Modern Polymer Spect..

196 3 IG!wtioiinl Specfrri us N Probe of Sfiw-tiird Order
tan,, t Hours)
Figure 3-60. 1 : 1 molar mixture
of n-CzJHqg and n-C.5HF2. Kinetics
of the process of diffusion
at four different temperatures.
Data from calorimetric
measurements
conformational deformations at chain ends; (iii) diffusion which generates the
interpenetration of chains; and (iv) the full collapse towards a liquid-like structure.
Conclusion no. 7
As a consequence of such longitudinal motion, if crystallites of n-alkanes are suitably
brought together thermally activated transport of matter can take place and
diffusion of molecules from one crystallite to another can occur. The kinetic of
diffusion is function of temperature, length of the chain, contacts between crystallites
(ie., pressure put on the sample), etc.
We can proceed further and try to understand the mechanism at the molecular
level which drives the chains outside their own lamella by a thermally activated
process.
We refer the reader to [ 1031, [ 1551 and [ 1451 for a first analysis of the various data.
We simply mention the line of thought followed by various authors on this rather
complex problem.
Several theoretical models have been proposed in an attempt to account for the