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21.
Solid bisphenol-A epoxy
resin of medium molecular mass was cured using a Lewis acid initiator (ytterbium(III)
trifluoromethanesulfonate) in three different proportions (0.5, 1 and 2 phr).
A kinetic study was performed in a differential scanning calorimeter. The
complete kinetic triplet was determined (activation energy, pre-exponential
factor, and integral function of the degree of conversion) for each system.
A kinetic analysis was performed with an integral isoconversional procedure
(free model), and the kinetic model was determined both with the Coats-Redfern
method (the obtained isoconversional value being accepted as the effective
activation energy) and through the compensation effect. All the systems followed
the same isothermal curing model simulated from non-isothermal ones. The growth-of-nuclei
Avrami kinetic model A3/2 has been proposed as the
polymerization kinetic model. The addition of initiator accelerated the reaction
especially when 2 phr was added. 0.5 and 1 phr showed very few kinetic differences
between them. 相似文献
22.
In this essay we explore a new form of political communication, the meta-image , or the communicative act whereby political campaigns and their chroniclers publicly display and foreground the art and practice of political image construction. We examine a compelling example of meta-imaging-the 1993 film, The War Room . We identify how the film functions as a reflection of the hyperreality of U.S. politics. We then argue that The War Room , through the use of naturalized military metaphors, works toward the edification of image making as a normative campaign process and a reaffirmation of U.S. national identity. 相似文献