Rheological properties of spinning dopes and spun fibres produced from plasma - alginate mixtures

Summary The tensile and shear strengths of fibres produced by extruding dopes of 2.0% sodium alginate and 6.0% blood plasma into a coagulating bath of calcium chloride (5% w/v) at pH 4.0, varied according to the guluronic acid block content and molecular weight (viscosity) of the alginates. The shear resistance of the fibres was not dependent on guluronic acid block content or alginate viscosity. However, when calculated per gram of dry matter, fibres containing alginates of high guluronic acid block contents had significantly greater resistance to shear than fibres spun from alginates of low guluronic acid block content although there was still no significant dependence on alginate viscosity or degree of polymerization. The tensile strength of fibres produced from high guluronic acid block alginates was not related to the viscosity of the sample. However, in fibres containing low guluronic acid block contents the strength increased as the degree of polymerization increased. These relationships were equally valid whether calculated on a wet or dry basis. In addition there was an inverse correlation between percentage elongation at maximum tensile stress and the viscosity of the spinning dopes. Possible explanations for these observations are discussed.