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研究了以棉短绒(精制棉)为原料、氯乙酸为醚化剂,合成羧甲基纤维素钠。探索了纤维素在碱化、醚化阶段的反应机理。考察了渗透剂、氢氧化钠溶液浓度及其用量、醚化时间4种因素对所合成羧甲基纤维素钠的水溶液粘度的影响。通过检测醚化后羧甲基纤维素钠的取代度和2%水溶液的粘度,确定了最佳工艺条件:碱化温度为30~35℃,碱化时间为50 min,醚化温度为70~75℃,醚化时间为70 min,碱溶液浓度为25%,渗透剂添加量为3%。此条件下制备的羧甲基纤维素钠,水溶液浓度为2%时,粘度达到600~650 MPa.s,取代度为0.530~0.560。
The cotton linter (refined cotton) as raw materials, chloroacetic acid as etherifying agent, the synthesis of sodium carboxymethyl cellulose. The reaction mechanism of cellulose in alkalization and etherification was explored. The effects of osmotic agent, concentration of sodium hydroxide solution and its dosage, etherification time on the viscosity of aqueous solution of sodium carboxymethylcellulose were investigated. The optimum conditions were determined by measuring the degree of substitution of sodium carboxymethylcellulose and the viscosity of 2% aqueous solution after etherification. The optimum conditions were: alkalization temperature 30 ~ 35 ℃, alkalization time 50 min, etherification temperature 70 ~ 75 ℃, the etherification time was 70 min, the concentration of alkali solution was 25% and the amount of penetrant added was 3%. The sodium carboxymethyl cellulose prepared under this condition had a viscosity of 600 ~ 650 MPa.s at a concentration of 2% and a degree of substitution of 0.530 ~ 0.560.