Journal of Applied Polymer Science, Vol.66, No.1, 117-127, 1997
Coagulation Rate Studies of Spinnable Chitosan Solutions
The coagulation properties of some mixtures of 5% chitosan in 2% aqueous acetic acid were investigated with the goal of determining the optimal coagulation conditions for the spinning of chitosan fibers. The chitosan was characterized and found to possess a deacetylation value of 84.9 +/- 0.2%. Molecular weight of the chitosan was also measured; based on intrinsic viscosity, the M-V value was 7.73 x 10(5) g mol(-1), and based on high-pressure liquid chromatography, the M-w value was 1.14 x 10(5) g mol(-1). Solutions of 5% chitosan/2% acetic acid were prepared, filtered, and extruded through a large-diameter hole syringe into coagulation baths of varying composition that were all strongly basic in nature, at least a pH of 12 or greater. For each coagulant, time was varied from between 22 s and 2 minutes at room temperature. A second set of experiments was conducted where the temperature was varied from 20 degrees C to 70 degrees C at a constant time of 45 s. In a third set of experiments, using a 1M NaOH coagulant, different chitosans were also analyzed. Throughout all of the experiments, a distinct moving boundary between coagulated and uncoagulated polymer was observed within the cylindrical-shaped polymer fibers. Using a series of equations based on Fick’s 2nd Law, a straight line relationship has been demonstrated between boundary motion and time and between boundary motion and temperature for each coagulant tested. The activation energy for each coagulant was also determined.