The roles of polymer relaxation phenomena,aqueous dye solubility and the physical properties of water in the mechanism of adsorption of a disperse dye on poly(ethylene terephthalate) fibres: Part 4 further aspects related to polymer relaxation phenomena

To further investigate the contribution of polymer relaxation times to the mechanism of disperse dye adsorption on poly(ethylene terephthalate) fibres, the temperature-dependent uptake of Teratop Yellow HL-G 150% on both cotton and polyamide 66 fabrics at temperatures between 30 and 130°C was compared with that on poly(ethylene terephthalate) fabric. Although uptake of the commercial grade dye on polyester fabric is governed by the thermally regulated, broad glass transition of the water-saturated poly(ethylene terephthalate) substrate, as this was not observed for either cotton or nylon 66 fabrics, the respective cellulose or polyamide 66 polymer glass transition does not present a major thermal impediment to dye uptake over the wide range of dyeing temperatures used. This is because the onset and end-set temperatures of the glass transition of the water-plasticised poly(ethylene terephthalate) material reside within the range of dyeing temperatures employed, whereas those of the water-plasticised cotton and polyamide materials occur below the lowest dyeing temperature examined (30°C). The thermal dependency of disperse dye solubility also likely makes a meaningful contribution to the temperature-dependent dye uptake observed for each type of fibre.     

The roles of polymer relaxation phenomena,aqueous dye solubility and the physical properties of water in the mechanism of adsorption of a disperse dye on poly(ethylene terephthalate) fibres: part 5 analysis of polymer relaxation phenomena for different polymers

The temperature dependent uptake of a commercial disperse dye on cotton and polyamide 66 fabrics at dyeing temperatures between 30°C and 130°C adhered to the Williams–Landel–Ferry equation, insofar as, very good correspondence was observed between plots of experimentally determined colour strength data points (log1/f_k) and the respective structural relaxation times of the cellulose and nylon 66 polymers (loga_T data points), as a function of the parameter (T − T_g). Adsorption of the dye on both types of fibre therefore concurs with the fundamental precept of the free volume model of dye diffusion. Comparison of the adherence of the uptake of the commercial dye on cotton and polyamide 66 fabrics with that secured on polyester fabric revealed that despite the major chemical and physical differences between the three types of fibre, the same dyeing mechanism likely applies to each fibre type. The marked temperature dependent uptake of the commercial grade disperse dye each of the three types of substrate is the consequence of two, different, but inherently interconnected, thermally activated phenomena, namely the relaxation times of the molecular rearrangements occurring within the respective cellulose, nylon 66 or poly(ethylene terephthalate) macromolecule, in which polymer glass transition assumes the principal role, and the aqueous solubility of the commercial grade disperse dye.     

The roles of elevated temperature and carriers in the dyeing of polyester fibres using disperse dyes: Part 1 fundamental aspects

This review concerns the application of disperse dyes to poly(ethylene terephthalate) (PET) fibres using aqueous immersion dyeing processes and the roles of both elevated dyeing temperatures and carriers in such dyeing systems. This part of the paper presents a review of the fundamental properties and characteristics of PET fibres, disperse dyes and dyeing accelerants. In the next part of the paper, the various theories and concepts that have been proposed to explain the promotional effects imparted by elevated dyeing temperatures and carriers to disperse dye uptake on PET and other types of fibre, are reviewed and analysed, from the viewpoints of the essential physico-chemical aspects of both the aqueous disperse dye/PET and disperse dye/carrier/PET systems. Later parts of the paper will present a mechanistic model of the disperse dye adsorption process based on dye solubility as well as a novel plasticisation model of dye diffusion.     

Vinyl graft polymerization-induced modification of some properties of poly(ethylene terephthalate) fabric

Polymerization of glycidyl methacrylate (GMA), methyl methacrylate (MMA), and acrylic acid (AA)/styrene (St) mixtures with poly(ethylene terephthalate) (PET) fabric to different polymer add-ons was performed. Moisture regain, dyeability, and soiling properties of the modified PET were examined. It was found that introduction of poly(GMA) in PET structure brings about (a) improved moisture regain, (b) enhanced dyeing with disperse dyes, (c) affinity and possible dyeing with acid, direct, and reactive dyes, (d) improved aqueous and nonaqueous oily soil resistance, and (e) decreased ease of soil removal. The magnitude of moisture regain, dyeability, and soiling properties are dependent upon the percent of polymer add-on. Polymerization of MMA with PET improved the dyeability of the latter with the disperse dye as well as its resistance to nonaqueous oily soil while decreasing the resistance to aqueous soiling and ease of both aqueous and nonaqueous soil removal. In the case of PET polymerized with poly(AA/St), there was a considerable enhancement in moisture regain, dyeing with the disperse dye, and resistance to aqueous and non-aqueous oily soiling. On the other hand, both aqueous and nonaqueous soil characteristics of PET were imparted by polymerization of the latter with AA/St mixtures.     

