淀粉接枝丙烯酰胺絮凝剂合成及机制

应用水溶液聚合法合成淀粉接枝丙烯酰胺聚合物,研究了聚合反应机制。以过硫酸铵为引发剂,淀粉与丙烯酰胺在水溶液中进行接枝共聚反应,研究了反应温度、淀粉种类、糊化、pH值对接枝反应的单体转化率、接枝率、接枝效率以及产品支链聚合物相对分子质量的影响。结果表明:在反应温度50℃、丙烯酰胺与淀粉的质量比2∶1的条件下,产品接枝率71%,单体转化率97%,支链聚合物的相对分子质量700万。用偏光显微镜、扫描电镜分析等手段表征了淀粉及其接枝共聚物的形态结构。结果显示:合成的淀粉接枝共聚物保持团粒结构,表面接枝丙烯酰胺均聚物低;糊化的淀粉接枝后,形成了均匀的淀粉接枝共聚物。

Synthesis of Starch Grafted Acrylamide Copolymers and its Mechanism

Starch grafted acrylamide copolymer was synthesized using starch and acrylamide as raw materials and ammonium persulfate as initiator, respectively. The polymerization mechanism was also discussed. The influ ences of temperature, types of starch and gelatinization on monomer conversion rate, grafting ratio, graft efI＇ieieney and the molecular weight of polyacrylamide grafted, were investigated during the synthesized processes. The results showed that the grafting ratio,the monomer conversion rate, and the molecular weight of polyacrylamide starch is 71% ,97 % , and 7 million, respectively,when tile reaction temperature was 50 ~C and the mass rylamide to starch was 2 ＂ 1. The morphology of starch graft copolymers were characterized by polarizing grafted on ratio of ac microscope and SEM. After the graft reaction of ungelatinized starch, the morphology of the copolymers kept the aggregate struc ture, and acrylamide copolymer is grafted on the surface of starch;The gelatinized starch forms homogeneous poly mer, which is totally different from ungelatinized products.