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Topics - nawshin farzana

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31
Textile Engineering / Intelligent textiles -(part6)
« on: July 22, 2014, 05:45:42 AM »
    Other Intelligent textiles

    Stomatex

    Patterned new cold protection apparel. Cell foam materials such as neoprene and polyethylene can be used in the construction of garments. Stomatex NE is ideal for close contour fitting apparel for unhindered body movement. Stomatex PE is a lightweight apparel and has a significant cost advantage over neoprene. Stomatex PE is suitable for use in multi-layered clothing systems and footwear where weight may be an important factor.

    Hydroweave:

    Patterned product is meant for comfortably in extreme cold and wet condition. Super water-absorbing polymer fibre blended into fibrous matting, this matting is positioned between a breathable exterior shell and a conductive, waterproof inner lining. The breathable outer shell can be made from a variety of woven or knitted fabrics to deliver the performance needed for a wide range of applications. The inner lining is a thermally conductive micro-porous membrane. This special material allows perspiration to escape, and keeping the wearer cool and dry. The advantages are

    .   Evenly distributes cooling effect over the entire fabric.
    .   Flexibility.
    .   Wearer will feel good comfort.
    .   Machine-washable.
    .   Re-usable.

    Photonic fibres:

    Dielectric mirror alternative layers of two materials with different refractive indices produce Photonic band gap. It reflects light in a certain range of wavelength and absorb light out side this range this fibres can be woven in to a fabric to form shields and filters in military operations. Bar codes made with this fibre are authentic.

    Electronic systems incorporated in Textiles:

    There have been some very exciting developments recently regarding clothing with electronic systems incorporated into the constituent fibres and fabrics. Some examples of this are:


    1.Music t-shirts- they allow to the wearer listen his/her favorite music stored on a chip, or to tune into the favorite radio station. They can also have moving images on the back.


    2.Businessman garments-, which has a microphone, incorporated in the collar, a display, and a personal digital assistant in the sleeve.


    3.Solar energy re-charge jacket- it includes some tools for creative playing and communication, such as a camera, display and microphone attachments.

    4.Massage kits- It gives a soothing massage to the wearer that can be regulated depending on the level of relaxation desired by the user by applying vibration and pressure.
    [/list][/list]

    32
    Textile Engineering / Intelligent textiles -(part5)
    « on: July 22, 2014, 05:40:57 AM »
    Conductive materials

    Exploration of human/machine interaction and wholly new types of interface sensor technology has resulted in the development of sensory fabric. These materials also afford designers new opportunities in developing for product markets. The ability to dispense with fixed casings, rigid mountings and inflexible substrates facilitates new radical possibilities in flexible, user-friendly interfacing textiles. By using conductive plastics, pressure sensitive inks and piezo films the above application succeeded in textiles. The main emphasis is currently on X-Y position sensing and pressure sensors.


    1 X-Y position sensing

    The structures of these materials offer the capability of reading the location, within a fabric sheet (Pad), of a point of pressure (such as a finger press). It is possible to incorporate this function into an elastic sheet structure, allowing the sheet to conform to many 3-D shapes, including compound curves, while still accurately measuring an X-Y position. The Fabric structures that provides an X-Y position function can also be used to provide accurate 'switch matrix' functionality. Interpreting electronics are used to identify the location of switch areas in any configuration to suit product requirements. Since this is done in software, an endless array of configurations can be addressed at the touch of a piece of fabric.


    2 Pressure sensors


    Readings can be obtained from smart fabrics according to force and area. This allows the user to differentiate between separately identified inputs ranging from high-speed impact to gentle stroking. The force/area reading is versatile, as fabrics can be constructed to be more sensitive to either force or area.
    There are other applications for conductive materials such as heated clothes for extreme winter conditions or heated diving suits to resist very cold water. In these cases a heat or energy source is needed as the conductive material is not able to generate energy, it is only capable of conduction, to distribute the heat throughout the entire garment or suit.

    The advantages and benefits that conductive materials over the existing wire system are uniform temperature distribution, pliability, strength (resistance to flex and stress), non-corrosive nature, and cost effectiveness.

