Using fast scanning calorimetry to detect guest-induced polymorphism by irreversible phase transitions in the nanogram scale

CrystEngComm ◽  
2019 ◽  
Vol 21 (6) ◽  
pp. 1034-1041 ◽  
Author(s):  
Karina V. Gataullina ◽  
Aleksey V. Buzyurov ◽  
Marat A. Ziganshin ◽  
Pavel L. Padnya ◽  
Ivan I. Stoikov ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Heating Rate ◽  
Scanning Calorimetry ◽  
Fast Scanning Calorimetry ◽  
Irreversible Phase Transitions

Fast scanning calorimetry with a heating rate of 1000 K s−1 enables successful screening of polymorphs for separate microcrystalline aggregates in thiacalixarene powder.

Fast Scanning Calorimetry of Phase Transitions in Metals

2016 ◽  
pp. 691-721 ◽  
Author(s):  
Yulai Gao ◽  
Bingge Zhao ◽  
Bin Yang ◽  
Christoph Schick
Keyword(s):  
Phase Transitions ◽  
Scanning Calorimetry ◽  
Fast Scanning Calorimetry

scholarly journals Double-Chain Cationic Surfactants: Swelling, Structure, Phase Transitions and Additive Effects

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 3946
Author(s):  
Rui A. Gonçalves ◽  
Yeng-Ming Lam ◽  
Björn Lindman
Keyword(s):  
Phase Transitions ◽  
Phase Behaviour ◽  
Double Chain ◽  
Scanning Calorimetry ◽  
Alkyl Chains ◽  
X Ray Scattering ◽  
Amphiphilic Compounds ◽  
Liquid Phases ◽  
Lamellar Phases ◽  
Water Layers

Double-chain amphiphilic compounds, including surfactants and lipids, have broad significance in applications like personal care and biology. A study on the phase structures and their transitions focusing on dioctadecyldimethylammonium chloride (DODAC), used inter alia in hair conditioners, is presented. The phase behaviour is dominated by two bilayer lamellar phases, Lβ and Lα, with “solid” and “melted” alkyl chains, respectively. In particular, the study is focused on the effect of additives of different polarity on the phase transitions and structures. The main techniques used for investigation were differential scanning calorimetry (DSC) and small- and wide-angle X-ray scattering (SAXS and WAXS). From the WAXS reflections, the distance between the alkyl chains in the bilayers was obtained, and from SAXS, the thicknesses of the surfactant and water layers. The Lα phase was found to have a bilayer structure, generally found for most surfactants; a Lβ phase made up of bilayers with considerable chain tilting and interdigitation was also identified. Depending mainly on the polarity of the additives, their effects on the phase stabilities and structure vary. Compounds like urea have no significant effect, while fatty acids and fatty alcohols have significant effects, but which are quite different depending on the nonpolar part. In most cases, Lβ and Lα phases exist over wide composition ranges; certain additives induce transitions to other phases, which include cubic, reversed hexagonal liquid crystals and bicontinuous liquid phases. For a system containing additives, which induce a significant lowering of the Lβ–Lα transition, we identified the possibility of a triggered phase transition via dilution with water.

scholarly journals Physical Aging Behavior of a Glassy Polyether

Polymers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 954
Author(s):  
Xavier Monnier ◽  
Sara Marina ◽  
Xabier Lopez de Pariza ◽  
Haritz Sardón ◽  
Jaime Martin ◽  
...  
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Physical Aging ◽  
Glassy State ◽  
Aging Behavior ◽  
Scanning Calorimetry ◽  
Narrow Temperature Range ◽  
Glass Forming ◽  
Fast Scanning Calorimetry

The present work aims to provide insights on recent findings indicating the presence of multiple equilibration mechanisms in physical aging of glasses. To this aim, we have investigated a glass forming polyether, poly(1-4 cyclohexane di-methanol) (PCDM), by following the evolution of the enthalpic state during physical aging by fast scanning calorimetry (FSC). The main results of our study indicate that physical aging persists at temperatures way below the glass transition temperature and, in a narrow temperature range, is characterized by a two steps evolution of the enthalpic state. Altogether, our results indicate that the simple old-standing view of physical aging as triggered by the α relaxation does not hold true when aging is carried out deep in the glassy state.

scholarly journals Comprehensive Thermal Characteristics of Different Cultivars of Flaxseed Oil (Linum usittatissimum L.)

Molecules ◽  
2021 ◽  
Vol 26 (7) ◽  
pp. 1958
Author(s):  
Jolanta Tomaszewska-Gras ◽  
Mahbuba Islam ◽  
Liliana Grzeca ◽  
Anna Kaczmarek ◽  
Emilia Fornal
Keyword(s):  
Differential Scanning Calorimetry ◽  
Heating Rate ◽  
Fatty Acid Content ◽  
Thermal Characteristics ◽  
Principal Component ◽  
Flaxseed Oil ◽  
Scanning Calorimetry ◽  
Total Oxidation ◽  
Increasing Temperature ◽  
Linear Correlations

The aim of this study was to describe the thermal properties of selected cultivars of flaxseed oil by the use of the differential scanning calorimetry (DSC) technique. The crystallization and melting profiles were analyzed depending on different scanning rates (1, 2, 5 °C/min) as well as oxidative induction time (OIT) isothermally at 120 °C and 140 °C, and oxidation onset temperatures (Ton) at 2 and 5 °C/min were measured. The crystallization was manifested as a single peak, differing for a cooling rate of 1 and 2 °C/min. The melting curves were more complex with differences among the cultivars for a heating rate of 1 and 2 °C/min, while for 5 °C/min, the profiles did not differ, which could be utilized in analytics for profiling in order to assess the authenticity of the flaxseed oil. Moreover, it was observed that flaxseed oil was highly susceptible to thermal oxidation, and its stability decreased with increasing temperature and decreasing heating rate. Significant negative linear correlations were found between unsaturated fatty acid content (C18:2, C18:3 n-3) and DSC parameters (OIT, Ton). Principal component analysis (PCA) also established a strong correlation between total oxidation value (TOTOX), peroxide value (PV) and all DSC parameters of thermo-oxidative stability.

Probing Three Distinct Crystal Polymorphs of Melt-Crystallized Polyamide 6 by an Integrated Fast Scanning Calorimetry Chip System

2021 ◽  
Author(s):  
Xiaoshi Zhang ◽  
Anne Gohn ◽  
Gamini Mendis ◽  
John F. Buzinkai ◽  
Steven J. Weigand ◽  
...  
Keyword(s):  
Polyamide 6 ◽  
Scanning Calorimetry ◽  
Fast Scanning Calorimetry

scholarly journals Irreversible phase transitions induced by an oscillatory input

2000 ◽  
Vol 52 (1) ◽  
pp. 8-14 ◽  
Author(s):  
A. C López ◽  
G. P Saracco ◽  
E. V Albano
Keyword(s):  
Phase Transitions ◽  
Irreversible Phase Transitions
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