Factors controlling the local dynamics

It is of interest to define a reference state in which all the polymers are in equivalent states from the point of view of their local mobility. In order to define such equivalent states, one has to look for a property in relation to the frequency window of each experiment. For the CNMR relaxation experiments, the temperature, at which the spin-lattice relaxation 

The next step of this approach is to relate the reference temperatures to data obtained from viscoelastic experiments. Fractional free volumes fj are expressed as 

The free volumes Vf( at the reference temperatures can be derived from and Van Krevelen s data on amorphous polymers [22]. They represent the free volume per mole of repeat unit of the polymer divided by the number of main-chain atoms per repeat unit. Once more, the values differ from one polymer to another, which implies that other molecular parameters have to be considered. 

Such a result implies that, at these reference temperatures, the polymers share 

The detailed analysis of carbon-13 spin-lattice relaxation times of a number of polymers either in solution or in bulk at temperatures well above the glass-transition temperature has led to a general picture involving several types of motions. The segmental reorientation can be interpreted in terms of correlated conformational jumps which induce a damped orientation diffusion along the chain. It is satisfactorily described by the well-known autocorrelation functions derived from models of conformational jumps in polymer chains [4,5] which have proven to be very powerful in representing fluor- 

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