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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。
Many photo (thermal) initiators can decompose into two non-active free radicals. Based on the concept of non-isomeric primary radical termination, the following equation can be derived: plotting Rp / [M] ~ 2 with ln (Rp / 2 / [I] [M] and found that over a broad range of initiator concentrations Both better reflect the contribution of non-isomeric active primary radical termination to the polymerization.For benzoin and O-acyl-α-ketoxime photoinitiators, when their concentration is more than 1.0 × 10 -2 mol · 1 ~ (-1), the termination reaction of the non-active primary radical obviously existed in the polymerization system.With the increase of the temperature of the reaction system, the extent of the termination reaction decreased relatively, indicating that E_ (prt) -E_i-E_p <0, For O-acylketoxime and bis (O-acyl) - (α, β-dioxime-triethylamine photoinitiator systems, there are also primary radical termination reactions at low initiator concentrations. The more stable the free radicals are, The effect of the primary free radical termination reaction is more pronounced.