Pyrolysis decomposition modes

Combination techniques such as microscopy—ftir and pyrolysis—ir have helped solve some particularly difficult separations and complex identifications. Microscopy—ftir has been used to determine the composition of copolymer fibers (22) polyacrylonitrile, methyl acrylate, and a dye-receptive organic sulfonate trimer have been identified in acryHc fiber. Both normal and grazing angle modes can be used to identify components (23). Pyrolysis—ir has been used to study polymer decomposition (24) and to determine the degree of cross-linking of sulfonated divinylbenzene—styrene copolymer (25) and ethylene or propylene levels and ratios in ethylene—propylene copolymers (26). 

This fragmentation mode is not altered for silacyclobutanes bearing a vinyl group at the silicon17, as the same Arrhenius parameters are found for the decomposition of 1 and of 1 -methyl-1-vinylsilacyclobutane 3 (logA = 15.64 s 1, E = 62.6 kcalmol-1), in sharp contrast to the pyrolysis of cyclobutanes where a vinyl group accelerates the pyrolysis by a factor of nearly 60018. 2-Silabuta-l,3-diene 4 was produced in a laser-photosensitized (SFg) decomposition (LPD) of 1-methyl-1-vinylsilacyclobutane 3... 

Gas theories. — These attribute the retardant action to modification of the behavior of the volatiles (from the pyrolysis) by gases evolved from the decomposition of the retardant. Two suggested modes of action are (a) prevention of the formation of inflammable mixtures of air and volatile compounds (derived from the cellulosic material), by dilution with noninflammable gases derived from decomposition of the retardant, and (b) inhibition of free-radical chain-reactions in the flame, by introduction of decomposition products (from the retardant) that act as chain breakers. 

Thermal Decomposition of Liquid Gun Propellant The Liquid Gun Propellant (LGP) tested in the solids recirculation was LP XM-46, which is 24% TEAN (triethanol ammonium nitrate) and 76% HAN (hydroxy-ammonium nitrate. The mixture was diluted 1 3 in water. The diluted LGP was injected at an initial rate of 0.06 gal/min and later increased to 0.1 gal/min. The operation was run in pyrolysis and combustion modes. 

In the pyrolysis mode, the decomposition products were removed from the moving bed reactor, and the driver gases were recycled. This produced a small, concentrated stream of decomposition products, where 18% of the feed nitrogen was emitted as nitrogen-bearing oxides. Over 60% of the injected carbon is accounted for as COz, with the remainder as CO. 

Recently, the thermal decomposition processes of various aUphatic-aromatic polyamides were investigated by Py-GC/MS and Py-MS using both Cl and El modes. The thermal decomposition of the polyamides of aromatic-diamine and aliphatic-dicarboxylic acid was strongly influenced by the structure of the aliphatic subunits. The formation of compounds with succinimide and amine end groups was observed in the pyrolysis of the polyamides containing succinic subunits via an intramolecular exchange and a concomitant N-H hydrogen transfer. 

Direct pyrolysis in the ion source of a mass spectrometer (DPy-MS) operating both in electron impact and chemical ionisation modes was used in these studies. Flash Py-GC-MS was also used in the case of polythiomethylene to confirm the DPy-MS results. The overall evidence indicated that the primary thermal decomposition of these polymers yielded a wide range of cyclic sulfides by an intramolecular exchange process. A 3-CH hydrogen transfer reaction, occurring in parallel with the former process, produced primary pyrolysis compounds with SH end-groups. 

---