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Indomethacin: The Interplay between Structural Relaxation, Viscous Flow and Crystal Growth
Year: 2022
Type of publication: článek v odborném periodiku
Name of source: Molecules
Publisher name: MDPI
Place: BASEL
Page from-to: "5668-1"-"5668-23"
Titles:
Language Name Abstract Keywords
cze Indometacin: Vzájemný vztah mezi strukturní relaxací, viskózním tokem a krystalovým růstem Neizotermní DSC studie vlivu velikosti částic a rychlosti krystalizace na strukturní relaxaci, růst krystalů a rozkladnou kinetiku amorfního indometacinu byla provedena. Strukturní relaxace a rozkladný proces vykazují kinetiku nezávislou na průměru částic. V kinetice růstu má dominantní roli nukleace, která významně mění kinetický mechanismus. Dále se uplatňuje vliv mechanicky indukovaných nukleí a skladování při teplotách pod skelným přechodem.. amorfní indometacin; DCS; růst krystalů; strukturní relaxace; viskózní tok; velikost částic
eng Indomethacin: The Interplay between Structural Relaxation, Viscous Flow and Crystal Growth Non-isothermal differential scanning calorimetry (DSC) was used to study the influences of particle size (d(aver)) and heating rate (q(+)) on the structural relaxation, crystal growth and decomposition kinetics of amorphous indomethacin. The structural relaxation and decomposition processes exhibited d(aver)-independent kinetics, with the q(+) dependences based on the apparent activation energies of 342 and 106 kJ center dot mol(-1), respectively. The DSC-measured crystal growth kinetics played a dominant role in the nucleation throughout the total macroscopic amorphous-to-crystalline transformation: the change from the zero-order to the autocatalytic mechanism with increasing q(+), the significant alteration of kinetics, with the storage below the glass transition temperature, and the accelerated crystallization due to mechanically induced defects. Whereas slow q(+) led to the formation of the thermodynamically stable gamma polymorph, fast q(+) produced a significant amount of the metastable alpha polymorph. Mutual correlations between the macroscopic and microscopic crystal growth processes, and between the viscous flow and structural relaxation motions, were discussed based on the values of the corresponding activation energies. Notably, this approach helped us to distinguish between particular crystal growth modes in the case of the powdered indomethacin materials. Ediger's decoupling parameter was used to quantify the relationship between the viscosity and crystal growth. The link between the cooperativity of structural domains, parameters of the Tool-Narayanaswamy-Moynihan relaxation model and microscopic crystal growth was proposed. amorphous indomethacin; DSC; crystal growth; structural relaxation; viscous flow; particle size

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