Starch acetate potato, viscosity

In some cases the solutions have exhibited structural effects, the nature or extent of which have not been fully established. Staudinger and Eilers° found that the viscosity of their starch triacetate solutions displayed little dependence on temperature and considered the acetate to be mono-dispersed. Higginbotham and Richardson, on the other hand, found a noticeable temperature dependence for viscosities of carefully prepared potato starch triacetate in tetrachloroethane solutions. For example, a 0.25% solution was thbcotropic at 25°, but not at 60°. The existence of structural effects in starch acetate solutions was likewise noted by Mullen and Pacsu for potato starch triacetate dissolved in tetrachloroethane. 

As a rule, the viscosity of potato starch triacetate solution appears to be higher than the viscosity of other starch acetates while the viscosity of waxy corn starch triacetate is lower than the viscosity of other starch acetates in keeping with the relative molecular weights of these starches. 

Not all modified starches are suitable for removal by aqueous dissolution alone. Such modifications of natural starches are carried out to reduce solution viscosity, to improve adhesion and ostensibly to enhance aqueous solubility. Commercial brands vary [169], however, from readily soluble types to those of limited solubility. Indeed, some may be as difficult to dissolve as potato starch if they have been overdried. It is thus very important to be sure of the properties of any modified starch present. If there are any doubts about aqueous dissolution, desizing should be carried out by enzymatic or oxidative treatment. Even if the size polymer is sufficiently soluble, it is important to ensure that the washing-off range is adequate. Whilst the above comments relate to modified starches, other size polymers such as poly(vinyl acetate/alcohol) and acrylic acid copolymers vary from brand to brand with regard to ease of dissolution. 

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