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Murti Vemuri N. Chrzan Zofia Cavatur Raghu 《Journal of Thermal Analysis and Calorimetry》2004,78(1):47-54
Solid-state transformation kinetics of two crystal forms of a synthetic tetrapeptide was monitored by isothermal microcalorimetry
and complementary solid-state analytical techniques. Form B, the crystal form obtained from the synthetic process transformed
to Form D upon exposure to higher relative humidity conditions (>60% RH). The transformation occurred rapidly at higher temperature,
and relative humidities. An intermediate phase of very low crystallinity (amorphous-like phase) was observed when transformation
was slow. Form D was observed to be physically stable at higher relative humidities and thus the preferred crystal form for
development. Exposure of Form B to high relative humidity was the only process through which Form D was obtained. Optimal
conditions for transformation of Form B to Form D were determined by microcalorimetric experiments and were used for larger
scale processing of Form B to Form D. 相似文献
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Murti Vemuri N. Chrzan Zofia Cavatur Raghu 《Journal of Thermal Analysis and Calorimetry》2004,78(1):55-62
Low amounts of amorphous phase present in predominantly crystalline powders were quantified by using various analytical techniques
with an emphasis on the use of Isothermal Perfusion Microcalorimetry. The amorphous phase was plasticized using ethanol vapor
and enthalpy of re-crystallization of amorphous phase was used for generation of a calibration curve. Amorphous content as
low as 5% was quantified using this technique. Although baseline noise was very low, additional processes occurring during
re-crystallization confounded quantification of lower amorphous fractions.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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