The polymers that are likely to be added to the bitumen 105/35 production are most often elastomers such as polyisoprene, butyl rubber, polybutene, polyisobutene, ethylene vinyl acetate copolymers, polymethacrylates, polychloroprene, ethylene propylene copolymers, ethylene propylene diene terpolymers (EPDM), polynorbornene or alternatively random or block copolymers of styrene and of a conjugated diene.
Among the polymers added to the bitumen, the random or block copolymers of styrene and of conjugated diene and alternatively of styrene and of butadiene are particularly efficient as they dissolve easily in the bitumen 105/35 and provide them with excellent mechanical and dynamic properties and namely very good viscoelasticity properties.
We also know that the stability of bitumen polymer compositions in which the polymer added to the bitumen is an elastomer, namely a copolymer of styrene and of conjugated diene such as butadiene, can be improved by reactions, done in situ, of chemical coupling of the polymer with the bitumen, using a sulfur donor coupling agent (FR-A-2376188, FR-A-2429241, FR-A-2528439 and EP-A-360656), or of functionalization of the polymer using a functionalization agent of the acid or carboxylic ester type with thiol or disulfide groups (WO-A-9714754) or of the thiolcarboxylic acid polyester type (WO-A-9847967).
We have now found that we can still improve some mechanical and rheological properties, namely consistency and tensile mechanical properties, and reduce the susceptibility to temperature of bitumen/polymer compositions, called cross-linked and/or functionalized bitumen/polymer compositions, obtained from the reaction of the chemical coupling of the polymer and the bitumen and/or of the functionalization of the polymer, when the bitumen used in the preparation of the cross-linked and/or functionalized bitumen/polymer composition contained an appropriate quantity of oxidized bitumen.
