Dynamics of poly(propyl methacrylate) as a function of temperature and pressure

The local segregation and dynamics of poly(propyl methacrylate) (PPMA) are studied as a function of temperature by X-rays and by dielectric spectroscopy and rheology, respectively. Pressure is employed in dielectric spectroscopy for investigating the origin of segmental dynamics and for separating the segmental from the faster β-process. The segmental dynamics of PPMA is controlled mainly by temperature via the intramolecular barriers. The pressure coefficient of the glass temperature is one of the lowest ever reported (dTg/dP = 150 K/GPa). Based on this finding we examined a possible correlation between the values of the ratio of the apparent activation energy.