Scientific Results

Calorimetric and dielectric effects during polymerization of an elastomer-containing mixture and liquid-liquid phase separation

Year: 1999

Authors: Ferrari C., Tombari E., Salvetti G., Johari G.P.

Autors Affiliation: CNR, Ist Fis Atom & Mol, I-56127 Pisa, Italy
McMaster Univ, Dept Mat Sci & Engn, Hamilton, ON L8S 4L7, Canada

Abstract: Calorimetry and dielectric spectroscopy of an elastomer, amine terminated butadiene acrylonitrile (ATBN), dissolved in a stoichiometric mixture of ethylene diamine and diglycidyl ether of bisphenol-A, were studied in real time during the polymerization and phase separation of the mixture. In the two polymer compositions containing 8 w/w % ATBN and 20 w/w % ATBN, the total enthalpy released per mole of DGEBA’s reaction was the same, indicating indetectably small changes in molecular interactions before and after the phase separation. The dielectric relaxation spectra showed no evidence for phase separation, which indicated a gradual phase separation with time and the extent of polymerization, and relatively small differences in the permittivity and conductivity between the ATBN particles and the network matrix at the time of phase separation. The equilibrium permittivity and de conductivity showed a nonideal mixing of ATBN. The stretched exponential relaxation parameter remained at 0.36, but the characteristic dielectric relaxation time and the de conductivity increased on addition of ATBN. An increase in the temperature had a greater effect on the relaxation time than the increase in the extent of polymerization.

Journal/Review: JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS

Volume: 37 (15)      Pages from: 1911  to: 1919

KeyWords: CURING KINETICS; SPECTROSCOPY; RELAXATIONS; THERMOSETS;
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