2.10. Intrinsic viscosity measurement

Dilute solutions of LPSG were prepared by adding a distinct amount of the solvents to the stock solution (0.125%, w/v). The intrinsic viscosity of all LPSG solutions were measured using an Ubbelohde capillary viscometer (Cannon Instruments Co.; viscometer constant, k = 0.007690 mm²s⁻²), immersed in a thermostatic water bath equipped with a precise temperature controller to maintain the selected temperatures (25, 35, 45, 55 and 65°C). The data reported for each dilute solution are the average of three replicates.

Based on the literature, various models have been used for calculation of intrinsic viscosity η, based on which the η could be obtained from their intercepts (Huggins (Equation [2]) and {Kraemer (Equation [3])} or slopes {Higiro (Equation [4])}:

which in these equations, ηsp is specific viscosity, ηrel is relative viscosity, and k′, k″ and C are, respectively, the Huggins constant, Kraemer constant and solute concentrations (g/dl).