Simultaneous diffusion of a disperse dye and a solvent in PET film analyzed by rutherford backscattering spectrometry

Poly(ethylene terephthalate) (PET) is a difficult fiber to dye from an aqueous dyebath due to its high degree of crystallinity and lack of polar groups. One method used to increase the dyeing rate of the fibers is the addition of an organic solvent, called a dye carrier, to the aqueous bath. This study utilized Rutherford backscattering spectrometry and neutron activation analysis to examine both simultaneous diffusion and individual diffusion characteristics of a disperse dye and dye carrier into PET film. The dye exhibited Fickian diffusion above and below glass transition temperature (T_g) of the PET film both in the presence and absence of solvent. The presence of carrier in the dyebath was found to increase the diffusion coefficient of the dye at each temperature condition; increasing from 10⁻¹⁴ to 10⁻¹¹ cm²/s below T_g (65°C) and 10⁻¹² to 10⁻¹⁰ cm²/s above T_g (90°C). Bromobenzene exhibited case II diffusion below T_g of the film, which indicates that the solvent is swelling the near surface regions of the film. This increase in void volume resulted in an increased dye uptake when films dyed inthe presence of carrier were compared with those dyed without carrier. In fact, the penetration depth of the dye was found to be equivalent to that of the swollen region of the film (∼ 600 nm) after 15 s. Above T_g, the bromobenzene exhibited Fickian diffusion. The coupling of the increased thermal motion of the polymer at the higher temperature and the solvent effect increased dye uptake when compared either with dye uptake at the lower temperature or with uptake when no solvent was present. The application of the dye and solvent simultaneously did not affect the diffusion mechanism of either species, leading to the conclusion that there was no competition for specific sites between these two species in the PET film. Similar results were obtained for chlorobenzene when used as the dye carrier. © 1996 John Wiley & Sons, Inc.     

Using carbon black nanoparticles to dye the cationic‐modified cotton fabrics

Carbon black (CB) aqueous dispersion was prepared and used to dye the cationic‐modified cotton fabrics through exhaust dyeing process. The effects of CB concentration, CB nanoparticles size, dyeing bath pH, dyeing time and dyeing temperature were investigated. The color yields of dyed fabrics were evaluated on Kubelka‐Munk value K/S. The surface morphologies of cationic modified and nonmodified cotton fabrics were measured by video microscope. The fabrics presented 18.9 of the color yield with the dyeing conditions: the dyeing solution contained 2% o.w.f. CB and dyeing at 80°C for 30 min with pH 13 using a 50 : 1 liquor ratio. The images of the video microscope demonstrated a clear surface profile for the cationic‐modified cotton fabrics dyed with smaller CB particle size solutions. These results indicated that CB nanoparticles were suitable for dyeing the cotton fabrics. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Incorporation of disperse dye in N,N-dimethylacrylamide modified poly(ethylene terephthalate) fibers with supercritical CO2

The effects of modifying agents and dyeing conditions of dispersed dyes for PET films and fibers has been thoroughly studied. This research reports on the dye incorporation process of non-modified and N,N-dimethylacrylamide modified PET fibers with supercritical CO₂. Spectral analysis in the infrared region to the modified PET fibers showed peaks of the modifier, but the thermal stability of the modified fiber did not show variation when compared with the non-modified. The amount of disperse dye incorporated in the PET fibers was determined by UV–Vis spectroscopy at 579 nm through the dye extraction using N,N-dimethylformamide. A 2⁴ factorial design was realized with the purpose to study the influence of variables in the dye incorporation process as well as their interaction effects. The pre-treatment of the PET fibers with N,N-dimethylacrylamide increases the amount of incorporated dye 3.8 times, in average. The main effect on the dye incorporation was the dyeing time for the modified fibers, but for the non-modified fibers, the pressure and the temperature presented analogous main effect     

Decolorisation by Bacillus flexus of exhausted dyebaths containing CI Acid Red 249 and their reuse for wool dyeing

A dyebath containing left-over CI Acid Red 249 after dyeing of wool was completely decolorised using an isolated bacteria Bacillus flexus. Optimisation was carried out by varying the pH, temperature, dye concentration, and microbial loading. Complete decolorisation of a 50 mg l⁻¹ dye solution was achieved in 8 h at pH 7 and 37 °C with 10% v/v loading of the bacteria. The decolorised bath was utilised for dyeing of wool fabric with the same dye at 5% shade. This cycle of dyeing–decolorising–dyeing was repeated 5 times. The evaluation of dyed fabric was done using K/S, colour values, and fastness to light and washing. Comparison of a sample dyed with the conventional exhaust process showed that the dyeing quality is not affected for all five successive reuse cycles. The results are important from the viewpoint of reducing water consumption and chemicals.     

