ISSN:
0021-8995
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
Notes:
The cure behavior of commercial grade TGDDM-DDS mixtures of compositions ranging from 10 to 100 phr of hardener and the thermal polymerization of the epoxy component are analyzed by means of differential scanning calorimetry. The kinetic parameters and heats of reaction determined in isothermal and dynamic scans suggest that DDS primary amine addition and epoxide etherification dominate the cure reactions. The primary amine epoxide addition is characterized by overall heat of reaction (referred to the weight of the epoxy component) of 255 cal/g and by an activation energy of 16.6 kcal/mol. The corresponding values for the etherification reaction are, respectively, 170 cal/g and 41 kcal/mol. A method of derivation of the epoxide conversion from the heat evolved in DSC thermal scans of these systems is presented. The results are in good agreement with independent IR determinations. The steady shear and oscillatory viscosity measurements and the calorimetric analysis of the isothermal cure at 140°C, 160°C, and 180°C of a TGDDM-DDS mixture containing 35 phr of hardener indicate that gelation is principally governed by the primary amine addition. The gelation limits calculated in isothermal tests by combining the calorimetric analysis and the theory describing the nonlinear copolymerization of the tetrafunctional TGDDM with an essentially difunctional DDS were in good agreement with the values experimentally determined through rheological measurements.
Additional Material:
6 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/app.1984.070290616
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