Additive analysis differential scanning calorimetry

The modified NBR samples were characterized by differential scanning calorimetry [11,78-80,98]. The glass-transition temperature (T ) decreased with the level of hydrogenation. In the case of HFNBR, Tg increased with an increase in the addition of aldehyde groups to the polymer chain. Thermogravimetric analysis of the modified polymers have also been carried out [15]. 

It was recognized quite some time ago that DTA analysis could be used to deduce the compatibility between a drug substance and its excipients in a formulation. The effect of lubricants on performance was as problematic then as it is now, and DTA proved to be a powerful method in the evaluation of possible incompatibilities. Jacobson and Reier used DTA to study the interaction between various penicillins and stearic acid [17]. For instance, the addition of 5% stearic acid to sodium oxacillin monohydrate completely obliterated the thermal events associated with the antibiotic. Since that time, many workers employed DTA analysis in the study of drug-excipient interactions, although the DTA method has been largely replaced by differential scanning calorimetry technology. 

In another study, thermodiffractometry was used to study phase transformations in mannitol and paracetamol, as well as the desolvation of lactose monohydrate and the dioxane solvatomorph of paracetamol [56]. The authors noted that in order to obtain the best data, the heating cycle must be sufficiently slow to permit the thermally induced reactions to reach completion. At the same time, the use of overly long cycle times can yield sample decomposition. In addition, the sample conditions are bound to differ relative to the conditions used for a differential scanning calorimetry analysis, so one should expect some differences in thermal profiles when comparing data from analogous studies. 

Thermal analysis is a group of techniques in which a physical property of a substance is measured as a function of temperature when the sample is subjected to a controlled temperature program. Single techniques, such as thermogravimetry (TG), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), dielectric thermal analysis, etc., provide important information on the thermal behaviour of materials. However, for polymer characterisation, for instance in case of degradation, further analysis is required, particularly because all of the techniques listed above mainly describe materials only from a physical point of view. A hyphenated thermal analyser is a powerful tool to yield the much-needed additional chemical information. In this paper we will concentrate on simultaneous thermogravimetric techniques. 

An additional insight into the contribution of various interactions for protein stability and rigidity may be gained by a comparative data analysis of the differential scanning calorimetry (DSC) of the hyperthermostable and mesophilic enzymes. Accordingly, the... 

A recent study on the stability of various indium alkyl derivatives has been performed using differential scanning calorimetry (DSC), which provides a comprehensive thermal fingerprint of the compounds. In addition, when this method of thermal analyses is used in conjunction with thermogravimetric analysis coupled to FTIR and/or GCMS evolved gas analysis, it can provide a complete mechanism for the decomposition pathway of prospective compounds. ... 

Differential scanning calorimetry usually involves heating and/or cooling samples in a controlled manner, whereas microcalorimetry maintains a constant sample temperature. The DSC instruments are considered to be part of the Thermal Analysis armamentarium for additional information, the reader should refer to the Thermal Analysis section of this Encyclopedia. 

Differential scanning calorimetry (DSC), X-ray diffraction (XRD), and infrared spectroscopy are the common techniques used in the characterization of the structure of the congealed solid. Thermal analytic methods, such as DSC and differential microcalorimetric analysis (DMA), are routinely used to determine the effect of solutes, solvents, and other additives on the thermomechanical properties of polymers such as glass transition temperature (Tg) and melting point. The X-ray diffraction method is used to detect the crystalline structure of solids. The infrared technique is powerful in detecting interactions, such as complexation, reaction, and hydrogen bonding, in both the solid and solution states. 

Thermal analysis techniques (differential thermal analysis (DTA), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and evolved gas analysis (EGA)) provide qualitative, semiquantitative, and in special cases, quantitative measurements of the energetic evolution of nanophase materials on heating. Variation of the heating rate and the atmosphere surrounding the sample provide additional information. Some examples are given below in the context of specific systems. 

Based on the structure-related addition schemes for the thermal properties, it should, for example, be possible to quantitatively generate differential scanning calorimetry curves for polymers, copolymers and their mixtures. With easy access to the data bank, it should be possible for thermal analysts to compare their newly measured DSC curves with the computer generated standard curves for on-line analysis of macromolecules. 

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