Formation of graphitisable carbons from gilsonite pitch and polyvinyl chloride—a mass spectrometric and N.M.R. study

Abstract

Gilsonite pitch and polyvinyl chloride (PVC) were carbonised at slow rates of 0 . 5 "~ min-I and the products of carbonisation examined by chromatography, mass spectrometry, nuclear magnetic resonance spectroscopy, optical microscopy, scanning electron microscopy and electron spin resonance spectroscopy. The original Gilsonite pitch contains -5 % of aromatic protons, rising to 24 % in soluble material just prior to formation of the graphitisable semi-coke at 410"~. The carbonised PVC melts ( 3 8 9 "~) to form a black isotropic liquid with 23 % aromatic protons, rising to 41 % at the onset of the coalescence of the mesophase spheres ( 4 2 0 4 4 0 "~) .The constituent molecules are considered to be hydrogenated cyclic structures possessing a great variety of saturated and unsaturated side-groups . During carbonisation, there is loss of side-groups, but it is the essentially aliphatic cyclic structures which co-cdense to form the mesophase. Further aromatisation must occur within the mesophase and semi-coke. The presence of heteroatoms within the Gilsonite pitch is considered to restrict the Rrowth of the mesophase structures and their ability to coalesce to form the much larger units of anisotropic character observed in the case of PVC. Electron spin resonance spectroscopy suggests that free radicals are not necessary to form the mesophase, the free radical character being developed afrer formation of the mesophase, probably as the aromaticity is developed.

Dimensional change, irradiation creep and thermal/mechanical property changes in nuclear graphite

“…18 was obtained from measurements made on virgin, medium fluence and very high fluence irradiated Gilsocarbon graphite samples, including some highly radiolytically oxidised samples irradiated at NRG Petten in a recent Materials Test Reactor programme. The MTR CTE data are compared to the theoretical CTE calculated using equation (19) and the graphite crystal data given in Fig. 12.…”

“…The samples were compressed to around 80% of their original 19 Change in CTE, orientation factor and porosity factor in virgin Gilsocarbon graphite as a function of stress. CTE data taken from reference, 57 measurements taken at room temperature.…”

“…These spherules harden, establishing the principal features of a lamella-form graphitisable coke morphology containing many fissures, cracks and folds. 19,20 It is the selection, by the graphite manufacturer, of the particular structure of the filler coke to be used, that is the main contribution to the properties of the final graphite product. Two very different examples of coke are the needleshaped particles and the spherical particles used for the production of two nuclear graphite grades, PGA and Gilsocarbon.…”

“…These spherules harden, establishing the principal features of a lamella-form graphitisable coke morphology containing many fissures, cracks and folds. 19,20 It is the selection, by the graphite manufacturer, of the particular structure of the filler coke to be used, that is the main contribution to the properties of the final graphite product.…”

Kimberlite emplacement temperatures derived from the thermal history of organic matter, Lac de Gras, Canada

“…Semi-graphitic cokes derived from high temperature thermal cracking of petroleum liquids are present in a restricted zone in the Nancy pipe between 68 and 106 m depth. Petroleum cokes begin to form from thermal cracking of liquid petroleum at around 400-450 °C during rapid Q, A A carbonization in an 02-free system (Marsh et al, 1971;White, 1976;Khorasani and Michelson, 1993), thus corroborating the alteration temperatures indicated by huminite % Ro for Thermal Zone D. The petroleum cokes in this zone were most likely sourced from rapid thermal alteration of hydrogen-rich terrestrial resinite and cutinite DOM noted at various levels in the pipe.…”