44 research outputs found
Supercritical CO2 dyeing of polyester fabric with photochromic dyes to fabricate UV sensing smart textiles
Photochromic molecules are well-established colourants in the manufacturing of niche products, providing reversible colour change effects when irradiated with ultraviolet (UV) light. The high mater ..
Digital inkjet functionalization of water-repellent textile for smart textile application
Digital inkjet printing is a production technology with high potential in resource efficient processes, which features both flexibility and productivity. In this research, waterborne, fluorocarbon-free ink containing polysiloxane in the form of micro-emulsion is formulated for the application of water-repellent sports- and work wear. The physicochemical properties of the ink such as surface tension, rheological properties and particle size are characterized, and thereafter inkjet printed as solid square pattern (10âĂâ10 cm) on polyester and polyamide 66 fabrics. The water contact angle (WCA) of the functional surfaces is increased fromâ<â90° to ca. 140° after 10 inkjet printing passes. Moreover, the functional surface shows resistance to wash and abrasion. The WCA of functional surfaces is between 130° and 140° after 10 wash cycles, and is ca. 140° after 20000 revolutions of rubbing. The differences in construction of the textile as well as inkâfilament interaction attribute to the different transportation behaviors of the ink on the textile, reflected in the durability of the functional layer on the textile. The functionalized textile preserves its key textile feature such as softness and breathability. Inkjet printing shows large potential in high-end applications such as customized functionalization of textiles in the domain of smart textiles
Studies of novel phases and states produced by means of high pressure : Polymer and polymer based carbon nanocomposites
Inkjet printing and UV-LED curing of photochromic dyes for functional and smart textile applications
Health concerns as a result of harmful UV-rays drive the development of UV-sensors of different kinds. In this research, a UV-responsive smart textile is produced by inkjet printing and UV-LED curing of a specifically designed photochromic ink on PET fabric. This paper focuses on tuning and characterizing the colour performance of a photochromic dye embedded in a UV-curable ink resin. The influence of industrial fabrication parameters on the crosslinking density of the UV-resin and hence on the colour kinetics is investigated. A lower crosslinking density of the UV-resin increases the kinetic switching speed of the photochromic dye molecules upon isomerization. By introducing an extended kinetic model, which defines rate constants kcolouration, kdecayand kdecolouration, the colour performance of photochromic textiles can be predicted. Fabrication parameters present a flexible and fast alternative to polymer conjugation to control kinetics of photochromic dyes in a resin. In particular, industrial fabrication parameters during printing and curing of the photochromic ink are used to set the colour yield, colouration/decolouration rates and the durability, which are important characteristics towards the development of a UV-sensor for smart textile applications
Effects of ink characteristics and piezo-electric inkjetting parameters on lysozyme activity
Inkjet printing of enzymes can facilitate many novel applications where a small amount of materials need to be deposited in a precise and flexible manner. However, maintaining the satisfactory activity of inkjet printed enzyme is a challenging task due to the requirements of ink rheology and printhead parameters. Thus to find optimum inkjetting conditions we studied the effects of several ink formulation and jetting parameters on lysozyme activity using a piezoelectric printhead. Within linear activity range of protein concentrations ink containing 50â”g/mL lysozyme showed a satisfactory activity retention of 85%. An acceptable activity of jetted ink was found at pH 6.2 and ionic strength of 0.06 molar. Glycerol was found to be an effective viscosity modifier (10â15 mPa.s), humectant and protein structure stabilizer for the prepared ink. A non-ionic surfactant when used just below critical micelle concentration was found to be favourable for the jetted inks. An increase in activity retention was observed for inks jetted after 24âhours of room temperature incubation. However, no additional activity was seen for inkjetting above the room temperature. Findings of this study would be useful for formulating other protein-based inks and setting their inkjet printing parameters without highly compromising the functionality
