Chemical Finishing Research Articles

Improved coloration of hemp fabrics via low-pressure argon plasma assisted surface modification

Interest in hemp as a viable cellulosic fibre for clothing has increased, driven partly by its economic benefits and the importance of natural renewable materials in emerging circular economies. However, the coloration and chemical finishing of lignocellulosic fibres such as hemp typically require large quantities of water and chemicals. Argon plasma pretreatment provides a way of modulating the physical properties of hemp fibres to improve the coloration process without compromising other bulk properties such as tensile strength. Such plasma treatments may contribute to alleviating the negative environmental impacts associated with liquid pretreatments, heating, or the use of auxiliary chemicals. Dyeing of hemp fibres is particularly challenging due to its crystalline chemical structure. In this study, low-pressure argon plasma-assisted surface modification of woven hemp fabrics up to 600 s at 40 and 80 Hz was explored for enhanced dyeability, resulting in enhanced dye-fibre bonding. Fourier-transform infrared spectroscopy and Raman spectroscopy of argon plasma pretreated hemp fabrics produced no noticeable changes in the functional groups of the fibres, but a physiochemical modification was observed in terms of the density of polar groups. Scanning electron microscopy (SEM) images revealed marked morphological changes including nano-etching of the fibre surface at certain argon plasma process conditions. The pretreatment process increased fibre hydrophilicity, and enhanced reactivity of the surficial –OH groups towards fibre-reactive and vat dyes, resulting in higher colour strength in dyed woven hemp fabrics. Overall, we envisage such plasma pretreatments may impact positively on the material and energy efficiency of the hemp fabric dyeing process.

Novel magnetic field array optimization method for the chemical magnetorheological finishing of Ti-6Al-4V alloy with SiO2 abrasive and Fe3O4 magnetic particles

Novel magnetic field array optimization method for the chemical magnetorheological finishing of Ti-6Al-4V alloy with SiO2 abrasive and Fe3O4 magnetic particles

Nano Photo Bleaching Method of Cotton Fabrics for a Sustainable Finishing

In modern textile-bleaching methods, H2O2 is commonly preferred due to its less harmful effects on the environment. The use of hydrogen peroxide in bleaching processes, although biodegradable on its own, increases the waste load due to the high amount of auxiliary chemicals used. The long processing times and high-temperature requirements of hydrogen peroxide bleaching led to increased energy consumption. Moreover, the high-water consumption required for post-treatment is also a disadvantageous factor. In other words, while the use of a high amount of auxiliary chemicals in hydrogen peroxide bleaching increases the waste load, long time and high-temperature requirements also increase energy consumption, and the high-water consumption required for post-treatment has a disadvantageous effect. In this study, raw cotton fabric is subjected to chemical finishing treatments that either oxidize or reduce it as part of the bleaching process. The results of photo bleaching were compared with conventional hydrogen peroxide finishing applications. Our findings showed that nano-TiO2-treated cotton had a better whiteness value than treated with H2O2 cotton according to the color spectrum whiteness indexes. It is strongly considered that this method could be a new alternative way for bleaching textile materials in the finishing departments.

Cavitation resistance of FeMnCrSi coatings processed by different thermal spray processes

Cavitation-resistant FeMnCrSi coatings were developed in the past years as a cost-effective alternative to Co-containing alloys to increase the lifespan of hydraulic machinery. The effect of different chemical compositions, surface finishing, and post-processing treatments was investigated for various processing techniques, namely: Arc Spraying Process (ASP), High-Velocity Oxy-Fuel (HVOF), High-Velocity Air-Fuel (HVAF), Plasma Transferred Arc (PTA), and Cold Gas Spray (CGS). This works consists of a compilation and review of original and literature results, and discusses the microstructure changes imparted by each type of processing and their impact on the coating properties and cavitation resistance. Low heat input high-velocity processes (HVOF, HVAF, CGS) developed a reduced degree of oxidation and porosity, accounting for a cavitation resistance higher than that of the coatings that ASP processed. In addition, ASP coatings showed reduced cohesive strength, with the oxidized inter-splat interface being a preferential site for crack propagation.

