Yingjie Cai

Multi-Response Optimization of Resin Finishing by Using a Taguchi-Based Grey Relational Analysis

In this study, the influence and optimization of the factors of a non-formaldehyde resin finishing process on cotton fabric using a Taguchi-based grey relational analysis were experimentally investigated. An L27 orthogonal array was selected for five parameters and three levels by applying Taguchi’s design of experiments. The Taguchi technique was coupled with a grey relational analysis to obtain a grey relational grade for evaluating multiple responses, i.e., crease recovery angle (CRA), tearing strength (TE), and whiteness index (WI). The optimum parameters (values) for resin finishing were the resin concentration (80 g·L−1), the polyethylene softener (40 g·L−1), the catalyst (25 g·L−1), the curing temperature (140 °C), and the curing time (2 min). The goodness-of-fit of the data was validated by an analysis of variance (ANOVA). The optimized sample was characterized by Fourier-transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and scanning electron microscope (SEM) to better understand the structural details of the resin finishing process. The results showed an improved thermal stability and confirmed the presence of well deposited of resin on the optimized fabric surface.

Combined use of cationization and mercerization as pretreatment for the deep dyeing of ramie fibre

In order to produce deep shades of colour, ramie fibre was subjected to pretreatment by cationization, caustic mercerization (slack and tension condition), and liquid ammonia mercerization. The untreated and pretreated samples were dyed with 0.5 to 7 % concentrations (on mass of fiber (o.m.f)) of Liyuansol Red FL-2BL reactive dye. The dyeing properties of dye exhaustion, fixation, colour uniformity, wash fastness, and rubbing fastness were investigated. The results indicated that these pretreatments improved dye exhaustion and fixation on ramie fibre, with no loss of fastness. For the untreated and treated substance, the amount of dye mass absorption increased linearly with increased dye o.m.f. Cationic treatment improved performance, with 89 % and 98 % for exhaustion and fixation, respectively, and the maximum K/S values of all fibers receiving pretreatment. The colour uniformity was acceptable and similar for the untreated and treated ramie fibers, with the exception of cationic-treated fabric dyed at 7 % dye o.m.f that showed a high standard deviation value of colour uniformity. The Freundlich and Langmuir adsorption isotherm models were also used to study the adsorption of dye on ramie fibre; all of the adsorption processes fit the Freundlich model.

Reactive dyeing of ramie yarn washed by liquid ammonia

The washing efficiency of water, nonionic soap solution, reflux solution, pure liquid ammonia (99.99%), and solvated liquid ammonia was studied on dyed ramie yarns. The ramie yarn samples were dyed with a 2% on weight of fiber (o.w.f) shade with five types of reactive dye by the classical exhaustion method. The washing performances of these solvents were quantified by the dye removal rate, the color uniformity, and the color fastness properties (washing, rubbing, and lightness). Furthermore, the influence of these wash methods on the physical properties of the final yarn samples including shrinkage, tensile strength, and elongation was schematically examined. The results of these measurements revealed that the dye removal rates during the washing in pure liquid ammonia and solvated liquid ammonia were lower than the yarn washed in water, soap solutions, or reflux solutions. The color uniformity (expressed as the standard deviation of K/S values for all dyed ramie yarns) was within the acceptable limits with the satisfactory color fastness levels. The shrinkage values of yarns that were washed in the pure liquid ammonia and the solvated liquid ammonia were both similar (9.0%) and considerably higher than the samples washed in water (1.8%), soap solution (2.4%), or reflux solution (2.6%). The tensile strength and the elongation of the resultant yarns improved significantly when the samples washed in pure liquid ammonia. The yarns that were washed in the solvated liquid ammonia solutions had decreased tensile strength and elongation. The cause of the decrease was determined by the XRD measurements, which confirmed that the crystallinity, and the orientation of these fibers decreased dramatically after being washed in the ammonia system solutions. The samples that were washed in the liquid ammonia had a smoother surface morphology than the other washing processes.

