Influence of grafting with acrylic acid on the dyeing properties of polyamide 6.6 fibres

Polyamide 6.6 fibres were modified for the improvement of dyeing affinity using a graft copolymerisation method. These fibres were grafted with acrylic acid as monomer. The influence of the chemical modification of polyamide 6.6 fibres on the dyeing properties was investigated using a cationic dye (Red Astrazon 5BL). It was shown that the dye uptake of the modified fibres was greater than that of the unmodified fibres. The kinetic study of the cationic dye used at various grafting percentages showed an improvement of the dye build‐up rate, such as its exhaustion. In addition, an increase in the adsorption of the dye quantity fixed on the surface layer of the fibre made up of the grafted molecules was announced. Colour fastness to washing was improved with the grafting percentage. The modelling of the adsorption isotherms using Langmuir, Freundlich and Jossen relations allows the determination of isotherm constants. The results obtained from this modelling study show the existence of several models corresponding to various percentages of grafting.     

Chemical functionalization of polyamide 6.6 fabrics

Polyamide 6.6 (PA 6.6) fibers, produced from adipic acid and hexamethylenediamine, are among the most consumed synthetic textile fibers used for garments. Fibers are hydrophobic, which makes dyeing difficult and affects wearing comfort. In the present work, chemical treatments of PA 6.6 fibers were carried out and compared with respect to their effect on fiber properties and obtained surface modifications. Scoured knitted PA 6.6 fabrics (opaque) were treated with hydrochloric acid (0–3 M) and sodium hydroxide (3 M) for up to 3 h at 60 °C. The fibers were characterized with respect to bulk and surface modifications such as amino and carboxyl end groups, superficial dyeing below the T_G of the fiber, surface structure with SEM and AFM analysis. Furthermore a new analytic procedure for the determination of surface amino groups was tested. Both chemical treatments resulted in a significant increase in the amount of amino groups on the fiber, but especially the treatment with HCl 3 M caused a more drastic surface modification of the fibers, however, not only restricted to the fiber surface. AFM and SEM analysis have shown a significant change in surface roughness on the nanoscale, which in addition to the creation of surface functional groups increases the fiber’s hydrophilicity and reactivity.     

Investigations of electrokinetic properties of dyed polyamide fibres

Changes of the electrokinetic flow intensity Q_v and the zeta potential for polyamide fibres colourless and dyed with Polan dyes were analyzed. Essential differences in determined quantities were found for fibres dyed with dyes of different steric structure.     

Morphological studies of glass-microbead-filled polyamide 6.6-polypropylene blends

This article deals with the study of the morphology of glass bead (10% in volume) reinforced compatibilized blends of polypropylene (PP) and polyamide (PA) 6.6. The morphology, as well as some physical and mechanical properties, are determined. The blends are studied in relation with the PP-PA ratio and according to the glass bead's sizing. We have seen the existence of a boundary PA-glass beads interface (independently of the sizing), and the best compatibilization effect is obtained with PP size glass beads and for 50% PP content. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67: 201–208, 1998     

Solvent system for steady state electrospinning of polyamide 6.6

A mixture of formic acid/acetic acid makes it possible to electrospin polyamide 6.6 in steady state conditions. Steady state conditions are essential in nozzle electrospinning to generate a stable process which fabricates reproducible material, permitting industrial upscaling. This study shows that only a limited mixture range of formic acid/acetic acid allows electrospinning of polyamide 6.6 in steady state. Furthermore, the weight concentration in solution; the tip to collector distance and the flow rate have been changed to control the average diameter of the nanofibres. The average diameter increases by increasing weight concentration in solution, increasing volume fraction of acetic acid in the mixture, increasing tip to collector distance and increasing flow rate. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Application of ant colony optimization to color matching of dyed cotton fabrics with direct dyestuffs mixtures

Color matching and recipe prediction is one of the most important aspects of color science. In this article, a new method using ant colony algorithm is developed to optimize the color formulation step. Four direct dyes, namely CI Direct Red 227, CI Direct Orange 34, CI Direct Blue 85, and CI Direct Black 22 were used and mixed to dye cotton fabrics. The aim is to reproduce the desired shades by determining the dyes and their respective concentrations to add in the dye bath. The criterion of optimization is to minimize the CMC color differences between the target color and the color obtained by the proposed recipes. The developed algorithm showed good performances with small color differences all lower than the unit.     

