OP-II-3

PP-III-70Therefore, it was clarified thatASP RE RE ARO SATdecomposition of SBS occurredRaw 1788 953 884 1024during preparation of MT and SA 5 days 1914 964 834 99610 days 2258 1093 972 1192MH. The height ratio of SBS inRaw 1828 976 850 1020both MT and MH increased with MT 5 days 1963 1104 948 111210 daysthe increase of term of thermal2149 1098 961 1143Raw 1861 1064 938 1124degradation. The content ofMH 5 days 1861 1000 868 1024radicals (not shown in this 10 days 1872 1073 914 11110 2040 60 80 100abstract for lack of space) in MHYield (wt%)Values in the figure denote the average molecular weight of each constituent.was lower than those of SA andMT. Therefore, it is considered Fig. 1. Yields of four constituents before or afterthermal degradation of SA, MT and MH.that generation of radicals wassuppressed by addition of SBS. The contents in SA, MT and MH increased with theincrease of term of thermal degradation. However, the increased contents of radicalsof MT and MH were lower than that of SA, and the suppressive effect in MH with theincrease of term of thermal degradation was stronger than that in MT. Accordingly,with the increase of term of thermal degradation, it is considered that the contentdoes not increase significantly for MH with small content of radicals. It was reportedthat the asphalt constituents in MT and MH were swelled into SBS molecules due tothe incorporation of 9 hold weight of the asphalt constituents (RE, ARO) into the SBSmolecule [1]. Therefore, only a part of asphalt constituent was swelled by SBSmolecule in MT because SBS content in MT is only 5%. Accordingly, the asphaltconstituents outside the SBS molecules in MT formed a continuous phase of straightasphalt. On the other hand, most part of the asphalt constituents in MH was swelledinto the SBS molecules owing to the high content (9%) of SBS in MH. Therefore, theSBS molecules in MH formed a continuous phase of SBS. During thermaldegradation process of MH, it was estimated that the thermally stable SBS moleculesprotected the thermally unstable asphalt constituents in MH due to incorporation ofthe asphalt constituents into the SBS molecules. Therefore, the content of radicals inMH was lower than those of SA and MT. During thermal degradation process of MT,the content of radicals increased because the thermally unstable asphalt constituents(SAT, ARO) outside the SBS molecules decomposed. It was considered that theradicals formed from the thermally unstable asphalt constituents polymerized with theSBS molecules and other asphalt constituents. As a result, both decomposition of the570