Surface topography assessment using chemical assisted ball end magnetorheological finishing

The generation of residual stresses by grinding process on the surface for a soft material result in poor performance and diminished life. Ball end magnetorheological finishing (BEMRF) process is a recently developed process that is effectively used for fine figuring and polishing of a variety of magnetic and non-magnetic materials. In this paper, grinding-induced residual stresses are addressed, and an attempt is made to relieve these residual stresses while achieving high surface finish using chemical assisted ball end magnetorheological finishing (CA-BEMRF) process. The chemical used in the present work is applied first time in BEMRF process and aluminium 7075 alloy workpiece has not been finished with this novel finishing process. The impact of various CA-BEMRF variables on percentage surface roughness reduction and percentage reduction in residual stresses are discussed statistically and graphically. Residual stresses of workpiece surfaces have been measured by using portable x-ray residual stress analyzer. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) of the finished workpiece before and after CA-BEMRF process is carried out to assess the effects of magnetizing current, tool rotation and working gap on surface topography of machined surface. It has been observed that reduction in residual stress is achieved along with high surface finish on aluminium workpiece surface using CA-BEMRF technique. Significant process parameters affecting the residual stresses and surface roughness during polishing of workpiece are obtained using Analysis of variance (ANOVA) and F-test. The optimization problem for maximum percentage reduction in surface roughness and maximum percentage reduction in residual stress is formulated as multi objective, multi variable, nonlinear optimization problem. Maximum percentage surface roughness reduction and minimum residual stress has been found at magnetizing current 2.3 A, rotational speed of tool 550 rpm and working gap of 0.5 mm. Confirmatory experimental tests have been conducted and results obtained were found very close to the predicted outcome.

Chemical assisted ball end magnetorheological finishing of aluminium 7075 alloy

Areas like aerospace, solar, medical, electronics, optics widely use nano-finished or high precision aluminium alloys. These nano-finished aluminium alloys are being used as metal mirrors, micro-electronics devices, diaphragm in optical sensors etc. In general, aluminium alloys are finished by conventional processes such as grinding, lapping. However, to achieve nano-level finish on soft material like aluminium alloys which possess high malleability and ductility is difficult for traditional processes without producing high residual stresses, subsurface damage etc. In this work, the surface finish of aluminium 7075 alloy workpiece was improved using a novel finishing technique viz. chemical assisted ball end magnetorheological finishing (CA-BEMRF). To validate the results a comparison of % decrease in surface roughness obtained after ball end magnetorheological finishing (BEMRF) as well as achieved after CA-BEMRF process is carried out. Results showed a 1.84 % improvement in % decrease in surface roughness after CA-BEMRF process as compared to BEMRF without chemical assistance. The statistical and graphical effects of various changing process parameters on % decrease in surface roughness are addressed. Using analysis of variance (ANOVA) and the F-test, significant process factors impacting surface roughness during workpiece finishing are identified. Optimum value of % decrease in surface roughness has been found as 55.316 at magnetizing current 3.43amp, tool rotational speed 326.97 rpm and working gap of 0.74 mm. Confirmatory experimental tests have been conducted and results obtained were found very close to the predicted outcome. Scanning electron microscopy (SEM) of the workpiece finished using BEMRF process and CA-BEMRF technique are compared to assess the effects of magnetizing current, tool rotation and working gap on surface topography of machined surface.

Investigation on the properties of chemically treated flexible parts fabricated through material extrusion based additive manufacturing technology

AbstractThe poor strength and surface texture of the additively manufactured components has restricted its usage as a functional part. The post processing methods can overcome this limitation and open new opportunities in different application areas. In the present study, chemical finishing process has been employed for the flexible components build through material extrusion based additive manufacturing technology. Thermoplastic polyurethane (TPU) has been chosen as the material for printing flexible parts. Taguchi orthogonal array‐based design of experiments has been employed. Three process parameters that is, solvent type, infill density and immersion time have been selected for the study. The percentage improvement in the surface roughness as physical property and compressive strength as mechanical property has been chosen as the response parameters. The dimensional deviation was investigated by measuring the change in the dimensions of the manufactured components. It has been observed from ANOVA analysis that the improvement in surface roughness and compressive strength depends significantly on the immersion time. The Dimethyl sulfoxide (DMSO) solvent and immersion time of 125 s has been found significant for different properties of the chemically treated TPU parts.

Environmentally Friendly Approach to the Reduction of Microplastics during Domestic Washing: Prospects for Machine Vision in Microplastics Reduction.