Thermal Conductivity and Heat Capacity of a Nylon- 6/Multi-wall Carbon Nanotube Composite Under Pressure
Abstract. The thermal conductivity, Îș, of nylon-6 increased 22% whereas the heat capacity per unit volume, Ïc p , decreased 10% by adding 2.1 wt% Multi-Wall Carbon Nanotubes MWCNTs. Simultaneously, the glass transition temperature, T g , which was detected as a weak sigmoidal increase in Ïc p and a decrease in dÎș/dT, increased 11 K. These results show that the MWCNTs-nylon-6 interaction restricts the segmental mobility of nylon-6 and decreases c p of nylon-6
Digital inkjet printing of antimicrobial lysozyme on pretreated polyester fabric
Lysozyme was inkjet printed on two different polyester fabrics considering several challenges of printing enzymes on synthetic fabric surfaces. Wettability of both the fabrics were improved by alkaline pre-treatment resulting reduction in water contact angle to 60±2 from 95°±3 and to 80°±2 from 115°±2 for thinner and coarser fabric respectively. Activity of lysozyme in the prepared ink was 9240±34 units/ml and reduced to 5946±23 units/ml as of collected after jetting process (before printing on fabric). The formulated ink was effectively inkjet printed on alkali treated polyester fabric for antimicrobial applications. Retention of higher activity of the printed fabric requires further studies on enzyme-fibre binding mechanisms and understanding protein orientation on fabric surface after printin
Sequential Inkjet Printing of Lysozyme and Tyrosinase on Polyamide Fabric: Sustainable Enzyme Binding on Textile Surface
An ink containing tyrosinase catalyzes the tyrosine residues on lysozyme protein to bind it on a plasma-treated polyamide-6,6 (PA) fabric. Inkjet printing enables controlled and sequential deposition of two enzymes on PA which is necessary for proper binding. The effect of different printing sequences on crosslinking stability and enzymatic activity is presented. The lysozyme bound on the fabric shows satisfactory antimicrobial activity. The printed fabric retains about 68% of the ink activity when tyrosinase is printed before lysozyme. Further, this fabric retains about 24% of the initial activity up to four reuses. The fabric shows acceptable inhibition of bacterial growth and retains almost half of its initial activity when cold stored for a month. This work shows the potential of protein binding on textile surface using various means of sustainable technologies, namely enzyme, inkjet, and plasma. This work was financially supported by the research school at the University of BorÄs. The authors are thankful for the support from TEKO (Sveriges Textil- och Modeföretag) and Sparbanksstiftelsen SjuhÀrad.</p
Effect of physical parameters and temperature on the piezo-electric jetting behaviour of UV-curable photochromic inks
Although resource-efficient processes like inkjet printing have a large potential to foster the development of smart and functional textiles, one bottleneck still is the development of functional inks. To make inkjet printing and UV curing given production techniques for smart and functional specialty products, e.g. photochromic textiles, deepened knowledge about the development, rheological behavior and jetting behavior of functional ink is needed. This paper focuses on the formulation and performance of UV-responsive and UV-curable inkjet inks, which are based on photochromic dyes and their application to produce UV-responsive textiles. Two commercial photochromic dyesâReversacol Ruby Red (RR) and Sea Green (SG), which represent dyes of the naphthopyran and spirooxazine class, respectively, have been used to develop the inks. The photochromic inks are characterized according to their physicalâchemical and rheological properties in respect to temperature. The influence of temperature on the drop formation of the inks in an industrial print head is analyzed using a high-speed camera, which reveals important information regarding challenges in ink jettability. It was found that the dye structure and type used in the ink can influence the jetting behavior of photochromic UV-curable ink. More pronounced temperature sensitivity of dyes can increase the temperature-related effects of drop formation as was observed for SG ink. The printability of the RR and SG inks is framed and underpinned by theoretical calculations of the Z number. Discrepancies are observed and discussed between existing theory of ink jettability and visual evaluation of the photochromic ink