The dyeability and properties of some structurally modified poly(ethylene terephthalate) filaments

The effect of solvent treatment on the dyeability and mechanical properties of drawn poly(ethylene terephthalate) (PET) filaments has been studied. It is observed that strongly interacting solvents such as N,N-dimethyl formamide (DMF) improved the dyeability of PET which has been treated with these solvents at 74°C for 15 min before dyeing with disperse dyes at 100°C. Pretreatment in N,N-dimethyl formamide and acetonitrile also resulted in a lowering of tensile strength and initial modulus, whereas subsequent dyeing caused further reduction in extensibility but initial modulus results are less consistent.     

Dyeing mechanism and model of nylon 6 fiber dyeing in low‐temperature hydrogen peroxide–glyoxal redox system

This article reports the results of a study of nylon 6 fiber dyed in a low‐temperature hydrogen peroxide–glyoxal redox system. It was expected that the dyed fiber would have better dye fastness and higher economic value than would conventional fiber. In addition, this article presents the proposed mechanism for and model of a free‐radical dyeing system as well as a derived theoretical equation. From the experimental results, it was found that formation of covalent bonds by the coupling of the dye and the fiber radical in free‐radical dyeing was only 25%–40%, whereas with the conventional type of ionic dyeing, it was almost 60%–75%. Because the initiation efficiency of free‐radical formation is affected by many factors, such as the pH of the dye bath and the concentrations of the oxidant and reductant, the aims of this study were to investigate the formation of free radicals and the effects on dye uptake of the concentrations of dye, oxidant, and reductant and of the fiber amine end group. In addition, the dyeing properties of dyed fiber were investigated, and the dyeing order and rate constant of the rate equation were evaluated from the experimental data. From the experimental results, the following conclusions were drawn. (1) The hydrogen peroxide–glyoxal redox system produced many free radicals in the dye bath as temperature reached 70°C. (2) The amine end group in the nylon fiber was the main site of ionic and covalent bonding between nylon 6 fiber and dye. (3) The proposed model of free‐radical dyeing showed, from the fit of the experimental data into the equation and the evaluation of the equation parameters, that the order fit the theoretical value well, with the rate constant dependent on the dyeing conditions; at pH = 3, it could match the equation's best (rate equation of the proposed model: d[D]_R/dt = k_A[GO]¹[H₂O]^m[D]^1/2[F]^1/2). (4) The optimum dyeing conditions in the hydrogen peroxide–glyoxal redox system were: [H₂O₂] = 0.15–0.20M, [glyoxal] = 0.07–0.10M, pH = 3, dyeing temperature = 70°C, and dyeing time = 45–50 min. (5) The redox dyeing system had better dye fastness than did the conventional system. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4197–4207, 2006     

Improving the UV resistance of aromatic poly(l,3,4‐oxadiazole) fiber using a disperse dye modified with octavinyl POSS. Part 1: Preparation of dye and dyeing

Modified dyes were obtained by grafting of disperse dyes with octavinyl polyhedral oligomeric silsesquioxanes (POSS) using a Friedel‐Crafts alkylation reaction and using different ratios of POSS and the original disperse dye. The modified dyes are used to dye aromatic poly(l,3,4‐oxadiazole) (p‐POD) fiber to improve its UV resistance. Then the structure of the modified dye is characterized by Fourier transform infrared spectroscopy and NMR, and the effects of the structure of the modified dye and the dyeing conditions on the UV resistance and color strength (K/S value) of the dyed samples are investigated. The results indicated that the UV adsorption peaks of the modified dye solutions are located at the specified UV wavelengths. The UV resistance of the p‐POD fiber dyed with the modified dye (1:3) can be effectively improved, and the dyed p‐POD fiber can obtain a higher K/S value simultaneously. During the dyeing process, increasing the dyeing temperature and prolonging the dyeing time are both beneficial in improving the anti‐UV ability of the dyed p‐POD fiber; these changes can effectively promote the fixation of dye molecules into p‐POD fibers due to stimulating the motion of dye molecules and p‐POD macromolecules. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44745.     

