Thermogravimetric Analysis TGA

TGA was performed using an SDT 2960 TGA-DTA instrument, in a atmosphere, at a heating rate of 10°C.min from 30 to 600°C to obtain derivative curves (DTG) for composites and fibers. 

TGA apparatus is equipped with a microfumace, which can be rapidly cooled. The heating element is made of platinum (reliable up to 1000 °C). An external furnace with a heating element made of an alloy of platinum and 30% rhodium can extend the temperature range to 1500 °C. 

A modern apparatus is usually equipped with a computer that can calculate the weight-loss fraction or percentage. A commercial TGA is capable of 

org/home.html, UK Surface Analysis Forum, 1998. 

University of Alberta, Center for Surface Engineering and Science, www.ualberta.ca/ACSES/ ACSES3/ Techniques/iss.htm (2003). 

Chan CM. Polymer Surface Modification and Characterization. Munich Hanser Publishers 1994. 

A modem apparatus is usually equipped with a computer that can calculate the weight loss fraction or percentage. A commercial TGA is capable of greater than 1,000°C, 0.1 pg balance sensitivity and variable controlled heat-up rate under an atmosphere of air or another gas. The heat-up rate capability of TGA can vary from 0. l°C-200°C/min. 

This technique is useful in the analysis of compounded plastic samples. It is possible to obtain accurate quantifications of the principal compound constituents such as plasticiser, polymer and inorganic species. This data can be obtained on small (e.g., 10 mg) samples in a relatively short time (around 45 minutes). By the use of the temperature maxima at which weight events occur it is also possible to use the technique to obtain some qualitative assignments for the plasticiser and polymer. 

Heat from ambient to 550 °C in a nitrogen atmosphere at 20 °C/min until no further weight loss occurs. Then, reduce the heat to 300 °C, change the atmosphere to air and heat at 20 °C/min to 1,000 °C. 

It is common to plot the weight loss derivative in conjunction with the weight loss, and this can be used to detect the presence of a polymer blend of two or more components. Thermal decomposition temperatures of a range of plastics are shown in Table 3. 

DMTA results for (a) crosslinked and (b) standard grades of PMMA 

Other uses for the technique include the production of compositional fingerprints for quality control purposes and the investigation of thermal stability and the effects that additives such as flame retardants and antioxidants have on it. 

In general, the thermogravimetric Analysis (TGA) gives valuable information about the thermal stability and behaviour of materials. Moreover, information like composition or weight percentage can be determined using TGA. 

In general, a good correlation between TGA curves and OMt morphology can be obtained. This makes TGA very useful in the characterization of OMts. 

Thermal stabdity data was obtained using the TGA Q500 (TA instruments) thermogravimetric analyzer imder linear temperature conditions. The samples were heated in platinum crucibles within the temperature range 35-600°C at a rate of 10°C/min in a nitrogen atmosphere. 

This method measures the weight of a substance heated at a controlled rate as a function of time or temperature. To perform the test, a sample is hung from a balance and heated in the small furnace on the TGA unit according to a predetermined temperature program. As all materials ultimately decompose on heating, and the decomposition temperature is a characteristic property of each material, TGA is an excellent technique for the characterization and quality control of materials (Figs. 10-15 and 10-16). 

Properties measured include thermal decomposition temperatures, relative thermal stability, chemical composition, and the effectiveness of flame retardants. TGA also is commonly used to determine the filler content of many thermoplastics. 

A typical application of TGA is its use in compositional analysis. For example, a particular polyethylene part contained carbon black and a mineral filler. The electrical properties were important in the use of this product and could be affected by the carbon black content. TGA was used to determine the carbon black content and mineral-filler content for various lots, which were considered either acceptable or unacceptable. The samples were heated in nitrogen to volatilize the PE, leaving carbon black and a mineral-filler residue. The carbon content was then determined by switching to an 

This system measures dimensional changes as a function of temperature. The dimensional behavior of a material can be determined precisely and rapidly with small samples in any form—powder, pellet, film, fiber, or molded part. The parameters measured by thermomechanicai analysis are the coefficient of linear thermal expansion, the glass-transition temperature (Fig. 10-17), softening characteristics, and the degree of cure. Other applications of TMA include the taking of compliance and modulus measurements and the determination of deflection temperature under load. 

Tensile-elongation properties and the melt index can he determined by using small samples such as those cut directly from a part. Part uniformity can be determined by using samples taken from several areas of the molded part. Samples also can be taken from an area where failure has occurred or continues to occur. This permits comparisons of material properties in a failed area with properties measured either at an unfailed section or from a sample of new material. Samples also may be taken from within a material blend to ensure that a uniform blend is being supplied. The results of such testing can be used either for evaluation of part failure or in the acceptance testing of incoming materials or parts. 