    33
    Textile Engineering / Intelligent textiles -(part4)
    « on: July 22, 2014, 05:37:17 AM »
    Chromic Materials

    Chromic materials are the general term referring to materials which radiate the color, erase the color or just change it because its induction caused by the external stimuli, as "chromic" is a suffix that means color. It can be classified depend on the Stimuli. Out of this the first four chromic materials are important and has potential to cater the market


    .   Photochromic: external stimuli energy is light.
    .   Thermochromic: external stimuli energy is heat.
    .   Ionochromic: external stimuli energy is pH value
    .   Electrochromic: external stimuli energy is electricity.
    .   Piezorochromic: external stimuli energy is pressure
    .   Solvatechromic: external stimuli energy is liquid.
    .   Carsolchromic: external stimuli energy is electron beam.



    1 Photochromic :

    In this kind of chromism the color change is due to the intensity of the light(UV radiation also). The photochromic dyes interact with the electromagnetic radiation in the near UV (300-400nm),Visible(400-700nm) and near IR(700-1500nm) to produce verity of effects, which is reversible when the radiation is withdrawn. Photochromism is of Two types. Positive and Negative. In Positive Photochromism the colorless substance converted in to colored object when exposed in to the light due to Uni-molecular reaction system. Bi molecular reaction system is called Negative Photochromism i.e. from colored to colorless. the transformation is between two states that have different absorption spectra. It may be induced in one or both the direction by electromagnetic radiation. This process is a non destructive process., but side reactions may occur. Oxidation is the major cause for the degradation of the Photochromism. Main class of Photochromism is Spiropyrans. It is used in Optical switching data and Imaging system rather then the textile applications.


    2 Thermochromic:

    Thermally induced reversible color change occur in the thermochromism. A large variety of substrates such as Organic ,Inorganic Orgonomatallic and Macro molecular systems exhibit this phenomena. Mercury Iodide salts like Ag2 HgI4 shows color change from yellow to orange at 51C.This is due to the reason that each compound can under go phase change at particular temperature .Majority of thermochromic systems are unacceptable simply because of the change in the color requires large amount of energy due to involvement of inter molecular transformation. Using verity of liquid crystals ,it is possible to achive significant changes in the appearance over the narrow temperature range(5-15C) and to detect small variation in the temperature(≤1C).The thermochromic dyes used extensively in the printing of Textiles, Micro encapsulation ,coating or dope dyeing .


    3 Ionochromic dye:
    These chromic materials are sensitive to pH. Widely used these classes dyes are Phthalides, Triarylmethans and Fluorans. In analytical chemistry these dyes are used extensively. There are no commercial application of these dyes in textiles but direct thermal printing can be used. In this process substrate contain both the color former and acid co reactant in a single layer. simply by heating the surface of the paper with a thermal head causes the components to react and to produce color.


    4 Electochromic dye:

    The material that change color upon the application of Voltage are called electrochromes. This is due to oxidation and reduction process with in the electochromic material. This are of three types. First type, the coloring species remain in the solution. In the second type the reactants are in solution but the colored product is of solid. In the third type is both reactant and the color is in form of solid e.g. composite Film. Most available electochromic dyes are of inorganic oxides such as cobalt oxide, nickel oxide, molybdenum trioxide. A research is going on in MIT,USA to use thin film composite electrode material with layer by layer assembly technique, to identify whether electrochemical cell is fully charged or discharged by using color change. The most important commercial application of the electrochemic dye in the textile is of US-Military IR camouflage material (Dynam IR) .

    5 Solvantochromic dye:

    The Solvantochromism is a reversible variation of the electronic spectroscopic properties (absorption and emission)of a chemical species, induced by the solvents. It is one of the oldest chromism have been described as long as ago 1878.This is used as probes for application in polymer characterization. Where they can be used to look for localized polar features at the molecular level.
    Chromic dyes contain highly specialized components that require extraordinary careful manufacturing technique and has great potential for both fashion and higher end market.

    34
    Textile Engineering / Intelligent textiles -(part3)
    « on: July 22, 2014, 05:32:58 AM »
    Shape Memory Polymers(SMP)

    These types of materials can revert from the current shape to a previously held shape, usually due to the action of heat. This technology has been extensively pioneered by the UK Defense Clothing and Textiles Agency. When these shape memory materials are activated in garments, the air gaps between adjacent layers of clothing are increased, in order to give better insulation. The incorporation of shape memory materials into garments thus confers greater versatility in the protection against extremes of heat or cold.


    Shape memory alloys, such as nickel-titanium, used to provide increased protection against sources of heat, even extreme heat. A shape memory alloy possesses different properties below and above the temperature at which it is activated. Below this temperature, the alloy is easily deformed. At the activation temperature, the alloy exerts a force to return to a previously adopted shape and becomes much stiffer. The temperature of activation can be chosen by altering the ratio of nickel to titanium in the alloy.


