Effect of Temperature on the Wide Angle X-Ray Diffraction of Nanocrystalline Triacylglycerols

Abstract

The peak position of wide angle x-ray diffraction patterns of nanocrystalline triacylglycerols is affected by the temperature. To observe this effect quantitatively, pure triacylglycerols and triacylglycerol mixtures were crystallized in a desired polymorph in capillaries or a Couette system. The crystallized samples were kept at different temperatures and shear rates. The detailed WAXD patterns were obtained using in-house x-ray and synchrotron x-ray sources. When the temperature increased, the d-spacing for the peaks with small d-spacing increased as well. However, the d-spacing for other peaks remained unchanged or just had a very small change. The relationship between differences of d-spacing for the peaks with small d-spacing and temperature can be used to estimate the real sample temperature, especially under higher shear rate. This provides a new way to monitor and control the temperature of the system under study and the effect of high shear rate on nanocrystalline triacylglycerol crystallization.