Sorption Properties of Recycled Polyethylenes and Their Thermal Behavior in the Mixture with Oil

Sorption properties of recycled polyethylenes and thermal behavior of mixtures of recycled polyethylenes of different types (low- and high-density polyethylene) with a mineral oil, used as simplified model of bitumen, have been investigated by means of calorimetry, viscometry, IR spectroscopy, and gravimetry. The effects of type and structure of the recycled polyethylene on its sorption properties as well as thermal and rheological behavior of the oil–recycled polyethylene mixtures have been elucidated. It has been found that sorption properties of recycled polyethylene in the mixture with oil are determined by the content of the amorphous phase in the polymer, and the ability of the crystalline phase to restore its structure in the mixture is related to the polymer branching. The strongest polymer network has been formed in the mixtures of oil with linear low-density polyethylene, which has revealed the strongest sorption capacity towards hydrocarbons among the considered types of recycled polyethylene and has not been completely amorphized upon the oil sorption.