Abstract
Unique information about the properties of free-volume sites in polymers is gained from positron annihilation lifetime spectroscopy (PALS). After calibration with the free-volume hole-fraction h PVT from pressure–volume–temperature and equation-of-state ( PVT–EOS) analysis using the Simha–Somcynsky theory, PALS data ( ortho-positronium ( o-Ps) lifetime τ 3 and o-Ps intensity I 3) may be used to calculate free-volume fractions h PALS from h PALS= C× V( τ 3)× I 3, where V( τ 3) is the subnanometer cavity hole-volume. The widespread use of this equation, in particular the correlation constant C, is given some attention, clarification and further improvement. From PVT data and PALS data, measured on chemically and physically identical amorphous poly(methyl methacrylate) samples, both below and above the glass transition temperature, we find improved relations: h B= B× V( τ 3) and h PVT= k 1+ k 2× V( τ 3), where B, k 1, and k 2 are correlation constants. We propose and show that the freezing fraction of polymer glasses can be calculated from the temperature coefficients of V( τ 3), which further supports its close relation to h PVT.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
