PHYSICAL AGING PHENOMENA IN AN AMORPHOUS POLYMER AT TEMPERATURES FAR BELOW THE GLASS-TRANSITION

Isothermal agings have been carried out on poly(methyl methacrylate) a t temperature far below the glass transition temperature region. Aging effects have been investigated by calorimetric and dynamic mechanical techniques; influence of quenching rate, time and temperature of agin g have been studied. It is seen that the beta-relaxation is not affect ed by physical aging and that the alpha-relaxation spreads out in the beta-relaxation temperature domain. Comparison of the results obtained from the two techniques shows the occurrence of a specific mechanism for aging temperature far below the glass transition temperature.