The increase in the global population is directly responsible for the acceleration in the production as well as the consumption of textile products. The use of textiles and garment materials is one of the primary reasons for the microfibers generation and it is anticipated to grow increasingly. Textile microfibers have been found in marine sediments and organisms, posing a real threat to the environment as it is invisible pollution caused by the textile industry. To protect against the damaging effects that microplastics can have, the formulation of mitigation strategies is urgently required. Therefore, the primary focus of this review manuscript is on finding an environmentally friendly long-term solution to the problem of microfiber emissions caused by the domestic washing process, as well as gaining an understanding of the various properties of textiles and how they influence this problem. In addition, it discussed the effect that mechanical and chemical finishes have on microfiber emissions and identified research gaps in order to direct future research objectives in the area of chemical finishing processes. In addition to that, it included a variety of preventative and minimizing strategies for reduction. Last but not least, an emphasis was placed on the potential and foreseeable applications of machine vision (i.e., quantification, data storage, and data sharing) to reduce the amount of microfibers emitted by residential washing machines.

Impact of Different Modern Chemical Finishing on Cotton Knitted Fabrics Dyed with Anthraquinone Vat Dye

Impact of Different Modern Chemical Finishing on Cotton Knitted Fabrics Dyed with Anthraquinone Vat Dye

Surface Characterization of Three-Dimensional Printed Fiber-Reinforced Polymer Following an In-Process Mechanical–Chemical Finishing Method

AbstractFiber-reinforced polymer (FRP) additive manufacturing has transformed fused filament fabrication (FFF) by manufacturing products with excellent mechanical characteristics. However, the surface finish and dimensional characteristics of printed FRP parts are typically poor due to protruding fibers and the stair-stepping effect. This parametric study examined an in-process combined mechanical plus chemical finishing technique to improve the surface finish of FRPs manufactured through FFF. This process is particularly useful for internal or complex features that cannot be otherwise finished after printing. In this work, a custom-built three-axis machine with printing, machining, and chemical finishing capabilities was used for the experiments. The effect of mechanical finishing on surface characteristics was first quantified using chip load and spindle speed as independent parameters. Following that, chemical treatment was performed on the already machined surface at two pressing depths (PD), which control the normal contact force acting on the surface. The best surface characteristics were observed at a low chip load of 0.007 mm and a moderately high spindle speed of 20,000 rpm. After chemical treatment using a lower PD, a surface roughness reduction was observed (from 8.041 to 4.988 µm). Increased PD led to even lower Ra values (from 4.988 to 3.538 µm) due to the enhanced fiber encapsulation phenomenon. Finally, the dimensional analysis revealed that the final combined finished samples had less than 1%-dimensional error (0.05 mm), which is an order of magnitude less than the typical error in FFF-printed parts (0.5 mm). This study provides means to conduct finishing in an additive manufacturing environment to reduce the time, labor, and cost associated with post-processing.

An approach to improve the elasticity of rib fabric through mechanical and chemical finishing

In recent years, the demand for knit fabric has increased significantly due to some of its unique properties like comfortability, stretchability, easy care, excellent wrinkle resistance and a high degree of fashion features. Among the different types of knit fabric, rib fabric is very popular for its elasticity. There is a demand for more elasticity of rib fabric in manufacturing apparel like sportswear. A common practice is to use elastane yarn along with native yarn to increase the knit fabric’s elasticity. Elastane fibres are synthetic fibres which are not comfortable. Elastane yarns are costly and cause a few difficulties during knitting. In this study, a combination of mechanical and chemical finishing processes has been introduced to increase the elasticity of 100% cotton rib fabric. The best possible finishing route was incorporated to maximize the rib fabric elasticity. It was observed that rib fabric elasticity can be increased up to 1.5 times from its native value. The material cost between the new proposed process and the existing elastic fabric manufacturing process was compared. It was found that the new process is much cheaper. This is an approach to finding an easy, industrially applicable and cost-effective method to maximize rib fabric elasticity without using any elastane yarn.

