SEDL / STP / STP1108-EB / STP17837S

Thermo-Oxidative Degradation of Polymer Modified Bitumen

Linde, S
research engineers, The Swedish National Testing and Research Institute, Borås,

Johansson, U
research engineers, The Swedish National Testing and Research Institute, Borås,

Pages: 10    Published: Jan 1992

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Abstract

Mixtures of the styrene-butadiene-styrene (SBS) and styrene-ethylene-butene-styrene (SEBS) respectivly with different types of bituminous materials or oils have been investigated. We can here, with the aid of size exclusion chromotography (SEC), suggest that pronounced molecular size changes occur both in the bitumen and the polymer phase due to processing and ageing. The processing temperature was chosen to 200 °C (392 F) and the ageing temperature to 70 °C (158 F). The changes in molecular size are correlated to changes in mechanical properties. Compatibility conditions also seem to influence the degradation course. Prolonged exposure of the materials to 200 °C in inert, nitrogen, atmosphere has also been performed. No detectable difference in molecular weight could be found. The results give important implications for both processing handling and long term properties of modified bitumen.