Thennogravimetric analysis

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

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 ... 

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. 

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. 

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]. 

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.)...

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

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. 

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. 

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