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Free volume changes in mechanically milled PS and PC studied by positron annihilation lifetime spectroscopy (PALS)
Author(s) -
GüntherSchade K.,
Castricum H. L.,
Ziegler H. J.,
Bakker H.,
Faupel F.
Publication year - 2004
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.20130
Subject(s) - materials science , polycarbonate , volume fraction , polystyrene , polymer , positron annihilation , volume (thermodynamics) , glass transition , brittleness , positron , spectroscopy , composite material , gel permeation chromatography , chain scission , polymer chemistry , chemical engineering , thermodynamics , nuclear physics , physics , quantum mechanics , electron , engineering
The effect of mechanical milling on free volume was studied by means of positron annihilation lifetime spectroscopy (PALS) in polystyrene (PS) as a typical brittle polymer and in polycarbonate (PC) as a tough representative. Long‐time milling increases the free volume, while a decrease is observed for short milling times. The changes are mostly irreversible in PS. The irreversible fraction is much smaller for PC. Gel permeation chromatography (GPC) measurements show a decrease of the molecular weight, which is much more pronounced in PS. The milling‐induced irreversible changes in free volume are attributed to chain‐end defects resulting from chain scission. In PC, other deformation‐induced defects that anneal upon heat treatment above the glass transition temperature dominate. Polym. Eng. Sci. 44:1351–1359, 2004. © 2004 Society of Plastics Engineers.