Carrier‐free dyeing of radiation‐grafted polyester fabrics with disperse dyes

Carrier‐free dyeing of radiation‐grafted polyester fabrics with disperse red dye was studied in the temperature range 283–363 K. 1‐vinyl 2‐pyrrolidone (NVP), acrylic acid (AA) or their mixture was used to graft poly(ethylene terephthalate) (PET) fabric. The effects of pH of the dye solution, graft yield (GY), dyeing time (t), dye concentration (C), and dyeing temperature (T) on the colour difference (CD) of PET fabric were studied. The best dyeing condition was achieved at pH 5.5. CD increases linearly with the increase in GY, with slopes depending on the type of grafted copolymer. CD increased rapidly as the dyeing time increased; this was followed by a relatively slow dyeing rate within a few minutes. The initial dyeing rate (R) was found to increase with an increase in C and T. The dyeing rates for all grafted samples followed 0.35‐order kinetics and are temperature‐independent. Average activation energy 9.26 kJ mol^?1 is calculated for the dyeing process and is independent of the fabric treatment. Pre‐exponential rate constants 1976, 1839, and 1579 (CD/GY) s^?1 were calculated for dyeing PET samples grafted with AA/NVP mixture, NVP and AA, respectively, while 1074 CD s^?1 was evaluated for carrier dyeing of ungrafted fabric. Analysis of the kinetic parameters and the dyeing mechanism revealed that dyeing PET fabric was diffusion‐controlled. Grafting PET fabric improved significantly the dyeing affinity of the DR dye over ungrafted samples dyed in solutions containing a carrier. Copyright © 2005 Society of Chemical Industry     

Effect of Dye‐Bath pH on Photostability of Dyed Nylon 66

Nylon 66 films were dyed in aqueous dye‐bath with C. I. Acid Blue 25 (1‐amino‐4‐(aminophenyl)‐2‐anthraquinone sodium sulfonate) at various pH values ranging from 2.0 to 7.0. Films were exposed to polychromatic irradiation (λ ⪈ 290 nm) at 60°C in air. The extent of photo‐oxidation was monitored by FT‐IR spectroscopy. Fading of dye with polychromatic irradiation was monitored by UV spectroscopy. We observed a peculiar effect of dye‐bath pH on the photostability of dyed nylon 66. Samples were more stable when dyed at pH 3 and above that (up to pH 7), whereas the samples dyed at pH < 3.0 showed sensitized photo‐oxidative degradation in nylon 66. Formation of quaternary ammonium salt on dye‐chromophore was considered responsible for the pH‐controlled behavior of anthraquinone acid dyes. The dyeing pH significantly effects the photofading behavior of dyed samples. The effect of dye‐bath pH on photofading of the dyed samples was more pronounced at lower dyeing pH and prevailed up to pH 4. The hydronium ion concentration was considered to be responsible for the enhanced fading of dye for the samples dyed at the lower pH.     

Energy‐efficient dyeing of nylon 6 using indigo powder dyestuff after atmospheric plasma treatment at ambient pressure

Nylon 6 was treated with a dielectric barrier discharge, i.e. atmospheric plasma at ordinary air pressure. Factors influencing the dyeing process of nylon 6 using indigo blue powder were studied. The mechanism and effect of this dyeing technology were compared with those of conventional technology. Dyeing after plasma treatment at 30–50 °C can produce high dye uptake in a short time. Notably, dyeing after plasma treatment is beneficial for energy conservation. However, at 60–70 °C, the K/S values of plasma‐treatment dyeing sharply increased over a short time, after which they remained largely unchanged. This finding indicated that the dyeing mechanism changed. The speed constant of dyeing after plasma treatment is 2.8 times that of conventional dyeing. The K/S values of dyeing samples after plasma treatment approached the dyeing saturation K/S value in a short time; therefore, this method of dyeing after plasma treatment achieves energy conservation and efficiency in a brief period of time. Conversely, conventional dyeing is more effective at high temperatures but consumes more energy. The adaptive electro‐discharge condition is achieved under the treatment conditions of 375 W for 2 min. The chromatic aberration of the dyed samples after plasma treatment is smaller than that of conventional dyeing at 50 °C for 75 min.     

