Process rheo-kinetics of the bitumen modification by isocyanate-based reactive prepolymers
Advancing the chemical engineering fundamentals
Rheology (T2-4P)
Keywords: Rehology, bitumen, polymer, processing, isocyanate, MDI
The final mechanical properties of polymer-modified bitumens are strongly affected by a suitable selection of the processing conditions, because, in most cases, bitumen and polymer are just compatible to a certain extent. It is necessary to establish optimum processing conditions, involving temperature and operation time, in order to get the desirable properties. The mixing process can be followed by measuring the viscosity of the blend as a function of time. Once the values of viscosity become constant, the mixing process is considered to be finished. Knowledge on the process kinetics of polymer-bitumen blends is of great interest since it provides information on the behaviour of the binder in different stages of the mixing operation. In addition, the mixing process gives rise to significant changes in the microstructure of the blend, which can be detected by following the variation of the rheological parameters along time.
The main objective of the present work was to study the mixing process of bitumen and reactive isocyanate-based prepolymers. Measurements of the evolution of viscosity with time, at different temperatures, were carried out with the experimental device known as “rheomixer”. Microstructure and rheological behaviour of the blend during processing and curing have been followed by Atomic Force Microscopy (AFM), MDSC measurements and viscous flow and oscillatory tests. The experimental results showed that the addition of a small quantity of this reactive polymer leads to enhanced rheological properties mainly at high in-service temperature (50ºC). However, processing temperature seems to be the main parameter to be controlled, which affects both mixing process and polymer modification ability.
Presented Thursday 20, 13:30 to 14:40, in session Rheology (T2-4P).
