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On the increase of viscoelastic modulus with advancement of reaction of an epoxy resin
Author(s) -
Serrano D.,
Harran D.
Publication year - 1989
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.760290807
Subject(s) - epoxy , viscoelasticity , materials science , shearing (physics) , isothermal process , composite material , dynamic mechanical analysis , modulus , glass transition , gel point , calorimetry , dynamic modulus , polymer chemistry , atmospheric temperature range , thermodynamics , polymer , physics
Log G * = f ( X ) isothermal variation curves were determined at various temperatures for two epoxy‐aromatic amine systems widely used in industry. G * = G ′ + j G ″ is the viscoelastic modulus, determined by sinusoidal shearing at constant frequency between parallel plates; X represents the degree of reaction, determined by calorimetry. These curves clearly show the phenomena of gelation and glass transition. In the temperature range studied, the value of X at the gel point varies between 0.7 and 0.9 for the DGEBA‐DDS system, and from 0.3 to 0.8 for the TGDDM‐DDS system. These variations reflect a major modification of the reaction mechanism, particularly before the gel point.