Partial hydrolyzed polyacrylamide(HPAM)and associating partial hydrolyzed polyacrylamide(AHPAM) were compared focusing on the structure and rheology relations

which play important roles in enhanced oil recovery.The molecular associating state in AHPAM aqueous solutions is studied in terms of molecular weight measured by intrinsic viscosity and static light scattering method

associate size and behaviors by the dynamic light scattering and viscosity method

as well as the rbeologlcal properties at various concentrations

temperature and salinity.The results on AHPAM aqueous solution reveal that the association exists in broad concentrations．It is suggested that the concept of crifical association concentration should be related to the range of semi-dilute to entangled region rather than the starting concentration of bydrophobic association．The change of the associating structure under shear was reflected in the shear viscosity which dropped down suddenly

when the shear rate was up to 10 s-1

but this phenomenon became less evident at highly entangled concentrations．In addition

the elongational viscosity of AHPAM in converging flow decreased with flow rate and also reflected the intrinsic feature of short range interaction of the association．The relevant influences of polymeric hydrophobic association on the enhanced oil recovery were discussed．