| Vitrimer is a kind of polymer with dynamic network structure.The rearrangement of the permanent crosslinked network at high temperature lead it to be reprocessed or reshaped,which made it have a broad application prospect in the fields of plastic recycling and self-healing materials.In this work,we synthesized epoxy vitrimer by bisphenol A diglycidyl ether and dodecanedioic acid in the presence of a catalyst,and further blended with thermoplastic PMMA to prepare PMMA/epoxy vitrimer blends in order to investigate the effects of epoxy vitrimer content on the structure and properties of PMMA matrix by different blending methods.The main progress and results are as follows:(1)Preparation of epoxy vitrimer:Swelling experiment and stress relaxation indicated that epoxy vitrimer with dynamic network structure was synthesized successfully,and its network structure can rearranged topology under heating conditions so that epoxy vitrimer showed Arrhenius-like gradual viscosity variations.Further characterization revealed that blends had excellent toughness and the elongation at break was 132%;and had good heat stability,which could withstand a high temperature of 427?.(2)Preparation of PMMA/epoxy vitrimer blends by solution blending:FT-IR and swelling experiments showed that hydroxyl transesterification of PMMA and vitrimer occurred.TGA showed that the addition of epoxy vitrimer increased the heat resistance temperature of PMMA from 307.1? to 376.1?,and the blend(PMMA/epoxy vitrimer)still had 50%residual at 427?.Stress relaxation showed that the blends exhibited a stress relaxation behavior of linear polymer from 0 to 80s and dynamic crosslinked network after 80s.The tensile test showed the blends exhibited brittle-ductile transition when the content of vitrimer was 10?20 wt.%.The mechanical properties PMMA/epoxy vitrimer 6/4 was very similar to those of epoxy vitrimer,and the tensile strength was 22.5 MPa and the elongation at break was 150.1%,which showed that the epoxy vitrimer had a significant toughening effect on PMMA.(3)Preparation of PMMA/epoxy vitrimer blends by melt blending:Rheological curves,FT-IR and swelling experiments showed that hydroxyl transesterification between PMMA and vitrimer occurred.TGA showed that the residual content of the blend(6/4)was still 50%at the temperature of 400?,which had higher thermal stability.Stress relaxation result was similar to(2).The tensile test showed the blends exhibited brittle-ductile transition when the content of vitrimer was 20?30 wt.%.When the content of epoxy vitrimer was 40wt.%,the tensile strength of the melt blend was 37.79 MPa,and the elongation at break was 44.6%,indicating that the epoxy vitrimer had a better toughening effect on PMMA. |
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