Thermal parameters study of 1,1-bis(tert-butylperoxy)cyclohexane at low heating rates with differential scanning calorimetry

Abstract The thermal degradation of bulk and miniature samples of expanded polystyrene (EPS) has been investigated in a neutral atmosphere at 800°C and by differential scanning calorimetry over a range of temperatures. The differential scanning calorimetry experiments showed that the foam volatilization temperature is significantly affected by heating rate and varies from 380°C to 470°C at heating rates from 10–60°C/min. Bulk degradation due to the 800°C heat source appeared to occur instantly as the foam pattern approached the close proximity of the heat source. The chamber pressure increased and the heat source temperature dropped during degradation. The gas yield at 800°C was determined to be about 610 cm3 (STP)/g of EPS.

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Application of Differential Scanning Calorimetry (DSC) and Modulated Differential Scanning Calorimetry (MDSC) in Food and Drug Industries

Polymers ◽

10.3390/polym12010005 ◽

2019 ◽

Vol 12 (1) ◽

pp. 5 ◽

Cited By ~ 5

Author(s):

César Leyva-Porras ◽

Pedro Cruz-Alcantar ◽

Vicente Espinosa-Solís ◽

Eduardo Martínez-Guerra ◽

Claudia I. Piñón-Balderrama ◽

...

Keyword(s):

Differential Scanning Calorimetry ◽

Heat Capacity ◽

Thermomechanical Analysis ◽

Mechanical Analysis ◽

Heating Rates ◽

Scanning Calorimetry ◽

Modulated Differential Scanning Calorimetry ◽

Accuracy And Precision ◽

Wide Range ◽

Transition Issues

Phase transition issues in the field of foods and drugs have significantly influenced these industries and consequently attracted the attention of scientists and engineers. The study of thermodynamic parameters such as the glass transition temperature (Tg), melting temperature (Tm), crystallization temperature (Tc), enthalpy (H), and heat capacity (Cp) may provide important information that can be used in the development of new products and improvement of those already in the market. The techniques most commonly employed for characterizing phase transitions are thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), thermomechanical analysis (TMA), and differential scanning calorimetry (DSC). Among these techniques, DSC is preferred because it allows the detection of transitions in a wide range of temperatures (−90 to 550 °C) and ease in the quantitative and qualitative analysis of the transitions. However, the standard DSC still presents some limitations that may reduce the accuracy and precision of measurements. The modulated differential scanning calorimetry (MDSC) has overcome some of these issues by employing sinusoidally modulated heating rates, which are used to determine the heat capacity. Another variant of the MDSC is the supercooling MDSC (SMDSC). SMDSC allows the detection of more complex thermal events such as solid–solid (Ts-s) transitions, liquid–liquid (Tl-l) transitions, and vitrification and devitrification temperatures (Tv and Tdv, respectively), which are typically found at the supercooling temperatures (Tco). The main advantage of MDSC relies on the accurate detection of complex transitions and the possibility of distinguishing reversible events (dependent on the heat capacity) from non-reversible events (dependent on kinetics).

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Determination of Solidification Parameters Used for the Prediction of the Thixoformability of Several Steel Alloys

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.116-117.54 ◽

2006 ◽

Vol 116-117 ◽

pp. 54-57 ◽

Cited By ~ 4

Author(s):

Jacqueline Lecomte-Beckers ◽

Ahmed Rassili ◽

Marc Robelet ◽

Claude Poncin ◽

R. Koeune

Keyword(s):

Differential Scanning Calorimetry ◽

Heating Rate ◽

Liquid Fraction ◽

Heating Rates ◽

Scanning Calorimetry ◽

Steel Alloys ◽

Fraction Versus ◽

Solidification Parameters ◽

Industrial Heating

This paper focuses on the liquid fraction curves of several steels and the correlation between liquid fraction, temperature and heating rate. The work has been performed along two main axes. First, the solid fraction versus temperature has been obtained experimentally by differential scanning calorimetry (DSC), limited to low heating rates. Then, a shift of the liquid fraction curves has been noticed at high industrial heating rates. The quantification of this effect could not be carried out by DSC and required the elaboration of another experimental device.

