Thermal stability thermogravimetric analysis

The ability of polymers to withstand elevated temperatures is critical to many applications. For example, the excellent thermal stability of polysiloxanes is the basis for many of their uses, including their application in low molecular weight 

Alper and G. L. Nelson, Polymeric Materials Chemistry for the Future, American Chemical Society, Washington, DC, 1989. 

Allcock and R. West, Inorganic Polymers, 2nd edn., Oxford University Press, New York, 2005. 

Sperling, Introduction to Physical Polymer Science, Wiley, New York, 2001. 

Allcock, F. W. Lampe and J. E. Mark, Contemporary Polymer Chemistry, 3rd edn., Pearson/Prentice Flail, Upper Saddle River, NJ, 2003. 

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A variation of these methods, in which the volume of gas evolved in a vacuum at a fixed temperature is measured, is also in common use. This approach is particularly useful when treating long-term, relatively mild thermal effects and the compatibility of explosives with other materials. Still other techniques for determining thermal stability are differential thermal and thermogravimetric analysis. These are coming into more common use, but are not yet standardized with respect to the explosive azides. 

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. 

In most of the studies discussed above, except for the meta-linked diamines, when the aromatic content (dianhydride and diamine chain extender), of the copolymers were increased above a certain level, the materials became insoluble and infusible 153, i79, lsi) solution to this problem with minimum sacrifice in the thermal properties of the products has been the synthesis of siloxane-amide-imides183). In this approach pyromellitic acid chloride has been utilized instead of PMDA or BTDA and the copolymers were synthesized in two steps. The first step, which involved the formation of (siloxane-amide-amic acid) intermediate was conducted at low temperatures (0-25 °C) in THF/DMAC solution. After purification of this intermediate thin films were cast on stainless steel or glass plates and imidization was obtained in high temperature ovens between 100 and 300 °C following a similar procedure that was discussed for siloxane-imide copolymers. Copolymers obtained showed good solubility in various polar solvents. DSC studies indicated the formation of two-phase morphologies. Thermogravimetric analysis showed that the thermal stability of these siloxane-amide-imide systems were comparable to those of siloxane-imide copolymers 183>. 

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). 

Ando and co-workers have reported the synthesis of a silyl-carborane hybrid diethynylbenzene-silylene polymer (108) (Fig. 66) possessing high thermal stability.136 The polymer contained Si and —C=C— group in the main chain and m-carborane and vinyl groups in the side chain. The 5% weight-loss temperature of the cured polymer in air was over 1000°C as determined by thermogravimetric analysis. 

Three flame retardants were compared in this study, namely, a brominated polycarbonate oligomer (58% bromine), a brominated polystyrene (68% bromine), and a brominated triaryl phosphate ester (60% bromine plus 4% phosphorus). These are described in Table I. Figures 1 and 2 compare the thermal stability of the brominated phosphate with commercial bromine-containing flame retardants by thermogravimetric analysis (TGA) and by differential scanning calorimetry (DSC). The brominated phosphate melts at 110°C and shows a 1% weight loss at 300°C. Brominated polycarbonate and brominated polystyrene are polymeric and are not as volatile at elevated temperatures as the monomeric flame retardants. 

Generally, fluorene homo- and copolymers show excellent thermal stability the Tdec of many PF exceeds 400°C (according to thermogravimetric analysis (TGA) analysis under inert atmosphere) [224]. 

Thermal stabilities were assessed by thermogravimetric analysis (TGA). Samples were held at constant temperature (290°C) for 1 h in air in a Perkin-Elmer TGA. Much of the weight loss, particularly for Kel-F 6060, is suspected to be emulsifier used during polymerization. 

Thermogravimetric analysis In thermogravimetric analysis (TGA) a sensitive balance is used to follow the weight change of the sample as a function of temperature. Its applications include the assessment of thermal stability and decomposition temperature, extent of cure in condensation polymers, composition and some information on sequence distribution in copolymers, and composition of filled polymers, among many others. 

Fig Relative thermal stability of polymers as determined by weight loss on heating at 5°C/min in nitrogen in thermogravimetric analysis. 

The thermal stability of these materials was examined by thermogravimetric analysis (TGA) and IR spectroscopy. As anticipated from their structures, the thermal properties of these polymers are far superior to those found in a typical diazoketone/phenolic resin resist. TGA (in air) of the material depicted in Scheme II shows that the polymer does not change in weight up to a temperature of 300°C. 

Thermogravimetric analysis, though not necessarily indicative of all high temperature properties, is a convenient way to indicate the degree of thermal reaction occurring at a particular temperature. The thermal stability of polyimides has been the subject of many studies (10). Our results obtained from free films of 1-2 mils are shown in Fig. VII and are in agreement with Heacock and Berr(ll). Since 1-2 mil films are not used here, we decided to study the thermal degradation of... 

The long-term operation of a continuous reaction process with catalyst recovery requires a catalyst with very good thermal stability. Unfortunately the tetra(n-alkyl) ammonium iodides which have good solubility properties also have poor thermal stability due to breakdown by dealkylation. This was observed during operation of the continuous process and in thermal analysis. Thermogravimetric... 

Improved heat-resistant UV compositions for optical fiber applications These compositions are nonurethane UV cure compositions that have neither carbamate moieties nor long-chain poly(alkylene oxide) soft segments and exhibit inherently better thermal stability measured by thermogravimetric analysis (TGA) than typical coatings for optical fibers based on urethane acrylate oligomers. 

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