Lipase treatment of polyester fabrics

The aim of this paper is to improve moisture regain of PET fabrics using a lipase treatment. Effects of nine lipase sources, lipase activator and nonionic surfactant on moisture regain of PET fabrics are examined. Moisture regains of lipase-treated samples improve by two times in average compared with untreated and buffer-treated samples. Alkaline treatment creates larger pitting by more aggressive attack into fiber which is proved by SEM and water contact angle measurement. Moisture regain by alkaline treatment (0.568 % ± 0.08) does not improve. However, lipase-treatment (L2 treatment) improves moisture regain up to 2.4 times (1.272 % ± 0.05). Although lipase treatment is more moderate than alkaline treatment, lipase hydrolysis on PET fabrics improves moisture regain, efficiently. K/S values improved confirm that carboxyl and hydroxyl groups are produced on the surface of PET fabrics by lipase hydrolysis. Moisture regain and dyeability improve by lipase hydrolysis on PET fabrics.     

Facile fabrication of superhydrophobic cotton fabric from stearyl methacrylate modified polysiloxane/silica nanocomposite

The stearyl methacrylate modified polysiloxane/nanocomposite was synthesized by graft copolymerization between stearyl methacrylate modified polysiloxane with pendent epoxy groups and amino-functionalized nano silica. Then it was utilized to fabricate the superhydrophobic cotton fabric by one-step method. The structures, chemical compositions, thermal properties, surface morphology and wettability were characterized by Fourier Transform Infrared Spectrum (FT-IR), X-ray photoelectron spectroscopy (XPS), Thermo-gravimetric analyzer (TGA), Scanning electron microscopy (SEM) and Static contact angle analyzer. Results showed that a hydrophobic polysiloxane film and many nano-scaled tubercles were coated on the surface of the treated cotton fabrics plus their inherent microscaled roughness, which were the reasons why cotton fabric changed from hydrophilicity to hydrophobicity. In addition, with increase of the amount of nanocomposite, hydrophobicity of the treated cotton fabric would be enhanced; water contact angle of this fabric could attain 157°, which was higher than 141.5° reached by the fabric treated with stearyl methacrylate modified polysiloxane. The superhydrophobic cotton fabric also possessed favorable washing durability. On the other hand, its air permeability, color and softness would not be influenced instead.     

Highly Durable and Robust Superhydrophobic/Superoleophilic Cotton Fabric with Well-designed Roughness for Oil/Water Separation

Herein we report a simple and reproducible method for fabricating highly durable and robust superhydrophobic and superoleophilic cotton fabrics via simultaneous radiation-induced graft polymerization of glycidyl methacrylate and subsequent chemical modifications with aminopropyltriethoxysilane and hexamethyldisilazane. The chemical structure and the surface topography of the pristine and the modified cotton fabrics were investigated in detail by ATR-FTIR, XPS, and ²⁹Si NMR, and a grafting layer was successfully immobilized onto the surface of the cotton fabric by forming covalent bonds. Multi-dimensional surface roughness was created by combining micro-sized fibers of the cotton fabric, nanoscaled protuberances of the grafting chain, and molecular level spherical projection points of silicon methyl. The superhydrophobic cotton fabric exhibited long-term stability, ultra-high durability and robustness, and maintained its properties even after 25 wash cycles. The fabric also showed excellent water repellency with a water contact angle of 153 ° and a high efficiency of oil/water separation (98 %). The superhydrophobic/superoleophilic cotton fabric developed in the present work exhibits important potential applications in superhydrophobic textiles and oil/water separation.     

