Blends of bitumen with polar polymers

Blends of a Venezuelan 100 penetration grade bitumen have been made in a Z- blade masticator mixer with four common polar polymers - poly(vinyl chlorid e), poly(ethylene terephthalate), Nylon 11, and a thermoplastic polyurethan e - at levels ranging from 10 to 40 pph (i.e. 9 to 29 wt-%). They were char acterised by fluorescence optical microscopy, differential scanning calorim etry, and dynamic mechanical thermal analysis. All blends were stiffer than the bitumen by at least a factor of 50 at temperatures below the glass tra nsition, which was lowered by the presence of the polymer. Loss processes w ere detected at about 40 to 60 degreesC 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 flowe d readily at temperatures between 70 and 120 degreesC.