【摘要】 采用消晶活化预处理的方法,制备出了取代度高达1.72的羧甲基纤维素(CMC)。研究了用水量、反应温度、反应时间、消晶活化法预处理NaOH浓度(活化碱浓度)对产品取代度的影响,并通过SEM及XRD观察和分析消晶活化反应中NaOH浓度对纤维形态和结晶结构的影响。结果表明:反应时适宜的用水量为8~10 mL,反应温度在65~75℃之间,反应时间为3 h;纤维素经浓NaOH溶液处理后发生溶胀,且浓度越高,纤维素溶胀越剧烈,结晶度越低,反应活性越高,CMC取代度越高,最佳的NaOH质量浓度为500~600 g/L;3%含固量的CMC在30 r/min下黏度高达35 000 mPa·s;溶液黏度在pH值为6~10范围内变化不大,具有良好的耐酸碱和硬水能力;所配溶液存放2周后,黏度变化不大,具有良好的贮存稳定性。更多还原

【Abstract】 The production of carboxymethylcellulose( CMC) with a substitution degree of up to 1. 72 was achieved through a new approach of lowering crystallinity and activating pretreatment. The experiments sought to examine the effects of water amount, reaction temperature, reaction time and NaOH concentration on the degree of substitution( DS) of CMC,as well as to test the morphologic and crystal structures of the product as affected by the alkali concentration using SEM and XRD. The results showed that the appropriate process conditions were as follows: amount of water 8- 10 mL,reaction temperature 65- 75 ℃,and reaction time 3 h. The results demonstrated that the cellulose swelled after the treatment of high concentration of alkali; higher the concentration,more swollen the cellulose; and lower the degree of crystallinity,more active the reaction and higher the DS. Thus,the optimal concentration of alkali should be 500- 600 g / L. Moreover,CMC with a solid content of 3% had a viscosity of as high as 35 000 mPa·s when the viscosimeter was running at 30 r / min. The viscosity of such CMC solution varied little when the pH was 6- 10,and the solution appeared to have better stability under different pH conditions and in hard water. After this CMC solution was preserved for two weeks,and its viscosity remained almost the same,which indicated it had good storage stability.更多还原