Rate Of Dye Diffusion Research Articles

Dye diffusion and the phenomenon of barriness on polyamide fabrics

Dyed polyamide fabrics tend to exhibit barriness, particularly when acid dyes of good wet fastness are used. The causes of this phenomenon have been investigated by studying the diffusion kinetics of the dyeing process. The conditions used in the pretreatment of the yarn have been considered, in particular the effect of mechanical and thermal conditions during thermal pretreatment. It has been demonstrated that barriness is dependent only on the kinetics of diffusion. If drawing is increased, the rate of dye diffusion is reduced, whereas an increase in the texturising temperature tends to increase it. The influence of dye diffusion decreases as the dyeing temperature rises. The traditional practice of dyers to attempt to reduce barriness by raising the dyebath temperature very slowly therefore makes matters worse. To reduce barring it would be preferable to introduce the dyestuff to the dyebath only once the dyeing temperature has been reached.

Improvement of the storage stability and photostability of colored latex prepared by miniemulsion polymerization

Polymer particles containing oil-soluble dyes (colored latex) were prepared by miniemulsion polymerization. The dye preservation properties of colored latex loaded with different types of dye were studied; preservation depended on the rate of dye diffusion and thus on the size of the dye molecules and the hardness of the polymer matrix in the latex particles. Hindered amine stabilizers (HAS) were used to improve the photostability of colored latex. The effect of HAS in colored latex was investigated both as an additive and as a comonomer. The photostability of latex particles containing a simple mixture of dye and HAS was improved with increasing HAS content up to 20% in particles. In the case of colored latex particles combined with HAS by a covalent bond, the optimal amount of HAS for photostability improvement was between 8 and 20%.

Some studies on the action of some ketones on Quiana-polyamide fibres.

Pretreatment of Quiana polyamide fabric (Q-PA) with some ketones was performed to induce some structural changes in order to improve fibre dyeability. Isothermal shrinkage rate curves of modified Q-PA were characterized by an induction period. The molecular volume of the interacting ketones/solvents influenced the corresponding energy of diffusion (ΔE) into the polymer. The difference in ΔE among the ketones/solvent may be associated with some difference in their binding capacity with the substrate. The dynamic shrinkage increased sharply with increasing temperature of pretreatment. Measurement of iodine sorption by modified polyamide allowed detection of induced structural differences.Changes in capability of modified polyamide to uptake cationic dyes were noticed. Evaluation of time of half dyeing and specific dyeing rate constant indicated that the pretreatment had more powerful influence in disordering polyamide fibre structure. The rate of dye diffusion in the modified polymer increased with rise of dyeing temperature. The apparent activation energy of diffusion showed the ability of the dye molecules to move within the fibre matrix. Calculation of the dye affinity and heat of dyeing anticipated that more disorder in fine structure due to pretreatment was imparted.

Effects of Fiber Structural Modification on the Dyeing Behavior and Mechanical Properties of Polyamide Yarns

Pretreating nylon 6 and nylon 66 yams in interactive chemical systems or in saturated steam enhances dye transport within the fiber and increases the capacity of the fiber for dye. Chemical treatments with aqueous and nonaqueous solutions of phenol are more effective in promoting rapid dye transport than steam treatments. The increased rate of dye diffusion in the treated yams can be attributed to greater polymer segmental mobility as reflected by decreased dyeing transition temperatures and orientation changes in the amorphous (noncrystalline) domains. Mechanical properties of the treated yams have also been correlated with orientation in the amorphous domains. In contrast to the disorder produced in the amorphous domains, the treatments improve chain packing in the crystalline domains.

Structure-Property Relationships in Polytetramethylene Terephthalate/ Polytetramethylene Isophthalate Copolyesters Part II : Relationships Between Dyeability and the Glass-Transition Temperature

The dyeing properties of a series of poly tramethylene terephthalate/polytetramethylene isophthalate copolyester films with C.I. Disperse Orange 3 have b investigated. Incorporating isophthalate units into polytetramethylene terephthalate leads to an increase in both the rate of dye diffusion and the amount of dye sorbed at equilibrium. The rate of dye diffusion in the series of copolyesters is found to depend on (T — Tg) for Tg measured by several methods. Linear relationships between log D and (T — Tg) allow empirical equations relating the rate of dye diffusion in the series of copolyesters to (T — Tg) to be derived. An application of these equations in studies of dye diffusion in polymers is envisaged. The relationships obtained between log D and (T — Tg) for the diffusion of C.I. Disperse Orange 3 in the series of copolyesters are compared with those found by workers in other dye-fiber systems. In addition, the effects of varying annealing temperature and dyeing temperature on the dyeing properties of the series of copolyesters have been studied.

Microwave versus Conductive Heating Their Effect on the Solvent–assisted Dyeing of Polyester Fibre with Anthraquinonoid Disperse Dyes

The rates of dyeing of polyester fibre with amino– and hydroxy–substituted anthraquinones in aqueous N, N–dimethylformamide (DMF) using microwave and conductive heating have been compared. Structural changes, commonly associated with interactions between DMF and polyester fibre, were limited and minimal shrinkage occurred due to the low DMF to water ratio and short dyeing times. Tensile properties reflected this minimal shrinkage through increased elongation at break, and differential scanning calorimetry also indicated that structural changes were minimal. Microwave radiation increased dye diffusion, shrinkage, and elongation at break compared to conductive heating. It is believed that molecular oscillation within the microwave–irradiated dyebath increases the rate of migration of dye to the fibre interface and enhances the plasticization of the polymer by DMF, thereby increasing the rate of dye diffusion within the fibre. Localization of energy associated with the use of microwave radiation is believed to be the predominant cause of increase in the rate of dyeing.

