The known theories and models of dispersing mixing of polymeric compositions are unsatisfactory: the Theylor model is inadequate to real processes, while the Rayleigh — Theylor — Tomotika model get no information on mixing formula and technological properties affected the dynamics of the process. In 1976, N.Tokita proposed a model based on the following concept: two competitive processes (the fracture and adhesion of disperse particles) run simultaneously. However, the Tokita model is the model of general type and its practical implementation is difficult. Using previous publications, we propose a model of dynamics of the process of disintegration. This model based on the law of energy conservation and the law of volume conservation for the dispersed phase. Energy consumption due to the disintegration is assumed equal to the strain energy plus the energy expended for generation of a new surface. The process of adhesion is described by a relationship that takes into consideration the character of motion (plane-parallel motion or chaotic motion) of liquid melt. The model of chaotic motion of liquid melt is preferable for description of size of particles of the disperse phase. The model proposed may be useful for description of the dynamics of disintegration when mixing formulas and technological parameters as well as design factors of installations are taken into consideration. Dimensions of disperse particles may be calculated by this model.