Some properties of water‐soluble hydroxyalkyl celluloses and their derivatives

The effect of increasing the substitution of water‐soluble hydroxyethyl cellulose (HEC) and hydroxypropyl cellulose (HPC) is to decrease their affinities for water. This is consistent with data given on the cloud point, salt tolerance, surface tension of aqueous solutions, and solubility in organic solvents, all as functions of MS. Ionizable substances have a great influence on temperature‐solubility behavior of the hydroxyalkyl celluloses. If the ions are present as inorganic salts in solution, they cause hydration of the polymer to decrease with some loss in solubility. In the case of HPC, ions derived from substituent groups, present in small amounts, improve hot water solubility and impart unusual viscosity‐temperature behavior. Mechanical properties of HEC film and thermoplasticity of HPC are functions of the extent of substitution rather than the hydrophilicity.