Evolution Of The Starch Derivatives Instant Clearjel and Primogel As Suspending agents For Sulphadimidine Suspensions

AbstractInstant Clearjel, which is a pregelalinised maize starch and Primojel, which is a sodium starch glycolate prepared from potato starch, have been used throughout this work. The suitability of both these derivatives for use as suspending agents was initially investigated by continuous shear and creep analysis using a specially constructed air turbine viscometer. The starch derivatives exhibited pseudo plastic like flow curves with thixotropy and little irreversible shear breakdown.Apparent viscosities, determined from the apices of flow curves obtained at constant maximum shear rate/decreased progressively with increase in temperature over the range 10-50o C. An Arrhenius plot was constructed to calculate the activation energy for flow of each starch derivative. Decrease in pH over the range 11 to 3 caused a marked reduction in the apparent viscosity of both starch deriv¬atives used. The effect of combinations of Instant Clearjel and Primojel on continuous shear properties was also investigated.Examination of the Theological properties of both polymers at very low shear rates (creep analysis) was also carried out. The significance of these rheological results in terms of the usefulness of these polymers as suspending agents was discussed.