Evaluation of colour fastness and thermal migration in softened polylactic acid fabrics dyed with disperse dyes of differing hydrophobicity

This paper addresses the relative effects of softeners having different properties and their method of application (exhaust vs pad) on the colour fastness of poly(lactic acid) fabrics dyed with a range of disperse dyes with different levels of hydrophobicity. A comparison was made with a correspondingly finished polyethylene terephthalate fabric. Possible relationships between the levels of hydrophilicity/hydrophobicity of the dye, and softener, and the colour fastness were explored. Finally, the amount of dye thermally migrated into the finish on the softened poly(lactic acid) and polyethylene terephthalate fabrics was examined in comparison with their colour fastness. Softened poly(lactic acid) fabrics dyed with CI Disperse Red 167.1 exhibited more thermal migration, and hence lower colour fastness, than the corresponding polyethylene terephthalate fabrics. Conversely, softened poly(lactic acid) fabrics dyed with Dianix Deep Red SF exhibited less thermal migration, and hence better colour fastness, than the corresponding polyethylene terephthalate fabrics. Overall, no clear relationship was found between the hydrophobic nature of the disperse dye and the hydrophobic character of the softener on the colour fastness.     

Surface photografting: New application for flame retardant finishing of polyamide6.6 (PA6.6) fabric

Surface photografting modification with maleic anhydride (MAn) under UV irradiation in association with a post reaction with triethanolamine has been used to improve the flame retardancy of polyamide6.6 (PA6.6) fabric in this study. The effects of irradiation time and monomer concentration on the fabric surface grafting were investigated. The flame retardancy and thermal decomposition behavior of the samples were characterized by limiting oxygen index test (LOI), thermogravimetric analysis (TGA), and differential scanning calorimetric (DSC), and the results indicate that flame retardancy of the treated PA6.6 fabric samples has been significantly improved. The chemical structures of the treated samples' surface were characterized by attenuated total reflection infrared spectroscopy (ATR‐FTIR), and the possible photochemical mechanisms were discussed. It is suggested that this could be the first time to use photografting technology to enhance the flame retardancy of PA6.6 fabric. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Improving the colour fastness of dyed nylon‐6 fabric by graft copolymerisation and curing of acrylic acid

The influence of grafting and grafting–curing of acrylic acid on the colour fastness of nylon‐6 fabric dyed with an acid dye of low wash fastness was investigated. The variables involved in grafting were initially optimised for pristine nylon‐6 fabric prior to grafting the same monomer onto the dyed fabrics. The highest graft yield achieved for the pristine and dyed nylon‐6 fabrics was 44 and 14% respectively. Grey scale testing and colorimetric analysis revealed that the highest colour fastness and the smallest drop in colour strength belonged to the dyed–grafted–cured nylon‐6 fabric. The colour components were measured, and the total colour difference of each sample after five washing cycles was computed. The specific colour difference showed that the implementation of either grafting or grafting–curing processes will alter the reference colour of the dyed fabric. The tensile strength of the grafted and grafted–cured fabrics was respectively 2.7 and 6.3% lower than that of dyed nylon‐6.     

Change in colour of dyed aramid fabrics by sputter etching

The aramid fabrics Technora and Conex, dyed with CI Disperse Yellow 54, CI Disperse Red 60 and CI Disperse Blue 56, were treated with sputter etching and argon low-temperature plasma. The colour depth of Technora was considerably increased by sputter etching, whereas that of Conex was not. Changes in colour were investigated by the L*, C*, h colour system. The increase in colour depth due to sputter etching was greatly dependent on the decrease of metric lightness L* and the increase of metric chroma C*.     

