Calorimetric Study of Mixtures of Polypropylene with 90 wt % Low-Molecular Organic Compounds after Plastic Deformation at a High Pressure

Abstract

Mixtures of polypropylene (10 wt %) with anthracene, phthalocyanine, indigo, adamantane, congo red, spiropyran, safranin, methyl orange, bromocresol purple, phenolphthalein, fluorescein, phenol red, thymol blue, aspartic acid, cyanuric acid, thymolphthalein, and rhodamine were subjected to plastic deformation at a pressure of 1 GPa on an anvil-type high-pressure apparatus. It was found by DSC that the thermograms of heating of the deformed mixtures in the temperature range below Tm of the polymer contain endothermic peaks of melting of small polymer crystallites with enthalpies reaching 220–240 J/g in some samples, as well as exothermic peaks of cold crystallization with enthalpies reaching 430–470 J/g. The melting was described by bi- and trimodal peaks, whose total enthalpy reached 2200–2400 J/g in some mixtures. The polymer crystallization in the deformed mixtures was described by single exothermic peaks, whose enthalpies differed little from the crystallization enthalpy of the starting polypropylene. An increase in the enthalpies of thermal processes in the deformed mixtures was attributed to the appearance of double electric layers at interfaces between the mixed phases.