Deep‐colour vat dyeing of cotton knit fabric on a modified jet dyeing machine

To improve the vat dyeing of cotton knit fabric with Indanthren Black RB Coll. (CI Vat Black 9), the basic parameters of dyeing, including the concentrations of chemicals, the dyeing temperature and duration, and the apparent diffusion coefficient of the dye, were obtained by test dyeing with a stoppered Erlenmeyer flask and the cellophane film roll method. A stable vat dyeing process has been developed on a modified jet dyeing machine for the first time without using nitrogen to purge oxygen. Modifications were made to improve the airtightness of the machine and the equipment in the liquor circulating system, with a water inlet and outlet for the gentle oxidation of dyed fabric, and with monitoring by means of a sensor inserted in the liquor circulating system for in situ measurements of the redox potential and the pH of the dyeing liquors. These measurements made it possible to follow to their completion the process of dyeing and the process of gentle oxidation by overflow washing with water and final oxidation. Optimal conditions with regard to the amount of reducing agent, the dyeing temperature (80 °C), and oxidising processes were established with this machine. It was found that, by using the modified machine and process conditions, dyeing proceeded stably and reproducibly (at 80 °C) to yield grade A dyed fabric. Visual inspection confirmed that faultless deep‐colour dyeing of the fabric was attained. Production has been proceeding successfully for the past 2 years. Owing to its insolubility, complete removal of the dye from the wastewater has been possible.     

DNA adsorption on poly(N,N‐dimethylacrylamide)‐grafted chitosan hydrogels

In this study, poly(N,N‐dimethylacrylamide) grafted chitosan (PDMAAm‐g‐CT) hydrogels were prepared for deoxyribonucleic acid (DNA) adsorption. Instead of directly grafting the N,N‐dimethylacrylamide (DMAAm) monomer onto the chitosan (CT) chains, poly(N,N‐dimethylacrylamide) with carboxylic acid end group (PDMAAm‐COOH) was firstly synthesized by free‐radical polymerization using mercaptoacetic acid (MAAc) as the chain‐transfer agent and then grafted onto the CT having amino groups. The synthesis of PDMAAm‐COOH and its grafting onto the CT chains were confirmed by attenuated total reflectance Fourier transform infrared (ATR‐FTIR) spectroscopy. From gel permeation chromatography measurements, the number‐average molecular weight (M _n) and polydispersity index of PDMAAm‐COOH were found as 2400 g/mol and 2.3, respectively. The PDMAAm‐g‐CT hydrogels were utilized as the adsorbents in DNA adsorption experiments conducted at +4°C in a trisEDTA solution of pH 7.4. The hydrogels produced with higher PDMAAm‐COOH content exhibited higher DNA adsorption capacity. The DNA adsorption capacity up to 4620 μg DNA/g dry gel could be achieved with the PDMAAm‐g‐CT hydrogels prepared in 80.0 wt % PDMAAm‐COOH feed concentration. This value is approximately seven times higher than that of CT alone. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Optimising by response surface methodology the dyeing of polyester with a liposome‐encapsulated disperse dye

Optimisation of conditions for dyeing polyester with liposome‐encapsulated CI Disperse Red 50 was performed using response surface methodology. The effects of temperature, time, and lecithin:dye ratio on the colour strength of dyed fabrics were investigated by a central composite design. The coefficient of determination, the probability value in analysis of variance, and the normality plot of residuals demonstrated sufficient significance of the proposed fitness function. It was found that the temperature and time of the dyeing cycle were effective factors in the dyeing of polyester fabrics with encapsulated dye. It was also established that the colour yield of dyed fabrics was above 25 in the case of a dyeing time of >80 min, a lecithin:dye ratio of ≤2, and a temperature of ca. 128 °C. Comparison of colour strengths produced by liposome‐encapsulated dye and commercial dye revealed that there was approximately the same build‐up on polyester. Dyeings from encapsulated CI Disperse Red 50 exhibited very similar fastness to dyeings from conventional CI Disperse Red 50.     

