The Effects of Free and Bonded Sulfur both in the Presence and Absence of Vulcanization Accelerators on the Rheological, Technological, Aging, and Thermal Stability of Asphalts
Titel:
The Effects of Free and Bonded Sulfur both in the Presence and Absence of Vulcanization Accelerators on the Rheological, Technological, Aging, and Thermal Stability of Asphalts
Auteur:
Onabajo, Adekunle Kopsch, Heinz
Verschenen in:
Energy sources. Part A, Recovery utilization and environmental effects
Paginering:
Jaargang 9 (1987) nr. 3 pagina's 189-202
Jaar:
1987
Inhoud:
Rheological and technological experiments have been carried out on sulfur-modified asphalts in the temperature range of 353 K to 453 K over a wide range of shear rates (0-4800 sec-1) The results indicated that the activation energy of the viscous flow increased with increasing amount of bonded sulfur The irreversible shear degradation observed in sulfur-modified asphalts is caused by the high shear forces which rupture the aggregated molecules Thermogravimetric analysis and aging experiments on asphalts and their sulfurized products, containing varying amounts of free sulfur (0-5.5 wt.-%) and vulcanization accelerators (0.5-2.5 wt.-%), have shown that mixes containing vulcanization accelerators have higher thermal stabilities and are more resistant to thermal and non-thermal aging than the unaccelerated asphalt-sulfur mixed prepared at the same or higher temperatures. The changes in the rheological and physical properties of the mixes with time is not only explained by the changes in the physical state of unreacted free sulfur, that is, from plastic to crystalline state (physical process), but also attributable to the effect of chemical reactions.
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