Assessing the rate of solid-phase crystallization for lactose: The effect of the difference between material and glass-transition temperatures

Assessment of the rate of solid-phase crystallization for lactose with recent experimental data is relevant for modelling and predicting the extent of crystallinity that can be expected during the drying of solutions using spray dryers. There is some evidence that the rates rise sharply when there are differences of around 30 K between the material and the glass-transition temperatures. There is also strong evidence, for any particular material, that this rate is related to the (positive) difference between the material and the glass-transition temperatures (T − Tg), as suggested by the WLF equation, and that the rate decreases significantly below the glass-transition temperature.