Study On Preparation And Properties Of Epoxy-Poss Nanocomposite Vitrimers

Thermosetting resins have excellent mechanical properties and solvent resistance,but once cross-linked,they cannot be processed and reshaped.Thermoplastic resin can be processed repeatedly,but its mechanical properties and solvent resistance are poor.Vitrimer,which combines the advantages of thermosetting and thermoplastic resin,has shown a broad application prospect in the fields of plastic recycling and self-healing materials.In this thesis,epoxy-POSS nanocomposite vitrimer was prepared on the basis of epoxy vitrimer and its properties were characterized.The research results obtained are as follows:(1)By incorporation of glycidyl polyhedral oligomeric silsesquioxane(POSS)as a nanoscale filler in epoxy,we produced epoxy-POSS nanocomposite vitrimers that show high strength,toughness,thermal stability,and efficient relaxation.With 10 wt.%POSS,the tensile strength and strain at break of the epoxy-POSS nanocomposite vitrimers increased by～64%and～76%,respectively,while the stress relaxation time increased by～60%in comparison to that of pure epoxy vitrimer.The epoxy-POSS nanocomposite vitrimers show high malleability due to the efficient transesterification reaction and reprocessability with little degradation of their initial mechanical properties.(2)The cooperative rearranging region(CRR)of epoxy vitrimer was studied by differential scanning calorimetry.The CRR sizes of the three transesterification vitrimers with different glass transition temperatures ranged from 1.4 nm to 1.7nm.As they are all epoxy vitrimer,there is no obvious difference in the values.