Termodynamika deformacji krystalitów polimeru zanurzonych w naprężonym ośrodku amorficznym

The system of small crystals embedded in the deformed amorphous matrix is considered. The amorphous part of the system is treated as a homogeneous continuum with uniform field of stress controlled by the affine deformation of polymer chains. The stress tensor in the amorphous matrix is presented as the series expansion over. This form of the stress tensor results from the deformation theory of the isolated chain macromolecule. It has been assumed that crystalline inclusions are small as compared with the macroscopic dimensions of the considered system, and their number in a unit volume is small. On the other hand, these small inclusions are much larger than the kinetic elements of the amorphous phase (statistical chain segments). The stress resulting from the deformation of the amorphous matrix affects the crystalline inclusions. Deformation of the inclusions is much smaller than the deformation of the amorphous part. Free energy of deformation of crystalline inclusions subjected to the uniform stress field on its surface has been calculated as a function of the orientation of crystal axes with respect to the main axes of the stress tensor. The orientation – dependent free energy has been subsequently averaged over the orientation distribution of crystal axes. Example calculations concerned polyethylene.