The intrinsic viscosity of polyacrylamide (PAM) can be measured by the solution viscosity method, usually using an Ostwald viscometer.
The determination steps are as follows:
Take a certain amount of PAM, add a certain amount of solvent (usually water or methanol), fully dissolve it and prepare solutions with different concentrations.
Inject the prepared PAM solution into the Ostwald viscometer, and record the time t between the two marked lines inside the viscometer, namely the flow time of the viscometer.
Use the same method to measure the flow time of pure solvents.
Calculate the relative viscosity ηrel or specific viscosity ηsp according to the standard formula, and calculate the intrinsic viscosity [η].
The formula is as follows:
ηrel = t/t0
ηsp = ηrel × ρ
[η] = (ηsp - 1)/c
Among them, t is the time for the PAM solution to flow between the two marked lines inside the viscometer, t0 is the flow time of the pure solvent, ρ is the density of the pure solvent, and c is the molar concentration of the PAM solution.
North and South Tide reminds you: It is necessary to maintain a constant temperature during the measurement process, and to take the average value of multiple measurements to improve the measurement accuracy. At the same time, there may be differences in the measurement conditions of different types of PAM solutions, which need to be adjusted according to the actual situation.