Studying the thermodynamic parameters of disperse dyeing of modified polyethylene terephthalate sheets using hyperbranched polymeric additive as a nanomaterial

Thermodynamic parameters of disperse dyeing of modified PET sheets by various loads of a polyesteramide hyperbranched polymer are investigated in terms of standard affinity (?Δμ°), enthalpy change (ΔH°) and entropy change (ΔS°). The results show that the standard affinity of dye to the modified PET is higher than that to the virgin PET. The bath containing virgin PET displays the highest negative values of the ΔH° and ΔS°, while the bath containing the modified PET with 2% hyperbranched polymer shows the lowest negative values of them. Surface morphology and thermal properties of the samples are analyzed by AFM and DSC.     

Dyeing of cotton with the natural dye extracted from waste leaves of green tea (Camellia sinensis var. assamica)

Due to an increase in the production of green tea, the amount of leaf waste has increased enormously, causing serious environmental problems. With regard to environmental awareness, the possibility of reusing the waste leaves of green tea as a low‐cost and abundantly available source of natural dye for dyeing cotton fibres was investigated. Natural dye powder from the waste leaves of green tea (NDPT) was successfully applied to dye cotton fibres without mordant by batch experiments. NDPT was obtained as a dark brown powder with a yield of 2.7 ± 0.5% w/w from dried waste leaves of green tea. The optimal conditions for dyeing NDPT onto cotton fibres were: pH of dye solution, 3; material to liquor ratio, 100:1; dyeing time, 180 min; concentration of dye solution, 3.0 mg/ml; and dyeing temperature, 100 °C. The colour of cotton fibres dyed with NDPT was observed to be dark brown. The adsorption data of NDPT on cotton fibres was best fitted with a Langmuir adsorption isotherm model with a correlation coefficient (R²) of 0.997. It is clear that there is a strong possibility of reusing the waste leaves of green tea as a low‐cost and abundantly available source of natural dye for dyeing cotton fibres.     

Reactive dyeing of silk using commercial acid dyes based on a three‐component Mannich‐type reaction

Acid dyes are employed for commercially dyeing silk, which results in ionic bonds between the silk fibroin and the dye. This generally leads to low wet fastness properties for dyed silk fabrics. In this work, three commercial acid dyes with aromatic primary amine structures were selected to dye silk using a Mannich‐type reaction, resulting in improved wet fastness of dyed silk by forming covalent bonds between silk fibroin and dye. The Mannich‐type reactive dyeing was applied to silk fabrics at both 30 and 90°C in trials. Dyeing at 90°C can shorten the dyeing time compared with dyeing at 30°C, even although dye exhaustion and relative fixation at 90°C were a little lower. The dyeing process was optimised when the dyeing temperature was 90°C, dyebath pH 4, dye‐to‐formaldehyde ratio 1:30 and holding dyeing time 60 minutes. The results showed that the dye exhaustion on silk fabrics for the three aromatic primary amine‐containing acid dyes exceeded 94% and their relative fixation was over 80%. Their washing and rubbing fastness reached grade 4 or higher. Hence, the colour fastness properties of dyed silk fabrics using the Mannich‐type reactive dyeing method is superior to the conventional acid dyeing method using the same aromatic primary amine‐containing acid dyes. The Mannich‐type reactive dyeing for silk fabrics at 90°C can be developed into a novel and rapid reactive dyeing method, promising an effective dyeing process with excellent colour fastness.     

