Preparation And Application Of Non-isocyanate Polyurethane Material

Polyurethane（PU）is a kind of polymer that contains urethane group in the molecular chain.Due to the existence of strong polar urethane group,PU has good oil resistance,toughness,aging resistance,wear resistance,and other characteristics,which lead to the wide application of PU in the field of construction,machinery,medicine,and other industries.However,the preparation of PU involves the application of isocyanate.Because of the high active chemical properties,poor water resistance and high toxicity of isocyanate,there are certain safety risks of isocyanate storage and transportation during the process of PU preparation.Therefore,the development of non-isocyanate polyurethane（NIPU）has become a hotspot in the field of new materials.Compared with traditional PU,isocyanate,which causes the safety risk,was not need in the preparation process of NIPU.Moreover,both NIPU and traditional PU have urethane group on their main molecular chain,which make them have similar physical and chemical properties.Meanwhile,there is a hydroxyl group connected with theβcarbon atom of each urethane group in the NIPU molecular chain,which can form intarmolecular hydrogen bond with the carbonyl group in the urethane group and form a stable six-membered ring.This ring structure makes NIPU have better chemical resistance and permeability resistance than traditional PU.Therefore,more and more countries begin to pay attention to the development of NIPU material,the related theory,and NIPU application.In this paper,the cyclic carbonate and the diamine were copolymerized to prepare NIPU material.Then,bamboo fiber was added during the preparation process of NIPU to prepare NIPU composite.The main research contents include:Preparation of cyclic carbonate.A biomass derived raw material,epoxy soybean oil（ESBO）,was reacted with carbon dioxide to prepare cyclic carbonate soybean oil（CSBO）.The effects of reaction temperature,reaction pressure,reaction time,and catalyst dosage,on the conversion of ESBO were studied.Moreover,FT-IR and ¹H-NMR technique were applied to characterize the structure of CSBO.The investigation results show that when the reaction temperature was 120℃,the amount of catalyst was 2wt.%,the pressure of carbon dioxide was2 Mpa,and the reaction time was 20 h,the conversion of ESBO can reach 98.5%.The FT-IR analysis of CSBO indicated that the band of carbonyl group in cyclic carbonate appeared at 1793cm^-1,and the band of epoxy group disappeared at 823cm^-1 and 843cm^-1.At the same time,the¹H-NMR analysis of CSBO showed that the chemical shift of the hydrogen atom in the cyclic carbonate of CSBO appeared at 4.40～4.94 ppm,and the chemical shift of the hydrogen atom in epoxy functional group at 2.83～3.25 ppm disappeared.All these evidence indicated that CSBO was prepared.Preparation of NIPU material.NIPU was prepared by copolymerization of CSBO and diamines.The effects of the ratio of CSBO to diamine,curing temperature,curing time and the type of diamine on the properties of NIPU were studied.The relationship between structure and properties of NIPU was studied by means of FT-IR,TG,DSC,and mechanical property test.The results showed that the optimum preparation condition of NIPU were CSBO to diamine molar ratio of 1:1.1,curing temperature of 80℃,and curing time of 9 h.When ethylenediamine was used to copolymerize with CSBO,the NIPU material with the best mechanical property was obtained,which tensile strength and young’s modulus reached 7.0 Mpa and 5.5 Mpa,respectively.Preparation of NIPU composite.During the preparation process of NIPU,the eco-friendly bamboo fiber was blended with the CSBO and hexamethylene diamine.Then,the NIPU composite was prepared after the copolymerization.The influence of the addition of bamboo fiber on the structure and property of NIPU composite was studied by FT-IR,TG,DSC,and mechanical property test.The results of FT-IR showed that there was a strong interaction between bamboo fiber and NIPU.The mechanical property test results showed that the mechanical properties of NIPU can be effectively improved by the addition of bamboo fiber.Compared with corresponding NIPU material,the tensile strength and Young’s modulus of the NIPU composite increased 5.3 and 910.9 times,respectively,when the content of bamboo fiber reached 40wt.%.