Differential scanning calorimetry and thermal

Characterization. Differential scanning calorimetry and thermal mechanical analysis data were obtained on a DuPont 990 thermal analyzer coupled with a DuPont DSC or TMA cell. Isothermal aging studies were carried out with an automatic multisample apparatus. 

Permeability changes in full-thickness skin have been associated with temperature or solvent pretreatment. The molecular basis of these permeability changes has been attributed to lipid melting or protein conformational changes. The current studies have probed the role of lipid fluidity in the permeability of lipophilic solutes, and examined the effects of temperature on the physical nature of the stratum corneum by differential scanning calorimetry and thermal perturbation infrared spectroscopy. Combining molecular level studies that probe the physical nature of the stratum corneum with permeability results, a correlation between flux of lipophilic solutes and nature of the stratum corneum barrier emerges. 

Permeability studies coupled with differential scanning calorimetry and thermal perturbation infrared spectroscopy investigations of the stratum corneum and its lipid and protein components have enabled the physical structure of the stratum corneum to be probed on a molecular level. 

Differential scanning calorimetry and thermal gravimetric analysis have been used by several authors (27,53) to show that plasma-derived polymers have no phase transitions until decomposition occurs. The remarkable thermal stability of these materials is evidenced by data which show that 80 wt.% of a film prepared from methyl chloride remains at 800 C and that 40 wt.% of a styrene derived film remains at 700°C. 

Lamure, A., Pommert, J.-J., Klaebe, A., Lacabanne, C., and Perie, J.-J. (1988). Effect of polyphosphate binding on the chain dynamic of caseins Investigation by differential scanning calorimetry and thermally stimulated currents. J. Dairy Res. 55,401-412. 

The use of combined thermoanalytical techniques for materials characterization has increased in the last few years. For example, differential scanning calorimetry and thermally stimulated current (TSC) have also been used to study polyurethane and mono- and bilayer paints.[ 1 TSC (considered a relaxation technique) is based on the degree of chain and... 

Polyurethane acrylate resins cured by two different methods, thermally and photochemically, are investigated by means of differential scanning calorimetry and thermally stimulated depolarisation currents. Even if both curing methods lead to the same material from a chemical point of view, important differences exist between the thermocured resin and the photocured resin in terms of molecular relaxation behaviour. 8 refs. 

The thermal glass-transition temperatures of poly(vinyl acetal)s can be determined by dynamic mechanical analysis, differential scanning calorimetry, and nmr techniques (31). The thermal glass-transition temperature of poly(vinyl acetal) resins prepared from aliphatic aldehydes can be estimated from empirical relationships such as equation 1 where OH and OAc are the weight percent of vinyl alcohol and vinyl acetate units and C is the number of carbons in the chain derived from the aldehyde. The symbols with subscripts are the corresponding values for a standard (s) resin with known parameters (32). The formula accurately predicts that resin T increases as vinyl alcohol content increases, and decreases as vinyl acetate content and aldehyde carbon chain length increases. 

Define thermal analysis, differential thermal analysis, differential scanning calorimetry, and ther-... 

Zaiss, K. and R. Jaenicke. 1999. Thermodynamic study of phosphoglycerate kinase from Thermotoga maritima and its isolated domains reversible thermal unfolding monitored by differential scanning calorimetry and circular dichroism spectroscopy. Biochemistry 38 4633 -639. 

Riga, A. and Collins, R. (2000). "Differential Scanning Calorimetry and Differential Thermal Analysis. Encyclopedia of Analytical Chemistry.". John Wiley and Sons, London. 

Brack, H.-P, Ruegg, D., Biihrer, H., Slaski, M., Alkan, S. and Scherer, G. G. 2004. Differential scanning calorimetry and thermogravimetric analysis investigation of the thermal properties and degradation of some radiation-grafted films and membranes. Journal of Polymer Science Part B Polymer Physics 42 2612-2624. 

