Polymers Under Pressure
- 135 Downloads
Using the bulk Grüneisen Parameter, an equation of state V(p,T) is derived from thermodynamics. It can be successfully applied to crystalline as well as glassy polymers and in a first approximation also to polymer melts. This is shown for high pressure crystallized Polyethylene and — in a contribution by Dollhopf — for Polycarbonate and Polystyrene.
Next, the pressure dependence of the glass relaxation process (in PVAc), as measured by dielectric spectroscopy, is discussed and analysed using the dislocation concept in the meander model and an appropriate Grüneisen parameter γdisl. The latter turns out to be about half the value of the bulk parameter, which might be checked by measuring the pressure dependence of the shear modulus G(p).
Finally, the pressure dependence of phase transitions and its transition data will be described for several examples, including the high temperature transition of PE into a CONDIS-phase and the subsequent melting, as well as the nematic/isotropic transition of LC-polymers and — in a contribution by Schwarzenberger — the lamellar/isotropic transition of PDES.
KeywordsPressure Dependence Activation Diagram Orientational Order Dislocation Wall Mesogenic Group
Unable to display preview. Download preview PDF.
- 1.P. Bolsaitis, I. L. Spain, in “High pressure technology”, Marcel Dekker, New York, I. L. Spain and J. Paauwe Ed. 477–545 (1977).Google Scholar
- 3.R. Simha, in “High Pressure Science & Technology”, Pergamon Press, B. Vodar and Ph. Marteau Ed. 682-684 (1980).Google Scholar
- 5.W. Pechhold, B. Stoll, Motion of Segment Dislocations as a Model for Glass Relaxation, Polym.Bull. 7:413 (1982).Google Scholar
- 8.W. Pechhold, A. A. Mansour, E. Sautter, B. Stoll, Factors affecting glass relaxation in polymers, to be published in Colloid & Polymer Sci.Google Scholar
- 10.W. Pechhold, P. Schwarzenberger, Phasediagram, Superstructure and Properties of Poly(diethylsiloxane), PDES, this volume.Google Scholar
- 12.I. N. Makarenko, A. M. Nikolaenko and S. M. Stishov, in “High-Pressure Science and Technology”, Plenum Press, New York, K. D. Timmerhaus and M. S. Barber Ed. 347–356 (1979).Google Scholar
- 14.W. Pechhold, H. P. Großmann and E. Sautter, On the Nature of Mesophase Transitions in Polymers, I. The Isotropic-Nematic Transition, Colloid & Polymer Sci. (1991), in press.Google Scholar