    Cuprous-zinc alloys are capable of a two-way activation and therefore can produce the reversible variation needed for protection from changeable weather conditions. They will also react to temperature changes brought about by variations in physical activity levels.
    A shape memory alloy is usually in the shape of a spring.


    flat below the activation temperature but becomes extended above it. By incorporating these alloys between the layers of a garment, the gap between the layers can be substantially increased above the activation temperature. In consequence, considerably improved protection against external heat is provided.

    For clothing applications, the desirable temperatures for the shape memory effect to be triggered will be near body temperature. Polyurethane films, which can be incorporated between adjacent layers of clothing. With temperature of the outer layer of clothing has fallen sufficiently, then polyurethane film responds so that the air gap between the layers of clothing becomes broader. Bi-Material Film laminates rely on differing coefficients of thermal expansion to produce a reversible bending effect. Encapsulated Bi-Gels absorb liquid at differing rates according to temperature, which causes them to bend used to actuate variable insulation system. Other uses of SMPs in domestic purpose are in shower mixer valves, coffee makers, rice cookers, safety shut off valves for fuel lines in the event of fire and in air conditioning systems.

    35
    Textile Engineering / Intelligent textiles -(part2)
    « on: July 22, 2014, 05:30:47 AM »
    Phase Change Materials (PCM)

    Every material absorbs heat during heating process and its temperature will rise constantly. The heat stored in the material is released into the environment through a reverse cooling process and the material temperature decreases continuously. A normal textile material absorbs about one kilo joule per kilogram of heat while its temperature rises by one degree Celsius. Phase Change Material (PCM) will absorb higher amount of heat when it melts. This thermo regulating effect of textiles can be obtained with the application of PCM.


    Tthe PCM incorporated clothing action A paraffin-PCM, absorbs approximately 200 kilojoules per kilogram of heat if it undergoes a melting process. During the complete melting process, the temperature of the PCM and its surrounding area remains constant. The paraffin's are either in solid or liquid state. In order to prevent the paraffin's dissolution in the liquid state, it is enclosed into small plastic spheres with diameters of only a few micrometers. These microscopic spheres containing PCM are called PCM-microcapsules. The microencapsulated paraffin is either permanently locked in acrylic fibres and in polyurethane foams or coated onto the surface of a textile structure.


    Normal garments do not balance the heat generated and released in to the environment from the body. PCM incorporated textiles provide good thermal balance due to its thermo regulating effect. PCM controls the heat flux through the garment layers and adjusts the heat flux to the thermal circumstances, for example, if the heat generation of the body exceeds the possible heat release through the garment layers into the environment, the PCM will absorb and store this excess heat. On the other hand, if the heat release through the garment layers exceeds the body's heat generation during lighter activities, the heat flux through the garment layers is reduced by the heat emission of the PCM. The figure2 shows the thermoregulation effect of PCM incorporated clothing over the conventional clothing.

    Intensity and duration of the PCM's active thermal insulation effect depend mainly on the heat storage capacity of the PCM-microcapsules and the applied quantity. Thin high-density materials support for cooling process. Thick and less dense textile structure leads to more efficient heat release. To ensure a suitable and durable active thermal insulation effect in an active-wear garment, it is necessary to apply the correct PCM in the appropriate quantity. The selected PCM is normally microencapsulated and incorporated in a textile substrate. Requirements of the textile substrate in a garment application include sufficient breath ability, high flexibility and mechanical stability. The substrate incorporated with PCM-microcapsules needs to be integrated into a suitable location of the garment design and certain design principles need to be taken into account.

    36
    Textile Engineering / Intelligent textiles -(part1)
    « on: July 22, 2014, 05:28:36 AM »
     Introduction

    Intelligent textiles represent the next generation of fibres, fabrics and articles produced to respond in time. It can be described as textile materials that think and act for themselves. This means, it has keep us warm in cold environments or cool in hot environments or provide us with considerable convenience in our normal day-to-day affair. Intelligent textiles are not confined to the clothing sector alone. It is used in protection, safety, added fashion and convenience.

     The most important intelligent materials at present in are classified as -
    1) Phase change materials,
     2) Shape memory materials,
     3) Chromic materials
     4)Conductive materials and
     5)Electronics incorporated textiles.

