机械活化淀粉接枝丙烯酰胺/丙烯酸反相乳液聚合动力学*

摘要

淀粉接枝共聚物是一种新型功能性材料。以机械活化淀粉(mSt)为接枝母体,丙烯酰胺(AM)和丙烯酸(AA)为接枝单体,研究了在淀粉/单体/乳化剂/油/水反相乳液体系中引发机械活化淀粉与丙烯酰胺/丙烯酸接枝共聚反应的动力学,考察了引发剂浓度[I]、单体浓度[M]、淀粉乳浓度[mSt]和乳化剂浓度[E]等因素对表观聚合速率Rp 的影响。结果表明,在本文考察范围内动力学关系式为 Rp ∝[mSt ]1.5[M]1.7[I]0.9[E]0.92,单体浓度和淀粉乳液浓度对聚合反应速率影响显著,聚合反应速率随体系温度升高而加快,在45~60℃范围内,聚合反应的表观活化能为89.5 kJ/mol,聚合过程中单基终止与双基终止反应同时存在。%The graft copolymer of strach was a new kind of functional material.The kinetics of graft co-poly-merization of in the inverse emulsion system,mechanically-activated starch(mSt)/monomer/emulsifier/oil/wa-ter,were investigated with mechanically-activated starch and acrylamide(AM)/acrylic(AA)as the raw materi-al.The rate orders of graft co-polymerization with respect to the concentrations of initiator,monomer,starch, and emulsifier were determined.The results show that the dependence of the polymerization rate RP on the components concentration in the polymerization system can be expressed for all four components by the follow-ing equation:RP∝[mSt]1.5 [M]1.7 [I]0.9 [E]0.92 .The influences of concentrations of starch and monomer on the rate orders of graft co-polymerization are predominant in four factors.The overall activation energy for the pol-ymerization process was 89.5 kJ/mol,and the unimolecular and bimolecular terminations of free radicals are concomitant presence in the reaction process.