Abstract
The polyglutamic acid (PGA) fibers were spun from concentrated poly-sodium-L-glutamate (PSLG) aqueous solution, using inorganic acids such as HCl, H2SO4 and H3PO4, as coagulant. The relations between the spinning conditions, such as drafting and drawing and the properties of the spun fibers, such as the molecular conformation the crystallinity and the mechanical properties were investigated.
The molecular chains of undrafted and undrawn fibers have the α-helix conformation regardless of acids used as coagulant, and the crystals were unoriented. On the other hand, the conformation of molecular chains of drafted and drawn fibers depended on acids as coagulant. The crystals comprised of molecular chains with β-structure were formed and the well-oriented fiber was obtained when H3PO4 was used as coagulant. The crystals of H2SO4-coagulated fiber were a mixture of α-helix and β-structure. However, with HCl-coagulant the α-helix conformation did not change and the crystals were oriented.
The mechanical properties and the stability of the fibers against hot water varied widely depending on the acids used as coagulant and the spinning conditions. The fiber spun with H3PO4 coagulant was more stable against water than those spun with other coagulants.
