Free Volumes and Grüneisen Parameters in Mixed-Tacticity Polyhydroxybutyrates

Recently, nonlinear progressions of mechanical and thermal properties of mixed-tacticity polyhydroxybutyrates have been discovered with their fraction of meso diads (Formula presented.). Characteristic (Formula presented.) is traced by a measure (Formula presented.) of polymer chain segment length disturbance, due to the inclusion of S enantiomers in chains consisting otherwise of R monomers. In this article, the material compositions' thermal expansion coefficients are reported on as determined by X-ray diffraction and connect the qualitative (Formula presented.) to their free volume fractions. Further, it is demonstrate that the previously determined Einstein oscillator modes correlate to Grüneisen parameters determined for a range of mixed-tacticity polyhydroxybutyrates.