VISCOSITY STUDIES ON ETHYLENE-PROPYLENE COPOLYMERS IN OILS

Viscosity studies on solutions of ethylene-propylene copolymers with 58 to 80 mol % ethylene in mineral and synthetic oils revealed that copolymers with 80% ethylene and slight crystallinity could give lower viscosities than expected on the basis of their molecular weights. This was true for intrinsic viscosities and shear viscosities of solutions of 1.0% copolymer. All copolymer solutions were lower in viscosity at about - 10-degrees-C or below than those of copolymers with 60-70% ethylene and no crystallinity. In the synthetic base stock, polydecene- 1, their viscosities were also lower than expected at room temperature and above. It is believed that this is due to structural domains involving the longer ethylene sequences of the copolymer chains with 80% ethylene.