Thermal volatilization analysis

The characterization of the physical and chemical changes that occur in montmorillonite/PDMS nanocomposite elastomers as they are thermally aged is reported. Broadband Dielectric Spectroscopy (BDS) was used to track changes in the physical interaction between the polymer and clay associated with increases in non-oxidative thermal stability (as determined by TGA). The evolution of volatile siloxane species from the elastomers was characterized with Thermal Volatilization Analysis (TVA). Results suggest that the improved thermal stability and the increases in polymer/clay association are a result of significant re-structuring of the polymer network. 

Thermal volatilization analysis (TVA) A pyrolysis technique in which the pressure of... 

Thermal volatilization analysis (TVA) of blends or mixtures of PP and poly(methyl methacrylate) (PMMA) reveals that the PMMA component tends to be stabilized and the PP destabilized. Pre-Irradlatlon of blends strongly suppresses the yield of monomeric methyl methacrylate but methyl methacrylate units appear In the chain fragment fraction. 

Figure 5 compares Thermal Volatilization Analysis (TVA) thermograms for unlrradlated and preirradiated polypropylene. The lack of coincidence of the traces In each thermogram Indicates a... 

The degradation behaviour of polymethylmethacrylate is easily characterized by thermal volatilization analysis [87] (Fig. 29). Monomer is obtained in very high yield in all cases. A polymer sample prepared by a free radical reaction undergoes a rapid depolymerization at about 275°C as indicated by the first peak. The second peak, situated between 350 and 400°C, corresponds to a second mode of initiation of chain depolymerization. For samples prepared by anionic polymerization, the first peak is not observed. Depolymerization of the whole sample occurs above 350°C. 

A thermal volatilization analysis of polyvinylacetate degradation has been reported by Gardner and McNeill [200] (Fig. 54). Two maxima are observed at 322 and 435°C. The Pirani gauge situated after the 0°C trap responds to all volatile products, while the gauge situated after the —196°C trap responds only to non-condensable gases. Infrared analysis has shown the presence of carbon monoxide and methane in this last fraction. The... 

Fig. 54. Thermal volatilization analysis for polyvinylacptate. 100 mg film sample, 5 degCmin-1 1200].

The rates of production of volatile material from polyvinylacetate, polyvinylchloride and vinylacetate vinylchloride copolymers, covering the entire composition range, have been compared by thermal volatilization analysis. It has been found that, at both extremes of the composition range, incorporation of the comonomer unit induces de-stabilization. Minimum stability occurs for composition of approximately 40—50 mole % vinylacetate. The rate of volatilization as a function of the composition of the copolymers is given in Fig. 74. The results were confirmed by a study of the thermal degradation in tritolylphosphate solution. The stability of the copolymers is a minimum at 30—40 mole % vinylacetate. HC1 and acetic acid catalyse the degradation of the... 

The thermal volatilization analysis of a mixture of polyvinylchloride and polystyrene is given in Fig. 81. The first peak corresponds to the elimination of HC1 and the second to that of styrene. Dehydrochlorination is retarded in the mixture. The production of styrene is also retarded styrene evolution, in fact, does not occur below 350°C. This contrasts with the behaviour of polyvinylchloride-polymethylmethacrylate mixtures for which methacrylate formation accompanies dehydrochlorination. The observed behaviour implies that, if chlorine radical attack on polystyrene occurs, the polystyrene radicals produced are unable to undergo depolymerization at 300° C. According to McNeill et al. [323], structural changes leading to increased stability in the polystyrene must take place. This could also occur by addition of Cl to the aromatic ring, yielding a cyclohexadienyl-type radical which is unable to induce depolymerization of the styrene chain. 

Thermal volatilization analysis EGA (51) Pirani gauge used for pressure measurement... 

Special identification detectors Thermal conductivity detector Thermal energy analyzer Temperature-programmed reduction Thermoparticulaie analysis Thermal volatilization analysis Thin-layer chromatography Titrimetry Volume changes... 

Troare et al. [162] performed thermogravimetric analysis of emeraldine hydrochloride under high vacuum in conjunction with thermal volatilization analysis. The initial weight loss was attributed to the... 

One model of the above-mentioned Derivatograph (Hungarian Optical Works, Budapest) is designed for collecting and analyzing the decomposition products with the advantage of simultaneous monitoring of the TG, DTG and DTA curves (the technique is named thermal volatilization analysis TVA). 

Grassie and McGuchan (1970-72) [176-184], using TGA, DTA, TVA (thermal volatilization analysis) and IR, carried out a series of pyrolysis investigations on powder forms of PAN and substituted PAN polymers in order to determine the effect of introducing various copolymers. 

Thermal volatilization analysis (pyrolysis analysis, TVA) n. Ramp heating of a plastic with passage of the evolved volatiles through one or more chemical detectors, sometimes with intervening, controlled-temperature, vapor-condensing traps. TVA is a powerful technique when coupled with thermogravimetric analysis. 

Thermal Volatilization Analysis. While tgahas been one of the most popular techniques for studying kinetics of pol5mier thermolysis, thermal volatilization analysis (tva) has been a popular method of studying product distribution (see eg. Ref 38). Despite its utility no commercial tva instrument has been produced. 

Apparatus and experimental techniques have been discussed in several papers. The techniques include thermal volatilization analysis," pyrolysis-gas chromatography, pyrolysis-molecular weight chromatography-i.r. spectrophotometry, and pyrolysis-mass spectrometry. Methods have also been described for collecting and separating pyrolysis products. - ... 

The thermal degradation of poly(vinyl bromide), of blends of this polymer with polyfmethyl methacrylate) and of the copolymer of vinyl bromide and methyl methacrylate have been investigated by sub-ambient thermal volatilization analysis and thermogravimetry. The results are discussed in relation to the use of the vinyl bromide unit as a Are retardant. 

With respect to apparatus, the design and operation of a sub-ambient thermal volatilization analysis (TVA) system has been described. A technique, which is essentially TVA, has also been used for the qualitative and quantitative analysis of trace amounts of volatiles produced during polymer degradation. A pyrolytic mass spectrometric method has also been developed which gives information on the yield of volatile degradation products, on their nature and on the kinetics of their formation. 

The volatile products from the decomposition of blends of polystyrene with polybutadiene have been examined by thermal volatilization analysis. Compared with the pure homopolymers there was no change in the nature of the degradation products, but the rate of polystyrene degradation was markedly reduced. The polybutadiene broke down first and its decomposition products diffused into and inhibited the subsequent breakdown of the polystyrene. 

A very detailed study of thermal PLA degradation was carried out by McNeill and Leiper [17,18]. They used TG, DSC and thermal volatilization analysis (TVA) in combination with H-NMR, IR and MS for product identification. Jamshidi et al. [19] and Zhang et al. [20] discussed inter- and intramolecular transesterfications as causes for tiie reduction of the molar mass when heated above the melting point. Five mechanisms have been postulated (Fig. 8.3). 

The differential distillation technique (also known as subambient thermal volatilization analysis (SATSVA) is a very simple technique which allows a rapid indication (both qualitative and quantitative) of small amounts of gaseous and/or liquid low molecular weight compounds which can be trapped and frozen at liquid nitrogen temperature [1439, 1440]. 

The Use of Thermal Volatilization Analysis of Polylactic Acid and Its Blends with Starch... 

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