Impact of molecular structure of PP on thermo-rheological properties of polymer-modified bitumen

[Display omitted] •Using different types of PP to produce polymer modified bitumen.•Influences of PP type on thermomechanical behaviour of polymer modified bitumen.•Impact of PP type on formation of a polymer network in polymer modified bitumen. Polymers have been widely used to improve the performance of bitumen. Polypropylene (PP), one of the most common plastomer for bitumen modification, is utilized specially in roofing application adding up to 30 wt% to bitumen. This article presents an investigation of four different polypropylene (PP) polymers having differences in tacticity (atactic and isotactic), molecular weight (Mw ~ 12 000 g/mol and ~250 000 g/mol) and functional side groups (polar) producing modified bitumen with 5, 10 and 16 wt% polymer content, respectively. To investigate the polymers and the resulting polymer-modified bitumen (PMB) dynamical shear rheometer (DSR), dynamic scanning calorimetry (DSC) and fluorescence microscopy (FM) is performed. The aim of the study is to understand the dispersion of the polymer within the bitumen and its effect on the thermo-mechanical performance of PMB. Based on the obtained results molecular weight as well as functional side groups were identified as the key parameter affecting the dispersion behaviour of the polymer within the bitumen and, hence, the thermo-rheological properties of PMB.