酸性偶氮染料的好氧生物降解性能试验研究

研究了呼吸法、基质去除法、微生物细胞增殖法等4种有关好氧生物降解酸性偶氮染料的测定方法,为污染物的生物降解性能研究以及开发生物处理技术提供参考和实践指导.     

Synthesis of novel dyestuffs containing sulphonamido moieties and their application on wool and polyamide fibres

A new series of azo disperse dyestuffs were prepared by the reaction of sulphanilamidodiazonium chloride derivatives with indan-1,3-dione. Application of these dyes on wool and nylon 6.6 gave excellent results. The synthesised compounds show good biological activity towards different microorganisms.     

Effect of content of fluorescent brightening agents on colour change of dyed cotton fabric

The effect of fluorescent brightening agents at a range of concentrations on the colour change of cotton fabrics was investigated by means of the CIELab colorimetric system. The reduction of b * (i.e. Δ b *) was determined as a function of the content of the fluorescent brightening agents. By plotting the values of L * versus Δ b * for the dyed fabrics, the critical lightness ( L _c*) was calculated which varied according to the hue of the fabrics and the content of the fluorescent brightening agents.     

The colour fastness of optionally aftertreated metal complex acid dyes on nylon 6.6 during washing in an activated oxygenbleach containing detergent

Previous studies examining the fading exhibited by optionally aftertreated acid levelling and acid milling dyes on nylon 6.6, during washing in an oxidative-bleach containing detergent, have been extended to metal complex dyes. It has been shown that, in the main, such dyes exhibit low levels of (oxidativebleach) fading in both the single cycle, stressed UK-TO (60 °C) test and after 20 machine washes at 50 °C.     

Comparison of the toughening behavior of nylon 6 versus an amorphous polyamide using various maleated elastomers

The toughening effect of two types of elastomers based on ethylene/α-olefin copolymers, viz, an ethylene/propylene copolymer (EPR) with its maleated version, EPR-g-MA, and an ethylene/1-octene copolymer (EOR) with its maleated versions, EOR-g-MA-X% (X=0.35, 1.6, 2.5), for two classes of polyamides: semi-crystalline nylon 6 versus an amorphous polyamide (Zytel 330 from DuPont), designated as a-PA, was explored. The results are compared with those reported earlier based on a styrenic triblock copolymer having a hydrogenated midblock, SEBS, and its maleated version, SEBS-g-MA, elastomer system. Izod impact strength was examined as a function of rubber content, rubber particle size and temperature. All three factors influence the impact behavior considerably for the two polyamide matrices. The a-PA is found to require a somewhat lower content of rubber for toughening than nylon 6. Very similar optimum ranges of rubber particle sizes were observed for ternary blends of EOR-g-MA/EOR with each of the two polyamides while blends based on mixtures of EPR-g-MA/EPR and SEBS-g-MA/SEBS (where the total rubber content is 20% by weight) show only an upper limit for a-PA but an optimum range of particle sizes for nylon 6 for effective toughening. Higher EPR-g-MA contents lead to lower ductile-brittle transition temperatures (T_db) as expected; however, a-PA binary blends with EPR-g-MA have a much lower T_db than do nylon 6 blends when the content of the maleated elastomer is not high. A minimum in plots of ductile-brittle transition temperature versus particle size appears for ternary blends of each of the matrices with EOR-g-MA/EOR; blends based on SEBS-g-MA/SEBS, in most cases, show higher ductile-brittle transition temperatures, regardless of the matrix. However, blends with EPR-g-MA/EPR show comparable T_db with those based on EOR-g-MA/EOR for the amorphous polyamide but show the lowest ductile-brittle transition temperatures for nylon 6 within the range of particle sizes examined. For the blends with a bimodal size distribution, the global weight average rubber particle size is inappropriate for correlating the Izod impact strength and ductile-brittle transition temperature. In general, trends for this amorphous polyamide are rather similar to those of semi-crystalline nylon 6.     

