| Epoxy resin(EP)is widely used in the field of electronic devices and coatings because of its low expansion coefficient,excellent mechanical properties,corrosion resistance and adhesion.At present,90%of the epoxy resin in the world is petroleum based on bisphenol A epoxy resin.However,recent studies show that bisphenol A seriously affects the human reproductive system,and European countries have explicitly banned its application in children's daily necessities.Therefore,the research of bio-based epoxy resin has attracted much attention in order to replace petroleum based bisphenol A.Reed is a kind of water plant,which grows in humid areas and has the function of water purification and decontamination.Reed straw is different from other straw,it contains not only cellulose,hemicellulose and lignin,but also a large amount of Nano-Si O2 from soil transformation,the content is about30%.With the decrease of reed use value and the management planning of Xiong'an New District,developing high value-added reed products is on the agenda.In this paper,reed based epoxy resin coatings were prepared by using agricultural waste reed,which not only synthesizes new bio based materials,but also"turns waste into treasure"and makes use of renewable resources.It is expected to replace petroleum based epoxy resin and solve the energy crisis.Part one:Reed liquefaction.Reed powder was liquefied into reed based polyol(R-L)by using polyethylene glycol 400 and gallic acid as liquefaction reagent,concentrated sulfuric acid as catalyst.The effect of different factors on liquefaction efficiency was analyzed by single factor experiment.The optimum liquefaction conditions were obtained by orthogonal analysis:the ratio of M(polyethylene glycol 400):m(gallic acid):m(Reed)was 5:1:1,the catalyst was 4.28%,the liquefaction temperature was 160?,the liquefaction time was 1.5 h,and the liquefaction rate was up to 95.8%.FTIR analysis showed that R-L contained a lot of hydroxyl groups with viscosity of 5.29 Pa·s,hydroxyl value of 196 mg KOH/g and relative molecular weight of 5881.Part two:Synthesis of epoxy resin based on reed and characterization of its curing film-forming properties.The ring opening reaction between R-L and epichlorohydrin was carried out under the catalysis of boron trifluoride,and the closed-loop reaction was realized under the alkaline condition of Na OH,The epoxy resin based on reed(R-EP)with epoxy value of 0.216 and relative molecular weight of 7368 was obtained.FTIR showed that the hydroxyl absorption peak of R-L disappeared at 3300 cm-1,and the epoxy absorption peak of R-EP appeared at 909 cm-1,which proved the formation of epoxy resin based on reed.Epoxy coatings with different properties were obtained by curing R-EP with different curing agents.Thermodynamic analysis shows that the temperature of 1%thermal weight loss of the prepared R-EP coating film is greater than 200?,the thermal weight loss remains relatively stable at 484?,and the final residual mass is greater than 15%.The mechanical properties show that the mechanical properties of the films with different curing agents are excellent,the pencil hardness is more than 5 h,and the adhesion is more than grade 1.SEM element analysis showed that Si O2 was evenly distributed in the film,indicating that the natural Si O2in reed could improve the heat resistance and mechanical properties of the film.Part three:Preparation and performance test of water-borne epoxy coatings based on reed.In the presence of the initiator BPO,?-methacrylic acid,butyl acrylate,and styrene were grafted onto R-EP,neutralized with amine to form a salt,and water-borne epoxy resin based on reed(W-R-EP)was prepared by emulsification with water.The prepared emulsion has good mechanical stability.TEM and Mapping analysis showed that Si element was evenly distributed in the coating film. |
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