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Synthesis, Properties And Application Of Vanillin-Based Recyclable Epoxy Resin

Posted on:2024-05-05Degree:MasterType:Thesis
Country:ChinaCandidate:Y JiangFull Text:PDF
GTID:2531307124499514Subject:Materials and Chemical Engineering (Professional Degree)
Abstract/Summary:PDF Full Text Request
Epoxy resin is widely used in electronic packaging,coatings,adhesives and other fields because of its good dimensional stability,mechanical properties and chemical corrosion resistance.However,carbon fiber is often added to prepare carbon fiber reinforced composite polymers(CFRP)because of its high density and insufficient mechanical strength in aerospace and wind power blade applications.And,more than 90%of current epoxides come from the diglycidyl ether of bisphenol-A(DGEBA)series,a petroleum-based product that has been shown to interfere with human endocrine systems.Moreover,due to the irreversibility of the permanent three-dimensional network structure formed by epoxy resin curing,carbon fiber(CF)is difficult to recover from the discarded CFRP,which increases the environmental load and resource waste.Therefore,the development of recyclable bio-based epoxy resins has become an urgent need.In view of the above problems,this paper takes vanillin from biological sources as raw material,the structure design of the biobased resources,through introducing of reversible covalent bond,the preparation of excellent performance,both degradable and recyclable epoxy resin.After curing and preparing CFRP,the nondestructive recovery of carbon fiber was realized.The research content is divided into the following three parts:(1)Diphenol monomer was prepared with vanillin and 4-amino-cyclohexane,and then reacted with epichlorohydrin to prepare epoxy resin containing imine structure(VAN-AC-EP).Firstly,the structure of diphenol monomer and epoxy resin was characterized by ~1H-NMR and FT-IR.VAN-AC-EP was cured under 4,4’-diaminodiphenylmethane(DDM)to obtain thermosetting resin(VAN-AC-EP/DDM).The thermal properties,mechanical properties,solvent resistance,ductility,degradability and recyclability were studied in detail.The results showed that the thermosetting resin has higher mechanical strength and ductility than bisphenol A epoxy resin,and can be chemically degraded in acidic solution.The thermosetting resin can be reformed after 30 min of hot processing at 170 ~oC,and the tensile strength can be restored to 65.9%of the original resin.Using VAN-AC-EP/DDM as matrix,carbon fiber(T300-3K)reinforced composites can be recovered by hot pressing after fracture,and the tensile strength of recovered CFRP can recover to 67.2%of the original CFRP.The carbon fiber in CFRP can be recovered without loss by washing the thermosetting resin with acid solution.(2)In order to improve the mechanical strength of the recovered bio-based thermosetting resin,vanillin,1,2-cyclohexediamine and epiclorohydrin were used as raw materials to prepare epoxy resin(VAN-DA-EP)containing two imine bonds.The structure of epoxy resin monomer was characterized.Then the resin was cured with DDM,and the thermal properties,mechanical properties,solvent resistance,ductility,degradability and recyclability of the thermosetting resin VAN-DA-EP/DDM were investigated.The results showed that the thermosetting resin has excellent tensile strength,Young’s modulus,excellent thermal stability and good solvent resistance,it could be completely degraded in acidic organic solution.The tensile strength of thermosetting resin recovered by heat treatment at190 ~oC can be restored to 73.0%of the original resin.Using VAN-DA-EP/DDM as matrix to prepare carbon fiber reinforced composites,and the tensile strength of recovered CFRP recovered to 67.3%of the original CFRP after hot-pressed at 190 ~oC for 30 min.Carbon fiber can be recovered without damage by removing the thermosetting resin from the surface of carbon fiber with acid solution.(3)In order to improve the recovery efficiency of thermosetting resin,epoxy resin(VAN-TA-EP)containing three imine bonds was prepared with vanillin,tri(2-aminoethyl)amine and epiglorohydrin as raw materials to further increase the content of imine bonds.The structure characterization of epoxy resin monomer proved successful synthesis.VAN-TA-EP was mixed with glycerol triglycide at a mass ratio of 5:1,and then cured with DDM,4,4’-diaminodicyclohexylmethane(PACM)and polyether amine(D-230),respectively.The thermal properties,mechanical properties,solvent resistance,ductility,degradability and recyclability of thermosetting resin were systematically studied.The results showed that the three thermosetting resins have excellent tensile strength and can be recovered by hot pressing.After recovery,the tensile strength of VAN-TA-EP/DDM,VAN-TA-EP/PACM and VAN-TA-EP/D-230 can be restored to 70.2%,71.7%and 99.8%,respectively.Three kinds of carbon fiber reinforced composites were prepared using VAN-TA-EP as matrix,and the damaged CFRP was recovered by heat treatment.The tensile strength of recovered CFRP was65.5%,91.2%and 103.5%of the original CFRP,respectively.After the thermosetting resin in CFRP was washed with acid solution,the surface of the recovered carbon fiber was observed,and there was no obvious difference between the surface and the original carbon fiber.
Keywords/Search Tags:Bio-based Epoxy resin, Vanillin, Recyclable, CFRP
PDF Full Text Request
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