Investigation on multifunctional modification of cotton fabrics for salt-free dyeing, resisting crease and inhibiting bacteria

Study on a cationic agent-based salt-free reactive dyeing process for cotton knit fabric and comparison with a traditional dyeing process

Since the majority of reactive dyes only have a moderate affinity for cotton, significant amounts of electrolytes are frequently needed to cause tiredness. As a result, wastewater contains significant amounts of salt and dye, and the increasing salinity of the rivers has an effect on the delicate biochemistry of aquatic life. The aim of the study was to find a sustainable dyeing process for cotton knit fabric using EPTMAC (2, 3-epoxypropyl trimethyl ammonium chloride) as a cationic agent and comparison of the cationic dyeing process (salt free dyeing) with the regular dyeing process (dyeing with salt). For this purpose, cotton knit fabric samples were dyed with reactive dyes following salt free process and with salt. Afterwards, color fastness (wash and rubbing), spectrophotometric evaluation, bursting strength test, analysis of dye bath discharge water and Scanning Electron Microscope (SEM) image of the dyed samples were carried out. Moreover, water consumption was also evaluated for the both cationic and regular dyeing process. In terms of color fastness, cationized dyed fabric showed no change to a slight loss in depth (rating of 4-5) for both wash and rubbing fastness. From the spectrophotometric evaluation, it was found that cationized dyed fabric appeared darker and less yellowish tone. Moreover, in case of bursting strength, cationized black, hot pink, and light pink colored fabrics possessed bursting strengths of 287 kPa, 337 kPa, and 440 kPa, correspondingly. After analysis of dye bath discharge water, Biological Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Total Dissolved Solids (TDS) value of regular colored water samples were 45%, 39%, 54% greater than that of cationized dyed water samples respectively. Cationized dyed water value for Dissolved Oxygen (DO) was 6.39 mg/l, which was within the acceptable limit. The SEM image asserted that the cationized colored samples had consistent dye dispersion, greater adhesion, and no dye anomalies. Considering water consumption, it was found that 37%, 27% and 23% less amount of water required for dyeing dark, medium and light shade of cationized samples due to fewer washes after dyeing and elimination of fixing steps. In addition of that, total cost of cationic dyeing process was less due to less chemical consumption, less utility use, shorter process time and less amount of dyes needed. Cationic dyeing process is a sustainable practice of dyeing cotton fabric with reactive dyes that offers numerous advantages when compared to the regular dyeing process with less cost consumption and low amount of environmental pollution.

Tensile Strength Improvements of Ramie Fiber Threads through Combination of Citric Acid and Sodium Hypophosphite Cross-Linking

Ramie (Boehmeria nivea) is believed to be one of the strongest natural fibers, but it still remains behind synthetic materials in terms of tensile strength. In this study, ramie materials were prepared to evaluate the modification crosslinking effect of natural fiber. The aim is to optimize various concentrations of citric acid (CA) crosslinking by adding Sodium hypophosphite (NaPO2H2), which is activated at different temperatures, to obtain the highest tensile mechanical strength. This crosslinking effect has been confirmed by FTIR to show the esterification process in the molecular structure of cellulose. The changes in the character of the fiber surface were analyzed by SEM. The tensile strength increased from 62.33 MPa for 0% CA to 124-172.86 MPa for decorticated fiber with a CA concentration of 0.75-1.875% (w/w). A significant increase in tensile strength was observed more than 19 times when CA/SHP 1% was treated at an activation temperature of 110 °C with a superior tensile strength of 1290.63. The fiber crosslinked with CA/SHP should be recommended for application of Natural Fiber Reinforced Polymer Composite (NFRPC), which has the potential to use in functional textile and industrial sector automotive or construction.

Green and sustainable fabrication of a durable superhydrophobic cotton fabric with self-cleaning properties

The use of more toxic reagents in the finishing of superhydrophobic cotton fabrics is one of the main factors that limit the application of the fabrics. Therefore, a green and sustainable method for preparing superhydrophobic cotton fabrics is urgently needed. In this study, a cotton fabric was etched with phytic acid (PA), which can be extracted from plants, effectively improving the surface roughness of the fabric. Subsequently, the treated fabric was coated with epoxidized soybean oil (ESO)-derived thermosets and then covered with stearic acid (STA). The finished cotton fabric exhibited excellent superhydrophobic properties, with a water contact angle of 156.3°. The superhydrophobic coatings of the finished cotton fabric endowed the fabric with excellent self-cleaning properties, irrespective of the liquid pollutant or solid dust. In addition, the inherent properties of the finished fabric were largely retained after the modification. Therefore, the finished cotton fabric with excellent self-cleaning properties has great potential for applications in the household and clothing fields.

Cotton functionalized with polyethylene glycol and graphene oxide for dual thermoregulating and UV-protection applications

A thermoregulating smart textile based on phase change material (PCM) polyethylene glycol (PEG) was prepared by chemically grafting carboxyl-terminated PEG onto cotton. Further deposits of graphene oxide (GO) nanosheets were made on the PEG grafted cotton (PEG-g-Cotton) to improve the thermal conductivity of the fabric and to block harmful UV radiation. The GO-PEG-g-Cotton was characterized by Attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), Raman spectroscopy, X-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), and field emission-scanning electron microscopy (FE-SEM). With an enthalpy of 37 and 36 J/g, respectively, the DSC data revealed that the functionalized cotton's melting and crystallization maxima occurred at 58 °C and 40 °C, respectively. The thermogravimetric analysis (TGA) presented that GO-PEG-g-Cotton was thermally more stable in comparison to pure cotton. The thermal conductivity of PEG-g-Cotton increased to 0.52 W/m K after GO deposition, while pure cotton conductivity was measured as 0.045 W/m K. The improvement in the UV protection factor (UPF) of GO-PEG-g-Cotton was observed indicating excellent UV blocking. This temperature-regulating smart cotton offers a high thermal energy storage capability, better thermal conductivity, thermal stability, and excellent UV protection.