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Effect of oxygen on the crosslinking and mechanical properties of a thermoset formed by free‐radical photocuring
Author(s) -
Pilkenton Morgan,
Lewman Jeremiah,
Chartoff Richard
Publication year - 2010
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.32650
Subject(s) - materials science , thermosetting polymer , photopolymer , glass transition , monomer , composite material , irradiation , polymer chemistry , polymer , chemical engineering , oxygen , chemistry , organic chemistry , physics , nuclear physics , engineering
Abstract In this article, we report on the formation of optically transparent photopolymer films from hexanediol diacrylate (HDDA) by inkjet printing, where droplets of monomer approximately 5 μm in diameter were deposited onto a surface. The films were cured by irradiation with a UV‐light‐emitting‐diode light source. It was found that the inkjet‐printed HDDA films picked up a considerable amount of absorbed O 2 during printing. Exposure to increasing amounts of O 2 during photocuring severely restricted both the degree of conversion and the UV dose required for gelation in proportion to the O 2 concentration. Viscoelastic property data indicated that exposure to reduced oxygen concentrations during thermal postcuring (dark reaction) resulted in linear trends of increasing modulus above the glass‐transition temperature ( T g ) and increasing T g itself. Thus, the final crosslink density was greater in fully cured samples that were exposed to atmospheres with increasing inert gas concentrations. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011