FRONTINI patricia Maria
Rejuvenation of epoxy glasses subjected to uniaxial compression
P. A. OYANGUREN; C. I. VALLO; P. M. FRONTINI ; R. J. J. WILLIAMS
ELSEVIER SCI LTD
Lugar: Amsterdam; Año: 1994 p. 5279 - 5289
Two epoxy networks, differing significantly in their glass transition temperatures (Tss), were subjected touniaxial compression tests in the glassy state (20°C). One of the systems was based on the diglycidyl etherof bisphenol-A (DGEBA) cured.with ethylenediamine (EDA). The other one was based on an epoxidizednovolac (EPN) cured with 4,4'-diaminodiphenyl sulfone (DDS). Both systems were physically aged byspecific thermal treatments. The endothermic enthalpy relaxation peak, characteristic of aged glasses, couldbe erased at temperatures well below T~ by large mechanical deformations, i.e. close to the incipient strainhardening level in uniaxial compression tests. This phenomenon, which was accompanied by an increasein specific volume, constitutes a clear manifestation of rejuvenation produced by large mechanical stimuli.The validity of statements presenting an opposite point of view is also discussed.