Effect of Potassium Permanganate Modification on Plasticized Spinning Polyacrylonitrile Fibers with Different Diameters.

Xiang Li,Xiaonan Dang

doi:10.3390/polym10121330

Xiang Li, Xiaonan Dang

Open Access

https://doi.org/10.3390/polym10121330

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Abstract

Plasticized spinning polyacrylonitrile (PAN) fibers with different diameters were chemically modified by potassium permanganate (KMnO4). The modification effects of different diameter fibers were studied for the first time. Differential scanning calorimetry (DSC) results show that, compared with the large diameter ones, small diameter modified fibers show lower cyclization starting temperature (Ti) and activation energy (E). Both kinds of fibers exhibit better modification effects compared with solution-spun fibers. For the small diameter fibers, chemical modification can occur at low treatment temperature, even at 70 °C. X-ray diffraction analysis (XRD) results show that modification not only occurs in the amorphous region of the fibers but also in the crystalline region.

Highlights

Plasticized spinning is a novel method for preparing polyacrylonitrile fibers
The Ti of B sample is obviously lower than that of A sample under the same treatment temperature, indicating that the catalytic modification effect is more remarkable for small diameter fibers
A lower Ti for small diameter fibers means that the initiation of the cyclization reaction becomes easier in the subsequent stabilization stage, which is beneficial to improve the speed of the stabilization

Summary

Introduction

Plasticized spinning is a novel method for preparing polyacrylonitrile fibers. This method is very attractive because it requires only a small amount of plasticizer and the fiber structure is controllable [1].Currently, an ionic liquid possesses characteristics of strong polarity and high-temperature stability [2]and has exhibited significant advantages over other traditional plasticizers such as ethylene carbonate and propylene carbonate. 1-butyl-3-methylimidazolium chloride, as a water-soluble ionic liquid [3], is the most suitable plasticizer for PAN to achieve plasticized spinning [4]. Plasticized spinning is a novel method for preparing polyacrylonitrile fibers. This method is very attractive because it requires only a small amount of plasticizer and the fiber structure is controllable [1]. 1-butyl-3-methylimidazolium chloride, as a water-soluble ionic liquid [3], is the most suitable plasticizer for PAN to achieve plasticized spinning [4]. High-performance plasticized spinning PAN fibers still cannot be fabricated since the fiber properties are affected by many process parameters during the spinning process. A lot of effort has been made to prepare PAN fibers with excellent properties. [5,6] Some properties of the prepared fibers, such as tensile strength and initial modulus, have been comparable to those of commercial PAN fibers. The subsequent modification, pre-oxidation and carbonization processes are rarely reported

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Conclusion