engleski

Dynamic mechanical properties of polymer modified bitumens

The purpose of polymer modified bitumen and asphalt is to achieve desired engineering properties such as increase modules and reduce plastic flow at higher temperature and / or increase resistance to termal fracture at low temperature. For the application of bitumen in road service the rheological properties are very important. As modificator of bitumen rheological properties polymers are used. In the preparation of polymer bitumen and in the service conditions the temperature affects on polymer bitumen properties. In the first part of examinations the rheological properties of bitumens modified by styrene-butadiene-styrene block copolymer, SBS are investigated by mean dynamic mechanical analyser at the traffic frequency, 5 Hz. The curves of primary viscoelastic functions, storage modulus, E', loss modulus, E" and loss tangent , tg δ vs temperature of polymer bitumens differ from unmodified and indicate the presence of the swollen polybutadiene and poystyrene phases in bitumen phase. The curves E' vs temperature of polymer bitumens show the rubbery plateau. The dynamic mechanical measurements are discussed in terms of morphological characteristic of polymer bitumen, phase number, phase composition and phase content. In the second part of examinations the polymer bitumens are aged by mean of Rolling Thin Film Oven Test, RTFOT, at temperature 163 °C. The oxidative degradation of polymer bitumens are followed by IR spectras. The primary viscoelastic functions as well as IR spectras were determinated before and after ageing. After ageing the curves of primary viscoelastic functions vs temperature change and on the base of the changes in relaxation spectras and in IR spectras the thermooxidative stability of polymer bitumens are evaluated. The changes of aged polymer bitumens dependent on a combine effect of SBS and bitumen oxidation. On the base of the results obtained the correlation between intensity of ageing processes changes of examined properties and SBS content is discussed.

polymer bitumen; SBS copolymer; dynamic mechanical propereties; ageing; thermooxidative ageing.

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