Effects of positive and negative stretching on the structure and properties of polyacrylonitrile fibers in the pre-oxidation process

Abstract

Polyacrylonitrile (PAN) fibers were pre-oxidized in a temperature range of 180-275°C. The effects of positive and negative stretching on the structure and morphology of PAN fiber in the pre-oxidation process were studied by FTIR spectroscopy, XRD, and SEM. Mechanical property changes were also investigated. No changes in the movement and intensity of functional groups of PAN fibers were caused by positive stretching of up to 10% and negative stretching down to-8%. The crystal structure can be affected by the positive stretching and negative stretching. The maximum strength is 479.81 MPa when the stretching is positive, and the maximum strength is 420.55 MPa when the stretching is negative.

Influence of processing parameters on the properties of carbon fibres – an overview

“…Because of different mass and heat transport phenomena, the results cannot be directly transferred to a continuous conversion of fibres . Additionally, process investigations have been performed partly for batch and partly for continuous processes . This kind of process control leads to varying processes differing for instance in stabilisation (stepwise temperature treatment in continuous processes and linear change of temperature in batch processes) and can therefore hardly be compared.…”

“…Additional studies were performed on commercially available precursor fibres with unknown polymer compositions and precursor treatments . These did not take the influence of different compositions of copolymers and effects of molecular weight and distribution onto the fibre structure in the same process into account .…”

Indicators for evaluation of progress in thermal stabilization reactions of polyacrylonitrile fibers

“…Precise separation of temperature range in which reactions occur in crystalline or amorphous phases is difficult. Response of amorphous and crystalline chains to stretch is also different . It is essential to design the stretching process such that high chain orientation is obtained without hindering the cyclization reactions .…”

Hybride semi‐parametrische Modellierung der thermooxidativen Stabilisierung von PAN‐Precursorfasern

“…Die gewa ¨hlten Zugkra ¨fte zeigen keinen maßgeblichen Einfluss auf den SI und die Wa ¨rmeentwicklung. Die in [35] gezeigte Tendenz, eine ho ¨here Zyklisierung durch eine geringere Verstreckung zu erzielen, ist durch die Betrachtung des SI und die kumulierte Wa ¨rmeentwicklung der unterschiedlichen Reaktionen nicht darstellbar. Fu ¨r die Betrach-tung der Wa ¨rmeentwicklung und des SI ko ¨nnen die Zugkra ¨fte fu ¨r vereinfachte Modelle daher vernachla ¨ssigt werden.…”