Synthesis And Properties Of Multifunctional Bio-based Epoxy Resin Based On Vanillin Derivatives

Epoxy resins,dominating the thermosetting polymers market,have been widely employed in various applications including adhesives,coatings,electronics and composites materials because of their remarkable mechanical,thermal,chemical,adhesion,and dielectric properties.Unfortunately,nearly the epoxy networks currently being produced are synthesized from petroleum,it is worth noting that 90%of the commercialized epoxy thermosets are derived from diglycidyl ether of bisphenol A(DGEBA)which is the product of the reaction between bisphenol A and epichlorohydrin.In addition,the main raw material,bisphenol A has been shown to have adverse effects on the environment and human endocrine system.In recent years,polymers from bio-renewable raw materials have attracted much more attention.It is an inevitable tendency to synthesize epoxy resin from bio-renewable raw materials with low prices,non-toxic and enhanced environment benefits.Designed from the perspective of molecular structure,using bio-renewable resources glycerin,itaconic acid,vanillin as raw materials,and then reacting with phenol to synthesize polyphenol monomer with high bio-based content,and then reacting with epichlorohydrin to prepare hexa-epoxy functionalized bio-based epoxy resin monomers(HPVIGEP)with a multi-arm star structure,and through the FTIR,~1H-NMR,GPC test methods for the synthesis of intermediate products and the final bio-based epoxy monomer structural characterization.The viscosity of commercial epoxy resin(DGEBA)and HPVIGEP were compared by rheometer.The results showed that the viscosity of HPVIGEP at room temperature(25~oC)was 3406.9 mPa.s is much lower than bisphenol A epoxy resin(DGEBA),so at room temperature processing conditions,HPVIGEP has more excellent processing performance than DGEBA.Epoxy resin only has application value after reacting with curing agent to complete curing.In a comparative study,DGEBA and HPVIGEP were compared with methyltetrahydrophthalic anhydride(MeTHPA)and diamino after the curing reaction of diphenylmethane(DDM),the glass transition temperature,thermal stability and mechanical properties were tested separately.In the HPVIGEP/MeTHPA curing system,the glass transition temperature reaches 116 ~oC,the thermal decomposition temperature(Td5%=291.9 ~oC),and the tensile strength reaches 83.0 MPa.In the HPVIGEP/DDM curing system,the glass transition temperature reaches 135 ~oC,the thermal decomposition temperature(Td5%=251.2 ~oC),and the tensile strength reaches 74.9MPa.