Measurement of enthalpic relaxation by differential scanning calorimetry—effect of experimental conditions

2005 ◽  
Vol 433 (1-2) ◽  
pp. 173-182 ◽  
Author(s):  
Rahul Surana ◽  
Abira Pyne ◽  
Meena Rani ◽  
Raj Suryanarayanan
Keyword(s):  
Differential Scanning Calorimetry ◽  
Scanning Calorimetry ◽  
Experimental Conditions ◽  
Enthalpic Relaxation

Study of Model Copper-Based Catalysts by Simultaneous Differential Scanning Calorimetry, X-Ray Diffraction and Mass Spectrometry

1987 ◽  
Vol 111 ◽  
Author(s):  
Robert A. Newman ◽  
Joseph A. Blazy ◽  
Timothy G. Fawcett ◽  
Larry F. Whiting ◽  
Robert A. Stowe
Keyword(s):  
Mass Spectrometry ◽  
Differential Scanning Calorimetry ◽  
Copper Oxide ◽  
Cuprous Oxide ◽  
Copper Surface ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Experimental Conditions ◽  
Simultaneous Generation ◽  
X Ray

AbstractRecently, a new materials characterization instrument and technique employing simultaneous differential scanning calorimetry/X-ray diffraction/mass spectrometry (DSC/XRD/MS) have been developed at Dow. Use of this technology can be illlustrated by the study of various materials such as polymers, organics/pharmaceuticals, inorganics, and catalysts.Presented here is the use of the DSC/XRD/MS instrument to study the thermostructural behavior of four model copper-based catalyst systems during activation and regeneration. The instrument allows simultaneous generation of thermal, structural and chemical data in real-time during temperature programmed analysis and provides useful insights into the chemical and physical processes occurring. In addition, the calorimetry data yield qualititative information on the magnitude and rate of heat flow, while the diffraction data provide structural dynamics of reduction, oxidation and crystallite growth.The results of this study conclusively show cuprous oxide as an intermediate in the reduction of the copper oxide portion of each of the model catalysts. However, such features as the onset temperature and copper surface area varied widely among the four catalysts in response to the same chemical event conducted under similar experimental conditions. On the other hand, oxidation runs on the reduced catalysts were all similar to each other, first producing cuprous oxide from copper metal over a broad range of temperature, followed by the oxidation of cuprous oxide to copper oxide at even higher temperatures.

Thermal Stability of N-Heterocycle-Stabilized Iodanes – A Systematic Investigation

2019 ◽  
Author(s):  
Andreas Boelke ◽  
Yulia A. Vlasenko ◽  
Mekhman S. Yusubov ◽  
Boris Nachtsheim ◽  
Pavel Postnikov
Keyword(s):  
Thermal Stability ◽  
Differential Scanning Calorimetry ◽  
Thermogravimetric Analysis ◽  
Systematic Investigation ◽  
Scanning Calorimetry ◽  
Thermal Stability Of

<p>The thermal stability of pseudocyclic and cyclic <i>N</i>-heterocycle-stabilized (hydroxy)aryl- and mesityl(aryl)-l<sup>3</sup>-iodanes (NHIs) through thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) is investigated. NHIs bearing <i>N</i>-heterocycles with a high N/C-ratio such as triazoles show among the lowest descomposition temperatures and the highest decomposition energies. A comparison of NHIs with known (pseudo)cyclic benziodoxolones is made and we further correlated their thermal stability with reactivity in a model oxygenation. </p>

Optimasi Proses Pembuatan dan Karakterisasi Fisik Niosom Sinkonin

2019 ◽  
Vol 16 (2) ◽  
pp. 178
Author(s):  
Hariyanti Hariyanti ◽  
Sophi Damayanti ◽  
Sasanti Tarini
Keyword(s):  
Differential Scanning Calorimetry ◽  
Particle Size ◽  
Hair Follicle ◽  
Scanning Calorimetry ◽  
Span 60

Sinkonin praktis tidak larut dalam air, sedikit larut dalam kloroform dan alkohol. Hal ini berdampak pada rendahnya penetrasi transfollicular sinkonin, karena hanya bahan aktif hidrofilik yang mampu melewati hair follicle. Dengan demikian dibutuhkan satu sistem penghantaran yang mampu menurunkan hidrofobisitas sinkonin untuk meningkatkan penetrasi sinkonin ke follicle. Niosom merupakan vesikel ampifilik dengan struktur lapisan rangkap yang terbentuk dari hidrasi kombinasi surfaktan nonionik dan kolesterol yang mampu menurunkan hidrofobisitas sinkonin. Penelitian ini bertujuan untuk menentukan proses pembuatan niosom sinkonin yang optimum. Pembuatan niosom sinkonin diawali dengan menentukan temperatur gelasi (Tg) dari span 60 dengan Differential Scanning Calorimetry (DSC), kemudian dilanjutkan dengan optimasi proses meliputi: optimasi kecepatan rotavapor pembentukan film lapis tipis, temperatur hidrasi, kecepatan rotavapor hidrasi, waktu hidrasi, dan waktu sonikasi. Karakteristik vesikel niosom yang optimal meliputi: ukuran partikel dan indeks polidispersitas dengan menggunakan Particle Size Analized (PSA) serta efisiensi penjeratan sinkonin dengan menggunakan KCKT. Temperatur gelasi (Tg) span 60 45±2 oC, kecepatan rotavapor pembentukan film lapis tipis niosom 210 rpm, temperatur hidrasi 55±2 oC, kecepatan rotavapor hidrasi 210 rpm, waktu hidrasi 20 menit, waktu sonikasi suspensi niosom 1 menit. Ukuran vesikel yang diperoleh adalah 100–200 nm, indeks polidispersitas 0,2–0,4 dan efisiensi penjeratan niosom sinkonin 84,49±0,0025%. Proses pembuatan niosom sinkonin memiliki pengaruh besar terhadap hasil ukuran vesikel dan efisiensi penjeratan niosom sinkonin.

Improving Wire Sweep Performance by Measuring Degree of Cure of Epoxy Mold Compounds

2011 ◽  
Author(s):  
Sheila Liza B. Dal
Keyword(s):  
Differential Scanning Calorimetry ◽  
Shelf Life ◽  
Trial And Error ◽  
Active Components ◽  
Scanning Calorimetry ◽  
Degree Of Cure ◽  
Electronic Package ◽  
Viscosity Changes ◽  
Epoxy Mold Compounds

Abstract The choice of epoxy mold compound (EMC) for an electronic package is based mostly on how much protection it provides to the active components in the package. But the choice is not a straightforward process. Rather it is mostly trial and error using different assembly parameters to find the most robust material while assembly defects are monitored. One such defect associated to EMC processing is wire sweep, and many studies have shown that it is mainly caused by viscosity changes in the EMC. In this study, samples of EMC in various stages of shelf life and staging times were analyzed for degree of cure using a method called differential scanning calorimetry (DSC). Samples are then processed at assembly for wire sweep measurement. It was found out that degree of cure increases with staging time at different rates for each shelf life. It was also found out that wire sweep did not only increase with degree of cure but it was also found to be predictable with respect to the latter. Using this information, the age and staging limit for each material was identified that would not cause wire sweep issues.

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