Properties of Cuprammonium Rayon
1. The one important characteristic of these fibres is their extreme fineness. Filaments as fine as 1.33 deniers are produced regularly ( as compared to viscose rayon which have a usual denier of around 2.5). This increased fineness is due to the stretch that is applied to the filaments during spinning.
2. Because of its fineness, cuprammonium rayons produce a soft silk like handle.
3. It has all the properties of cotton except that the average DP is lower and a larger portion of this fibre is occupied by amorphous regions. Hence the rayon swells to a greater extent and hence chemical reactions take place faster in the case of rayon than in case of cotton.
4. Like viscose rayon it burns rapidly and chars at 180 deg C. It is degraded and weakened by exposure to sunlight in the presence of oxygen and moisture. On ignition, it leaves behind ash containing copper.
5. The average tensile strength of cuprammonium rayon is 1.7-2.3 in dry and 0.9-2.5 in wet state.
6. It has an elongation at break of 10-17% when dry.
7. Moisture content at 70 deg F and 65% RH is about 11% as in case of Viscose Rayon.
8. Dye absorption power for direct dyes of cuprammonium rayon is greater and shades obtained are deeper than viscose rayon.
9. The filaments appear uniform with surfaces having no markings, in the longitudinal view. Cross sections are round and smooth with occasionally slightly oval.