Length changes in PAN fibres during their pyrolysis to carbon fibres

TLDR: In this paper, the shrinkage of polyacrylonitrile (PAN) fibres is reported to occur from 200°C to 1000°C, the extent of which has been found to depend on the time of preoxidation, the type of oxidizing gas and the carbonization conditions.

Abstract: A systematic study of the shrinkage taking place during the carbonization of polyacrylonitrile (PAN) fibres is reported Shrinkage occurs from 200°C to 1000°C, the extent of which has been found to depend on (a) the time of preoxidation, (b) the type of oxidizing gas and (c) the carbonization conditions The carbonization shrinkage is found to be independent of length changes during the preoxidation but can decrease from the usual 23% to about 2% by applying tension during the carbonization A reaction is proposed to explain the shrinkage between 600°C and 800°C The strength as well as Young's modulus of carbon fibres of under-oxidized fibres can be improved by applying tension during the carbonization It is further predicted that the mechanical properties of carbon fibres preoxidized to the optimal level would decrease if carbonized under excessive tension Das Schrumpfen von PAN-Fasern wahrend der Carbonisierung wurde untersucht Das Schrumpfen erfolgt bei Temperaturen zwischen 200 und 1000°C, wobei das Ausamas von der Voroxidationszeit, der oxidierenden Atmosphare und den Carbonisierungsbedingungen abhangt Die Schrumpfung erwies sich als unabhangig von den Langenanderungen wahrend der Voroxidation, jedoch von 23%auf2% verringert werden, wenn wahrend der Carbonisierung ein Zug ausgeubt wird Es wird eine Reaktion vorgeschlagen, die die Schrumpfung zwischen 600 und 800°C erklart Mechanische Eigenschaften der Fasern konnen durch Ausubung von Zug wahrend der Carbonisierung verbessert werden