摘要
许多光(热)引发剂能分解成二个非等活性自由基。根据非等活性初级自由基终止的概念,可导出以下方程:以ln(R_p^2/[I][M]对R_p/[M]~2作图,发现在很大的引发剂浓度范围内都较好地反映出非等活性初级自由基终止对聚合反应的贡献。对于安息香和O-酰基-α-酮肟类光引发剂,当它们的浓度大于1.0×10^(-2)(mol·1^(-1)时,聚合反应体系中明显存在非等活性初级自由基终止反应。随着反应体系的温度增加,终止反应程度相对减少,说明E_(prt)—E_i—E_p<0,对于O-酰基酮肟和双(O-酰基)-(α,β-二肟-三乙胺光引发体系,在引发剂浓度很低时,也存在初级自由基终止反应。自由基越稳定,初级自由基终止反应影响越明显。
It is well known that some initiators can be decomposed to two radicals with different reactivities. Based on this fact, an equation of polymerizationis proposed. Semi-log plots of Rp2[I]][M] vs Rp/[M]2 clearly show the effect of un-equally reactive primary radical termination on polymerization in a wide range of concentration of initiator. For example when the concentrations of the initiator like benzoin and O-acyl-a-oximinoketones are greater than 1.0×10-2 (M), polymerization is clearly effected by un-equally reactive primary radicals termination, and this effect will decrease as the temperature of polymerization is increased, which means Eprt-Ei-Ep < 0. Primary radical termination is always existing in the polymerization initiated with O-acyloximers or bis (O-acyl)-a, B-dioximes-triethylamine systems, although the concentration of initiators is very low. The more stable these radicals are, the more efficient the primary radical termination will be.
出处
《高分子学报》
SCIE
CAS
CSCD
北大核心
1990年第5期586-592,共7页
Acta Polymerica Sinica
关键词
光聚合反应
初级自由基
终止
Primary radical termination, Un-equally reactive radical, Photopolymerization
