TEMPERATURE-DEPENDENCE OF MOLECULAR MOTIONS IN BULK POLYSTYRENE

被引:18
作者
BLACKBURN, FR [1 ]
CICERONE, MT [1 ]
EDIGER, MD [1 ]
机构
[1] UNIV WISCONSIN,DEPT CHEM,MADISON,WI 53706
关键词
TIME-RESOLVED OPTICAL SPECTROSCOPY; PROBE ROTATION; PROBE TRANSLATION; LABELED-CHAIN DYNAMICS; SEGMENTAL DYNAMICS; VISCOSITY;
D O I
10.1002/polb.1994.090321605
中图分类号
O63 [高分子化学(高聚物)];
学科分类号
070305 ; 080501 ; 081704 ;
摘要
Time-resolved optical spectroscopy is used to investigate the reorientation of three rigid probes and one labeled chain in bulk polystyrene. Orientational correlation times for these probes and labels are found to be in the range of 10(-8)-10(-10) s at temperatures of 180-300 degrees C. Consistent with previous studies, the attachment of a chromophore into the chain backbone slows its dynamics by about an order of magnitude. The temperature dependences of the correlation times are similar to the temperature dependence of the viscosity. When combined with probe reorientation times near and below T-g, these results indicate that probe reorientation tracks the temperature dependence of the viscosity quite well over twelve decades in time. In contrast, literature results for the translational diffusion of similarly sized probes indicates a substantially weaker temperature dependence near T-g. Thus it appears that a fundamental change in the mechanism of probe motion occurs near T-g. (C) 1994 John Wiley and Sons, Inc.
引用
收藏
页码:2595 / 2604
页数:10
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