INVESTIGATION OF ANTI-PILLING PROPERTIES OF DIFFERENT FABRICS APPLIED WITH POLYVINYLCAPROLACTAM

Pilling is one of the most important problems in the textile industry still not confidently solved. The problem is a kind of mechanically caused fabric defect consisting by a series of roughly spherical masses of entangled fibers called pills. Many studies have been carried out to define this problem in detail, determine the pilling intensity by different methods and improve the pilling grades of fabrics. One of the most beneficial methods to improve values is chemical finishing by applying specific polymers. In this study, a specific synthesized anti-pilling polymer was used for chemical finishing by padding method. A specific polymer based on polyvinylcaprolactam (PVCL) was synthesized and applied on the fabrics. The polymer has been characterized with FT-IR, NMR, DSC, elemental analysis devices also to optimize application-parameters. Especially pilling grades of blended fabrics of natural and synthetic staple fibres are often worser then other non blended fabrics, PVCL polymer was applied on a selection of different polyester cotton blends or polyester viscose blend, which have pilling values between 2-3. PVCL-Polymer applications were carried out by using these 7 different fabrics. As a result, approximately 1.5-2 pilling degree improvement was achieved. Anti-pilling polymers applied on the fabrics used to improve pilling values often decrease hydrophilicity values of the fabrics and worsen touch. However, the specific PVCL-polymer does not lead to a loss of smooth hand neighter to a loss of smooth fabric touch. On the contrary, it improves both hydrophilicity and smooth touch not causing fabric yellowing. PCVL is distinguished from other products used for pilling improvement in the textile industry.

The Post-Processing of Additive Manufactured Polymeric and Metallic Parts

The traditional manufacturing industry has been revolutionized with the introduction of additive manufacturing which is based on layer-by-layer manufacturing. Due to these tool-free techniques, complex shape manufacturing becomes much more convenient in comparison to traditional machining. However, additive manufacturing comes with its inherent process characteristics of high surface roughness, which in turn effect fatigue strength as well as residual stresses. Therefore, in this paper, common post-processing techniques for additive manufactured (AM) parts were examined. The main objective was to analyze the finishing processes in terms of their ability to finish complicated surfaces and their performance were expressed as average surface roughness (Sa and Ra). The techniques were divided according to the materials they applied to and the material removal mechanism. It was found that chemical finishing significantly reduces surface roughness and can be used to finish parts with complicated geometry. Laser finishing, on the other hand, cannot be used to finish intricate internal surfaces. Among the mechanical abrasion methods, abrasive flow finishing shows optimum results in terms of its ability to finish complicated freeform cavities with improved accuracy for both polymer and metal parts. However, it was found that, in general, most mechanical abrasion processes lack the ability to finish complex parts. Moreover, although most of post-processing methods are conducted using single finishing processes, AM parts can be finished with hybrid successive processes to reap the benefits of different post-processing techniques and overcome the limitation of individual process.

Development of Water Repellency on Jute Fabric by Chemical Means for Diverse Textile Uses

Jute is one of the natural cellulosic textile materials. It has many advantageous properties similar to cotton. Jute fibre has potential to impart different functionality by different chemical finishing for its diversification. In this research, Water repellent jute fabrics have been prepared by treating Nova TTC (fluorocarbon compound) different ratio and to find out the best formulation recipe. Treating fabrics have been impaired with a water repellent characteristic and showing good rating result on jute fabric .This water repellent fabric was suitable of various jute products for diverse textile uses.

Predictive modeling of surface and dimensional features of vapour-smoothened FDM parts using self-adaptive cuckoo search algorithm.

Despite numerous advantages of fused deposition modeling (FDM), the inherent layer-by-layer deposition behavior leads to considerable surface roughness and dimensional variability, limiting its usability for critical applications. This study has been conducted to select optimum parameters of FDM and vapour smoothing (chemical finishing) process to maximize surface finish, hardness, and dimensional accuracy. A self-adaptive cuckoo search algorithm for predictive modelling of surface and dimensional features of vapour-smoothened FDM-printed functional prototypes has been demonstrated. The chemical finishing has been performed on hip prosthesis (benchmark) using hot vapours of acetone (using dedicated experimental set-up). Based upon the selected design of experiment technique, 18 sets of experiments (with three repetitions) were performed by varying six parameters. Afterwards, a self-adaptive cuckoo search algorithm was implemented by formulating five objective functions using regression analysis to select optimum parameters. An excellent functional relationship between output and input parameters has been developed using a self-adaptive cuckoo search algorithm which has successfully found the solution to optimization issues related to different responses. The confirmatory experiments indicated a strong correlation between predicted and actual surface finish measurements, along with hardness and dimensional accuracy.

