The structure of polyacrylonitrile based carbon fibres as studied by electron spin resonance and other electronic properties

In view of their recently acquired technological importance, the structure and properties of carbon fibres are currently receiving considerable attention. Although the use of electron spin resonance (CSR) in the study of carbons and graphites has long been established, the application of this technique specifically to carbon fibres has not been previously reported. In this thesis the ESR characteristics of a number of high temperature fibres is investigated, in conjunction with other electronic properties such as the thermoelectric power (TEP), the magneto-resistance and the electrical resistivity. The discovery of an anisotropy in the g-value of the ESR absorption of carbon fibres has made it possible to confirm that the graphitic crystallites, which make up the fibre structure, are preferentially aligned with their basal planes parallel to the fibre axis. This anisotropy is shown to be insensitive to slight crystallite misalignments, but on the other hand it clearly affords a good measure of the deeree of graphitization in carbon fibres and indicates that crystallite development in these materials always remains inferior to perfect single crystal graphite. This is in line with their nominally non-graphitizing nature. Comparing the ESR information with the results obtained from the other electronic properties investigated, reveals that the heat treatment temperature (HTT) of l7S0°C is associated with a major electronic change in the structure of these materials. The processes occurring at this HTT are discussed in terms of the available structural and band models in the carbon field. It is suggested that the appearance of the g-shift in this region is controlled by a critical interlayer or c-spacing in the graphitic crystallites. Furthermore it appears that the stresses formed in the material during the process of heat treatment are annealed in this region and this possibly plays a more significant role in the appearance of negative magneto-resistance that hitherto suspected. It is found that hot stretching carbon fibres invariably produces a change in all the properties investigated, in the direction of increased graphitization. Finally it is shown that correlation between the properties of different fibres can be satisfactorily achieved when these are expressed in terms of the g-anisotropy, which it is suggested, affords a good practical measure of graphitization or 'graphitic order' in these materials

Fadel Assabghy Oral History

Fadel Assabghy was a 1966 alumnus of The American University in Cairo’s graduate program in solid state science, taught at AUC as a faculty member from 1970 to 2010 in the Science Department and later the Physics Department, and served as Dean of the School of Sciences and Engineering from 1999 to 2005, as well as Senate member and Chair in the 1990s. Assabghy recollects his education and study in AUC’s solid state physics program, explaining that like a number of AUC science faculty after completing his MA studies he went abroad for his doctorate (in his case to the UK), and returned in 1970 to serve as a faculty member. The contributions of his cohort of science faculty and others throughout his time at AUC are described throughout. He relates the efforts of 1960s president Tom Bartlett to elevate the sciences at AUC, and describes in detail the positive features of the Science Building on the downtown Tahrir Square campus which was constructed in that decade. The expansion of science education and research at AUC (like the origins of engineering) and longtime Science Department chairman Adli Bishay’s accomplishments are covered including his role in the launching of AUC’s Desert Development Center in the 1980s, plus Assabghy’s own participation in the DDC’s research activities. Assabghy was Dean of the School of Sciences and Engineering from 1999 to 2005, and he discusses major developments from his term like the reorganization of the school into multiple units by discipline, establishment of the Science and Technology Research Center and nanotechnology research, and the starting of the Electronics Engineering and Actuarial Science programs at AUC. His time on the Senate, including term as chair and the controversy over and resolution of the leading faculty issues from that time: the discrepancy in compensation and retirement age between foreign and Egyptian faculty