The Polychloroprene Crystallisation

As it is known [3, 33], crystallisation process kinetics can be described with the aid of the Kolmogorov-Avrami equation  

For oriented polymers it is shown that the value of n depends also on the drawing ratio [18,27]. Reduction in n with growth in A, is a general tendency. A considerable number of factors influencing the value of n makes its description within the frameworks of structnral and molecular models difficult. Therefore the authors of papers [34-36] generalised the influence of the indicated factors on the value of n with the application of fractal analysis methods in the example of uniaxially stretched PCP. Molecular characteristics of PCP crosslinked networks are adduced in Table 4.2. 

As it was shown earlier [11, 15], the fractal dimension of a chain part between chemical crosslinking nodes is characteristic of its molecular mobility and changes within strictly appointed limits 1 2. A number of methods for the estimation 

As is shown in papers [13, 18, 28], the transition from crystallisation with folding of chains to crystallisation with straightening of chains occurs at some critical value of P. As was shown above, the parameters P and are connected by Relationship 4.16. Combination of Equations 4.6 and 4.16 gives the following relationship [34]  

The data of Table 4.3 show that at different crosslinking degrees the values of P or can be different essentially even for the same polymen The existing modes of estimation of the critical parameters of P and do not allow their interconnection with structural characteristics and crystallisation conditions of polymers to be elucidated. Therefore in paper [38] theoretical estimation methods of critical parameters as a function of the characteristics of a non-stretched polymer were proposed and the physical essence of the parameters controlling critical values P and X was elucidated. This method is based on the fractal model stated above [34-36]. 

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