Structural relationships and optimization of resin-finishing parameters using the Taguchi approach

Formaldehyde-based materials pose a threat to human life due to their carcinogenic nature; therefore, the development of a non-formaldehyde-based process for resin finishing of cotton fabrics is required. Hence, the goal of this study is to establish a non-formaldehyde-based resin-finishing process for cotton fabrics using the Taguchi design with optimized experimental conditions. The influences of the resin concentration, softener, catalyst, curing temperature, and curing time at three levels on the crease recovery angle, tearing strength, and whiteness index were investigated. Subsequently, the predicted levels were confirmed using a validation and the resulting p value of 0.000 indicated the strong predictive capability of the regression model for all selected responses. Finally, the structural relationship of the optimized resin-finished samples was investigated by Fourier-transform infrared spectroscopy and thermogravimetric analysis and indicated a strong chemical interaction and enhanced thermal stability of the treated fabrics. Hence, the optimization method using the L27 Taguchi design resulted in the best parameter conditions that can be used in non-formaldehyde resin finishing processes in the near future.Graphical abstract

Cationic modification of ramie fibers in liquid ammonia

Anhydrous liquid ammonia was used as a solvent for the cationic modification of ramie fiber using 2, 3-epoxypropytrimethylammonium chloride (EPTAC). The processing parameters, including treatment temperature, treatment time, concentration of EPTAC, and concentration of NaOH were schematically investigated in order to control the properties of the fibers. The optimum parameters for cationic modification in liquid ammonia were analyzed through zeta potential measurement. The modified fibers were dyed in different conditions after modification, and the dyeing behaviors such as exhaustion and fixation properties were carefully examined. The modified fiber in liquid ammonia consisted of a higher number of cationic groups on the fibers compared to the fibers modified in water. The cationization reaction in liquid ammonia significantly decreased the crystallinity and the crystallite orientation of the resultant fibers. The decreased crystallinity slightly decreased the thermal resistance and tensile strength but increased the elongation ability of the fibers. The liquid ammonia cationic modification process turned the appearance of fibers from rough to smooth and lustrous due to swelling of fibers in the solvent. The exhaustion, fixation and wash fastness property of the fibers were improved after the cationic modification in liquid ammonia.Graphical Abstract

Investigation of Comfort Properties of Knitted Denim

Knitted denim was designed by using cross terry structure on circular knitting machine. Knitted denim looks like a denim fabric which has visual appearance like woven denim. Two type of cross terry structure 2/1 and 3/1 were used which gives twill effect with 2 and 3 floats respectively. Four types of materials, cotton, polyester, flax and polypropylene were used. With four materials and two structural combinations 8 samples were produced. Comfort properties of knitted denim including moisture management, air permeability, thermal, and bursting strength were tested. For checking the inherent anti-microbial property of materials anti-microbial test was also applied. Samples containing flax and polyester were found with best results and not even a single sample was found anti-microbial.

Effect of Bamboo Viscose on the Wicking and Moisture Management Properties of Gauze

Bamboo viscose or regenerated cellulose fibers were used to check their absorbency properties effect on the wicking and moisture management in gauzes. Bamboo viscose and cotton fibers were spun into five different yarn samples with different fiber proportion by ring spinning. Fifteen different gauze samples were made of these yarn samples. The gauze samples were subjected to wicking test to check the wicking ability. Water vapor transmission test was applied to check the vapor transmission rate. These tests were applied to measure the effectiveness of bamboo viscose, cotton and blended gauze samples in wound healing. Pure bamboo gauzes and gauzes with high content of bamboo fiber, i.e. 75B:25C and 50B:50C, shows better wicking and vapor transmission properties. It makes gauzes with high bamboo viscose suitable for wound care applications because of moisture absorbency.

Preparation and characterizations of polypyrrole on liquid ammonia pre-treated wool fabric

Wool fabric was treated with liquid ammonia at -40 °C for 30 and 60 s prior to the application of polypyrrole (PPy). The polymer was deposited on wool fiber using the chemical oxidation method with 0.02 and 0.05 mol/l (Py) monomer concentration and FeCl3 as a catalyst. Functional groups of wool samples were analyzed using FT-IR, and surface morphology was investigated using SEM micrographs. Properties such as water absorbency, surface resistivity, abrasion resistance, weight add-on, and air permeability of coated specimens were explored. The FT-IR outcomes revealed the liquid ammonia pre-treatment changed the amount of amide I (NH), cystic acid, cystic monoxide, and dioxide content of the fiber. SEM micrographs revealed the descaling of wool surface after pre-treatment and smooth coating of polymer. Pre-treatment of wool in liquid ammonia improved absorbency of wool fabric with respect to the treatment duration. The surface resistivity of wool fabric decreased with the increase of monomer concentration and pre-treatment duration. The results of abrasion resistance confirmed that the pre-treated fabric exhibited lower loss of polymer after 200 cycles of abrasion. The weight of the fabric was increased and air permeability decreased when the monomer concentration and liquid ammonia pre-treatment duration was increased.