    37
    Researchers at NASA's Johnson Space Center (JSC) have developed an automated method for producing intricate fabric-based circuits and antennas. The method enables the fabrication of complex single- or multilayer circuit patterns and will contribute to a new generation of mobile communication capabilities. Wearable electronics, or "e-textiles," currently operate in a number of niche areas, such as vests for firefighters and soldiers and shirts for monitoring patients' vital signs. To date, body-worn antennas encounter problems with comfort, degradation through flexure, and geometrical distortion. Unlike previous attempts, the JSC technology yields dimensionally stable conductive elements that have predictable and stable impedance characteristics and high surface conductivity, allowing operation at radio frequencies. The layout is compatible with conventional computer-aided design methods used to fabricate printed antennas. JSC has applied for patent protection for this technology.
    Benefits
    High performance: Enables complex circuitry through intricate patterns, such as those used for directional couplers or logarithmic spiral antennas
    Efficient: Improves control of impedances with directional accuracy, allowing efficient radio frequency operation
    Automated: Enables mechanized manufacturing techniques
    Cost-effective: Offers modest set-up cost that is comparable to that of printed circuitry
    Washable: Enables normal garment laundering
    Durable: Features ability to withstand small radius flexing without damage
    Applications
    Clothing-based electronics and antennas
    Fabric-skinned aircraft and balloons
    Sensors and sensor networks on fabric structures
    Membranes for large deployable reflector antennas
    Small deployable antenna systems
    Battlefield communication systems
    Stealth and surveillance electronics
    Antennas for sails and tents

    [source: internet]

    38
    Textile Engineering / Digital Textile Printing, a Demand of time
    « on: July 22, 2014, 05:17:02 AM »
     Digital textile printing can be described in two ways one is ink-jet based method of printing ants on fabric called DTG (Direct to garments printing) and another is sublimation inkjet printing, is the major technology used in digital textile printing. As polyester or polyester-mixed fabrics are major part textiles, sublimation inkjet printing is widely used in digital textile printing. The later is also a growing trend in visual communication, where advertisement and corporate branding is printed onto polyester media. Examples are: flags, banners, signs and retail graphics. Since traditional screen printing costs more in terms of labor, sublimation inkjet printing, is now becoming more and more popular in USA and Europe. Most notably, digital textile printing is referred to when identifying either printing smaller designs onto garments (t-shirts, dresses, promotional wear) and printing larger designs onto large format rolls of textile.


    Why print digitally?
    Traditional printing is efficient if you need to produce 10,000 meters of one design, but what if you need 1,000 mts of 100 designs? Inkjet printing offers a range of benefits compared to the conventional printing methods in terms of operational aspects and economic aspects. Major benefits include:

    • Built-in flexibility

    No limitation in number of pieces, design freedom.
    No limitation on repeat length
    Reduced response time.
    Excellent shade gradations and 3-D Effects
    Printing from selvedge to selvedge is possible.
    Limited change-over.
    Consistent and reproducible printings.
    Printing speed ranges from 1 to100 m2 per hour.
    Low amount of unfixed dyes, less water and energy for washing, less  in effluent.

    • Economic aspects


    System is very compact, requires very less floor space.
    Relatively low investment
    24-hour production possible.
    Reduction of sampling cost.
    No  kitchen, s mixed on fabric and no screen
    Lower stocks for whole supply chain
    Drop on demand, no waste and less ant usage

    • Co-operation through the digital printing value chain

    Digital Textile Printing is a solutions business.
    Essential that print head, machine, ink, and software manufacturers are technically aligned.
    ation solution must meet customer requirements in all respects; gamut, fastness,  depth, etc.
    Recommendations on pretreatments and post treatments essential for success
    Focus on correct ation solution based on end article specifications
    Digital print solution must give same technical ation result as screen printing

    Current Status & prospect of Digital Printing:

    Total global production volume of printed textiles currently is 25 - 30 billion meters per annum
    Around 97% is screen printed, remaining 3% is digitally printed today
    Over next 5-years, production volumes and a large percentage shift to digital printing applications is expected
    Analysts predict that within 5-years 15% of globally printed textiles will be made digitally
    Fast growing, but small sector of textile printing
    Largest application sector is printing of PES fiber for soft signage & flags.
    Fastest growing sector is wide format apparel on new industrial inkjet machines
    Digital is replacing flat -screen printing machines due to similar action costs and production speeds
    Garment T-Shirt printing is growing via online businesses
    Home textiles, automotive fabrics, outdoor applications were niche areas but now rapidly developing.