Equilibrium disperse-dye sorption by isotactic polypropylene films of varied thermal histories

Spherulitic polypropylene (PP) films prepared by a melt-quenched process and then exposed to isothermal annealing treatments at various temperatures ranging from 120°C to 155°C have been dyed at 80°C with C.I. Disperse Yellow 7(Y-7) or p-aminoazobenzene. Different PP films as crystallized isothermally in the range of 60°C to 155°C have also been dyed with the same dyes. The equilibrium dye sorption (M_o) obtained for these films increased slightly with an increase in polymer volume crystallinity (C_u). Using fine structural data of these films, the change in M_o were analyzed in terms of the mosaic-block structural model; e.g., the values of M_o were divided into sorption by the amorphous end region (M_e) located between lamella surfaces and sorption by the amorphous side region (M_s) located between crystalline cores parallel to the molecular chain axis. The value of M_s increased with increasing C_v in both cases of the dyeing systems, while the value of M_e decreased monotonically in an opposite manner. The amorphous chains in the side region seem to have a strong affinity to a long rodlike dye molecule of Y-7; this feature is considered to be associated with the extended chain conformation of the side region which originates from distorted lattice chains.     

Dyeing of silk fabric with phenazine from Pseudomonas species

Phenazines, namely oxychlororaphin and pyorubin, were extracted from Pseudomonas sp., purified and their dyeing potential as colorants for silk dyeing were examined. The effects of the process variables, such as phenazine concentration, pH, temperature, time, type of mordant, relative colour strength and fastness properties have been studied. The results showed that the optimum condition for dyeing was 90 °C at pH 3 and dyeing time 90 min for oxychlororaphin, and 70 °C at pH 3 and dyeing time 60 min for pyorubin. The K/S value of a pre‐mordanted silk fabric with oxychlororaphin was high when compared to that with the pyorubin. The antimicrobial activity of a dyed silk fabric was tested against Salomonella paratyphi, Escherichia coli and Shigella flexneri.     

Dyeability of cellulose fibers using dyestuff from African rosewood (Pterocarpus erinaceous)

Methanol extracted from the “heart wood” of the plant Pterocarpus erinaceous (African rosewood) gave a brick red dyestuff. Chromatographic separation of the dye produced a single homogenous component with an Rf value of 0.78, a yield of about 17.3% and a melting point of 86°C. IR spectrum of the purified dye showed the presence of an aromatic CC double bond band at 1620–1470 cm⁻¹ and NH₂ absorption characteristic of an aromatic amine N H stretch at 3590–3400 cm⁻¹, while para‐disubstitution on aromatic nucleus was observed at 850–840 cm⁻¹. A wavelength of maximum absorbance, λ_max, of 500 nm was recorded on a UV/visible scan for the solvent soluble dye. The dye, which was substantive to cotton, was applied quantitatively to it and reed fibers by exhaust dyeing technique from locally distilled alcohol. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 746–751, 2000     

Interpolymer‐specific interactions and miscibility in poly(styrene‐co‐acrylic acid)/poly(styrene‐co‐N,N‐dimethylacrylamide) blends

The miscibility or complexation of poly(styrene‐co‐acrylic acid) containing 27 mol % of acrylic acid (SAA‐27) and poly(styrene‐co‐N,N‐dimethylacrylamide) containing 17 or 32 mol % of N,N‐dimethylacrylamide (SAD‐17, SAD‐32) or poly(N,N‐dimethylacrylamide) (PDMA) were investigated by different techniques. The differential scanning calorimetry (DSC) analysis showed that a single glass‐transition temperature was observed for all the mixtures prepared from tetrahydrofuran (THF) or butan‐2‐one. This is an evidence of their miscibility or complexation over the entire composition range. As the content of the basic constituent increases as within SAA‐27/SAD‐32 and SAA‐27/PDMA, higher number of specific interpolymer interactins occurred and led to the formation of interpolymer complexes in butan‐2‐one. The qualitative Fourier transform infrared (FTIR) spectroscopy study carried out for SAA‐27/SAD‐17 blends revealed that hydrogen bonding occurred between the hydroxyl groups of SAA‐27 and the carbonyl amide of SAD‐17. Quantitative analysis carried out in the 160–210°C temperature range for the SAA‐27 copolymer and its blends of different ratios using the Painter–Coleman association model led to the estimation of the equilibrium constants K₂, K_A and the enthalpies of hydrogen bond formation. These blends are miscible even at 180°C as confirmed from the negative values of the total free energy of mixing ΔG_M over the entire blend composition. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1011–1024, 2007