Transmitted Light Intensity Measurement
The crystallization induction time and the crystallization behavior of MKF without and with the application of HIU were characterized using a light intensity measurement probe (PASCO airlink) connected with a light sensor. Light intensity is normally regarded as secondary tools to study crystallization, because the data analysis is not straightforward (Tiang and Dealy, 2012). However, it is a simple technique to use and is more useful for probing early kinetics than well-established techniques such as dilatometry, differential scanning calorimetry (DSC), x-ray scattering, optical microscopy and pulsed-nuclear magnetic resonance (Fritsch et al., 2006; Wright et al., 2000). A laser pointer was used as a light source. It was positioned so that the light went through the sample inside the glass cell and was received on the opposite side of the sample by the light detector. Changes in the transmitted light intensity signal during crystallization were monitored by the software SPARKvue (Roseville, CA 95747 USA) that was linked to the light detector. As the sample began to crystallize, less light could go through the sample, resulting in the drop in the transmitted intensity. The recorded light intensity was normalized so that the maximum intensity for each sample was set to be 1 and the minimum intensity was set to be 0.