Pyrolysis - hydrogenation gas chromatography

Van Schooten and Evenhuis [86, 87] applied their pyrolysis (500 °C)-hydrogenation-gas chromatography technique to unsaturated ethylene-propylene copolymers, i.e., ethylene-propylene-dicyclopentadiene and ethylene-propylene-norbornene terpolymers. The pyrograms show that very large cyclic peaks are obtained from unsaturated rings methylcyclopentane is found when methylnorbornadiene is incorporated cyclopentane when dicyclopentadiene is incorporated methylcyclohexane and 1,2-dimethylcyclohexane when the addition compounds of norbornadiene with isoprene and... 

Denig [118] has reported that the length and structure of the hydrocarbon chains of AOS may be determined by cleavage of the sulfo groups in presence of excess phosphorus pentoxide and hydrogenation of the hydrocarbons before determining the -alkanes and isoalkanes by pyrolysis gas chromatography. 

Several papers in this book and in the recent literature (3) discuss use of pyrolysis techniques coupled with gas chromatography and mass spectrometry to determine forms of organically bound sulfur, but these methods introduce an uncertainty due to the possible interconversion of these sulfur forms during the heating step. For example, it has been shown that when benzyl sulfide was heated to 290°C, tetraphenyl thiophene, hydrogen sulfide and stilbene were produced (4). Coupled with heat and mass transport limitation considerations, particularly for viscous liquids and solids, it is not unreasonable to question whether at least some of the thiophenic forms observed by these techniques were produced during the analysis and may not have been present in the original sample. 

Ghodsi and Neumann-Tilte (63, 64) constructed an isothermal balance with two symmetrical pans for use in the hydrogenation of coal chars to pressures of 5 MPa. Provision was made for the trapping of coal tar and other pyrolysis products that could be analyzed by gas chromatography. 

Prokai [2] used pulse probe mass spectroscopy (MS) and pyrolysis-gas chromatography-mass spectroscopy (Py-GC-MS) to study the thermal decomposition of high molecular weight phenol-formaldehyde resins. He showed that degradation occurred by cleavage of the phenol-methylene bond and subsequent hydrogen abstraction to form phenol and methyl substituted phenols. 

The technique mentioned in the previous section of pyrolysis and radiochemical gas chromatography was also applied in a study to thermal degradation of aromatic polyimides [512]. Aromatic polyimides are more stable thermally than previously discussed polymers and require higher temperature for decomposition. Based on the experimental results, the following mechanism was proposed [512]. Initially, hydrogen radicals form. They come from various places of the polymer backbone during the pyrolytic decomposition. Also, decomposition of amic acid may yield water (see Chap. 6). 

See alsa Gas Chromatography Oven/iew Pyrolysis. Infrared Spectroscopy Overview Industrial Applications. Lipids Fatty Acids. Nuclear Magnetic Resonance Spectroscopy-Applicable Elements Hydrogen Isotopes Carbon-13. Polymers Synthetic. 

The formation of the remaining products (CO, H2O) is e qilained in the same way as in pyrolysis [15]. In the photolysis of polycaproamide at 30°C by the complete spectrum of the lamp PRK-2, hydrogen, carbon monoxide, and small amounts of hydrocarbons (ethane, ethylene, propane, propylene, n-bulylene) were detected by the method of gas chromatography [71, 73, 74]. In 120hr of irradiation, less than two cleav-... 

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