The Influence of Stabilization under Various Conditions and Subsequent Treatment of Polyester Fabric on the Quantity and Composition of Extracted Oligomers

Abstract

The preparation of polyester fibers (PES) is usually carried out by polycondensation of dimethyl ester of terephthalic acids and diols using ester interchange. In addition to the polymer, both linear and cyclic oligomers are formed. The production of cyclic oligomers during the formation of poly(ethylene terephthalate) by melt polycondensation is inherent and therefore oligomers are natural constituents of all melt-extruded samples of the polymer [1]. Kricheldorf has proved that all step-growth polymerizations possess a tendency to yield cyclics as stable end-products [2]. However, there is no evidence that cyclic trimers would form during the textile processes of polyester (heat setting, dyeing, …), since the possibility of formation of cyclic trimers in the solid state is very low [3].Fibers in the manufactured state are susceptible to dimensional instability caused by the effects of load, temperature, or solvent [4]. Polyester and other synthetic fibers shrink when they are treated in a loose condition at a high temperature in water. For this reason the linear dimensions change and therefore heat setting is essential to improve the dimensional stability [5]. Industrial setting of polyester fabrics is usually done in the presence of some tension. The range of setting temperature used is quite wide, 140°C in steam and 190 to 220°C in dry air. The time of heat setting varies from less than 1 second to over 60 minutes [4]. 1 It is known that the presence of oligomers in polyester fibers cause problems at spinning, dyeing, etc [6]. The general belief is that structural changes in the polyester fiber Abstract The study examined the effect of stabilization under various conditions (temperature, time and tension) and the treatment of polyester fabric in buffered solution (pH 12) prior to hightemperature dyeing, on the migration of oligomers. The content of oligomers in the treated polyester fabric was determined by extraction in petroleum ether and dichloromethane. The extract was analyzed using gel permeation chromatography (GPC). Based on the results it was established that oligomer migration was affected by temperature, time, and the stabilization tension. The greatest reduction in the content of oligomers was in polyester fabric that was stabilized in a restricted state at higher temperatures and longer times (220°C, 600 seconds). The oligomer content decreased even further if the polyester fabric was alkaline pretreated. The GPC chromatograms showed that all oligomeric extracts consisted mainly of cyclic trimers, whereas the presence and proportion of other cyclic oligomers varied with treatment conditions.

Investigation from Synthesis to Crystal Structure to Application of Ecofriendly Disperse Dyes on One-Step Dyeing of PET Fabric

“…Figure shows that a heavy mass of oligomers adhere on the dyed fiber surface with conventional dyeing method, but only a little remained when the PET fiber was dyed with the one-step method in an alkali bath. It is reported that the water solubility of the oligomers was less than 2 mg/L at 130 °C in acid condition . However, the ester bonds of oligomers (Figure ) can be hydrolyzed into carboxylate groups in alkali condition and the products can be easily dissolved in water …”

“…It is reported that the water solubility of the oligomers was less than 2 mg/L at 130 °C in acid condition. 40 However, the ester bonds of oligomers (Figure 8) can be hydrolyzed into carboxylate groups in alkali condition and the products can be easily dissolved in water. 41 Figure 6c−f shows that D4 and D5 have a similar build-up property and reflectance between conventional and one-step dyeing method.…”

Electron beam effect on poly (ethylene terephthalate) fibres

“…Both of them were obtained from DSC results which are revealed in Table II. Degree of crystallinity is obtained as equation (1) express and some authors suggest (Hirao et al , 2010; Weon, 2010; Badía et al , 2009): Equation 1 Where ΔH c represents the crystallization enthalpy and ΔH 100 is the heat of crystallization for a 100 per cent crystalline PET, ΔH 100 =140 J/g (from literature) (Badía et al , 2009; Recelj et al , 2006).…”

“…The higher irradiation doses the higher degree of crystallization, although there are not significant changes on melting temperature. Some works shown that PET can change crystallinity and not vary melting temperature unless it is reprocessed (Recelj et al , 2006). We think that electron beam treatment induces oligomers to go through fibre surface and allows increasing crystallization.…”

The effect of hot water setting treatment on the dyeing properties of grafted polyamide 6.6 microfibres

“…As far as heat setting is concerned, polyester fibres are among the most studied fibres (Merian, Carbonell, Lerch, & Sanahuja, 1963;Radhakrishnan, Kanitkar, & Gupta, 1997;Recelj, Gorensek, & Zigon, 2006;Sardag, Ozdemir, & Kara, 2007); however, few investigations about heat setting of polyamide 6.6 fibres have been carried out. Venkatesh, Bose, Shah, and Dweltz (1978) heat set polyamide 6, polyamide 6.6 and polyester (polyethylene terephthalate) filament yarns at different temperatures in oil under a variety of experimental conditions.…”