DTGS

South Lake Tahoe 1 methanol Intemafional/Navistar DTG-460... 

DTGS = deuterated triglycine sulfate KRS — 5 = mixed thallium bromide-iodide LT = lithium tantalate MCT = mercury cadmium telluride and OPO = optical parametric oscillator. 

Thermoanalytical method is one of the widespread methods of physical and chemical reseai ches. Considerably broadens its possibilities combination with methods differential-thermal (DTA), differential-thermogravimetric (DTG), thermogravimetric (TG) analyses. 

The two complicating factors that are encountered most frequently are the linearity of detector response and stray light scattering at low signal levels. DTGS... 

Diverse thermogravimetric results can be obtained from samples with different pre-histories for example, TG and DTG curves showed that magnesium hydroxide prepared by precipitation methods has a different temperature of decomposition from that for the naturally occurring material.32 It follows that the source and/or the method of formation of the sample should be ascertained. 

FIGURE 3.26 TGA (under nitrogen) and DTG plots of cross-linked rubber-silica hybrid nanocomposites (a) and (b) TGA and DTG plots of acrylic rubber (ACM)-silica and (c) and (d) TGA and DTG plots of epoxidized natural rubber (ENR)-silica. (From Bandyopadhyay, A. and Bhowmick, A.K., Plastic Rubber Comp. Macromol. Eng., 35, 210, 2006. Courtesy of Maney Publishers.)... 

The thermo-gravimetric (TG) and differential thermo-gravimetric (DTG) curves of the gingko nut shell are shown in Fig. 2 where the moisture losses take place up to 200°C followed by the pyrolysis reaction. Then, the major weight loss due to the main degradation occurs at around 360°C. This zone is referred to as the active pyrolysis zone where the evolution of volatile compounds occurs during decomposition of the primary hemi-cellulose and cellulose [5]. 

The equilibrium relationships found by Sorrell (1977) were valid only for room temperature (22+2 °C) and, because samples were allowed to cure in sealed containers, for equilibrium water vapour pressures determined by the assembly of phases present. The phases which exist under such conditions were quite unequivocally found to be 4 1 5 and 1 1 2. However Sorrell pointed out that it is entirely possible that lower hydration states of either phase could be stable at higher temperatures or lower humidities. In particular the 4 1 4 phase (Feitknecht, 1933) may well be such a phase, particularly as one of the five waters of hydration is known to be held only loosely in the structure. Indeed, Sorrell reported that he observed a slight shoulder on the larger dehydration peak of the DTG curve of the 4 1 5 phase that might be assigned to the loss of this first water molecule. He did not, however, succeed in isolating or characterizing a 4 1 4 phase. 

FTIR instrumentation is mature. A typical routine mid-IR spectrometer has KBr optics, best resolution of around 1cm-1, and a room temperature DTGS detector. Noise levels below 0.1 % T peak-to-peak can be achieved in a few seconds. The sample compartment will accommodate a variety of sampling accessories such as those for ATR (attenuated total reflection) and diffuse reflection. At present, IR spectra can be obtained with fast and very fast FTIR interferometers with microscopes, in reflection and microreflection, in diffusion, at very low or very high temperatures, in dilute solutions, etc. Hyphenated IR techniques such as PyFTIR, TG-FTIR, GC-FTIR, HPLC-FTIR and SEC-FTIR (Chapter 7) can simplify many problems and streamline the selection process by doing multiple analyses with one sampling. Solvent absorbance limits flow-through IR spectroscopy cells so as to make them impractical for polymer analysis. Advanced FTIR... 

DTGS Deuterated triglycine sulfate EN Electronic nose... 

The source is usually a temperature-stabilized ceramic filament operating around 1500K. The detector in FTIR is usually a deuterium triglycine sulphate (DTGS) detector, although in RAIRS experiments the liquid nitrogen-cooled mercury cadmium telluride (MCT) detector is employed. 

Figure 27 (a) Thermogravimetry (TG) and derivative TG (DTG) curves of poly(bisphenol-A-carbonate) (PC) (b) total ion current (TIC) DPMS of PC. Reprinted with permission from Puglisi et al. [69]. Copyright 1999, American Chemical Society. 

The derivative DTG curves shown in the inset represent the degradation rates. Reprinted from Archodoulaki et al. [107]. Copyright 2004, with permission from Elsevier. 

The parent siliceous materials of the SBA-15 and MLV types were synthesised after typical procedures [2], The carbon replicas were prepared via polymerisation, catalysed by ferric chloride, of pyrrole introduced into the mesopores of matrices [3]. The products were characterised by the nitrogen adsorption, TEM, and thermal analysis (DTG, DTA). The nitrogen content in carbons was determined using elemental analysis, XPS, and EDX, while the Si and Fe contents, with XPS. The replicas of SBA-15 and MLV-0.75 are denoted as CMK-3Nx and OCM-.Nx, respectively, were x refers to the number of g of FeCl3 per 1 g of silica used for preparations. 

The DTG and DTA curves for CMK-3N1.25, CMK-3N2.00, OCM-.NO.25 and OCM-.N0.75 reveal two peaks in the 600-800 K range, which indicates two kinds of carbons of different graphitisation levels in these samples. The CMK-3 material does not bum up totally (Table 1). It may be due to extra-skeleton siliceous fragments possibly present in large cylindrical pores of SBA-15 and/or to iron species trapped in the carbon products. 

In case of CMK-3N2.00 and OCM-.NO.25, the areas under the second peak of the DTA curves are much smaller than the areas under the first peak, although they correspond to similar mass losses reflected in the DTG curves. Presumably, burning up of carbon more strongly bound to the siliceous skeleton is more difficult and some carbon may remain unbumt, trapped between siliceous layers. 

The TG analysis for pure PP proves a steep weight loss with a maximum in the DTG curve placed at 520 °C, which corresponds with the thermal degradation of this polyolefin. Fig 1 and 2 show TG analysis of PP/H-ZSM5 and PP/Ti-MCM41 catalyst mixture with 10 % catalyst content. 

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