Thermal migration of selected disperse dyes on poly(ethylene terephthalate) and poly(lactic acid) (Ingeo†) fibres

A study has been carried out to correlate the wet fastness properties of dyed knitted fabrics, derived from both poly(ethylene terephthalate) and poly(lactic acid) (Ingeo) fibres, with the thermal migration properties of the disperse dyes during heat treatment. The results indicate a greater amount of disperse dye at the surface of the Ingeo fibre fabric than the poly(ethylene terephthalate) fabric, after post heat‐setting using the conditions needed for fabric stabilisation, correlating well with its slightly lower wash fastness properties.     

Effects of absorbed water on physical properties of polyesters

In previous articles, we reported the change in physical properties of hydrophobic polymers caused by absorption of a very small amount of water. This article describes the changes in physical properties of three polyesters owing to absorption of water. The tested polymers were poly(ethylene terephthalate) (PET), poly(butylene terephthalate) (PBT), and polyethylene 2,6-naphthalate (PEN). PBT has more flexible main chains than that of PET, and PEN has more rigid main chains. The dielectric measurements revealed that water absorption results in shortening the relaxation time for PET, while the relaxation time for moist PBT becomes longer. The larger amount of absorbed water yields the higher density of PET and the lower density of PBT. The water absorption of the polyesters also yields increments in dielectric constants and relaxation strength. Distribution of relaxation time of the polyesters is narrowed by absorption of water.     

Structure of uniaxially drawn poly(ethylene terephthalate) films and its influence on dye sorption

Drawing temperature, draw ratio, and tension during thermal treatments were varied to obtain poly(ethylene terephthalate) (PET) films with different structural modifications. These PET films were disperse dyed using a C.I. Disperse Blue 7 dye. Qualitative and quantitative characterization of molecular order and orientation was carried out using infrared spectroscopy and x-ray diffraction methods. Dye sorption was inferred from reflectance measurements using an optical spectrophotometer. It was observed that there was no unique dependence of dye uptake of poly(ethylene terephthalate) films on either orientation or crystallinity separately. Structural models have been proposed to explain the dye sorption behavior with special emphasis on the efficiency of chain packing, tortuosity, or compactness of the structure as an important criterion in governing the diffusion of dye molecules into the film matrix.     

The effect of dyes and dyeing on the mechanical properties of polymeric materials

The effect of reactive and disperse dyes and dyeing on the mechanical properties of cotton and polyester fibers, respectively, has been studied. It is observed that reactive dye (Procion Brilliant Red MX-2B) and disperse dye (Dispersol Red B-2B) caused a decrease in the tensile strength of the fiber which was often accompained by a decrease in the extensibility and general improvement in the tensile stiffness of the fibers. A linear relationship exists between percent disperse dye on the fiber and the square root of time of dyeing for poly(ethylene terephthalate) fibers in the initial region of dye uptake.     

The effect of structural changes on dye diffusion in poly(ethylene terephthalate)

The diffusion of a disperse dye, 1-amino-4-hydroxyanthraquinone (C.I. Disperse Red 15) into poly(ethylene terephthalate) fibers has been studied as a function of heatsetting temperature and draw ratio. It was found that the dynamic loss modulus E″, measured under the dyeing conditions, was related to the dye diffusivity D. This indicates that the diffusion is controlled by the mobility of the polymer chain segments. Both the diffusivity and dye saturation values do not vary monotonically with heatsetting temperature but exhibit a minimum at a heat-setting temperature near 175°C. X-ray diffraction measurements were used to show that this behavior is attributable to crystallinity and crystal size changes resulting from heat-setting.     

Dyeing behaviour of poly(ethylene terephthalate) fibres in supercritical carbon dioxide

A new type of poly(ethylene terephthalate) fibre was developed via a high-speed spinning technique. The dyeing behaviour of this fibre in supercritical carbon dioxide was compared with that of a fibre produced by conventional methods. At lower temperature and pressure, the high-speed spun fibre, which had inherently larger crystallite sizes and lower birefringence, showed a larger dye uptake. However, when the supercritical conditions were elevated to 125 °C and 230 bar, the dye uptake of both types of fibre increased markedly and the difference in dye uptake between the fibres was reduced. The new type of fibre showed slightly higher grades in sublimation fastness tests.     

