Estimation of free volume in polystyrene-polyphenylene ether blend probed by the positron annihilation lifetime technique

摘要

Variations of size, content and size distribution of free volumes in linear polystyrenes (PS) synthesized by radical processes, with the addition of miscible polyphenylene ether (PPE) in PS, were observed by positron annihilation lifetime measurements. The average free volume radius of polystyrene was proved to increase from 0.30 nm (PPE: 0%) to 0.34 nm (PPE: 100%) and the average intensity, relevant to free volume content, decreased with the increase of PPE. The size distributions of free volume of various PS to PPE ratios also reveal that average free volume size increases and that smaller free volumes decrease by the increase of PPE ratio. The evidence that the size distribution curve of PS and PPE mixture (1:1) is more similar to that of PS suggest that free volumes produced in PS are stable with the addition of PPE and that more positroniums annihilate in smaller free volumes generated in PS than in bigger ones formed by PPE, since numbers of free volume overwhelm those of PPE.