Chemical ageing temperature

For example, the 1% Cloisite filled system experiences a 40X increase in onset degradation temperature after 504 hours aging under moist air compared with the same system under dry N2 conditions, which exhibits an 1 PC increase after the same period. Such changes cannot wholly be accounted for by passive degradant loss and these data suggest that a chemical aging process is responsible. 

Three methods that were used to measure the chemical changes associated with oxidative degradation of polymeric materials are presented. The first method is based on the nuclear activation of lsO in an elastomer that was thermally aged in an, 802 atmosphere. Second, the alcohol groups in a thermally aged elastomer were derivatized with trifluoroacetic anhydride and their concentration measured via 19F NMR spectroscopy. Finally, a respirometer was used to directly measure the oxidative rates of a polyurethane foam as a function of aging temperature. The measurement of the oxidation rates enabled acceleration factors for oxidative degradation of these materials to be calculated. 

This paper reports the study of the aging behavior of ultra-thin epoxy films on PVD layers of Al, Au, and Cu under varying environmental conditions by FTIR external reflection absorption spectroscopy (ERAS), to reveal influences of interphase interactions on crosslinking and on chemical aging processes at moderate temperature. 

---