Attaining optimal dyeability and tensile properties of polypropylene/poly(ethylene terephthalate) blends with a special cubic mixture experimental design

In this investigation, we attempted to enhance the dyeability of polypropylene (PP) with disperse dyestuffs without adversely affecting its tensile properties. To this end, a special cubic experimental design was used to predict the effect of variations in the properties of a tricomponent mixture composed of PP, poly(ethylene terephthalate) (PET), and maleic anhydride grafted polypropylene (PP‐g‐MA) on the dyeability and tensile properties of the resultant polymer blend. The results illustrate that there seemed to be critical PET content, above which the blend's dye uptake tended to remain constant, but the tensile properties were adversely affected. Further analysis of the results indicated that the PP/PET/PP‐g‐MA blends in which the PET and PP‐g‐MA contents were in the range 10–15 and 4–5 wt %, respectively, gave maximal dye uptake and desirable tensile properties. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Correlation of solubility data of azo disperse dyes with the dye uptake of poly(ethylene terephthalate) fibres in supercritical carbon dioxide

Solubility data of disperse azo dyes in supercritical carbon dioxide are presented for dyeings of poly(ethylene terephthalate) fibres with CI Disperse Red 167:1, carried out at 200–300 bar and 80–120 °C, with varying amounts of adulterants. The same dyeings were also carried out in water for comparison. Scanning electron micrographs were taken of the dyes which show a growth of dye crystals during treatment in supercritical carbon dioxide. The paper reports that at 120 °C, melting of the pure dye CI Disperse Red 167:1 is observed. The presence of adulterants in the dye formulations help prevent agglomeration by acting as spacers between the dye molecules. Dyeings of PETP carried out under conditions of the highest solubility of the dye in supercritical carbon dioxide do not necessarily result in a very high dye uptake. This was shown by pressure- and temperature-dependent dyeing experiments of PETP in supercritical carbon dioxide.     

Change of the amorphous state by heat treatment below the glass transition temperature

This study was undertaken to elucidate the state of a polymer in the amorphous state through a change of motion of the molecular chain caused by heat treatment below the glass transition temperature. From dielectric measurements of amorphous poly(ethylene terephthalate) heat-treated below T_g, it was found that the average relaxation time, the distribution of relaxation time and the dielectric strength increase with increase of heat treatment. From these results, it was concluded that the amorphous state becomes more random by heat treatment.     

Some sorption characteristics of poly(trimethylene terephthalate) with disperse dyes

Sorption characteristics, such as sorption kinetics and isotherms, relation between dye sorption and shade development of poly(trimethylene terephthalate) (PTT) and their comparison with poly(ethylene terephthalate) (PET), were reported. Results from two different dyeing rate studies, dyeing rate under constant temperature and under changing temperature, were examined to obtain the common rate constants, and to obtain information for the design of dyeing temperature profile and holding time. Rate constants of PTT were compared with that of PET. Sorption isotherms of disperse dyes on PTT were also studied. Both Nernst and Langmuir models were examined. The dye uptake ability of PTT was compared with PET. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 223–229, 2002     

A study on water and dye sorption capacities of novel ternary acrylamide/sodium acrylate/PEG semi IPN hydrogels

Here, a novel ternary semi interpenetrating polymer networks (semi IPNs) have been synthesized. An effective role to develop mechanically strong polymeric materials has been through the preparation of interpenetrating polymer networks (IPNs). The highly swelling superabsorbent semi IPNs were prepared by introducing poly(ethylene glycol), (PEG) into an acrylamide/sodium acrylate, (AAm/SA) hydrogels. For swelling characterization, swelling experiments were performed in water at 25 °C, gravimetrically. Water uptake and dye sorption properties of AAm/SA hydrogels and AAm/SA/PEG semi IPNs were investigated as a function of chemical composition of the hydrogels. AAm/SA hydrogels and AAm/SA/PEG semi IPNs were used in experiments on sorption of water-soluble cationic dye such as “Janus Green B” (JGB). For sorption of JGB into AAm/SA hydrogels and AAm/SA/PEG semi IPNs were studied by batch sorption technique at 25 °C. For the analysis of sorption mechanism and for calculation of some binding parameters of JGB from aqueous solutions, some linearization methods such as Klotz, Scatchard, and Langmuir linearization methods have been used.     

Relationship between the solubility of disperse dyes and the equilibrium dye adsorption in supercritical fluid dyeing

In order to understand the dyeing behaviour of synthetic fibres in supercritical carbon dioxide, the solubility of some disperse dyes in supercritical fluid, as well as the rate of dyeing and the equilibrium adsorption of these dyes, have been studied. Dye solubility was measured by a dynamic analytic method at a range of pressure (7.5–25 MPa) and temperature (50–145 °C). The apparent rate of dyeing was measured and the dyeing isotherm was obtained by plotting the equilibrium dye adsorption against the equilibrium dyebath concentration. Linear isotherms were obtained when poly(ethylene terephthalate) samples were dyed with the disperse dyes. The mechanism of dyeing using supercritical carbon dioxide was discussed by considering the solubility, the dyeing rate and the dyeing isotherm.     