A variety of techniques have been used to determine the extent of crystallinity in a polymer, including X-ray diffraction, density, IR, NMR, and heat of fusion [Sperling, 2001 Wunderlich, 1973], X-ray diffraction is the most direct method but requires the somewhat difficult separation of the crystalline and amorphous scattering envelops. The other methods are indirect methods but are easier to use since one need not be an expert in the field as with X-ray diffraction. Heat of fusion is probably the most often used method since reliable thermal analysis instruments are commercially available and easy to use [Bershtein and Egorov, 1994 Wendlandt, 1986], The difficulty in using thermal analysis (differential scanning calorimetry and differential thermal analysis) or any of the indirect methods is the uncertainty in the values of the quantity measured (e.g., the heat of fusion per gram of sample or density) for 0 and 100% crystalline samples since such samples seldom exist. The best technique is to calibrate the method with samples whose crystallinites have been determined by X-ray diffraction. 

Microwave spectroscopy indicates that aromaticity diminishes in the order 1,2,5-thia-diazole > thiophene > l,3,4-thiadiazole> l,2,5-oxadiazole> 1,2,4-oxadiazole <84CHEC-1(4)545, B-85MI 410-01>. The aromaticity of heterocycles has been discussed by Katritzky and Barczynski (90JPR885) and by Bird <94H(37)249>. The thermal stability of 2,5-substituted thiadiazoles (23) was studied by differential scanning calorimetry and shown to increase as the rt-contribution of the substituents becomes greater <89MI410-01>. 

Spectroscopy has become a powerful tool for the determination of polymer structures. The major part of the book is devoted to techniques that are the most frequently used for analysis of rubbery materials, i.e., various methods of nuclear magnetic resonance (NMR) and optical spectroscopy. One chapter is devoted to (multi) hyphenated thermograviometric analysis (TGA) techniques, i.e., TGA combined with Fourier transform infrared spectroscopy (FT-IR), mass spectroscopy, gas chromatography, differential scanning calorimetry and differential thermal analysis. There are already many excellent textbooks on the basic principles of these methods. Therefore, the main objective of the present book is to discuss a wide range of applications of the spectroscopic techniques for the analysis of rubbery materials. The contents of this book are of interest to chemists, physicists, material scientists and technologists who seek a better understanding of rubbery materials. 

Hipeaux, J. C., Born, M., Durand, J. R, Claudy, R, and Letoffe, J. M. 2000. Physico-Chemical Characterization of Base Stocks and Thermal Analysis by Differential Scanning Calorimetry and Thermomicroscopy at Low Temperature. Thermochim. Acta, 348,147-159. 

Baker, J. O., Tatsumoto, K., Grohmann, K., Woodward, I, Wichert, J. M., Shoemaker, S. R, and Himmel, M. E. 1992. Thermal denaturation of Trichoderma reesei Cellulases Studied by Differential Scanning Calorimetry and Tryptophan Fluorescence. Appl. Biochem. Biotechnol., 34/35, 217-231. 

The presence of cooperative motion of chain segments present in intercalated polymer chains can be examined using various analytical techniques such as Differential Scanning Calorimetry (DSC), thermally stimulated current (TSC) and dielectric spectroscopy. DSC measurements on an intercalated PEO, (Mw= 100,000)/montmorillonite hybrid (20 wt. % polymer), indicated the absence of... 

In this section, some case studies will be presented on the characterization of CMP pad and slurry [17-20] using such advanced analytical techniques as dynamic mechanical analysis (DMA), modulated differential scanning calorimetry (MDSC), thermal gravimetric analysis (TGA), thermal mechanical analysis (TMA), dynamic rheometry, dual emission laser induced fluorescence (DELIF), and the dynamic nuclear magnetic resonance (DNMR). More specifically, these techniques were used to characterize (a) the effect of heat... 

Labrooke BD, Williams RM, Chapman D. Studies on lecithin-cholesterol-water interactions by differential scanning calorimetry and x-ray diffraction. Biochim. Biophys. Acta 1968 150 333-340. Ladbrook BD, Jenkinson TJ, Kamat VB, Chapman D. Physical smdies of myelin. I. Thermal analysis. Biochim. Biophys. Acta 1968 164 101-109. 

Interest in the monomerization of anthracene photodimers continues the head-to-tail dimer (290) (see p. 361) produced by irradiation of 9-cyanoanthracene has been investigated by two groups. " From results of differential scanning calorimetry and emission spectroscopy of cleaved surfaces of partially monomerized single crystals, it is suggested that the first exothermic peak (and the subsequent ones) arises from monomer crystallization in the photodimer host matrix. " Theocharis and Jones have also examined this retroprocess and using single crystal X-ray techniques they have shown that the first step in the solid-state thermal monomerization of this dimer is a... 

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