Abstract
Gel permeation chromatography (GPC), nuclear magnetic resonance (NMR) spectroscopy, and elemental analysis techniques were used to study the molecular characteristics of six commercially available styrene-butadiene-styrene (SBS) block copolymers which are mostly used for modifying bitumen. The cis-1,4, trans-1,4, and 1,2-vinyl units in the polybutadiene (PB) parts and the styrene contents of the SBS block copolymers were investigated by means of 1H-NMR spectra. In addition carbon and hydrogen contents were estimated using 1H-NMR measurements. These estimated values were confirmed using the results of elemental analysis (EA). The glass transition temperatures (Tg) of SBS block copolymers were obtained using differential scanning calorimetry (DSC). The SBS block copolymers used in this study have different structural properties such as molecular weight and linearity. However, it is observed that the Tg-onset values are directly proportional to the percentage of the 1,2-vinyl units and inversely proportional to the percentage of the trans-1,4 units in the SBS block copolymers.
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