Synthesis and Characterization of Polyvinylimidazole and Investigation of its Antipilling Effect on Different Fabrics

Pilling is one of the biggest problems for all types of fabrics in textile industry. To improve pilling values of the fabrics, some methods have been reported. One of the most useful methods is chemical finishing. In this study, this method have been used. A key differentiator of this study is the fact that we synthesized the polymer employed as an anti-pilling agent ourselves and does not negatively affect the hydrophilicity and brightness parameters of fabrics, as most anti-pilling chemicals do. As an anti-pilling polymer, we have synthesized polyvinylimidazole (PVIM) and have applied this polymer to different fabrics for the aim of reducing pilling tendency of these fabrics. We have achieved nearly 1.5-2 pilling grades of improvement for different fabrics and generally obtained pilling grade: 4.5-5.0, means no pills on fabric surface. Also, it has been proven that PVIM can be used as an anti-pilling agent without negative effects on fabrics in terms of hydrophilicity, brightness and handle. To market PVIM under Rudolf-Duraner product list, we defined this polymer: EPW 18042.

Easy-Care Finishing of Cotton Fiber with DMDHEU - Crosslinking Agent for High Crease Recovery Angle and Low Washing Shrinkage Properties

Easy care finishing of textile materials is one of textile chemical finishing processes to make cellulosic textile materials crease free and dimensionally stable in its service life or during wear. Woven and knitted cellulosic textile fabrics are totally submerged in DMDHEU crosslinking agent with the concentration of 35 – 60 g/l and 30 – 50 g/l for woven and knitted fabrics respectively. In this treatment magnesium chloride is used as catalyst. Then, drying at 110 °C and curing at 150 °C for 3 min. This study shows the relationship between different level of concentrations of DMDHEU and catalysts on different textile properties such as CRA, strength and abrasion loss, washing shrinkage and stiffness. IR analysis also used in the research work. In this finding, in general, crease recovery angle - CRA, abrasion loss, stiffness increases as the concentration of DMDHEU and the catalyst increases whereas air permeability and water capillary rise, washing shrinkage decreases in woven cotton fabric. On the other hand, CRA, abrasion loss and air permeability as the concentration of DMDHEU and the catalyst increases whereas the wales and course washing resistance and water capillary rise diminished in knitted fabric.

Adsorbents Made of Inorganic Industrial Waste

Data demonstrate the possibility of manufacturing adsorbents by using inorganic industrial waste and provide raw material list for this purpose. Inorganic waste coming from water treatment, mining and construction industries, solid fuel combustion products, spent inorganic sorbents, catalysts and chemical absorbers, chemical, metallurgical and metal finishing industries waste are used as raw materials. Adsorbents production methods by using inorganic industrial waste have been analysed, and parameters of porous structure and adsorbents sorption activity in terms of organic compounds and cations of non-ferrous metals resulting from aqueous medium are listed.

The Influence of Finishing on the Pilling Resistance of Linen/Silk Woven Fabrics.

The pilling resistance of fashion fabrics is a fundamentally important and frequently occurring problem during cloth wearing. The aim of this investigation was to evaluate the pilling performance of linen/silk woven fabrics with different mechanical and chemical finishing, establishing the influence of the raw material and the peculiarities of dyeing and digital printing with different dyestuff. The pilling results of the dyed fabrics were better than those of the grey fabrics and even a small amount of synthetic fiber worsened the pilling performance of the fabric. Singeing influenced the change in the pilling resistance of the linen/silk fabrics without changing the final pilling resistance result. Singeing had a stronger influence on the fabrics with a small amount of synthetic fibers. The pilling resistance of printed fabrics was better than that of grey and dyed fabrics without and with singeing. The pilling resistance of pigment-printed fabrics was better than that of the reactive-printed fabrics.

A valuable observation on natural plants extracts for Valuable Functionalization of Cotton fabric (an overview)

Finishing textiles was widely used to impart various functionalities into fabric substrates, such as anti-microbial finishing, UV-protection, water repellent, self-cleaning and many others. However, the chemical finishing involves the use of large quantities of energy, chemicals, and water. Some chemical finishes in the wastewater can be harmful to humans, and the presence of chemicals in finished textiles can cause skin irritation in some people, so every day attempts to introduce cleaner, sustainable, and greener chemical finishing are urgently needed. Among the developed approaches are safer chemicals with minimal or no toxicity to human health and the environment, safe solvents and auxiliaries, energy efficiency (reduced temperature and pressure), natural, biodegradable, and renewable chemicals.