The effect of heat setting on the structure and mechanical properties of poly(ethylene terephthalate) fiber. III. Anelastic properties and their dependence on structure

Viscoelastic parameters for poly(ethylene terephthalate) (PET) fibers heat set under different conditions were determined at 110 Hz between room temperature and about 200°C. The correlation of dynamic mechanical properties with structure and their dependence on the temperature of the measurement are discussed. It was found that in addition to the structural parameters such as degree of crystallinity, crystallite and amorphous orientation, etc., morphological factors such as size and distribution of crystallites also influence the dynamic mechanical properties. The activation energy of the α-transition is reported, and the effect of the distribution of relaxation times on the activation energy is discussed.     

A microcellular processing study of poly(ethylene terephthalate) in the amorphous and semicrystalline states. Part I: Microcell nucleation

Microcellular semicrystalline polymers such as poly(ethylene terephthalate) show great promise for engineering applications because of their unique properties, particularly at higher densities. Recent studies reveal some high density microcellular polymers have longer fatigue lives and/or equal strengths to the neat polymer. Relatively few microcellular processing studies of semicrystalline polymers have been presented. In general, semicrystalline polymers are relatively difficult to microcellular process compared to amorphous polymers. In this paper and a companion paper, the microcellular processing of poly(ethylene terephthalate) in the amorphous and semicrystalline states is studied in order to quantify the processing differences. The microcellular processing steps addressed in this paper include gas/polymer solution formation and microvoid nucleation. Particular emphasis is given to microvoid nucleation comparing the processing characteristics of semicrystalline and amorphous materials. Moreover, this study identifies a number of critical process parameters. In general, the semicrystalline materials exhibit ten to one thousand times higher cell nucleation densities compared with the amorphous materials, resulting from heterogeneous nucleation contributions. The amorphous materials show a strong dependence on cell density, while the semicrystalline materials show a weaker dependence. Moreover, classical nucleation theory is not adequate to quantitatively predict the effects of saturation pressure on cell nucleation for either the amorphous or semicrystalline polyesters. Both the semicrystalline and amorphous materials exhibit constant nucleation cell densities with increasing foaming time. Foaming temperatures near the glass transition are found to influence the cell density of the amorphous polyesters, indicating some degree of thermally activated nucleation. Furthermore, classical nucleation theory is not adequate to predict the cell density dependence on foaming temperature. Similar to the amorphous polyesters above the glass transition temperature, nucleation in the semicrystalline materials is found to be independent of the foaming temperature.     

Effect of N,N‐diethyl‐m‐toluamide on the structure and dyeing properties of meta‐aramid and para‐aramid fibre

N,N‐Diethyl‐m‐toluamide has been widely used in the mosquito‐repellent finishing of textiles over the past few decades, but the use of N,N‐diethyl‐m‐toluamide as a dye carrier for aramid dyeing with disperse dye has been seldom reported. Meanwhile, the application of aramid fibre in clothing is limited because it is difficult to dye. In this work, the effect of N,N‐diethyl‐m‐toluamide on the dyeing properties of aramid fibre was examined by measuring the percentage disperse dye exhaustion under different conditions. In order to understand the mechanism by which N,N‐diethyl‐m‐toluamide promotes the exhaustion of disperse dye on aramid fibre, the ultraviolet‐visible spectrum of the dye and N,N‐diethyl‐m‐toluamide solution, the glass transition temperature, the crystalline structure, and the degree of orientation of aramid fibre treated with N,N‐diethyl‐m‐toluamide were measured by ultraviolet‐visible spectrophotometry, differential scanning calorimetry, X‐ray diffraction analysis, and velocity‐oriented tests respectively. The results indicated that N,N‐diethyl‐m‐toluamide not only could reduce the glass transition temperature and degree of orientation of aramid fibre but could also improve the solubility of disperse dye in aqueous solution, and therefore could enhance the percentage disperse dye uptake on aramid fibre, whereas treatment with N,N‐diethyl‐m‐toluamide showed little effect on the crystalline structure of aramid fibre. The results implied that N,N‐diethyl‐m‐toluamide was beneficial to the diffusion of disperse dye molecules into the amorphous region of aramid fibre under the dyeing conditions, but seldom affected the mechanical properties of aramid fibre.