ABSTRACT
Figure 1.1. Schematic representation of folded-chain (a) and extended-chain (b) local order regions [9]. The cluster consists of segments of different macromolecules, and the length of each segment length, lsh (of the “rigidity section” of chain [1 1 ]). In this case the effective (real) molecular weight of the chain part between
clusters M f f , can be calculated as follows [10]: (1.4)
where Md is the molecular weight of the chain part between clusters, calculated according to the equation ( 1 .2 ).It’s obvious that, at large enough values of F one can obtain reasonable values of M ff satisfying requirements of the Gaussian statistics. Further on, for the purpose of distinguishing parameters of the cluster entanglement network and macromolecular hooking network indices “c/” and “h” will be used, respectively. Thus, as assumed in the model suggested in the works [7-9], the structure of the polymer amorphous state represents regions consisting of collinear densely packed segments of different macromolecules (clusters), immersed in a loosely packed matrix. Simultane
ously, the clusters play the role of multifunctional nodes of physical entanglements. The value of F can be estimated (back again within the framework of the rubber elasticity concept) as follows [1 2 ]:
(1.5)
where G^ is the equilibrium shear modulus; k is the Boltzmann constant.Fig. 1.2 shows vc/(7) dependencies for polycarbonate based on the bisphenol A (PC) and polyarylate (PAr). These dependencies show \ d decrease with T rise that suggests thermofluctional origin of clusters (the local order regions). Besides, the mentioned dependencies display two characteristic temperatures.