Surface modification of polyester fabrics by enzyme treatment

In this study, the effect of enzymatic hydrolysis using lipase and cutinase on poly(ethyleneterephthalate) (PET) fabrics was investigated in an attempt to improve the hydrophilicity of these fabrics. The hydrolytic activity of the enzymes was expressed for variations in pH levels, temperatures, enzyme concentrations, and treatment times. The effects of using a nonionic surfactant were examined by measuring moisture regain and surface wettability. Finally, the fabric characteristics that were affected by enzyme treatment were evaluated by tensile strength and scanning electron microscopy. The optimal treatment conditions for lipase were determined to be a pH of 4.2, a temperature of 50 °C, a lipase concentration of 100 %, and a treatment time of 90 min; those for cutinase were determined to be a pH of 9.0, a temperature of 50 °C, a cutinase concentration of 100 %, and a treatment time of 60 min. At optimal enzymatic treatment conditions, we got the significant results of increase on the moisture regain and the water contact angle (WCA) and water absorbency effectively decreased. Triton X-100 facilitated cutinase hydrolysis on PET fabrics; however, it was ineffective for lipase. With enzymatic treatment, the tensile strength did not decrease.     

Influence of oxygen plasma pre-treatment on the water repellency of cotton fibers coated with perfluoroalkyl-functionalized polysilsesquioxane

Oxygen plasma pre-treatment was applied to cotton fabric with the aim of improving the water repellency performance of an inorganic-organic hybrid sol-gel perfluoroalkyl-functionalized polysilsesquioxane coating. Cotton fabric was pre-treated with low-pressure oxygen plasma for different treatment times and operating powers. Afterward, 1H,1H,2H,2H-perfluorooctyltriethoxysilane (SiF) was applied to the cotton fabric samples using the pad-dry-cure method. The surfaces of the untreated and modified cotton fibers were characterised using Fourier transform infrared spectroscopy, Xray photoelectron spectroscopy, scanning electron microscopy, and atomic force microscopy. The water repellency of the SiF-coated fabric samples was evaluated using static and sliding contact angle measurements with water. The results show that the plasma treatment with the shortest treatment time (10 s) and the lowest operating current (0.3 A) increased the atomic oxygen/carbon ratio of the cotton fiber surface from 0.6 to 0.8 and induced the formation of a nano-sized grainy surface. Increasing the plasma treatment time and/or operating current did not intensify the surface changes of the cotton fibers. Such saturation effects were explained by the large influence of reactive oxygen atoms during the plasma treatment. The measured static water contact angles on the surface of the untreated and plasma pre-treated and SiF-coated cotton fabrics showed that the oxygen plasma pre-treatment enabled the increase of the water contact angle from 135° to ≈150°, regardless of the applied plasma treatment time and discharge power. This improvement in the hydrophobicity of the SiF coating was followed by a decrease in the sliding angle of water droplets by more than 10° compared to the plasma untreated and SiF-coated sample characterized by a water sliding angle of 45°. Additionally, measurements of the water sliding angle revealed that the increase of the static contact angle from 149° to 150° corresponded to a drop of the water sliding angle from 33 to 24°, which suggests that the plasma pre-treatment of 20 s at an operating current of 0.3 A produced the best water-repellent performance of the SiF-coated cotton fabric.     

Surface Modification of Wool Fabric with POSS® Nanomaterial

Wool fabrics, without any surface treatment, can undergo undesirable and irreversible structural changes of wool fiber during washing under heat and mechanical agitation, leading to high shrinkage of wool garments. The traditional method based on polyamide resin can prevent felting and/or shrinkage of wool textiles, but adversely affect the surface hydrophobicity. In the present study, a treatment solution was developed based on TriSilanolIsooctyl POSS® and 3- mercaptopropyl trimethoxysilane, which created wool surface with increased hydrophobicity and highly resistant to shrinkage or felting, as measured after 3×5A wash cycles (equivalent to 24 domestic washes). After the treatment, the wool fabric appeared to be superhydrophobic with a water contact angle of above 150°, compared to the untreated fabric. The treatment has marginal effect on mechanical performance as observed in tensile properties. Scanning electron microscopic images revealed a coating of POSS® on the wool surface. The dyeing of untreated and treated fabrics appeared to be uniform to the naked eye, though spectrophotometric analysis indicated a difference in the extent of dyeing performance. This research showed that POSS®-based treatment is a potentially effective approach for developing shrink-resistant wool textiles with enhanced surface hydrophobicity, in contrast to traditional chlorine/polyamide resin treatment.     

