| Popis: |
A preliminary investigation of the preparation and properties of cellulose nitrate-acetate mixed esters was conducted. These mixed esters can be prepared in a wide range of amounts of substitution of both acetate and nitrate groups either through acetylation of cellulose nitrate or nitration of cellulose acetate. The degree of polymerization of the products, as estimated from viscosity data, shows the occurrence of chain degradation for both procedures. The hygroscopicity of the cellulose nitrate-acetate esters was found to be a linear function of total substitution. Films prepared from these mixed esters showed tensile strength at least comparable to that of films of cellulose nitrate or cellulose acetate. The impact sensitivity of the mixed esters varied from 6 to 18 inches for a 2-kilogram weight depending on the substitution of nitrate groups. Under the conditions of the explosion temperature test, the mixed esters decomposed violently without igniting. However, the minimum decomposition temperature appears to be the same as for similarly substituted cellulose nitrate. |