6 THERMAL AND ENVIRONMENTAL STABILITY MEASUREMENTS 11.6.1 Thermogravimetric Analysis (TGA) 

Thermogravimetric Analysis (TGA), a monitoring of the weight loss of a sample with increasing temperature under air, N2 or other enviroiunents, is perhaps the simplest and most direct method yielding thermal stability data on CPs. TGA behavior in air and in inert gas is found to differ considerably, and the first decomposition mode in most CPs is thought to be dopant loss or decomposition. 

11-17 TGA of (A) Z-N polyacetylene, (B) polyacetylene prepared using AsF, and (C) polyacetylene prepared using AsFj/AsFj. After Reference [405], reproduced with permission. 

Woo and co-workers [8] also applied DSC to the determination of the OIT of PF stabilised with a hindered phenol antioxidant and a phosphite synergist. 

Polymers generally exhibit mass loss, although mass gain may be observed prior to degradation at slow heating rates in an oxidizing atmosphere (see 

Thermal Analysis of Polymers Fundamentals and Applications, Edited by Joseph D. Menczel and R. Bruce Prime 

In this chapter we present background principles of thermogravimetric analysis and the various measurement modes issues associated with and recommendations for calibration measurement and analysis methods for characterizing polymeric materials, including recommendations for how to perform a TGA experiment and kinetics. At the end of the chapter we present selected applications of actual industrial problems where TGA has been instrumental in their solution. 

In thermogravimetry, the mass of a sample, or the change in its mass is monitored as a function of temperature or time and displayed in a thermogram. Either the temperature is varied in a controlled manner and a mass/temperature thermogram is obtained, or in isothermal studies, the temperature is kept constant and the mass/time plot is displayed. The loss of mass results from the loss of volatile or gaseous products whereas a mass 

The main processes which can be studied are loss of water of crystallisation, thennal decomposition, oxidation and desorption. Qualitatively, the identity of a sample can be confirmed by comparing its thermogram with that of a standard sample. In some decomposition reactions, an intermediate can be established from an inflection in the thermogram e.g. 2CUO.SO3 in the thermogram of CUSO4.5H2O. Limited quantitative analyses have been done e.g. a mixture of the oxalates of Ca, Sr and Ba which decompose at different temperatures. 

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The process known as transimidization has been employed to functionalize polyimide oligomers, which were subsequentiy used to produce polyimide—titania hybrids (59). This technique resulted in the successhil synthesis of transparent hybrids composed of 18, 37, and 54% titania. The effect of metal alkoxide quantity, as well as the oligomer molecular weight and cure temperature, were evaluated using differential scanning calorimetry (dsc), thermogravimetric analysis (tga) and saxs. 

The definition of polymer thermal stabiUty is not simple owing to the number of measurement techniques, desired properties, and factors that affect each (time, heating rate, atmosphere, etc). The easiest evaluation of thermal stabiUty is by the temperature at which a certain weight loss occurs as observed by thermogravimetric analysis (tga). Early work assigned a 7% loss as the point of stabiUty more recentiy a 10% value or the extrapolated break in the tga curve has been used. A more reaUstic view is to compare weight loss vs time at constant temperature, and better yet is to evaluate property retention time at temperature one set of criteria has been 177°C for 30,000 h, or 240°C for 1000 h, or 538°C for 1 h, or 816°C for 5 min (1). 

Mixtures can be identified with the help of computer software that subtracts the spectra of pure compounds from that of the sample. For complex mixtures, fractionation may be needed as part of the analysis. Commercial instmments are available that combine ftir, as a detector, with a separation technique such as gas chromatography (gc), high performance Hquid chromatography (hplc), or supercritical fluid chromatography (96,97). Instmments such as gc/ftir are often termed hyphenated instmments (98). Pyrolyzer (99) and thermogravimetric analysis (tga) instmmentation can also be combined with ftir for monitoring pyrolysis and oxidation processes (100) (see Analytical methods, hyphenated instruments). 

Thermal analysis using differential scanning calorimetry (dsc), thermogravimetric analysis (tga), and differential thermal analysis (dta) can provide useful information about organic burnout, dehydration, and decomposition. 

Thermogravimetric analysis (TGA) Onset temperature of weight loss... 

This phenomenon can be demonstrated by both measuring the changes of the thermal properties of the ECA homopolymer and in adhesion tests. The addition of only 1 wt.% of 9 to a sample of the ECA homopolymer significantly increases the onset of decomposition in the thermogravimetric analysis (TGA) of the polymer, as seen in Fig. 9 [29]. 

Thermogravimetric analysis (TGA) 97 Three-phase fluidization studies. . 156... 

Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) are also very useful tools for the characterization of polymers. TGA and DSC provide die information about polymer stability upon heating and thermal behaviors of polymers. Most of the polymers syndiesized via transition metal coupling are conjugated polymers. They are relatively stable upon heating and have higher Tgs. 