Superhydrophobic and Antibacterial Properties of Cotton Fabrics Treated with PVDF and nano-ZnO through Phase Inversion Process

Cotton fabrics exhibiting superhydrophobic and antibacterial properties were prepared through a non-solvent induced phase separation method using hydrophobic poly(vinylidene fluoride) (PVDF) and its hybrids with photocatalytic zinc oxide nanoparticles (nano-ZnO) as surface modifying agents for cotton fabric. The effects of coagulating medium and temperature on microstructural morphology and surface hydrophobictity of the cotton fabrics were investigated by FE-SEM observation and contact angle measurement. Superhydrophobic cotton fabrics exhibiting water contact angle higher than 150 ° could be obtained by coating the fabrics with solutions of PVDF and nano-ZnO followed by coagulation in ethanol as non-solvent. This phenomenon is considered to be originated from both chemically hydrophobic PVDF layer and physical micro- and nano-bumps formed on the surface of cotton fabric, which are essential requirements for Lotus effect. Moreover, antibacterial properties could be synergistically obtained by utilizing photocatalytic effect of nano-ZnO.     

Copper functionalization of polypropylene fabric surface in order to use in fog collectors

Polypropylene fabrics were coated with copper particles using electroless plating, screen printing and wire arc spray coating techniques. Surface morphology of the fabrics was studied using optical and scanning electron microscopes (SEM). Furthermore, tensile strength, electrical conductivity, thermal conductivity, air permeability, water contact angle and fog collection efficiency of the coated fabrics were measured and the obtained results were analyzed. SEM micrographs showed that a very thin and uniform layer of copper deposited on the surface of the electroless plated polypropylene fibers. In the printed or spray coated fabrics the copper particles filled the spaces between yarns and fibers. The polypropylene electroless copper plated fabrics showed higher tensile strength, electrical conductivity, air permeability and thermal conductivity when compared with the fabrics coated with copper screen printed and copper spray coated fabrics. Finally, the obtained results showed that copper electroless plating could increase the fog collection efficiency of polypropylene fabrics considerably. As a conclusion, the surface modified copper electroless polypropylene fabrics are good candidates for fog collection in appropriate regions which need further investigations.     

Water and oil-repellent coatings of perfluoro-polyacrylate resins on cotton fibers: UV curing in comparison with thermal polymerization

UV curing of perfluoro-alkyl-polyacrylate resins able to impart water as well as oil-repellency to cotton fabrics was studied in comparison with conventional thermal polymerization. The process was assessed through weight gain and gel content measurements while the properties conferred to cotton fabrics were determined in terms of water and oil contact angles, moisture adsorption, and water vapor permeability. The polymerization yields were of the same order (>80 %) of those obtained with thermal curing as well as the high contact angles with water (>127°) and oil (>118°) even at low resin add-on (3 %). UV cured resins yielded oil contact angles mostly higher than 120° denoting super oil-repellent surfaces. Moreover the water and oil-repellency was adequately maintained after washing. The moisture adsorption of finished fabrics was lower than that of untreated cotton, but slightly higher for UV cured than thermally treated fabrics. Water vapor transmission rate showed that the finish treatment, thermal as well as by UV curing, does not reduce the breathability of the original cotton. DSC analysis demonstrated that the fiber pyrolysis is affected by the polymer add-on, while FTIR-ATR spectra of all finished fabrics showed typical peaks of ester and C-F groups. XPS analysis showed small differences between thermal and UV curing coatings with each resin, while coatings with the lowest percentage of fluorine groups did not affect the water and oil-repellency.     

