羧甲基纤维素取代均一性的研究

羧甲基纤维素(钠盐,以下简称CMC)是一种重要的水溶性聚电解质。本文在传统溶媒法的基础上,采用乙醇作溶剂的两段加碱法新工艺制备CMC。研究表明,在低浴比(乙醇/纤维素=2.5—3.0)条件下,采用新工艺制得取代度约0.9,粘度(2％水溶液)为900—1000mPa·s,具有较高取代均一性和良好性能的CMC。用酶水解的方法,通过还原值测定,对CMC的取代基沿分子链的分布进行了表征;并对CMC的一些性能进行了测定,同时对其热稳定性进行了研究。

STUDIES ON THE UNIFORMITY OF SUBSTITUTION OF CMC

Carboxymenthylcellulose(CMC) is one of the important water soluble polyelectrolyte. In this paper, the CMC were prepared by the two—stage NaOH addition process. It was found that the CMC having a uniform substituent distribution with DS of about 0.9 and viscosity (2％ aqueous solution) in the range of 900-1000 mPa·s had be obtained by two—stage NaOH addition process at low ratio of ethyl alchol/cellulose being 2.5 to 3.0. The distribution of substituents along the cellulose chains were characterized through the analyses of enzymic hydrolysis. The results showed that the average number of structural unit in a substituted block (L_Sn) for the two—stage NaOH addition process was longer than that for the conventional addition manner and the substitution index (SI) was higher than that for the onventional addition manner. The DS, viscosity, sodium chloride and moisture content were measured by standard method. And the thermal stability of CMC had also be studied.