Pressure vitrification polymers

The vitrification of liquids and polymers can be effected not only by the decrease of temperature but also by the increase of pressure [4]. Shishkin and Novak [5] obser ved the dependence of free hydroxyl concentration upon pressure. This effect can be described by Eq. (6) or (8) in the same way as the course of vitrification upon decreasing temperature. 

The hydrogen bonds play the most important role in the process of the vitrification of liquids and polymers. This process is characterized by the sharp increase of the relaxation times with the decrease of temperature or the increase of pressure and is determined in many systems by the existence of hydrogen bonds. 

Conventional models or theories consider only the segmental relaxation of amorphous polymers and the primary relaxation of nonpolymeric glass-formers in the change of molecular mobility with temperature and pressure (and concomitant changes in free volume and/or configurational entropy) leading to vitrification. Here we wish to recognise two different kinds of secondary relaxation processes. There... 

Bercea M, Wolf BA (2006) Vitrification of polymer solutions as a function of solvent quality, analyzed via vapor pressures. J Chem Phys 124(17) 174902-174907... 

The sorption of compressed gases in polymers can now be well documented. Our results with CH4, CO2, and N2 confirm earlier studies of Condo et al. [81, 82] and more recent investigations of Handa et al. [83, 84] on retrograde vitrification of polymers observed when a decrease of Tg is observed at gas pressures high enough to overcome the purely hydrostatic effect. 

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