WET-SPINNING OF THE POLY(GLUTAMIC ACID) (PGA) FIBERS USING THE PHOSPHORIC ACID AS A COAGULANT

A conc. aqueous solution of poly (sodium-L-glutamate) (PSLG) was spun in an aqueous phosphoric acid solution as a coagulant. The coagulation parameters, such as the concentration, temperature and length of the coagulation bath, were discussed in relation to the chain conformation, crystal-type and mechanical properties of the resulting fibers. The fibers in good quality were obtained by the spinning under the optimum conditions; the concentration ranging from 30 to 50%, temperature 20 to 30°C and length of the coagulation bath 0.25m to lm. The molecular chains of fibers were found to be extended and formed β-type crystals. These crystals were highly oriented along the fiber axis. The conformation of PGA molecules changed from the α-helix to the β-structure at temperatures above 70°C. Therefore, it is preferable to be carried out the wet-spinning at temperatures below 70°C.