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RadTech
UV/EB Technology Conference & Expo 2008
May 4-7, 2008
Lakeside Center at McCormick Place
Chicago, Illinois - United States of America
CATIONIC
A Real-Time FTIR Study
of the Humidity Effect on Cationic Photopolymerization
of Epoxy-Siloxane Con
zhigang chen, Center for Nanoscale Science
and Engineering, NDSU
Abstract:
High humidity inhibits cationic photopolymerization. In order to seek
a approach to overcome the humidity interference, cationic photopolymeriztion
behavior of formulations containing both hydroxy-functional reactive
diluents and hydrophobic epoxy-siloxane monomer were examined using
real-time FTIR. The hydroxy-functional reactive diluents act as an
internal hydroxyl source that enhances monomer conversion through
chain transfer mechanism, and the hydrophobic epoxy-siloxane acts
as a "humidity blocker", mitigating the inhibiting effects
of humidity. Cationic UV curable formulations with an optimized combination
of these two components exhibited higher and more consistent monomer
conversion under all humidity conditions tested. This "humidity
blocker" strategy is a promising approach to overcome the negative
effect of humidity on cationic photopolymerization.
Lifetimes
and Mobility of Cationic Active Centers
Beth A. Ficek, University of Iowa
Abstract: Cationic photopolymerization exhibits essentially
no termination, which leads to active center lifetimes of hours
or even days. In this contribution the migration of these long-lived
active centers into regions that have never been illuminated is
characterized. In addition, the potential for creating active centers
photochemically prior to mixing with the monomer is investigated.
Photopolymerization
and Physical Properties of Thiol-Vinyl ether Hybrid
Qin Li, The University of Southern Mississippi
Abstract: This paper represents the first example of a thiol-ene
free-radical/vinyl ether cationic hybrid system in which thiols
copolymerize with vinyl ethers in a rapid radical step growth process
followed by vinyl ether cationic homopolymerization. The kinetics
of the photopolymerization were investigated. The combination of
thiol-ene and cationically polymerized vinyl ether results in networks
with thermal and mechanical properties that are unexpected combinations
of each system. The unique adhesive properties of the photocured
hybrids were investigated.
Stage-Curable
Hybrid Free Radical/Cationic Photopolymerizations
Leroy Magwood, University of Iowa
Abstract: Hybrid free radical/cationic photopolymerizations
of acrylates and epoxides provide a convenient method for producing
stage-curable systems. In these systems, stage 1 corresponds to
a viscous liquid, stage 2 is a moldable putty, and stage 3 corresponds
to the cured polymer. In this contribution, the physical property
development for hybrid photopolymerizations of a variety of acrylates
and epoxides will be considered. The property development will be
correlated to associated polymer structure.
Visible
light polymerization of epoxy resins: design for in-orbit curing
of spatial structures
Xavier COQUERET, Universite de Reims
Champagne Ardenne
Abstract: The curing reaction developed to meet the needs
of in-orbit curing of ultralight composite structures for spatial
applications involves the visible photopolymerization of epoxy resins
initiated by novel arene ferrocenium photolatent Lewis acids. The
reactivity of photosensitive formulations including various types
of epoxy resins and initiators was studied by monitoring the rate
of initiator photolysis under different visible light sources. The
resulting polymerization of epoxy functions was also monitored by
IRTF analysis to examine the kinetic profile of the reactions as
a function of composition and treatment (light source, temperature,
thermal post-curing). B. Defoort, X. Coqueret, D. Lacour, Rigidization
of structures to be deployed by inflation, particularly for use
in space - PCT Patent WO 2006 043009
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