| Lubricants have a wide range of applications in industrial and agricultural production and life.Traditional mineral-based lubricants can cause serious ecological pollution when they are lost to the environment.With the increasing environmental problems and the decline of petroleum resources reserves,it is of great social and economic significance to find renewable biodegradable biomass lubricants.Vegetable oil is a very promising alternative,but due to the presence of a large number of C=C in vegetable oils,oxidative stability and low-temperature fluidity are poor,which limits its practical application as a lubricating base oil.In this paper,the lubricant base oils were synthsized by non-edible vegetable oil,castor oil.The castor oil with methanol were first catalyzed by sodium carbonate through transesterification reaction to form fatty acid methyl ester（FAME）,after that,the FAME was epoxidized to form epoxy fatty acid methyl ester（EFAME）as lubricant base oil.a series of reaction conditions about EFAME were investigated.1H-NMR and 13C-NMR Spectra were performed on the corresponding products,and the iodine value,epoxy value,viscosity,low temperature fluidity and oxidative stability were calculated according to national standards,and the biodegradability of different lubricating base oils were studied.Finally,the screening of antioxidant additives and the compounding of various antioxidants were carried out.After transesterification of castor oil with methanol,FAME is formed,and its viscosity is significantly reduced,which is one tenth of that of castor oil.FAME and formic acid and aqueous hydrogen peroxide form EFAME by epoxidation under the action of catalyst sulfuric acid,and the product exhibits good oxidation stability and low temperature fluidity.When the dropping temperature of H2O2 is 50°C,the reaction temperature is 50°C,the reaction time is 10 h,the H2O2/HCOOH/FAME molar ratio is 5/1/1,and the catalyst dosage is 1.5 g,the better oxidation stability of EFAME was obtained,which were 0.7×10-6mg KOH/g of X1,0.5×10-8 mg KOH/g of X2,74.2%of X3,and 3.3×10-6 mg KOH/g of X4,correspondingly The iodine value is 2.8 g/100g and the epoxy value is 1.75 mol/100g.In the epoxidation reaction of FAME with ethyl acetate as solvent,it can be seen that the iodine value has a significant downward trend,but the epoxy value is always low.The viscosity of each product is significantly lowered,and the low-temperature fluidity is also increased,but the oxidation stability is remarkably improved.Comprehensively available,When the reaction time is 4 h,the dropping temperature of H2O2 is 30°C,the reaction temperature is 60°C,the amount of ethyl acetate is 100 ml per 50 g FAME,the product has the best performance,that the iodine value is 32.88 g/100g,the epoxy value is 0.426mol/100g,the pour point is-18°C,the freezing point is-20°C and the oxidation stability is38 min.In the biodegradability measurement,it can be seen that the obtained products have excellent biodegradability in different epoxidation systems using sulfuric acid as a catalyst and ethyl acetate as a solvent,and almost no difference from unmodified vegetable oil.The degradation time reached the optimum degradation rate at 6 days,and the basic degradation ended at 15 days.After the use of antioxidants,the oxidative stability of the oil is improved,and after the additives are compounded,there is a certain synergistic effect.The addition effect of single additive is TBHQ>BHT>DTB,which is best when the amount of TBHQ is 1.0%,and 65min when it is antioxidant.In the two-two compound,it can be seen that the overall oxidation resistance of the oil is enhanced,among them,BHT composite TBHQ is the best.When the compounding ratio is 5:5,the highest antioxidant time is 75 min.When the three additives are compounded,when the ratio is BHT:DTB:TBHQ=3:1:3,the oil achieved the best antioxidant effect with an antioxidant time of 80 min. |
PDF Full Text Request