Robust Water-Repellent Treatment of Cotton Fabrics with Polysiloxane Modified via Thiol-Ene Click Reaction

A facile and inexpensive way to prepare self-crosslinkable poly(dimethylsiloxane) (PDMS) for superhydrophobic treatment of cotton fabrics is reported in the study. Through thiol-ene click reaction between mercaptopropyltrimethoxysilane (MPTMOS) and vinyl-containing poly(dimethylsiloxane) (VPDMS), PDMS-g-TMOS can be simply and quickly synthesized. The trimethoxysilane group of PDMS-g-TMOS can react with hydroxyl group on cotton fabric and other -Si(OCH₃)₃ groups. The synthesized polysiloxane (PDMS-g-TMOS) was identified by FT-IR and ¹H-NMR. The morphology of the treated cotton fabric was observed by SEM and XPS was used to analyze the elemental composition on the surface of cotton fabric. The analysis results indicated that the surface was fully covered with PDMS. Due to the low surface energy of PDMS and the rough surfaces of cotton fabric, the optimized water contact angle (WCA) and sliding angle were respectively 154°±0.4° and 14°±0.5°, indicating superhydrophobicity. Moreover, water spray test (AATCC Test Method 22-2010) was also applied to evaluate the water repellency of treated cotton fabric and a score of 90 was assigned according to AATCC Test Method 22-2010. The durability of treated cotton fabric was tested by 50 laundering cycles. The resultant WCA barely decreased and the score of water spray test dropped from 90 to 80, showing the reasonable wash durability.     

Mechanical anisotropy in unidirectional glass fabric reinforced oligomeric siloxane modified polyester composites

In this study, the effect of incorporation of oligomeric siloxane into unsaturated polyester on mechanical behavior of unidirectional glass fiber/polyester composites has been investigated by means of tensile, flexural and short beam shear tests. The amount of oligomeric siloxane added into unsaturated polyester was in the range 1?C3 % by weight of the glass fabrics. Mechanical tests were conducted at different angles (0 °, 45 °, and 90 °) with respect to fiber direction. The higher siloxane content exhibited a tendency to have greater tensile, flexural and interlaminar shear strength values in machine direction, bias direction and cross direction. From Scanning electron microscopy images, the presence of polyester particles on the unidirectional glass fiber surface confirmed better adhesion.     

Surface treatments of jute fabric: The influence of surface characteristics on jute fabrics and mechanical properties of jute/polyester composites

In this study, jute fabrics were modified by alkali, micro-emulsion silicon (MS) and fluorocarbon based agents (FA) in order to enhance the interfacial adhesion between the polyester matrix and the jute fiber. X-ray photoelectron spectroscopy (XPS) and contact angle measurements were used to characterize fiber surfaces. The effects of various surface treatments on the mechanical and morphological of jute/polyester composites were also studied. All surface treatments were shown to improve the tensile, flexural strengths and interlaminar shear strengths of the composites. Moreover, the maximum improvement in the mechanical properties was obtained for the FA treated jute/polyester composites. SEM micrographs of the tensile fracture surface of jute/unsaturated polyester composites also exhibited improvement of interfacial and interlaminar shear strengths by the alkali, MS and FA treatments of jute fibers.     

Improvement of hydrophilicity of polylactic acid (PLA) fabrics by means of a proteolytic enzyme from <Emphasis Type="Italic">Bacillus licheniformis</Emphasis>

Polylactic acid (PLA) has received considerable attention as a biomass material for the textile industry. To use a PLA fabric in the textile industry, suitable postprocessing that can promote hydrophilicity of such fabrics is required. Here, hydrolytic action of a proteolytic enzyme (alcalase from Bacillus licheniformis) on PLA fibers was evaluated. In addition, the effects of an additive on the enzymatic hydrolysis were analyzed. The results revealed that the optimal enzymatic-hydrolysis conditions for this alcalase are pH 9.5, temperature 60 °C, enzyme concentration 50 % on weight of fabric (owf), and Lcysteine concentration of 3 mM. PLA fabrics were hydrolyzed effectively, however; there was no damage to these fabrics judging by tensile strength and surface observations. X-ray diffractometry identified a new peak (at 2θ=18.5 °), implying a morphological change caused by the treatment. Moreover, hydrophilic properties such as moisture regain and dyeing properties were enhanced by this proteolytic enzymatic hydrolysis. Therefore, according to this study, enzymatic hydrolysis is a suitable finishing method for improvement of hydrophilicity of PLA fabrics.     

