Preparation And Properties Of Eugenol-Based Epoxy Thermosets

Epoxy materials are one of the thermosets with excellent performance,which are widely used in construction,chemical and marine fields.However,most of the raw materials used are derived from non-renewable petrochemical resources.At the same time,these materials are difficult to be recycled and biodegraded after damage or disposal,which brings energy crisis and environmental pollution.Therefore,developing bio-based epoxy to replace petroleum-based epoxy is of great significance for the green and sustainable development of materials and the realization of "carbon peaking and carbon neutrality" goals.In this thesis,eugenol was employed as the raw material to synthesis eugenol-based epoxy monomer(EuEP)through a two-step modification method.On this basis,a serious of novel eugenol-based epoxy materials were prepared by reacting EuEP with various curing agents containing dynamic chemical bonds or without dynamic chemical bonds,and the relationship between the structure of eugenol-based material and properties was systematically investigated.The detailed research contents and results are as follows:(1)Eugenol-based epoxy monomer was prepared by a two-step process of 1,5-dibromopentane substitution and m-chloroperoxybenzoic acid oxidation using eugenol as the raw material,and the epoxy value of EuEP was 0.241 mol/100 g.(2)EuEP was used as the epoxy monomer and m-phenylenedimethylamine(MXDA)was used as the curing agent to prepare eugenol-based epoxy material without dynamic chemical bonds by regulating the molar ratio of epoxy group to amino group.The results showed that the EuEP-MXDA1.00 epoxy material had the best comprehensive properties when the molar ratio of epoxy groups to amino hydrogen(-NH-)is 1:1.The material had a tensile strength of 54.01 MPa,an elongation at break of 4.49%,a gel content of 92.8%and a T5%of 331.88 ℃.(3)EuEP was used as the epoxy monomer and 4,4’-dithiodiphenylamine(AFD)was used as the curing agent to prepare eugenol-based epoxy Vitrimer containing dynamic disulfide bonds.The results showed that when the molar ratio of epoxy group to amino hydrogen was 1:1,the gel content of the material was 89.2%,the swelling rate was 17.0%,the tensile strength was 39.23 MPa,the elongation at break was 2.89%,and the stress relaxation time of the material at 180℃ was 9.6 s.The mechanically crushed material could be physically reprocessed by hot pressing at 200℃ for 6 h,the scratches on the surface of the material could be completely recovered by heating at 180℃ for 2 h.Meanwhile,the material could be completely degraded in mercaptoethanol for chemical recycling.(4)EuEP was used as the epoxy monomer,2,2’-(1,4-phenylene)-bis[4mercapto-1,3,2-dioxaborolane](BDB)containing boronic ester bonds prepared via 1,4-phenylene boronic acid and 1-thioglycerol was used as the curing agent,and 4-dimethylaminopyridine was used as the catalyst to prepare eugenol-based epoxy Vitrimer containing dynamic boronic ester bonds.The results showed that the material had the best comprehensive properties when the molar ratio of epoxy group to sulfhydryl group was 1:0.75,the gel content was 91.6%,the swelling rate was 18.3%,the tensile strength was 14.75 MPa,the elongation at break was 5.32%,the material could be remolded and reprocessed by hot pressing at 160℃ for 0.5 h.