Relaxation transitions in poly(methyl methacrylate) as shown by dynamic mechanical spectroscopy, thermostimulated creep, and creep rate spectra

As shown by the data on the relaxation transitions in PMMA obtained in a wide temperature range from -200 to +450 degreesC by the methods of dynamic spectroscopy (internal friction spectra) and nondynamic mechanical spectroscopy (thermostimulated creep spectra and creep rate spectra), multiplicity of relaxation transitions as observed in the internal friction spectra is also typical of the data of nondynamic mechanical spectroscopy. In this case, relaxation transition temperatures and maxima in thermostimulated creep spectra and creep rate spectra coincide with the transition temperatures and maxima in the internal friction spectra at frequencies equivalent to the time regimes applied in the nondynamic testing of polymers. The molecular nature of relaxation transitions in PMMA as established by the methods of dynamic mechanical spectroscopy allows one to unequivocally identify the nature of maxima and transition temperatures in the spectra of nondynamic mechanical spectroscopy.