PRODUCTION OF STABLE POLYPROPYLENE-MODIFIED BITUMENS

The use of polypropylene polymers and copolymers as modifiers for road bitumens appears promising. The problem of stability during storage f or long periods at high temperatures can be solved by adding phosphoru s compounds, especially polyphosphoric acid, which changes the bitumen structure from sol to gel. It is demonstrated that the stability of p olymer-modified bitumens depends not only on the difference in density and viscosity between bitumen and polymer but also on bitumen structu re. Copyright (C) 1996 Elsevier Science Ltd.