain improvement in the bending strength of the material, up to 87.5 MPa. With introduction of phenolic resin, the bending strength increases from 87.5 MPa before modification to 126.9 MPa, and the tensile strength reaches 63.3 MPa. When the amount of phenolic resin added is too high, the crosslinking density of the material decreases, and the mechanical properties of the material show a downward trend. The study on the relaxation behavior of the epoxy vitrimer system cured with pure anhydride shows that increasing the catalyst content reduces the relaxation time of the materials, but the post curing reaction at high temperature could inhibit the relaxation process and suppress the self-welding strength. The stress relaxation of epoxy vitrimer material modified with phenolic resin is significantly faster than that of epoxy vitrimer system cured with pure anhydride. The relaxation of the samples with 10mol% catalyst shows a sudden change, and there is a significant acceleration when the temperature rises to 190℃, and the introduction of phenolic resin could advance the sudden change temperature
Ts to 180℃. Under no pressure conditions, scratches are repaired. The tensile shear strength and scratches repair effect of the samples repaired above
Ts are significantly improved. Compared to samples without phenolic resin, phenolic modified samples could be repaired better. Catalyst have a significant impact on the repair strength and repair speed of the samples.