Local free volumes in boron‐bombarded Kapton polyimide: A positron lifetime study

Positron annihilation lifetime spectroscopy study of Kapton thin foils

“…This is in agreement with the early bulk PALS reports of a single lifetime value of 382 ps [16], and 382(3) ps [10], and with the most recent study giving 385(3) ps [13]. The measurements provide further evidence that previously reported two component fits result from an artefact of the fitting process [11,12,14]. The AMOC results require the existence of at least two positron states [14], but are complicated by in-flight annihilation and by the high (3.5 MeV) positron energy and hence the requirement for thick samples.…”

Is Kapton Really That Simple?

“…Therefore we first fitted Eq. (1) The results for the lifetimes τ 2 and τ 3 and their intensities are now in very good agreement with the ones found by Dlubek et al [7]. It is also clear now that S 2 is only slightly smaller than S 3 which could correspond to the 2 different O sites.…”

The local free volume in deformed polyethylene: a positron lifetime study

“…Yu et al [43] observed a perfect agreement of the free volume fraction estimated from Ps experiments for polystyrene in the temperature range T A T g with a theoretical one deduced from experimental P-V-T data. A clear correlation between the thermal expansion of the (Ps) hole volume and of the macroscopic volume above T g was also observed for PE [17]. From these experiments we conclude that Ps bubble formation does not play an important role in our experiments.…”

“…We have studied PE of varying crystallinity (40% to 70%, estimated from DSC measurements) and found a similar behavior in I 3 and I 4 . (iii) As recently shown [17], s 3 increases between 80 K and 300 K as expected from the thermal expansion of the PE crystal unit cell.…”