EFFECT OF EXTENSION ON THE RATE OF DIFFUSION OF A DISPERSE DYE IN POLYETHYLENETEREPHTHALATE FIBER

The dye penetration coefficient of C. I. Disperse Red 15 in PET fiber was measured as a function of extension given to the fiber in dyeing, and the following results were obtained; The penetration coefficient remarkably increased with increasing extension. In order to explain the effect of the extension on the rate of diffusion of dye, the density and the intensity of small angle x-ray diffraction were also measured as a function of the extension. The changes of both of them strongly suggest that the density of the amorphous region decreased by extension, implying that the remarkable increase in the rate of diffusion of dye may be due to the increase in the free volume with extension. The change in the specific volume with the extension was calculated from the changes in the density and the small angle x-ray intensity. Specific volume calculated from the intensity was greater than that from the density. The increase in the specific volume thus estimated from the density was reduced into the temperature increase by use of the thermal expansion coefficient of the fiber. The penetration coefficient assumed from the temperature thus estimated, by use of W. L. F. relation for the temperature dependence of diffusion of the dye in the fiber, was much larger than that actually observed. From these results it was concluded that the remarkable increase in the rate of dye diffusion is attributable to the increase in free volume by extension, although the increase in the free volume effective for diffusion of dye seems smaller than that expected from the increase in the specific volume of the fiber.

Diffusion Rate of Dye in the Carrier Dyeing of Polyester Fibre

The dye penetration coefficients, the starting temperatures of contraction and other factors in the carrier dyeing of poly(ethylene terephthalate)fibre, were determined as a function of carrier concentration in the dyeing bath.The dependence of dye penetration coefficient on the concentration of carrier and the temperature was found to be shown formally by the Williams-Landel-Ferry equation, Here p and p, are the dye penetration coefficient at absolute temperature, T and that at temperature, Ts, respectively. The subscripts, (c) and (0) indicate the concentration of carrier added and that of zero, respectively. In the above equation, T8, (0) and Ts, (e) are the temperatures which are higher by 25°C than the starting temperature of contraction in each dyeing bath.

Effect of Fiber and Dyebath Variables on the Rate of Acid Dyeing of Nylon 6, 6

The results of an experimental study of the effects of several variables on the acid dyeing of nylon are presented. The dyeing rate was directly proportional to the number of amino-end groups (dye sites) in the fiber for the two dyes tested; the dyeing rate approached zero as the number of dye sites approached zero. The dyeing rate was the same for samples with viscosity average molecular weights of ∼25,000 and 30,000, but was somewhat higher for a ∼22,000 Mv sample, as might be expected from the dependence of other properties on molecular weight. The dyeing rate is shown to be linearly related to 1/√ d, where d is the denier per filament. The molecular size of the acid molecule used in the acid dyebath was investigated, and no effect was found for formic, acetic, propionic, and hexanoic acids. An effect is found on both rate and saturation, however, if the larger and more polarizable napthoic acid is used. Sodium chloride and sodium sulfate, when added to the dyebath, decrease both the dye absorbed at saturation and the rate of dye diffusion, although they offer benefits as leveling agents. The effect of sodium chloride is considerably greater than for sodium sulfate.

Relation between nylon fiber mechanical properties and dye diffusion behavior

AbstractThe mobility of polymer chain segments is shown to play a major role in the diffusion of dyes in nylon 66. The rate of dye diffusion has been related to the time‐dependent mechanical properties, such as creep and stress relaxation, which are controlled by the mobility of the chain segments. The theoretical relations derived by Fujita et al. relating the diffusion of small molecules in amorphous polymers to other properties are shown to be applicable for the dyeing of semicrystalline nylon. Data showing the effects of surface area, temperature, and the amount of dye absorbed at saturation on the dyeing rate are presented and discussed.

Benzylidenepolyhydric Alcohol類の膠質化学的研究 (第5報)

Various solvents undergo gelation by the action of dibenzylidene-d-sorbitol to form a jelly, and the hardness of jelly and diffusion rate of dye in this jelly were comparatively measured. It was found that there is approximate parallelism between these two factors. Since the hardness of jelly is affected by viscosity of that solvent, relationship with viscosity was also examined. It was thereby learned that an approximate parallelism existed between hardness and square root of viscosity.

Theory of Dyeing Polyester and Polyacrylic Fibers1

These two fiber classes are similar in that both are dyed by disperse-type dyes; however, polyacrylic fibers can be dyed with anionic dyes if positive sites are provided. This can be done, for example, by using fiber containing ammonium groups. Alterna tively, positive sites in the form of bound cuprous ions can be produced by treatment of the fiber with cuprous salts. In either case, ion exchange occurs in which colorless anions and dye amons compete for positive sites in the fiber. In contrast, disperse dyes, which are used on all common fibers except cellulose and wool, require no specific dyeing sites. In polyethylene terephthalate, the dyeing reac tion behaves like a simple solution in the tiber, with dipole interactions and dispersion forces probably very important. The rate of dyeing of polyethylene terephthalate tends to be inconveniently slow, and organic compounds called carriers are used frequently to increase the rate. They are effective by mcreasing the diffusion rate of dye through the fiber.