The Nano-Sized TiO2 Dispersions for Mass Coloration of Polyimide Fibers: The Nano-Sized TiO2 for Mass Coloration

The Nano-Sized TiO2 Dispersions for Mass Coloration of Polyimide Fibers: The Nano-Sized TiO2 for Mass Coloration

Natalja Fjodorova (National Institute of Chemistry, Ljubljana, Slovenia), Marjana Novic (National Institute of Chemistry, Ljubljana, Slovenia), Tamara Diankova (St-Petersburg State University of Technology and Design, St. Petersburg, Russia) and Anna Ostanen (St-Petersburg State University of Technology and Design, St. Petersburg, Russia)
Copyright: © 2016 |Pages: 16
DOI: 10.4018/JNN.2016010103
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Abstract

The implementation of nano-sized TiO2 dispersions for mass coloration of polyimide fibers is considered in the paper. Titanium dioxide (TiO2) is not classified as hazardous according to United Nations (UN) Globally Harmonized System of Classification and Labeling of Chemicals (GHS). The stability of TiO2 dispersions in dimethylformamide (DMF) medium in presence of different surfactants as well as the viscosity of poly(amic) acid spinning solutions was investigated. It was illustrated that nano fraction of mineral pigment increase the stability of spinning medium. Moreover, the introduction of 4,5% TiO2 in poly(amic) acid stabilized with 0,24% of surfactant (leukanol) caused the increasing of thermal stability on 10°C in comparison with non-colored fibers. Proposed method enables to get light colours and improve the thermal stability of polyimide fiber. The application of TiO2 in the mass coloration of fibers does not cause dangerous effect on consumer because the pigment is tightly connected with polymer inside fiber structure.
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Introduction

High performance fibers (including the polyimide fibers) are generally characterized by remarkably high unit tensile strength and modulus as well as resistance to heat, flame, and chemical agents that normally degrade conventional fibers. The aromatic polyimides are well known in films, enamels as well as in fibers due to their excellent resistance to high temperatures. Aromatic polyimide fibers have a very high level of thermal and dimensional stability and property retention at high temperatures, as well as a good, all-round level of other fiber properties (Herman, 2007).

These fibers are difficult to dye using classical methods (in a special solution containing dyes) due to their chemical structure and absence of sufficient amount of active groups on surface for binding dyes. Coloration of fiber-forming polyheteroarylenes from their synthesis to the textile production with using known methods (Cates & Fitzgerald, 1987; Hamid, 1993; Hamid & Va, 1992; Hartzler, 1991; Johnson, 1988; Kobayashi et al., 1995; Nicolai & Nechwatal, 1994; Riggins & Hansen, 1994; Riggins & Hauser, 1990) in processes of their realization in the industry lead to decrease in level of mechanical and thermal characteristics and also don't allow to receive various colors. The proposed in the study method of coloring was aimed to overcome these disadvantages (keeping safe the mechanical and thermal characteristics of fibers).

The diversity of dyeing methods is described in the Handbook of Textile and Industrial Dyeing (Clark, 2011). The mass coloration was employed in the study. It is an increasingly important alternative to classical methods of dyeing textiles using water-soluble or disperced dyes applied from as aqueous bath. Mass coloration (or spin coloration, solution dyeing, and dope dyeing) yields colored fibers by introduction of the coloring material during formation of fiber forming polymer. The color is thus disperced within the filament rather than absorbed on its surface (Holme, 2000). Mass coloration has low energy costs, no effluent or water costs, no dyehouse (dyebath) investments, reduced labor costs. It supports the large batches of uniform shade and makes the higher fastness properties possible.

The polyimide fibers have a yellow-brown original color. The aim of study was to obtain the light colors of fibers. For this purpose, the white pigment TiO2 in organic solution was applied.

Titanium dioxide (TiO2) is a white solid inorganic substance not classified as a hazardous according to United Nations (UN) Globally Harmonized System of Classification and Labeling of Chemicals (GHS). TiO2 is the ninth most common element in the earth's crust. TiO2 is typically thought of as being chemically inert. Since the introduction of TiO2 as a commercial product in 1923, there have been no identified health concerns associated with its exposure among consumers or general population. These facts are supported by the results from four large epidemiology studies involving more than 20,000 workers in the titanium dioxide manufacturing industry in Noth America and Europe which indicate no association with an increased risk of cancer or with any other adverse lung effects (Boffetta et al., 2001; Boffetta et al., 2004; Chen & Fayerweather, 1988; Fryzek et al., 2003; Garabrant et al., 1987; Ramanakumar et al., 2008). These studies did not specifically differentiate between the ultrafine and pigmentary TiO2.

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