Analysis Differential scanning calorimetri

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. 

The procedures of measuring changes in some physical or mechanical property as a sample is heated, or alternatively as it is held at constant temperature, constitute the family of thermoanalytical methods of characterisation. A partial list of these procedures is differential thermal analysis, differential scanning calorimetry, dilatometry, thermogravimetry. A detailed overview of these and several related techniques is by Gallagher (1992). 

Thermal Analysis - Differential Scanning Calorimetry (DSC) and thermal gravimetric analysis (TGA) were used to characterize the thermal properties of the polymers synthesized. DSC analysis was performed on a Perkin-Elmer Differential Scanning Calorimeter, Model 2C with a thermal analysis data station. Thermal gravimetric analysis (TGA) was carried out on a DuPont thermal gravimeter, Model 951. From the DSC and TGA plots of poly (N-pheny 1-3,4-dimethylene-... 

Most workers in the pharmaceutical field identify thermal analysis with the melting point, differential thermal analysis, differential scanning calorimetry,... 

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. 

Son and coworkers also reported the syntheses of hyperbranched poly(carbosilanes) via hydrosilylation. In one report, they prepared a series of AB3 carbosilarylene monomers (5, 6 and 7)173 which polymerized cleanly and rapidly to form soluble hyperbranched polymers in high yields. The polymers, ranging in appearance from sticky solids to oils, were characterized by NMR spectroscopy, thermogravimetric analysis, differential scanning calorimetry and vapor pressure osmometry. The polymers possessed subambient Tg... 

The microanalytical methods of differential thermal analysis, differential scanning calorimetry, accelerating rate calorimetry, and thermomechanical analysis provide important information about chemical kinetics and thermodynamics but do not provide information about large-scale effects. Although a number of techniques are available for kinetics and heat-of-reaction analysis, a major advantage to heat flow calorimetry is that it better simulates the effects of real process conditions, such as degree of mixing or heat transfer coefficients. 

Comparison of several techniques (namely Fourier transform infrared spectroscopy (FTIR), simultaneous thermogravimetric analysis-differential scanning calorimetry (TGA-DSC) and ultrasonic spectroscopy) for assessing the residual physical and mechanical characteristics of polymer matrix composites (PMCs) exposed to excessive thermal loads showed the measured power spectra of ultrasonic energy to correlate with performance of graphite fibre epoxy matrix composites exposed to thermal degradation, and also that analyses with the three techniques all pointed to the same critical temperature at which thermally induced damage increased sharply [58],... 

In this chapter, we report the results of a study of the synthesis of a more complete series of polymers, la-Ih, by the same low-temperature condensation polymerization reaction (equation 1), All these new polymers were characterized by NMR spectroscopy, gel permeation chromatography (GPC), thermal analysis (differential scanning calorimetry [DSC] and ther-mogravimetric analysis [TGA]), and elemental analysis. 

Loss on drying Karl Fischer titration Residue on ignition Thermogravimetric analysis Differential scanning calorimetry High-performance... 

SIMULTANEOUS THERMOGRAVIMETRIC ANALYSIS-DIFFERENTIAL SCANNING CALORIMETRY... 

Several samples of YBa2Cu307 x with controlled stoichiometries, 0.04 < x < 1.00, have been prepared and characterized by thermogravimetric analysis, differential scanning calorimetry, magnetic susceptibility and Meissner effect measurements. 

As has been noted for DTA analysis, differential scanning calorimetry can also be used to establish the melting points of polymorphic species. For example, gepirone hydrochloride has been obtained in three polymorphic forms, which were found to melt at 180°C, 200°C, and 212°C [92]. In this work, it was shown that Forms I and II, and Forms I and III, were enantiotropic pair systems, but that Forms II and III were monotropic with respect to each other. The two polymorphs of phenylephrine oxazolidine each exhibited well-defined melting... 

X-Ray Diffraction, Thermal Analysis (Differential Scanning Calorimetry, DSC, Thermogravimetric Analysis, TGA), and Micro-Eourier Transform Infrared Spectroscopy. 

Information on physical parameters of the molecular structure of polyamide fibers are usually obtained by x-ray diffraction methods, electron and light microscopies, infrared spectroscopy, thermal analyses such as differential thermal analysis, differential scanning calorimetry, and thermomechanical analysis, electron spin resonance, and nuclear magnetic resonance (NMR) spectroscopy. X-ray diffraction provides detailed information on the molecular and fine structures of polyamide fibers. Although the diffraction patterns of polyamide fibers show wide variation, they exhibit usually three distinct regions ... 

This book reviews in nine chapters the measurement of these properties in the main types of polymers in use today. Numerous techniques are discussed ranging from thermogravimetric analysis, differential scanning calorimetry, infrared and nuclear magnetic resonance based methods to pyrolytic techniques such as those based on pyrolysis, gas chromatography and mass spectrometry. 

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