Small-angle x-ray scattering study of density fluctuation in pressure-densified polystyrene glasses

✍ Scribed by Curro, J. J. ;Roe, Ryong-Joon

• Publisher: Wiley (John Wiley & Sons)
• Year: 1983
• Tongue: English
• Weight: 735 KB
• Volume: 21
• Category: Article
• ISSN: 0098-1273
• DOI: 10.1002/pol.1983.180210914

✦ Synopsis

Abstract

Densified polystyrene glasses, prepared by cooling from the liquid state under elevated pressure, were studied by small‐angle x‐ray scattering at ambient pressure. The density fluctuation, determined from the x‐ray data, showed a decrease with increasing pressure up to about 1.5 kbar, and then leveled off to a fairly constant value. The reduction in the density fluctuation produced by the pressure is much greater than the associated decrease in the specific volume. The observed change in density fluctuation is consistent with the view that the density fluctuation in glassy polymers consists of dynamic and quasistatic components and that the first of these can be correlated with the compressibility of the glass. The present data on the density fluctuation, in conjunction with the available data on volume and enthalpy, can be interpreted to mean that in pressure‐densified glasses unfavorable chain configurations are trapped in local energy minima, and the strain energy thus stored can promote segmental motion leading to volume expansion at temperatures far below T~g~. Some preliminary evidence indicating the formation of microcavities in these pressure‐densified glasses is also presented.