Glass-Rubber Transition Detected by the Spin Probe Method

5 Glass-Rubber Transition Detected by the Spin Probe Method 

The spin-probe method detects molecular motions of sohd polymers from ESR spectra of paramagnetic probes which are usually stable nitroxide radicals embedded in the polymer matrices. The spin-probe does not bond to the polymer chain and thus does not necessarily move with the polymer chain segment. Smaller probes only weakly interact with the chain and thus move independently with the chain 

packet (volume Vf). The figure is adapted from [14] with permission from Elsevier 

Of course, when the size of the spin probe is smaller than the segment size at Tg, and when the jumping mode occurs by the local motion of the segment, the ESR spectrum of the spin probe sometimes narrows at a temperature lower than Tg. When Tn and Tg are determined experimentally and the molecular size of the 

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