Similar results were observed with the other SBEBS samples.
The FTIR spectra of the [CS.sub.2] solutions of SBS (or SBEBS) clearly exhibited the characteristic signals of the 1,2-vinyl (910 [cm.sup.-1]) and 1,4-trans (965 [cm.sup.-1]) segments of polybutadiene, in contrast to that of the 1,4-n's-butadiene (730 [cm.sup.-1]), which was not well distinguished.
In contrast, the characteristic signals of styrene (756 and 698 [cm.sup.-1]) of both samples were unchanged, verifying that the Ti/Li catalytic system selectively saturated the polybutadiene block; similar results were observed for the other SBEBS polymers.
Data from the FTIR spectra of both the SBS and resultant SBEBS polymers were used together with Eq.
Table 3 summarizes the determined [S.sub.vy] and [S.sub.tr] of the SBEBS copolymers, as calculated from the FTIR spectra.
Samples of SBS and SBEBS were analyzed by GPC to determine the effect of the hydrogenation process on the molecular weight of the polymer; potential changes in the hydrodynamic volume of the SBS to the SBEBS were not considered.
Characteristics of the poly(styrene-b[[(butadiene).sub.1-x] -[(ethylene-co-butylene).sub.x]]-b-styrene) SBEBS used to prepare the polymer-modified asphalts.
Samples of P-MA with 3 and 10 wt% of SBS or SBEBS were produced through high-temperature mixing process, using a stainless steel tank equipped with a thermal jacket and high shear rate stirrer (IKA, Yellow Line OST 20); nitrogen atmosphere blanket was used to minimize polymer degradation.
1 and 2 and Table 2, P-MAs with 3 wt% of either SBS or SBEBS (Fig.
The asphalt was blended (hot-mixing process) with different amounts (3 and 10 wt%) of either SBS or SBEBS. These polymers are similar to each other in terms of their styrene content, and chain architecture, but in their overall molecular weight, blocks size, and isomeric composition of the elas-tomeric-b (Table 1).
To explain the fact that SBS-MAs and SBEBS-MA (with either 3 wt% or 10 wt% of polymer) exhibited somehow similar morphology yet the AP-PRP of SBS-MA was smaller than that of the corresponding SBEBS-MA (Table 2), it was considered that both SBS and SBEBS were able to interact with the asphalt components allowing the formation of a biphasic morphological structure with a polymer-rich phase and an asphalt-rich phase coexisting in metastable equilibrium, although these two types of polymers have different solubility and compatibility with asphalt.
Figures 3 and 4 show the storage modulus G'([omega]) and phase angle [delta]([omega])) master curves of neat asphalt NA and P-MAs prepared with 3 and 10 wt% of SBS or SBEBS, respectively.