两性聚丙烯酰胺的水分散聚合及其在纸张增强中的应用

Preparation of Amphoteric Polyacrylamide via Aqueous Dispersion Polymerization and the Use of the Copolymer in Paper Strengthening

以甲基丙烯酰氧乙基三甲基氯化铵(DMC)为阳离子单体,丙烯酸(AA)为阴离子单体,丙烯酰胺(AM)为主要单体,在硫酸铵水溶液中采用偶氮二异丁基脒盐酸盐(AIBA)引发的水分散种子聚合方法成功制备出两性聚丙烯酰胺(Amphoteric Polyacrylamide,Am PAM)。通过FTIR、GPC、旋转黏度仪和激光光散射仪等分析测试手段结合胶体滴定法探讨了引发剂用量、硫酸铵浓度以及阴阳离子单体配比等因素对水分散聚合所得产物的化学结构、相对分子质量、表观黏度、平均粒径以及阴阳离子度的影响。实验表明,随着引发剂用量增加,Am PAM的重均相对分子质量平均粒径均呈减小的趋势。当硫酸铵浓度增加,共聚物分散颗粒的平均粒径增大。随着DMC/AA比值的提高,阳离子度增加。并以脱墨浆为原料,模拟新闻纸的抄造工艺与配方,探讨自制的两性聚丙烯酰胺的分子量对成纸力学性能和印刷适应性的影响。结果表明Am PAM相对分子质量为1.38×105时,纸张强度性能得到显著提高,抗张指数为23.8N·m/g,临界拉毛速度为0.54m/s。

Amphoteric polyacrylamide（ Am PAM） was prepared from methacryloxyethyltrimethyl ammonium chloride（ DMC）,acrylic acid（ AA） and acrylamide（ AM） via the aqueous seeded dispersion polymerization initiated by2,2 ＇-azobis（ 2-methylpropionamide） dihydrochloride（ AIBA） in ammonium sulfate（ AS） solution. The chemical structure,the relative molecular mass and its distribution,the apparent viscosity and average particle size of the copolymers were characterized. Besides,the charge feature and ionic degree of copolymers were investigated.The influences of the initiator dosage,AS dosage and monomer ratio and the reaction conditions to prepare the copolymers on the structural characteristics and physical performances of the final products were investigated. The results showed that the weight average relative molecular mass and average particle size of Am PAM tend to decrease with the increase of the amount of initiator. The average particle size of the copolymer dispersed particles was found to increase with the concentration of ammonium sulfate. With the increase of DMC/AA ratio,the cationic degree increased. Am PAM dry strength agent was applied to deinked pulp to simulate newsprint making. The effects of the weight average molecular weight of Am PAM on paper sheet tensile strength and printability were investigated in this research. The results showed that an improved strength of the paper,i. e.,tensile index 23. 8 N ·m · g^（-1） and critical drawing speed 0. 54 m/s,was obtained when the relative molecular mass of the Am PAM was 1. 38 × 10~5.