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SOĞUK HADDELENMİŞ AA3105 VE AA5005 LEVHALARIN DSC ANALİZİ İLE YENİDEN KRİSTALLENME KİNETİĞİ

Euroasia Journal of Mathematics, Engineering, Natural and Medical Sciences ◽

10.38065/euroasiaorg.621 ◽

2021 ◽

Vol 8 (17) ◽

pp. 80-85

Author(s):

Atae RAOUGUI ◽

Ion GRECU ◽

Volkan Murat YILMAZ ◽

Kenan YILDIZ

Keyword(s):

Differential Scanning Calorimetry ◽

Aluminum Alloy ◽

Activation Energies ◽

Isothermal Kinetics ◽

Heating Rates ◽

Scanning Calorimetry ◽

Recrystallization Kinetics ◽

Model Free ◽

Cold Rolled ◽

Kinetics Of

In this study, the non-isothermal recrystallization kinetics of cold rolled AA3105 and AA5005 aluminum alloy sheets obtained from ASAŞ Aluminum located in Akyazı-Sakarya was studied by using differential scanning calorimetry (DSC). The non – isothermal kinetics was performed by using Kissenger, Boswell, Ozawa and Starink methods known as model – free methods. The recrystallization temperatures on DSC graphics at different heating rates (β) were deduced and the activation energies were calculated from the slopes from Y – 1/T diagrams. Y is ln(β/T2) for Kissenger, ln(β/T) for Boswell, ln(β) for Ozawa and ln(β/T1.92) for Starink. The results showed that the activation energies of recrystallization are in the range of 194 – 206 kJ/mol for cold rolled AA5005 sheet and in the range of 235 – 257 kJ/mol for cold rolled AA3105 sheet, according to four non-isothermal kinetics model.

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Reaction Chemistry and Thermodynamics of the Ni-Al and Fe-Al Systems

MRS Proceedings ◽

10.1557/proc-81-467 ◽

1986 ◽

Vol 81 ◽

Cited By ~ 2

Author(s):

Robert P. Santandrea ◽

Robert G. Behrens ◽

Mary A. King

Keyword(s):

Differential Scanning Calorimetry ◽

Enthalpies Of Formation ◽

Reaction Products ◽

Heating Rates ◽

Scanning Calorimetry ◽

X Ray ◽

Sample Heating ◽

Heats Of Reaction ◽

Standard Enthalpies Of Formation ◽

Shape And Size

AbstractThe reaction chemistry of the Fe-Al and Ni-Al systems was studied using differential scanning calorimetry (DSC). Experimentally measured heats of reaction and compositions of reaction products were characterized in terms of sample heating rates, reaction temperature, shape and size of aluminum powder, and sample preparation. Standard enthalpies of formation were derived from DSC results. Reaction products were identified by x-ray powder diffraction techniques.

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Precursors to crystallization in amorphous CdGeAs2

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100143845 ◽

1986 ◽

Vol 44 ◽

pp. 454-455

Author(s):

R.F. Speyer ◽

W.M. Kriven ◽

S.H. Risbud

Keyword(s):

Differential Scanning Calorimetry ◽

Thermal Treatment ◽

Chalcopyrite Structure ◽

Slow Heating ◽

X Ray Diffraction ◽

Heating Rates ◽

Scanning Calorimetry ◽

X Ray ◽

Dsc Studies ◽

Precursor Phase

A myriad of crystalline microstructures may be obtained by minute variations in thermal treatment during the devitrification of CdGeAs2 from the glass. Differential Scanning Calorimetry (DSC) studies show that the single crystallization exotherm observed under moderate heating conditions, splits into two superimposed exotherms (a moderately energetic one followed by a substantially energetic one) at very slow heating rates, as shown in Figure 1.It is believed that the first DSC exotherm represents the nucleation and partial growth of a non-stoichiometric. crystalline precursor phase. X-ray diffraction studies of samples sequentially quenched along the DSC exotherm indicated, to reasonable confidence, that the precursor phase was pure germanium, and with absolute confidence that the larger exotherm represents the formation of CdGeAs2 adopting the chalcopyrite structure. The TEM. STEM, and EDS studies described herein substantiate our elucidation of the precursor phase.

