| The Solubility and the thermal stability of the ammonium branched-chainpolycarboxylate in ethylene glycol solution are superior to ammonium straight-chaincarboxylate. It is important to develop ammonium polycarboxylate in improving performanceof working electrolyte and promoting quality of aluminium electrolytic capacitor.Experimental preparation of branched-chain polycarboxylic acid containing ammoniumas the working electrolyte of the process is:IConditions of the synthesis of branched chain polycarboxylic acid esterare:Alkyl cyclohexanone 0.3 moLAlkyl acrylic ester 0.3 moLmethanol 80 gvitriol 4 goxidizing agent 15 greducing agent 80 gtemperature of reaction temperature one: 5℃, temperature two: 0℃material was added for reaction 3h againThe structure and composition of the branched-chain polycarboxylic acid was analyzed by infrared spectrum and GC-M S, it is indicated that the branched chain acid in this studywere composed of 2-methyl azelaic acid and 7,8-dimethyl-1,7,8,14-tetradecantetraoic acid.A series of comparing test and TG test confirm that the branched-chain carboxylic acid mustbe superior to straight-chain carboxylic acid which has the same molecule weight on thermalstability, and the values of the ammonium branched-chain polycarboxylate on solubility andconductivity are higher than ammonium straight-chain carboxylate whose molecule weight issimilar. At 30℃, conductivity of 20% concentration of the ammonium branched-chainpolycarboxylate in glycol solution is 2510μS/cm, pH value is 6.83, moisture content is lessthan 0.5%, break-down voltage reachs 450V.We use working electrolyte which is composed of the ammonium branched-chainpolycarboxylate as main electrolyte and ethylene glycol,diethylene glycol as solvent to carryout a detailed study of the problem. The results have shown that the dosage of ammoniumsebacate is superior between 3.5% and 5.0% in working electrolyte which has two solutecomposed of ammonium branched-chain polycarboxylate and ammonium sebacate.Conductivity and break-down voltage of working electrolyte are higher when the dosage ofthe ammonium branched-chain polycarboxylate is between 15% and 30%. The paper alsostudy the performance on impedance, leakage current, capacitance,loss, total life of threecapacitors which are made into4.7uF/400V,φ10×16 style, which are made of differentsworking electrolyte including two sets of working electrolyte of the ammoniumbranched-chain polycarboxylate and a set of working electrolyte of ammonium straight-chaincarboxylate. The results indicated that both capacitors could pass the rated ripple experimentfor 1000h at 135℃in 100 Hz frequency,150mA ripple current, but the performance ofcapacitors which are made of electrolyte includig ammonium branched-chain polycarboxylateare superior to the latter, such as lower loss, larger capacitance, lower impedance, betterhigh-temperature stability.
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