CRYSTALLIZATION OF TRISTEARIN FROM ITS SOLUTION IN DODECANE

Abstract

A suspension of tristearin (SSS) crystals crystallized from 10% solution in dodecane (non-polar solvent), was studied using DSC (differential scanning calorimetry), Rheology, PLM (polarized light microscopy), and XRD (x-ray diffraction). Temperatures of -5, 0, 5, 12, 20, 28, and 35 °C, and shear rates of 0.9, 9, 90, and 900 s-1 were explored. DSC cooling rates of 1, 5, 10, and 15 C°/min showed two crystallization events (polymorphic changes). Onset temperatures (51.7 °C) suggests that the SSS molecules cluster in the liquid, and crystallize in the α form (54.1 °C). The viscosity from rheology (10-3 to 10-1 Pa·s) was shear thinning, with “n” of 0.4 to 0.6. The PLM flow micrographs showed segregation of the suspended crystals. The XRD showed that suspended β crystals increased their d-spacing 6 pm for 0.364 nm, and 2.5 pm for 0.383 nm (-5 °C to 35 °C). This is consistent with undiluted TAGs.