Can you recommend any natural alternatives for carboxymethyl cellulose ?
A part from carboxymethyl cellulose ( CMC ) there are a number of others likewise derived from cellulose, which can be used as water soluble, non-ionic thickeners. Their properties depend on a number of factors. The most important is molecular weight ( indicating the degree of polymerisation ), type of alkyl group used for esterification, and the degree of substitution taht has been achieved ( maximum value 3 ). Esterification usually takes place with methyl, ethyl, hydroxyethyl and / or hydroxypropyl groups.
There are quite distinct differences with regard to thickening effect, compability, purity and stability of such cellulose ethers, although generaly speaking these will meet the requirements as regards quality. Aqueos solutions of these compounds, like those of CMC, have a pH value of 7 although subsequent processing stages may require a slightly acid or slightly alkaline pH.
Certain application properties depend on the type and concentration of the ether groups, with which one can control such properties as solubility and compability with organic substances, heat resistance and resistance to enzyme attack to a considerable degree. When used in water based paints they help to stabilise viscosity under conditions of changing pH, impart shear resistance during application (e.g. by preventing splashing of emulsion paints ), improve flow and suppress the tendency to run.