Search Results
Abstract
Thermomechanical analysis (TMA) in a tube-compressive mode can be used to characterize pitch in a reproducible and sensitive way. In a single experiment, this technique enables simultaneous determination of the glass transition temperature, the softening temperature and the rheological behaviour of a pitch sample. Results on a typical Australian coal-tar pitch are consistent with Bingham fluid behaviour above its softening temperature with a yield stress of the order of 100 Pa. In a similar test a petroleum pitch sample exhibited no yield stress.
Abstract
During the production of pitch-based carbon fibers, oxidative thermal stabilization is an important intermediary step, because it permits the thermoplastic as-spun fibers to be rendered thermosetting. In the present work, DSC analyses are employed to assess the stabilization of eucalyptus tar pitch fibers. This is possible due to the pronounced differences noticed between DSC profiles of green and oxidized fibers, which reflect the changes that the fiber structure undergoes during stabilization.
Communication 57 . 181 – 208 . Xu , Yi and Q. Emily Wang . 2001 . Pitch targets and their realization: Evidence from Mandarin Chinese . Speech Communication 33 . 319 – 337 .
D. R. Feinberg 2009 Voice pitch alters mate-choice relevant perception in hunter-gatherers Proceedings of the Royal Society of London B 276
that also synthetic polymers can be used for the preparation of AC [ 4 , 5 ]. Coal-tar pitch (CTP) modified with polymers, e.g., poly(ethylene terephthalate) (PET), phenolic resins, polyacrylonitrile and polyvinylpyridine, can also be a precursor of
. Feinberg 2009 Voice pitch predicts reproductive success in male hunter-gatherers Biology Letters 3 682 684
of this article was summary and presentation of important conclusions from several years investigation of possibility of production concerning hydrophobic mesoporous mineral-carbon sorbents from aluminum hydroxide and compositions of coal-tar pitch
materials was about 1000 m 2 /g. Authors [ 9 ] obtained microporous materials from the pitch–polymer compositions. Carbonization of these materials was carried out in two stages. Initial carbonization was conducted by heating the sample to the
Thermoanalytical studies of pitch pyrolysis
Comparison with polycyclic aromatic hydrocarbons
Characterization of pitches by thermal analysis techniques is highly relevant to the practical use of these materials, as they undergo heat treatments in all of their utilization processes. The aim of this work was to improve the interpretation of the complex DTA curves of pitches by comparison with model compounds. For this, TG/DTG/DTA was used to study under identical conditions the pyrolysis of a petroleum pitch and a coal tar pitch as well as a number of polycyclic aromatic hydrocarbons. Results were interpreted as a function of the molecular structure, pyrolysis reactivity and graphitizability of cokes from the hydrocarbons. It is concluded that condensation and polymerization, which are the most likely exothermal reactions predominant in petroleum pitches, indicate the presence therein of reactive molecules. Alternatively, endothermal phenomena such as distillation, depolymerization and cracking, predominant in coal tar pitches, suggest the presence of light, little reactive aromatic molecules.
Abstract
First casein was processed by pyrolysis and investigated under optimal thermal treatment condition to obtain a good quality adsorbent with high developed porosity structure and liquid product as a complex raw material for different kind of organic compounds with interesting properties and structures. The yields of hard residue, pitch, pyrolysis water and gases were determined and compared with the yields of pyrolysis products of other investigated different kind of organic materials. The chemical composition of pitch was determined as following: free carbons - 4.52%, organic acids - 0.64%, organic bases -38.00%, phenols - 7.75%, asphaltenes - 0.97%, paraffin's - 1.30%, neutral oils - 16.20% and preasphaltanes - 30.10%. The pitch was fractionated by air distillation into 3 liquid fractions with different boiling range and a bitumen like residue with a lower softening temperature.
