Optical constants of polyacrylamide solution in infrared spectral region

Polyacrylamide (PAM) is a macromolecular polymer, and its solution is widely applied in oil exploitation, sewage treatment and paper making. Transmittance spectrum of PAM solution in the infrared wavelength region at normal incidence was investigated by an IRTracer-100 spectrometer, and the optical constants of PAM solution were obtained based on modelling transmittances combined with Kramers-Kronig (K-K) dispersion equation. The results show that the transmittance of PAM solution is higher than that of distilled water due to polyacrylamide. The transmission spectra shapes of PAM solution with different concentrations are similar in the wavelength range of 400-4000 cm−1, and it contains two strong absorption bands and two obvious peaks. The absorption index and refractive index of PAM solution all increased first and then decreased with the increase of concentration in the wavelength range of 2400-2800 cm−1. The absorption index and refractive index of PAM solution in the concentration range of 20-800 mg/L are 3.42 × 10−3-9.13 × 10−3and 1.22-1.43, respectively.