ISSN:
0323-7648
Schlagwort(e):
Chemistry
;
Polymer and Materials Science
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
,
Physik
Notizen:
Static and dynamic light scattering measurements were performed on a glass-forming polymer, poly(methyl-p-tolylsiloxane) (PMpTS; Tg=-17°C), in a temperature range of 30°C to 120°C. It was found that long-range density fluctuations, so-called clusters, are observed in this polymer. They are characterized by “excess” angular-dependent isotropic scattered intensity and additional slow decay in the photon correlation function. These properties are generally observed in low molecular weight glass formers as well as in glass-forming polymers. In addition, we found that the clusters completely disappear above about 90°C. The kinetics of the cluster growth was also studied by temperature jump experiments. During the cluster formation process after the temperature jump, we measured the angular-dependent polarized scattered intensities, and the photon correlation function as a function of annealing time. We discuss the cluster growth kinetics based on these results, especially the time evolution of the correlation length ξOZ evaluated using the Ornstein-Zernike formula, the isotropic scattering intensity IOZ(0) at q=0, and the correlation time τcl of the cluster decay. Finally, we briefly discuss some properties of the equilibrated clusters, which are well reproducible.
Zusätzliches Material:
11 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/actp.1994.010450302
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