Thermal mechanical analysis physical aging

With requenching and reaging, expansivity above Tg again increases with reaging time (96.6 % increase), demonstrating once again the thermoreversibility of physical aging. Table 2 summarizes the results of the thermal mechanical analysis. 

Physical Aging in PMMA Investigated Using Positron Annihilation, Dielectric Relaxation, and Dynamic Mechanical Thermal Analysis... 

Novel mechanical tests are being developed and shown to be useful tools to investigate thermal and structural relaxation. These include the modulated-temperature-thermomechanometry technique (mT-TM) which has been recently employed to investigate blends of core cross-linked (CCS) PS and PMMA (Spoljaric et al. 2011) and nanomechanical thermal analysis. By using silicon microcantilever deflection measurements, the latter technique can provide a measure of temperature-dependent thermal stresses and therefore investigate the influence of physical aging (Yun et al. 2011). 

INVESTIGATION OF PHYSICAL AGEING IN POLYMETHYLMETHACRYLATE USING POSITRON ANNIHILATION, DIELECTRIC RELAXATION AND DYNAMIC MECHANICAL THERMAL ANALYSIS Davis W J Pethrick R A Strathclyde,University... 

The general experimental approach used in 2D correlation spectroscopy is based on the detection of dynamic variations of spectroscopic signals induced by an external perturbation (Figure 7.43). Various molecular-level excitations may be induced by electrical, thermal, magnetic, chemical, acoustic, or mechanical stimulations. The effect of perturbation-induced changes in the local molecular environment may be manifested by time-dependent fluctuations of various spectra representing the system. Such transient fluctuations of spectra are referred to as dynamic spectra of the system. Apart from time, other physical variables in a generalised 2D correlation analysis may be temperature, pressure, age, composition, or even concentration. 

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