Polypropylene (PP) mixtures (10 wt %) with AgJ, V203, AgNO3, phenolic red, and phenolphthalein underwent plastic deformation at a pressure of 1 GPa on an anvil-type high-pressure device. It has been established by the DSC method that the enthalpy of PP melting in mixtures with inorganic components increased to 310 and 1840 J/g, while the enthalpy of melting was 62 J g–1 in the initial PP. In the deformed mixture with AgNO3, melting was described by a superposition of six endothermic peaks. The enthalpy of PP crystallization from the melt in mixtures with ionic crystals (AgJ, AgNO3) attained 360 and 264 J/g, respectively. Thermograms of mixtures with phenolic red and phenolphthalein showed superpositions of endothermic melting peaks of small polymer crystallites and exothermic peaks of cold crystallization. The enthalpies of endothermic processes in the deformed mixtures with phenolic red and phenolphthalein were identical. In these mixtures, the enthalpies of PP crystallization from the melt were identical to those of cold crystallization.