The dyeing and colour characteristics of alkali–treated polyester fibres dyed with disperse dyes

Alkali–treated and untreated polyester fabrics were dyed for up to 6 h at 100°C with a series of six disperse dyes of different chemical structures. The alkali–treated polyester samples adsorbed more dye and were dyed to deeper depths of shade and slightly different shades than was the untreated polyester. The greatest differences were observed for the alkali–treated polyester with the most outer surface or skin removed. Dye structure and molecular size also affected the amount of dye adsorbed on the fibres, but did not delineate the nature of differences between skin and core morphology. This study shows that significant differences exist between the molecular structure of the skin and core of melt–spun polyester fibres.     

A study on the effect of bulk water content and drying temperature on the colour of dyed cotton fabrics

In the present study, the effect of various levels of bulk and free water content and its distribution on the colour of cotton fabrics dyed with direct dyes and their combinations were analysed. Twill and plain structures with two different parameters of fabric construction were chosen. The dyed samples were adjusted to different levels of wet pick‐up, with water ranging from 50% to 125% on the bone dry weight of the fabric (odwf) to achieve various levels of bulk water content. Further, the residual moisture content of the samples was adjusted to 40–10% odwf by means of hot air drying at different temperatures to obtain different levels of free water content and its distribution. For the assessment of colour and its comparison, the parameters ΣK/S and values were used. In order to bring out the true effect of moisture distribution and fabric structure, normalisation of dye uptake in the fabric based on weight and area were considered, respectively. The plain structures show a higher increase in colour than the twill structures when the bulk water content increases. At the same time, the fabric structures do not play a significant role, with increase in colour attributable to change in drying temperature. The findings reveal that the bulk water content, drying temperature and fabric geometry affects the colour of the fabric significantly.     

Two-resistance mass transfer model for the adsorption of various dyestuffs onto chitin

The kinetics of the adsorption of various dyestuffs onto chitin have been studied. The dyestuffs used are Neoland Blue 2G, Eriochrome Flavine A, and Solophenyl Brown 3RL and a number of process variables were considered, such as adsorbent mass and dye concentration. The mass transfer model is based on the assumption of a pseudoirreversible isotherm and two resistances to mass transfer. These are external mass transfer and internal pore diffusion mass transfer. The rate of adsorption of dyestuffs onto chitin can thus be described by an external mass transfer coefficient and a pore diffusion coefficient. The external mass transfer coefficients are 5.0 × 10^?5, 5.0 × 10^?5, and 1.0 × 10^?5 m·s^?1 and the pore diffusivities are 3.0 × 10^?10 and 4.0 × 10^?11 m²·s^?1 for Neolan Blue 2G, Eriochrome Flavine A, and Solophenyl Brown 3RL, respectively.     

pH control in the dyeing of polyamide with acid dyes

In this study, we report a number of pH control systems for the dyeing of polyamide fibres in a closed dyeing procedure. These include a phosphate buffer system and four pH sliding systems (ammonium sulphate and three hydrolysable organic esters). The dyeing properties of these systems are compared with their ability to control the pH. In comparison with sodium dihydrogen phosphate and ammonium sulphate, hydrolysable organic esters showed a much more effective pH sliding and, consequently, showed higher dyebath exhaustion and colour yields. They also showed very low conductivity, typically less than 0.5 mS. However, no difference in the levelness of the dyed samples among the five acid donors studied was observed and no difference in colour fastness of the dyed fabrics under various pH control systems was detected.     

Successful commissioning of a polyamide 6.6 plant at Huafon Group in Ruian, China

工程公司德国伍德伊文达菲瑟于2012年3月1日宣布，为中国客户华峰集团建设的尼龙66装置已成功投产。该生产装置具有年产4万吨的能力，位于华峰集团在浙江省瑞安市的总部。伍德伊文达菲瑟公司能效、资源节约和降低成本的尼龙66技术，使华峰集团可生产高品质的尼龙66颗粒。