Studies of properties and potential applications of some soluble salts of cellulose acetate phthalate. Part 1: rheological behavior and aging effect.

Rheological behaviour for solutions of the sodium, ammonium, and triethanolamie salts of cellulose acetate phthalate was studied. The comparative resistance to microbial growth and to changes in pH values exhibited by these solutions on storage was also investigated. The results indicated that the viscosities of these solutions were temperature and concentration dependent and that increasing the rate of shear produced only a slight increase of viscosity. Solutions of ammonium and the triethanolamine salts did not support any apparent microbial growth during storage at room temperature of three weeks, but the sodium salt appeared to suffer from microbial contamination. However, the use of a mixture of 0.15% methylparaben and 0.05% propylparaben prevented such contamination. The pH values of all the slat solutions studied appeared to decrease on storage.