Volatile products analysis

VOLATILE PRODUCTS ANALYSIS AFTER IRRADIATION OF POLYETHYLENE [272]... 

Thus, the enthalpies of various decomposition reactions (e.g., gaseous olefin loss) can be readily measured for rather small samples (a few mg.) Drawbacks of this technique include the necessity of correcting data to 298 K, the uncertain influence that solid state effects may have on measured AH values, and the possibility of side reactions at elevated temperatures. The latter effects can be assayed by thermogravimetrie and volatile product analysis. 

The ESR spectra of PIB irradiated at low temperature consists of a broad doublet with a hyperfine coupling constant of 2 mT, attributed to either radical VIII (182) or a combination of contributions from radicals VII and VIII (183, 184). The primary radicals V and VI (Fig. 2) have not been observed by ESR spectroscopy. Despite extensive studies of the radiochemical changes in PIB by ESR, volatile product analysis, and UV and IR spectroscopy, the mechanism of degradation had been imcertain imtil the advent of high resolution NMR methods. In a comprehensive study, Bremner and co-workers (185) and Hill and... 

Pyrolysis gas chromatography is an indirect method of analysis in which heat is used to transform a sample into a series of volatile products characteristic of sample and the... 

Various techniques have been used for the determination of oligomers, including GC [135], HPLC [136-138], TLC for polystyrene and poly a-methyl-styrene [139] and SEC for polyesters [140,141]. GC and PyGC-MS can also profitably be used for the analysis of the compositions of volatile products formed using different flame retardants (FRs). Takeda [142] reported that volumes and compositions of the volatile products and morphology of the char were affected by FRs, polymers (PC, PPE, PBT) and their reactions from 300... 

Irradiation of at longer wavelengths (>280 nm) provided phenyl formate (6) as a major volatile product, together with minor amounts of phenol and phenoxyacetone (4), as well as other products. A possible pathway for formation of phenyl formate by oxidation and subsequent cleavage is provided in Scheme III. Phenoxyacetic acid (7) was also identified as a minor product by mass-gc analysis. Photolysis of phenoxyacetone ( ) and phenoxyacetic acid (7)12 yields phenol together with photo-Fries products (also shown in Scheme III). 

Although the majority of studies focus on the solid state, many applications focus more or additionally on the volatile products arising from polymer degradation. Evolved gas analysis (EGA) from thermal analysers and pyrolysers by spectroscopic and coupled chromatography-spectroscopy techniques can be particularly important from a safety and hazard viewpoint, since data from such measurements can be used to predict toxic or polluting gases from fires, incinerators, etc. 

V.A. Basiuk and J. Douda, Pyrolysis of poly glycine and poly 1 alanine analysis of less volatile products by gas chromatography/Fourier Transform infrared spectroscopy/mass spectrometry, J. Anal. Appl. Pyrol., 55, 235 236 (2000). 

In this chapter, we examine the various processes by taking a qualitative look at which parts need to be improved by further research in order to make them commercially attractive for the separation of lower volatility products and especially competitive with low pressure distillation. Once again we focus on the rhodium/tertiary phosphine catalysed hydroformylation of long chain alkenes, specifically 1-octene, since data concerning this reaction is provided in the preceding chapters. A summary of the best results obtained from each of the processes and the problems associated with their implementation appears in Table 9.1. A full economic analysis of each approach to the product separation problem is beyond the scope of this book, so any conclusions as to... 

Table V. Summary of the Volatile Product CGC Analysis for the Class I Extent of Reaction Ternary Mixtures at 390°C ...

Heating pure TBMS, TBS and TBSS films at 130 C gave no volatile products. Pyrolysis at 725°C gave rise to both deprotection (as determined by the evolution of isobutene and carbon dioxide), and depolymerization to afford the respective monomers, sulfur dioxide, 4-hydroxystyrene, or 4-hydroxy-a-methylstyrene. The compounds, 4-hydroxystyrene and 4-hydroxy-a-methylstyrene, were identified on the basis of their mass spectra, which were consistent with those reported in the literature for these materials (22,23). Additionally, TGA analysis confirmed that all three polymers undergo complete volatilization upon heating to >400 C. 

Van Poecke RMP, Posthumus MA, Dicke M (2001) Herbivore-induced volatile production by Arabidopsis thaliana leads to attraction of the parasitoid Cotesia rubecula Chemical, behavioral, and gene-expression analysis. J Chem Ecol 27 1911-1928... 

Weaver WA, Li J, Wen YL, Johnston J, Blatchley MR, Blatchley ER III (2009) Volatile disinfection by-product analysis from chlorinated indoor swimming pools. Water Res 43 3308-3318... 

TG-FTIR Analysis. The analysis of the volatile products are related to the... 

Similar studies were carried out with benzoic acid on porous palladium electrodes [150]. The objective of this work was to investigate the adsorption processes and the reactivity of benzoic acid on different noble metals, in order to compare these results with those obtained for related aromatic compounds. On-line mass spectroscopy analysis of volatile products revealed that the adsorption of benzoic acid is irreversible at platinum while it is mainly reversible on palladium. Accordingly, different catalytic activity of platinum and palladium was found in the electrooxidation. 

Evolved gas analysis QEGA). Temperature programmed (5°C/min) mass spectrometrlc (MS) techniques were used to analyze the volatile products formed during sample heating. 

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