Open AccessPhysical Ageing of Polystyrene: Does Tacticity Play a Role?
Author(s) -
Kalouda Grigoriadi,
Jeroen B. H. M. Westrik,
Georgios G. Vogiatzis,
van Lca Lambèrt Breemen,
Patrick D. Anderson,
Markus Hütter
Publication year - 2019
Publication title -
macromolecules
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.994
H-Index - 313
eISSN - 1520-5835
pISSN - 0024-9297
DOI - 10.1021/acs.macromol.9b01042
Subject(s) - ageing , enthalpy , tacticity , polystyrene , differential scanning calorimetry , kinetics , materials science , thermodynamics , glass transition , amorphous solid , chemistry , composite material , polymer , crystallography , polymerization , genetics , physics , quantum mechanics , biology
The ageing kinetics of amorphous atactic (a-PS), isotactic (i-PS), and syndiotactic (s-PS) polystyrene were studied by means of flash-differential scanning calorimetry. The specimens were aged for up to 2 h at six different ageing temperatures: the optimum ageing temperature, that is, the temperature at which the enthalpy overshoot at the glass transition is maximal for the given elapsed time, and five ageing temperatures ranging from 20 to 80 K below the optimum ageing temperature. A logarithmic increase of the enthalpy overshoot with ageing time is observed for specimens at their optimum ageing temperatures. For temperatures significantly lower than the optimum, there is a range where the enthalpy overshoot is constant, but for higher temperatures (still below the optimum), a logarithmic increase is also observed. Moreover, the ageing kinetics appear to depend on tacticity, with s-PS and i-PS exhibiting the slowest and fastest ageing kinetics, respectively, and a-PS exhibiting ageing kinetics between these two extremes.
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