Structure and Mechanical Properties of Triblock Copolymer Poly[styrene-block- (ethylene-co-propylene) -block-styrene] and Asphalt Mixture

Shingo KAMIYAMA*, Shigeru TASAKA† and Daisuke HOTTA††

Graduate School of Science and Engineering, Shizuoka University; 3-5-1, Johoku, Hamamatsu-shi 432-8561 Japan
† Faculty and Engineering, Shizuoka University; 3-5-1, Johoku, Hamamatsu-shi 432-8561 Japan
†† Shizuoka Rekisei Kogyo Co., LTD.; 810 Takashinden Oigawa-cho, Shida-gun, Shizuoka 421-0204 Japan

Structure and mechanical properties of the mixtures of asphalt and the triblock copolymer poly[styrene-block- (ethylene-co-propylene) -block-styrene] (SEPS) were studied by differential scanning calorimetry (DSC) , needle penetration and softening point, and tensile strength measurements. From the measurements of glass transition temperature in the mixture of asphalt components and SEPS, maltene, the soluble fraction extracted from the asphalt in heptane, was partially miscible with the ethylene/propylene block of SEPS, whereas asphaltene, the insoluble fraction in heptane, partially miscible with the polystyrene block. The mixture of asphalt and SEPS was a partially miscible system. The viscosity, needle penetration and tensile strength of the mixtures may be improved in the low concentration of SEPS (e.g. 5--10 wt%) . A microstructure model of SEPS-asphalt blend system with the lower amount of SEPS was proposed and efficaciously approached to explain the resulting phenomena. The small amount of SEPS in asphalt seem to act as a compatibilizer and emulsify the two components of asphalt to make a mechanically stable network.


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