Thennogravimetric

Fig. 15 Thennogravimetric weight loss-temperature profiles for the two dihydrate polymorphs of the experimental compound L-706000-001T. Upper plot type D lower plot type A.

Figure 7. Thennogravimetric curves of CF obtained with linear heating of NiC prepared by mixing. The catalyst and experimental conditions are identical to those given in the legend to Figure 6. The curve of DCP for the precipitated Ni/a-AI2O3 catalyst is marked by Pr .

Box 9.1 Thennogravimetric Analysis and Differential Scanning Calorimetry in the Study of Inclusion Compounds... 

Details can be found in Bellare (ref. 3). The experimental equipment consists of a cumene reservoir, a thennogravimetric analyzer (TGA) and a gas chromatograph (GC). The helium-cumene mixture enters the TGA, a Cahn System 113DC with a Cahn 2000 Recording Electrobalance, a quartz tubular reactor, and an external split-shell furnace. The catalyst is placed in the sample pan of the microbalance inside the quartz reactor, kept at a controlled temperature in the center of the split-shell furnace. The incremental weight due to coke deposition on the catalyst is monitored by an IBM PC. The reactor exit stream is injected into a Varian 3700 GC using FID. 

It is of interest that thennogravimetric analysis has been used as a means of determining end group purity of PMMA macromonomers formed by catalytic chain transfer. 

The reaction rate can be measured in various ways. In this study, Thennogravimetrical Analysis (TGA) in combination with Differential Scamiing Calometry (DSC) was used. Also tliis teclmique and tlie experimental method can influence the observed reaction rate. Tlie following parameters are of importance ... 

In conclusion, we have developed a new and effective method for the purification of SWNTs and MWNTs. The method involves acid washing followed by the high-temperature hydrogen treatment repeated twice. Excellent SWNTs containing little or no amorphous carbon and metal particles are obtained by this means, as verified by microscopy, XRD, and spectroscopic techniques. Equally importantly, thennogravimetric measurements of MWNTs and SWNTs show that the low-temperature weight loss due to amorphous carbon is eliminated after hydrogen treatment. In the case of laser SWNTs, the oxidation temperature is substantially increased after purification. 

Acid hydrolysis of chitosan followed by the HPLC detection of the amount of acetic acid liberated is able to give acetyl content of chitin/chitosan. Due to the high sensitivity, availability, easiness of method and effectiveness in detection of functional groups IR spectroscopy can give usefid information about the acetyl content of chitin/chitosan as well as possible cross-contaminations. The results of Differential Thennogravimetric Analysis (DTA) show increased thermostability compared to GlcNAc. Discussed biopolymer shows its main thermal process from 275 to 280 °C respectively. 

A plot of In F(C) versus /T yields the required slope d In F(C)/d T K This curve is nearly linear over the temperature intervals normally encountered in thennogravimetric decomposition analysis. Equation 3-26 is not a direct solution for the activation energy because d In p(j )/dr is a funciton of as well as of T. However by choosing a trial value of X (e. g. 40) a first approximation of E can be calculated using equation 3-26. Better values of E are then obtained by iteration of the same equation. The frequency (pre-exponential) factor A can be derived directly from equation 3-23 at each data point once E is known. 

Skala, D., Kopsch, H. et al. Thennogravimetrically and differential scanning calorimetri-cally derived kinetics of oil shale p5Tolysis. Fuel 66 (1987) p. 1185-1192. 

The thennogravimetric analysis curve of PBS reveals that this polyester shows weight loss of 5, 50, and 90% at 325,400, and 424°C, respectively, in air. It should be noted that this does not indicate that PBS polymer chains are thermally stable up to 325°C. On the contrary, PBS shows thermal degradation when extruded at 200°C, which is implied by the decrease of the shear viscosity with prolonged time. 

The packing of the sample is of importance if gases are evolved during the experiment because they may seriously affect the equilibrium. Questions of gas flow and convection effects should be addressed, and, if needed, eUminated by proper baffling. Noise in a thennogravimetric curve can often be attributed to irregular... 

The nature of this source of waste plasterboard means that some degree of impurities and contaminants is inevitable. Thermogravimetric analysis (TGA) of materials was carried out using a PerkinElmer Pyris 1 thennogravimetric analyser. The thermograph (Figure 3) confirms the presence of impurities in the PG. The loss of mass at >200° C implies the presence of a number of impurities and contaminants in the gypsum. 

FIGURE 15 The thennogravimetrical curves for the montmoriUonites, PET and nanocomposites PET/organoclay. 

Understanding the relationship between the molecular structure and the thermal stability (decomposition temperature and rate) of the organoclays and the subsequent influence on the stability of the polymer host is critical. Several analytical techniques have been used to determine the thermal stability of different organoclays and to indentify the decomposition products conventional and high-resolution thennogravimetric analysis (TGA) coupled with Fourier transform infrared spectroscopy (FITR) and mass spectrometry (MS), pyrolysis/gas chromatography (GC)-MS, and solid phase microextraction (SPME) [6-12]. 

Cone calorimeter tests were carried out at 35 or 50 kW/m heat flux with horizontal orientation of the samples [plates (100 x 100 x 3 mm) or cut cables] according to ASTM E1354. The data reported were the average of three measurements for each sample, with a standard uncertainty of the measured heat release rates of 5%. Thennogravimetric analyses were done under helium or airflow at a 20°C/min heating rate. 

Fig. 11 Thennogravimetric traces for TFSA anion based phosphonium and the corresponding ammonium RTILs...

F. 12 Thennogravimetric traces for dicyanamide anion based phosphonium and the eorresponding ammonium RTELs... 

Figure 23.11. TGA/FT-IR spectra obtained during the thennogravimetric analysis of PVC (a) after 13.61 min (trailing edge) and (b) 13.15 min (leading edge.) (c) Result of spectral subtraction of (b) from (a), giving the spectrum of HCl. (d) Result of spectral subtraction of (a) from (b), giving the spectrum of the phthalate plasticizer. (Reproduced ftom [52], hy permission of John Wiley Sons copyright 2002.)...

Rgure 16-11. Zinc loss rates for various sortients in a thennogravimetric reactor. [Gangwal, eteJ., 1991 At... 

Fig. 6.33 Differential thermal analysis (DTA) and derivative thennogravimetric analysis (DTG) for the sample (ZrSTAci) not calcined [33]...

Collett, G.W., Rand, B. 1980. Thennogravimetric investigation of the pyrolysis of pitch materials A compensation effect and variation in kinetic parameters with heating rate. Thermochim. Acta 41 153-165. 

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