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  • 1 Sumimoto Electric Industries Ltd. Analytical Characterization Center, R&D Group 1 Taya-cho, Sakae-ku 244 Yokohama (Japan)
  • 2 University of Tsukuba Institute of Materials Science 305 Tsukuba, Ibaraki (Japan)
  • 3 University of Tsukuba Radioisotope Center 305 Tsukuba, Ibaraki (Japan)
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The glass transition and relaxation processes in polystyrene resins with the number average molecular weight ranging from 7.0·102 to 9.8·104 were studied with the positron annihilation technique. The pick-off annihilation lifetime of ortho-positronium (3) and its intensity (I3) were measured in the temperature range from 20 to 430 K. The glass transition temperature (Tg) was determined as an onset temperature coefficient of 3.Tg shows the molecular weight dependence in these samples. BelowTg, local motions were detected by measurements ofI3. The local motions could be observed above 100 K in this experiment.I3 show the minimum at around 250 K and it does not show molecular weight dependence.