engleski

The rheological properties of aged polymer bitumen

The stability of materials in processing and in use is one of their the most important properties. The knowledge of the chemical and physical processes in ageing as well as their correlation with the ageing conditions and the compositions of the material has the main role in quality of the product. For modification of the rheological properties of bitumen polymers are used. One of the wide use polymer is thermoplastic elastomer styrene-butadiene-styrene, SBS, block copolymer. The susceptibility of SBS block copolymer to oxidative degradation influences on the polymer bitumen stability. From this reason it is very important to determine the intensity of thermooxidative degradation of SBS block copolymer, bitumen, BIT, and BIT/SBS blends under the conditions of artificial ageing. In the first part of examinations the thermooxidative degradation of the SBS was followed by differential scanning calorimetric, DSC. On the base of the isothermal heat of the thermooxidative degradation the conversion (a) the rate profile of thermooxidative degradation da/dt-t, the reaction rate, orders of the reaction and activation energy were obtained. In the second part of examinations the accelerate artificial thermooxidative ageing of BIT/SBS blends were performed with Rolling Thin Film Oven Test, RTFOT, at temperature 163oC. The ageing was followed through the changes of dynamic mechanical properties by Dynamic Mechanical Analyzer, DMA. On the base of the primary viscoelastic functions, storage and loss modulus as well as creep modulus the changes of the properties and thermooxidative stability of polymer bitumen was obtained. The oxidative degradations of SBS block copolymer and BIT/SBS blends were followed by IR spectras. On the base of the results obtained the correlation between intensity of ageing processes, the changes of examined properties and SBS content was discussed.

bitumen, polymer bitumen, ageing, thermooxidative degradation, kinetic, rheological properties

Glavni autor: Vesna Rek