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Effect of Molecular Weight on Glass Transition by Differential Scanning Calorimetry

Canadian Journal of Chemistry ◽

10.1139/v74-465 ◽

1974 ◽

Vol 52 (18) ◽

pp. 3170-3175 ◽

Cited By ~ 69

Author(s):

Louis-Philippe Blanchard ◽

Jean Hesse ◽

Shadi Lal Malhotra

Keyword(s):

Molecular Weight ◽

Differential Scanning Calorimetry ◽

Heat Capacity ◽

Glass Transition ◽

Heating Rate ◽

Low Molecular Weight ◽

Glass Transitions ◽

Heating Rates ◽

Scanning Calorimetry ◽

Polystyrene Sample

The influence of molecular weight (900 to 1.8 × 106) on the glass transition temperature of low polydispersity polystyrene (anionically prepared) has been studied by differential scanning calorimetry at heating rates of 5 to 80 °C min−1. Over the range of molecular_weight studied, and at an extrapolated heating rate of 1 °C min−1,[Formula: see text] A thermally prepared polystyrene sample ([Formula: see text]and Pd = 3.2) showed a Tge value of 93 °C, some 10° below the value predicted by the above equation. Low molecular weight species in the highly polydisperse sample are believed to be responsible for the discrepancy. The changes in heat capacity brought about by the glass transitions are accompanied in all cases on heating by an endothermic peak and this regardless of the heating rate (even extrapolated to 1 °C min−1) or the molecular weight of the sample, suggesting that the glass transition phenomenon encountered with polystyrene is a process involving a positive heat effect.

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Glass transformation temperature and stability of tellurite glasses

Journal of Materials Research ◽

10.1557/jmr.2003.0051 ◽

2003 ◽

Vol 18 (2) ◽

pp. 402-406 ◽

Cited By ~ 14

Author(s):

Raouf El-Mallawany

Keyword(s):

Activation Energy ◽

Differential Scanning Calorimetry ◽

Transformation Temperature ◽

Unit Volume ◽

Tellurite Glasses ◽

Heating Rates ◽

Scanning Calorimetry ◽

Glass Transformation ◽

Glass Series ◽

Calculated Number

The glass transformation (Tg) and onset crystallization temperatures (Tx) of (100 – x) TeO2–(x)V2O5, (x = 10, 35, and 50 mol%) glasses were measured in the temperature range 300–800 K by differential scanning calorimetry at different heating rates. From the variation of the heating rate, the glass transition activation energy was calculated by different methods. The glass stabilization range S = Tx – Tg was calculated for the whole glass series. Quantitative analysis of the glass transformation temperature was carried out using the calculated number of bonds per unit volume and oxygen packing density.

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Physical Ageing of Amorphous Indapamide Characterised by Differential Scanning Calorimetry

Pharmaceutics ◽

10.3390/pharmaceutics12090800 ◽

2020 ◽

Vol 12 (9) ◽

pp. 800

Author(s):

Agata Drogoń ◽

Marcin Skotnicki ◽

Agnieszka Skotnicka ◽

Marek Pyda

Keyword(s):

Differential Scanning Calorimetry ◽

Glass Transition ◽

Amorphous State ◽

Modulated Dsc ◽

Physical Ageing ◽

Heating Rates ◽

Scanning Calorimetry ◽

Different Temperatures ◽

Fragility Parameter ◽

Liquid States

The objective of this study was to characterise amorphous indapamide (IND) subjected to the physical ageing process by differential scanning calorimetry (DSC). The amorphous indapamide was annealed at different temperatures below the glass transition, i.e., 35, 40, 45, 65, 75 and 85 °C for different lengths of time, from 30 min up to a maximum of 32 h. DSC was used to characterise both the crystalline and the freshly prepared glass and to monitor the extent of relaxation at temperatures below the glass transition (Tg). No ageing occurred at 35, 40 and 45 °C at the measured lengths of times. Molecular relaxation time constants (τKWW) for samples aged at 65, 75 and 85 °C were determined by the Kohlrausch-Williams-Watts (KWW) equation. The fragility parameter m (a measure of the stability below the glass transition) was determined from the Tg dependence from the cooling and heating rates, and IND was found to be relatively stable (“moderately fragile”) in the amorphous state. Temperature-modulated DSC was used to separate reversing and nonreversing processes for unaged amorphous IND. The enthalpy relaxation peak was clearly observed as a part of the nonreversing signal. Heat capacities data for unaged and physically aged IND were fitted to Cp baselines of solid and liquid states of IND, were integrated and enthalpy was presented as a function of temperature.

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