Free volume microstructure of amorphous polymers at glass transition temperatures from positron annihilation spectroscopy data |
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Authors: | J Dr Barto? |
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Institution: | (1) Polymer Institute, Slovak Academy of Sciences, Dúbravská Cesta 9, 842 36 Bratislava, Slovak Republic |
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Abstract: | The analysis of annihilation characteristics of ortho-positronium at conventional calorimetric glass transition temperatures for a series of amorphous polymers reveals empirical correlations of average lifetime of o-Ps
, and of its product with a relative intensityI
3g with appropriateT
g
DSC
values. These trends in terms of free volume mean that both the average size of free volume hole entityv
hg and the fractional free volume grow with increasingT
g
DSC
. The results are discussed considering the chemical microstructure as well as possible mechanisms acting in glass transition. A relation is indicated between geometric and flexibility characteristics of chains and thev
hg andf
g parameters of free volume microstructure on the one side and potential motional processes responsible for solidification of the amorphous system on the other side. |
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Keywords: | Free volume glass transition amorphous polymers positron annihilation |
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