Blends of bitumen with polar polymers

Abstract

Blends of a Venezuelan 100 penetration grade bitumen have been made in a Z-blade masticator mixer with four common polar polymers –poly(vinyl chloride), poly(ethylene terephthalate), Nylon 11, and a thermoplastic polyurethane – at levels ranging from 10 to 40 pph (i.e. 9 to 29 wt-%). They were characterised by fluorescence optical microscopy, differential scanning calorimetry, and dynamic mechanical thermal analysis. All blends were stiffer than the bitumen by at least a factor of 50 at temperatures below the glass transition, which was lowered by the presence of the polymer. Loss processes were detected at about 40 to 60°C in the poly(ethylene terephthalate) and Nylon 11 blends, in the latter case being clear when the concentration rose to 40 pph, as if a polymer rich phase was then extensive. The blends at high temperatures were much more viscous than the bitumen, but all flowed readily at temperatures between 70 and 120°C.