A study of physical modification on grey cotton by laser irradiation

The surface morphology of the CO₂ laser treated grey cotton fabrics was studied which showed a characteristics sponge-like structure on cotton fibres after treating with CO₂ laser irradiation. The laser treatment parameters ranging from 100 to 150 pixel time and 40 to 70 dot per inch (dpi) were irradiated on the grey cotton fabrics directly and the degree of physical modifications, such as surface morphology, wettability and fabric strength, were changed accordingly with various laser treatment parameters. The surface morphology, wettability and tensile strength of cotton fibre treating with laser were evaluated using different instruments, such as Scanning Electron Microscope (SEM), contact angle meter and tensile strength machine. In spite of creating a sponge-like structure on fibre surface after treating with laser, the wettability of the samples was highly improved but the tensile strength was decreased.     

Synthesis of a dodecylphenylsiloxane oligomer resin/silica nanocomposite and its application to cotton fabrics

A novel dodecylphenylsiloxane oligomer resin/nanocomposite (PHDESR-SiO₂) was prepared by graft copolymerization between dodecyl modified phenylsiloxane resin with pendent epoxy groups (PHDESR) and amino-functionalized silica nanoparticles (BTEPA-SiO₂). PHDESR-SiO₂ was then used to prepare a super hydrophobic surface on cotton fabric by a facile solution-immersion process method. Chemical structures, chemical compositions, wettability, surface morphology, and thermal properties were investigated by Fourier Transform Infrared Spectrum (FT-IR), ¹H-NMR spectrum, X-ray photoelectron spectroscopy (XPS), static contact angle analyzer, scanning electron microscopy (SEM), Particle size distribution (PSD) and thermo-gravimetric analysis (TGA). The results showed that the target product PHDESR-SiO₂ has an anticipative structure with many micro/nanostructure tubercles, a cross-linked network hydrophobic organosilicon resin film and many clusters of cylindrical dodecyl molecular brushes. This created super hydrophobic structure on the surface of the treated cotton fabrics. XPS analysis indicated that the long carbon chain groups had a slight tendency to enrich the film-air interface. In addition, PHDESR-SiO₂ can provide good hydrophobicity for the treated fabric. As the dose of PHDESR-SiO₂ increased, the hydrophobicity of the treated fabric enhanced and consequently the water static contact angle reached 152.5 °. This had little influence on the softness, color, and gas permeability of the fabrics. This makes it slightly stiff at high doses, and the super-hydrophobic cotton fabric also had good launderability.     

Optimization of enzymatic treatment of polyamide fabrics by bromelain

In this study, we investigated the effects of enzymatic hydrolysis on polyamide fabrics by using bromelain as an enzyme. The hydrolytic activity of bromelain was evaluated on the basis of the number of carboxylic groups formed on the surface of the polyamide fabrics, and it was measured using the reactive dye absorbance. In addition, 2,4,6-trinitrobenzenesulfonic acid was added as an indicator to measure the number of amino groups released into the treatment liquid by the changes in color of the liquid. The optimum treatment conditions were bromelain pH of 6.0, treatment time of 120 min, temperature of 50 °C, concentration of 10 % (owf), and L-cysteine concentration of 70 mM. The weight loss in the fabric after treatment with bromelain facilitated by L-cysteine significantly improved; however, the tensile strengths of the polyamide fabrics did not show any differences. Bromelain hydrolysis of the polyamide fabrics thus improved hydrophilicity without damaging the fabrics’ strength.     

