An investigation for the performance of meta-aramid fiber blends treated in supercritical carbon dioxide fluid

Abstract

The physicochemical performance of meta-aramid fiber blends treated in supercritical carbon dioxide fluid was studied at different temperatures. The effects of treatment temperatures on the surface morphology, wettability, chemical and crystal structures, thermal and antistatic properties were investigated by employing Scanning electron microscopy, Dynamic wetting measurements, Fourier transform infrared spectrometry, X-ray diffraction, Thermal analysis and Static half period method, respectively. The result showed that the surface of the treated meta-aramid fiber blends was changed with the treatment temperature increasing and more mild grooves and stripes appeared. The dynamic wetting measurements showed that the water contact angles and absorption time for treated fibers were decreased with temperature increasing. The slight shifts of the characteristic bands of the treated meta-aramid fiber blends were observed in FT-IR spectra with the system temperature increasing. Meanwhile, XRD analysis showed that the diffraction intensities of treated samples were improved in the supercritical carbon dioxide fluid because some re-arrangements and re-crystallizations of the molecule chains generated. TG-DTG analysis indicated that the thermal property of meta-aramid fiber blends could be improved at various temperatures. In addition, supercritical carbon dioxide fluid had little negative influence on the physical and antistatic properties of the meta-aramid fiber blends.

Effect of Different Pressures of Supercritical Carbon Dioxide on the Microstructure of PAN Fibers during the Hot-Drawing Process

“…Supercritical carbon dioxide (Sc-CO 2 ) is usually used as non-toxic solvents in extractions [18,19], separations [20,21], chemical reactions [22], and various other applications [23,24,25,26]. At present, more and more experts use Sc-CO 2 to induce the crystallization of polymers and fibers [27,28,29]. Owing to the characteristics of the Sc-CO 2 fluid, it can be applied to the hot-drawing process of PAN fibers at low temperatures.…”

Investigations on the effect of carriers on meta-aramid fabric dyeing properties in supercritical carbon dioxide

“…Intensive interactions between the carbon dioxide uid and macro-chains of the polymers lead to the obvious swelling of the meta-aramid ber under a higher system pressure. 21,29 Furthermore, the swelling of the meta-aramid ber is enhanced in the presence of carriers. In particular, the solubilities of carriers in supercritical carbon dioxide were also increased with the increase of uid density, which further led to the swelling of meta-aramid.…”

“…However, a high degree of macromolecular orientation and dense crystal structure due to the numerous hydrogen bonds between amide groups in adjacent chains result in the extremely poor dyeability of meta-aramid ber. 21,22 Carrier, as a type of accelerant, is mainly used in the dyeing or printing of synthetic bers with disperse dyes by acting as a plasticising agent to reduce the glass transition temperature (T g ). 23 Theoretically, in the dyeing process, carrier can be absorbed by bers through polar and non-polar forces of interaction, hydrogen bonding and hydrophobic interaction.…”

Near room temperature dyeing of m‐aramid fabrics

“…Furthermore, removal of carriers from inside the fibers is difficult. Extensive research has been conducted to overcome such drawbacks including the application of liquid ammonia, a pretreatment with amine solutions, supercritical carbon dioxide, and even surface modification with different techniques has been practiced, for example, diblock copolymer, UV light combined with ozone, and photografting . Such studies have obtained excellent results in improving dyeability of meta‐aramid fibers; however, another hurdle remains when applying those techniques.…”