The effects of uronic acid ratio of alginate and metal ions on the physical properties of alginate fiber paper.

The effects of the ratio of mannuronate (M) and guluronate (G) (M/G ratio) of alginate on the physical properties of alginate fiber paper were investigated, by using five kinds of divalent metal ions, Cu, Ba, Ca, Ni, and Zn as the coagulant of alginic acid gel. At the same M/G ratio, the calcium- and nickel-coagulated fiber papers had similar strengths. Burst strength and breaking length increased with the increase in M/G ratio. On the other hand, tear strength decreased with the increase in M/G ratio except a few samples. These findings mean that the effect of the increase in M/G ratio on Ca- or Ni-alginate fiber pulps is the same as that of beating on cellulose fiber pulp, within the range of M/G ratio of this experiment. Electron microscopic observation revealed that little fibrillation occurred with the alginate paper with a M/G ratio of 1.19 but the fibers seemed to adhere in fusion. Thus the interfiber cohesion is thought to be a cause of mechanical strength of alginate fiber paper and the adhesion is governed by M/G ratio and by kind of metal ions.