Thermal stability is a crucial factor when polysaccharides are used as reinforcing agents because they suffer from inferior thermal properties compared to inorganic fillers. However, thermogravimetric analysis (TGA) of biocomposites suggested that the degradation temperatures of biocomposites are in close proximity with those of carbon black composites (Table-1). 

When solids react, we would like to know at what temperature the solid state reaction takes place. If the solid decomposes to a different composition, or phase, we would like to have this knowledge so that we can predict and use that knowledge In preparation of desired materials. Sometimes, intermediate compounds form before the final phase. In this chapter, we will detail some of the measurements used to characterize the solid state and methods used to foUow solid state reactions. This will consist of various types of thermal analysis (TA), including differentlEd thermal analysis (DTA), thermogravimetric analysis (TGA) and measurements of optical properties. 

Thermogravimetric analysis (TGA) measures changes in weight of a sample being heated. A typical Thermogravimetric analysis (TGA) apparatus is shown in the following diagram ... 

Typical characterization of the thermal conversion process for a given molecular precursor involves the use of thermogravimetric analysis (TGA) to obtain ceramic yields, and solution NMR spectroscopy to identify soluble decomposition products. Analyses of the volatile species given off during solid phase decompositions have also been employed. The thermal conversions of complexes containing M - 0Si(0 Bu)3 and M - 02P(0 Bu)2 moieties invariably proceed via ehmination of isobutylene and the formation of M - O - Si - OH and M - O - P - OH linkages that immediately imdergo condensation processes (via ehmination of H2O), with subsequent formation of insoluble multi-component oxide materials. For example, thermolysis of Zr[OSi(O Bu)3]4 in toluene at 413 K results in ehmination of 12 equiv of isobutylene and formation of a transparent gel [67,68]. 

Figure 6. Thermogravimetric analysis (TGA) of free 55 K PVP and 7.1 nm Pt-PVP nanoparticles in oxygen. Oxidative decomposition of free PVP begins at 573K, while significant weight loss due to the catalyzed oxidation of PVP on PVP-protected Pt nanoparticles occurs at 473 K. It appears that PVP layer is not a complete monolayer or the entanglement of PVP chains causes a porous polymer layer enabling oxygen diffusion to the nanoparticle surface [17]. (Reprinted from Ref [17], 2006, with permission from Springer.)...

Figure 10. Thermogravimetric analysis (TGA) of various syndiotactic polytalkyl methacrylates) PMMA, methyl PEMA, ethyl PIPMA, isopropyl PTBMA. t-butyl.

Thermogravimetric analysis (TGA), poly(alkyl methacrylates), 270,273/ Toluene... 

Thermal Properties. The glass transition temperature (Tg) and the decomposition temperature (Td) were measured with a DuPont 910 Differential Scanning Calorimeter (DSC) calibrated with indium. The standard heating rate for all polymers was 10 °C/min. Thermogravimetric analysis (TGA) was performed on a DuPont 951 Thermogravimetric Analyzer at a heating rate of 20 °C/min. 

Thermogravimetric analysis (TGA) of these poly(phosphazenes) shows their decomposition onset temperatures in an inert atmosphere to be ca. 350 to 400°C, depending on the side group. These temperatures are ca. 25-75°C higher than that reported for commercial materials based on the fluoroalkoxy substituted polymer, [(CFgCHjO PN],. (19) Interestingly, methyl rather than phenyl side groups yield the more stable materials, as shown by... 

First-order phase transitions can be detected by various thermoanalytical techniques, such as DSC, thermogravimetric analysis (TGA), and thermomechanical analysis (TMA) [31]. Phase transitions leading to visual changes can be detected by optical methods such as microscopy [3], Solid-solid transitions involving a change in the crystal structure can be detected by X-ray diffraction [32] or infrared spectroscopy [33], A combination of these techniques is usually employed to study the phase transitions in organic solids such as drugs. 

In a study on the thermal and UV ageing of two commercial polyfoxymethy-lene) (POM) samples, one of which was a copolymer (see related study discussed later under Section 4.3, thermogravimetric analysis (TGA)), used in car interior applications, involving both DSC and TGA, isothermal OIT measurements were made at several different temperatures [8]. One conclusion from this study was that "extrapolation of the OIT data from high temperatures (molten state) to ambient temperatures in the solid state does not reflect effective antioxidant performance at room temperature", and thus measurements close to the melting point are not appropriate for reliable lifetime estimations. 

High performance liquid chromatography (HPLC) and with mass spectrometry (LC-MS) Plasma emission spectroscopy (PES) Scanning electron microscopy (SEM) with elemental X-ray analysis Thermogravimetric analysis (TGA)... 

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