Thermal and rheological characterization of cellulose spinning dopes modified with nanosilica and antibacterial agents

The present study concerns cellulose spinning solutions prepared with the use of the organic solvent N‐methylmorpholine‐N‐oxide (NMMO). These solutions were modified with two types of antibacterial agents: an inorganic agent zirconium‐silver phosphate (Alphasan®) and an organic one Triclosan (Irgasan® DP300). Such spinning solutions allow to obtain antibacterial fibers of the Lyocell type. A nanomodifier, colloidal silica (Ludox SM 30®), was also incorporated into the spinning solutions as an additional component to increase the antibacterial activity of fibers. The effect of the compounds incorporated into the spinning solutions on their rheological and thermal properties was assessed by means of the oscillatory method and differential scanning calorimetry (DSC), respectively. The incorporation of nanosilica exerts a clear influence on the rheological properties of spinning solutions, whereas this effect is negligible in the simultaneous presence of nanosilica and antibacterial agents. The results of thermal measurements show that nanosilica affects the crystallization of the solutions examined. Depending on the type of antibacterial agent, nanosilica brings about either a delay or acceleration of the crystallization of the modified solutions. The effect of nanosilica can be explained in terms of interactions between hydroxyl groups occurring on the surface of silica nanoparticles and NMMO molecules. Copyright © 2007 John Wiley & Sons, Ltd.