Glass transition rheology methods

The macroscopic free-volume is an important parameter closely related to the rheological behavior of an amorphous material. It is generally accepted that the glass transition is regarded as an iso-free-volume state, and the free-volume fraction (fg) at the Tg is around 0.025 for many monomers and polymers. The WLF method has been widely used for determining the macroscopic fg value. On the other hand, the microscopic analysis of the free-volume has also been uti-... 

Indirect methods of miscibihty determination (e.g., from the glass transition temperature, viz., Tg from thermal, dielectric, or mechanical tests, NMR, spectroscopic methods, ODT through rheology, etc.)... 

Studies of the relationship of macroscopic properties to internal structure have been at the forefront of polymer science for many years. We are now in a position to use rheological studies as a method of elucidating internal stmcture and internal structural distortion mechanisms. This paper will use this approach to determine the characteristics of transitions above the glass transition temperature, Tg, in amorphous polymers with the objective of understanding the stmcture of these polymers and the mechanisms involved in the transitions. 

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