Thermochemical study of carbon fibres based on polyacrylonitrile modified by boron

Carbon fibres

“…In this case the boron, playing the role of an electron acceptor, assists in polarization of the planes and intensification of the interplanar interaction as a result. Therefore, the introduction of boron into a carbon fibre leads to an increase in its degree of graphitization [187], which, in conformity with equation (2.1), exceeds the plasticizing influence of the boron atoms and is accompanied by an increase in carbon fibre modulus of elasticity (Fig. 2.47).…”

“…Analysis of the influence of boron on the structure and consequently elastic characteristics of carbon fibres makes it obvious that this influence can be realized in the production of fibres in two stages. At the start of the process, boron-containing compounds are transformed into boron nitride, whose presence is confirmed by estimates of heat values [187] and direct data obtained with electron spectroscopy [194]. The presence of boron nitride in a carbon fibre at the stage preceding graphitization facilitates the formation of graphite crystallites due to the similarity of the crystallographic parameters of these compounds.…”

“…To estimate the modulus of elasticity of the fibre, it was suggested [187] to use the value of the degree of graphitization calculated in terms of the combustion heat of amorphous carbon, Ham (33798 kJ kg-I), carbon fibre, H f , and graphite, Hg (32806kJkg-I ), according to the equation…”

“…In [185][186][187] the enthalpy was taken as the thermodynamic function whose change with rising temperature was followed for a number of carbon fibres. The results obtained (Fig.…”

Anionic Polymerization of Para-Diethynylbenzene: Synthesis of a Strictly Linear Polymer

“…The behavior of boron-containing compounds is of practical interest in the synthesis of various carbon materials from the point of view of creating the necessary intramolecular structure of these materials [ 77 , 78 , 79 , 80 ].…”