Interdiffusion and phase equilibrium in systems based on cellulose nitrates and low-volatile solvents

Abstract

Phase equilibrium and interdiffusion in systems based on cellulose nitrates with different contents of nitrogen and several organic solvents, such as ethyl carbitol, dimethyl carbonate, and diethyl carbonate, have been studied. Cellulose nitrate containing 12.2 wt % nitrogen forms homogeneous systems with all studied solvents over the entire composition range. Systems based on cellulose nitrate with a high content of nitrogen (13.2 wt %) possess limited compatibility with the solvents. Phase diagrams constructed for these systems testify to the fact that the region of homogeneous solutions widens with a decrease in temperature. For the system composed of cellulose nitrate containing 13.2 wt % nitrogen and ethyl carbitol, the lower critical mixing temperature is −10°C. The presence of water in ethyl carbitol causes widening of the region of unstable solutions and leads to a reduction in the lower critical mixing temperature.