Microwave-mediated rapid tailoring of PET fabric surface by using environmentally-benign,biodegradable Urea-Choline chloride Deep eutectic solvent

Deep eutectic solvent, urea-choline chloride (URC), was used to control surface of poly(ethylene terephthalate) (PET) fabric under microwave irradiation with or without sodium hydroxide (NaOH) for hydrophilic-hydrophobic properties. Wicking and contact angle evaluations indicated that the URC-treated PET fabric drastically changed its surface characteristics from highly hydrophobic to highly hydrophilic (or vice versa) by carefully adjusting alkali concentration and microwave irradiation time. For instance, an instant wicking was achieved on URC-treated PET with 1 % NaOH at 60 s of microwave irradiation, whereas highly hydrophobic PET surface with 2600 s wicking time and 135.6 ° contact angle was acquired by adding 5 % NaOH at the same microwave irradiation. Methylene Blue staining and FTIR analyses suggested that a minimal hydrolysis occurred through URC-treatment with NaOH under microwave irradiation and hydrophilicity was mainly achieved by physical disruption of the fiber. The treated fabrics were further analyzed by DSC, TGA, and SEM. Therefore, a rapid control of hydrophilic-hydrophobic surface of PET fabric was achieved with a little side reaction by using environmentally-benign, biodegradable URC deep eutectic solvent.     

Development of Superhydrophobic Microfibers for Bandage Coatings

In this research work, a fabricated composite fiber is proposed to protect wound surfaces from infectious organisms present in water. The composite fiber comprising PMMA, ZnO, and zinc stearate was developed using an electrospinning technique. The fiber surface was scientifically studied using scanning electron microscope, Energy dispersive analysis of X-rays, powder X-ray diffraction analysis and Fourier transform Infra-Red analysis. The pores present in between perpendicularly aligned fibers serves as an excellent medium for vapor transport to a wound surface. The maximum water contact angle of the developed fiber surface was approximately 151 degrees. A commercial cotton bandage after coated with this composite layer behaves as a perfect barrier to the entry of infectious water towards the wound. The pores in the fiber surface support rich supply of environmental oxygen and transport of exudate vapor from the wound. This fiber when coated over a cotton bandage cloth on one side served as an excellent wound protecting bandage against the penetration of external microbial water and also it admits the air, water vapor etc., towards the interior. Water penetration ability of hydrophilic cotton bandage and the water arresting ability of superhydrophobic fiber coated bandage were evaluated using a facile technique. Furthermore, antimicrobial activity of test samples was evaluated against gram positive and gram negative microorganism. Also, a bacterial infiltration test supports the blocking capability of superhydrophobic fiber to water-borne bacteria. The results obtained through this experiment may be used in future as wound healing bandages in an efficient manner.     

The eco-friendly surface modification of textiles for deep digital textile printing by in-line atmospheric non-thermal plasma treatment

This study evaluated the potential application of an atmospheric plasma (AP) treatment as a pre-treatment for digital textile printing (DTP) of polyester (PET) fabrics and cotton, in order to determine its viability as an alternative to the usual chemical treatment. The surface properties of the AP-treated fabrics were examined through scanning electron microscopy (SEM) and contact angle, and the physical properties, such as electrostatic voltage and water absorbance, were tested. The properties of cotton and PET with the AP treatment were found to be dependent on number of repetitions and electric voltage. Although no remarkable surface differences were observed by SEM in the fabrics before and after treatment, the static contact angle of the PET after AP treatment was decreased from 85 ° to 24 ° at wave. In addition, the charge decay time decreased as the voltage and number of treatments increased. The absorption height of PET changed after exposure to 7 mm with increasing measurement time. The K/S with and without the AP pre-treated and DTP finished cotton was better than that with the usual chemical modification. In PET, the 0.5 kW and 1 time AP-treated specimen showed the highest K/S values.     

Effectiveness of flavourzyme treatment on polyamide fabric

We characterized the effectiveness of Flavourzyme treatment in the hydrolysis of amide bonds in polyamide fabric by quantitating the ionic groups released into the treatment liquid and those formed on the fabric surface. On the basis of hydrolytic activity, we demonstrated that Flavourzyme effectively hydrolyzed amide bonds in polyamide (PA) fabric. The optimal treatment conditions were found to be pH 7.0, temperature 40 °C, treatment time 120 min, and Flavourzyme concentration 10 % based on weight of fiber. PA fabric treated with Flavourzyme exhibited increased numbers of amino and carboxyl groups, as evaluated by zeta potential and color strength. As the amounts of ionic groups formed by Flavourzyme hydrolysis increased, the water contact angle and water absorbency time decreased.