Physicochemical Transformations of a Phenol Type Antioxidant during the Multiple Phase Transitions of Stabilized Polyethylene

This paper presents the results of Fourier transform infrared (FTIR) spectroscopic studies on the physicochemical and structural transformations of Irganox 1010, a phenol-type antioxidant, in the composition of polyethylene films during the solid ↔ melt phase transitions of the polymer. The intermittent oxidation regime consisted of cycles, each of which incorporated three testing stages, namely, the heating of the sample to a melted state, its isothermal treatment at 150°C, and the reverse transition of the polymer melt into a solid state. The FTIR spectra were recorded in situ, i.e., without removing the sample from the thermo attachment. The polymer was subjected to additional sorption saturation with antioxidant during every cycle of thermal treatment in melt with the simultaneous partial expenditure of its hydroxyl groups. The crystallization of the polymer composite was accompanied by antioxidant desorption: the partially damaged antioxidant was removed from the polymer, and therefore, the quality of the antioxidant that remained sorbed was slightly improved. The detected changes in the structure and physicochemical behavior of antioxidant were produced by the specific features of transformations in the supramolecular structure of the polymer.