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Asphalt binders are complex mixtures of a wide variety of hydrocarbon materials. Added to this complexity in recent years has been modification with a variety of polymer modifiers. Binders used in this study were commercial materials obtained directly from the suppliers. They include diblock poly (styrene-b-butadiene) rubber (SBR), triblock poly (styrene-b-butadiene-b-styrene) (SBS), and high-cure ground tire rubber. A study of the effect of these modifiers on oxidative aging and on changes in physical properties due to aging shows several effects. Modifiers can reduce oxidative aging rates to some degree, but a bigger effect tends to be to reduce the hardening of binders that occurs in response to oxidative aging. This reduction in hardening rate is expected to have a positive effect on pavement performance over time, relative to the performance of base asphalts. Furthermore, the effectiveness of modifiers varies with the base asphalt.

A thermoplastic polyolefin (TPO) containing 70 wt % styrene-ethylene-butadiene-styrene-g-maleic anhydride and 30 wt % polypropylene and its nanocomposites reinforced with 0.3-1.5 wt % organoclay were prepared by melt mixing followed by injection molding. The mechanical and fracture behaviors of the TPO/clay nanocomposites were investigated. The essential work of fracture (EWF) approach was used to evaluate the tensile fracture behavior of the nanocomposites toughened with elastomer. Tensile tests showed that the stiffness and tensile strength of TPO was enhanced by the addition of low loading levels of organically modified montmorillonite. EWF measurements revealed that the fracture toughness of the TPO/clay nanocomposites increased with increasing clay content. The organoclay toughened the TPO matrix of the nanocomposites effectively.

The solubility of methyl anthranilate in supercritical carbon dioxide was determined using dynamic and static equilibrium systems. Three temperatures (40, 60 and 80 • C) and a pressure range between 160 and 340 atm were applied for the dynamic solubility measurements. The flow rate was maintained at 0.5 mL min −1 in the dynamic solubility measurements, where the solute solubility was claimed to be independent of the flow-rate factor. Two temperatures (40 and 60 • C) and the pressure range between 100 and 265 atm were used in the static equilibrium system. The crossover pressure region was observed between 220 and 240 atm in the static system, but was not seen in the dynamic system. The solubility of methyl anthranilate determined by the static system was consistently higher than the dynamic solubility measurement, indicating that the static technique provided more reliable solubility data for methyl anthranilate than the dynamic technique. The solubility data obtained with the static system were in good agreement with the predictive models based on the Chrastil equation and the Peng-Robinson equation of state with the Panagiotopoulos and Reid mixing rule.