Crystal growth rates of tricaprin and trilaurin under high pressures

The effect of hydrostatic pressure on a linear crystal growth rate of tricaprin and trilaurin was investigated by the use of a capillary method in the pressure range up to 200 MPa. The undercooling temperature, ΔT, was varied from 0.65 to 16 K. In order to investigate crystal growth kinetics of triacylglycerols, the melting temperature, density and viscosity were also measured under high pressures. The crystal growth rates of tricaprin and trilaurin decrease with increasing values of pressure applied. It was found that the crystal growth rate, v, can be expressed by the form v = AΔTⁿ with n which can take large value in a range of small ΔT value, whereas n decreases with increasing ΔT value. From the comparison with several theories for the crystal growth from melts, the present result suggests that the two triacylglycerols freeze by the dislocation mechanism in the small ΔT range and by the continuous mechanism in the large ΔT range.