Optical constants of polyacrylamide solution in the infrared between 20 and 70 °C

The optical properties of polyacrylamide(PAM) solution play an important role in measuring PAM concentration of the solution in the polymer flooding of oilfield based on optical methods. Transmittance spectra of optical cell filled with PAM solution in the infrared wavenumber range from 400 to 4000 cm−1 at normal incidence were measured at the temperature range of 20-70 °C by an infrared spectrometer IRTracer-100. Then the optical constants of PAM solution were calculated by the transmission method combined with Kramers-Kronig(K-K) relation. The results show that the absorption index of PAM solution decreases with solution temperature increasing, and the values of absorption index of PAM solution are in the range of 1.56E-3-5.83E-3. The refractive index of PAM solution increases with the increase of temperature, and the values of refractive index of PAM solution are in the range of 1.32-1.38.