CHARACTERISTICS OF AKD EMULSION PREPARED BY CATIONIC STARCH WITH WELL-DEFINED STRUCTURES

作     者：Y.S. Chew,H. Xiao,G. Peng,J. C. Roberts,K. Nurmi,K. Sundberg 

作者机构：Paper Science Department UMIST Manchester UK Department of Chemical Engineering University of New Brunswick Canada Raisio Chemicals Raisio Finland. Paper Science Department UMIST Manchester UK Raisio Chemicals Raisio Finland. Raisio Chemicals Raisio Finland. 

出 版 物：《天津科技大学学报》 (Journal of Tianjin University of Science & Technology)

年 卷 期：2004年第S1期

页      面：333-338页

学科分类：082903[工学-林产化学加工工程] 08[工学] 0829[工学-林业工程] 082201[工学-制浆造纸工程] 0822[工学-轻工技术与工程] 

主　　题：AKD CHARACTERISTICS OF AKD EMULSION PREPARED BY CATIONIC STARCH WITH WELL-DEFINED STRUCTURES 

摘      要：Alkyl ketene dimers (AKD) have been used in the papermaking industry as reactive internal sizing agents for more than 30 years. AKD emulsions are normally stabilised by cationic starch. The advantages and disadvantages of the emulsions prepared in this way have been well documented. However, the influence of factors such as electrolytes, polyelectrolytes oligomers and pH on AKD emulsion stability has not been addressed. Polyelectrolyte oligomers often arise as impurities in cationic starch or as by-products during the cationisation of starches. The key objectives of this work have been to use starches purified by dialysis and precipitation to study (a) emulsion stabilising properties, (b) factor affecting emulsion characterisation and (c) the adsorption behaviour on AKD *** exclusion chromatography (SEC) and intrinsic viscosity measurements were performed to evaluate molecular weight and MW distribution of cationic starches. NMR and Elemental analysis were conducted to characterise the degree of substitution (DS), and electrophoresis mobility was used to measure the surface charge characteristics of the emulsion particles. Within the experimental concentration ranges, the amount of the cationic starch adsorbed on the AKD particle surfaces has been shown to increase proportionally with the addition level but a high proportion remained unabsorbed. Molecular weight and charge density of cationic starch have also been observed and shown to be important. The zeta-potential of the emulsion particles was strongly dependent on the concentrations of the electrolytes added as well as pH. Excessive electrolytes and extreme pH conditions tended to reduce the zeta potential of the AKD particles.