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Effect of tertiary amines on yellowing of UV‐curable epoxide resins
Author(s) -
Chiang Tzu Hsuan,
Hsieh TsungEong
Publication year - 2007
Publication title -
polymer international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.592
H-Index - 105
eISSN - 1097-0126
pISSN - 0959-8103
DOI - 10.1002/pi.2300
Subject(s) - amine gas treating , chemistry , tertiary amine , epoxide , phenol , radical , peroxide , curing (chemistry) , reactivity (psychology) , imidazole , polymer chemistry , organic chemistry , catalysis , medicine , alternative medicine , pathology
The work reported demonstrates that the yellowness of UV‐curable epoxide resins can be improved by adding certain tertiary amines in appropriately determined amounts. According to the results of our experiments, 2.0 wt% benzoyl peroxide added to a resin effectively enhances the crosslinking density, and phenolic free radicals are produced during UV curing, which consequently induce yellowness via the reaction of oxygen and the free radicals. Imidazole (1‐amine) and tertiary amines, including 1,2‐dimethylimidazole (2‐amine), 2,4,6‐tris(dimethylaminomethyl)phenol (3‐amine), 1‐methylimidazole (4‐amine) and 2‐methylimidazole (5‐amine), were chosen to be added to resins, and their effects on UV conversion and yellowness were investigated. According to the experimental results, tertiary amines in the resin can provide a certain degree of improvement in yellowness index (ΔYI) and color parameter (Δ E * ab ) of the resin sample. Whatever the type of tertiary amine, it is found that the optimum content of amine in resin is 1.0 wt%. Also, among the studied amines, the 3‐amine exhibits the highest UV reactivity and the best efficiency for yellowness improvement with values of Δ a *, Δ b *, ΔYI and Δ E * ab as low as − 1.4, 6.23, 11.27 and 6.48, respectively. Copyright © 2007 Society of Chemical Industry