    39
    Textile Engineering / 5 Unexpected Natural Sources of Dye
    « on: July 22, 2014, 04:47:56 AM »
    Avocado pit: yields delicate pink/orange.
     Avocados are classified as fruits and not veggies.Avocado pits have been used centuries to color textiles a deep orange color. Word is that the pits smells awful when being prepared… they must be boiled and soaked in water for hours (some say days) before beginning to leach orange and pink. Holy guacamole!
     
    Chamomile leaves: yields deep green. Chamomile serves several purposes beyond lulling our eyes shut. The leaves can be boiled with water to create a deep green dye for all sorts of fibers!
     
    Red onion skin: yields light green.
     red onion skin is strong enough to leach permanent dye. What does surprise all is the color it creates – a light green. The skins need to be soaked and rubbed onto the material.
     
     
    Red Cabbage: yields lavender
    Boiling red cabbage with salt and water isn’t just a dieting trend. It produces a beautiful lavender color that can be used to dye many types of fiber..
     
    Prickly Cactus Pear: yields magenta and purple
    Native American groups have been using cactus pear juice for dyeing textiles for centuries. The most effective way to utilize this fruit for dye is by fermentation. The cactus juice will need to stand in a warm place for a couple of weeks before the fermentation process begins. If vinegar is added, the solution will become more blue.  The pigment in prickly pear is betalain, which is the same pigment in beets! Pretty!

    40
    The use of alternative textiles has become a significant trend as of late, particularly in the fashion world. Cellulose-based fabrics such as rayon have been especially popular due to their high quality- they are beautiful as well as sustainable.
    Recently, a promising new member of the cellulose family was unveiled: Ioncell-F is a textile created from plant material and ionic liquid. Developed by Scandinavian science and design students, it is considered to be an improvement on the fabrics that have come before it.
    Like other cellulose fabrics, Ioncell-F is a wood-based fiber.
    How is Ioncell-F made?
    Wood chips are dissolved into a pulp by the fabric’s namesake ionic liquid. The pulp is then processed to create the finished fibers that can be spun into yarn.
    Despite the complex production methods, the process does not yield any toxic chemicals, and the resulting fabric is made of all-natural materials, which is good news for the sustainable designer.
    It requires much less water than cotton, and less than even it’s sister fabric, rayon.
    Ioncell-F also performs better than its cellulose-based predecessors. The ion liquid solution and wood cellulose form  solid bond. As a result, when compared to viscose, it turned out to be much stronger; while viscose fibers weaken when wet, the fibers of Ioncell-F do not change. The fabric also has high water retention.
    One of the students working on the project, Marjaana Tanttu, did a fashion field test on the fabric by using it as a base for scarf design. For the rest of us who want to use it however, it will likely be a bit of a wait before this textile becomes commercially available (namely, five to ten years).
    There is still plenty of research and testing to be done in order to create a product that can be scaled up for mass-production.

    41
    Textile Engineering / Dye in Solar Cell?
    « on: July 21, 2014, 06:31:29 AM »
    A dye-sensitized solar cell (DSSC, DSC or DYSC) is a low-cost solar cell belonging to the group of thin film solar cells. It is based on a semiconductor formed between a photo-sensitized anode and an electrolyte, a photoelectrochemical system.

    In the late 1960s it was discovered that illuminated organic dyes can generate electricity at oxide electrodes in electrochemical cells. In an effort to understand and simulate the primary processes in photosynthesis the phenomenon was studied at the University of California at Berkeley with chlorophyll extracted from spinach (bio-mimetic or bionic approach). On the basis of such experiments electric power generation via the dye sensitization solar cell (DSSC) principle was demonstrated and discussed in 1972.The instability of the dye solar cell was identified as a main challenge. Its efficiency could, during the following two decades, be improved by optimizing the porosity of the electrode prepared from fine oxide powder, but the instability remained a problem.

     A modern DSSC is composed of a porous layer of titanium dioxide nanoparticles, covered with a molecular dye that absorbs sunlight, like the chlorophyll in green leaves.

     In the dye-sensitized solar cell, the bulk of the semiconductor is used solely for charge transport, the photoelectrons are provided from a separate photosensitive dye.

    The dye molecules are quite small (nanometer sized), so in order to capture a reasonable amount of the incoming light the layer of dye molecules needs to be made fairly thick, much thicker than the molecules themselves. To address this problem, a nanomaterial is used as a scaffold to hold large numbers of the dye molecules in a 3-D matrix, increasing the number of molecules for any given surface area of cell. In existing designs, this scaffolding is provided by the semiconductor material, which serves double-duty.
     

    42
    Carbon nanotubes have been highly studied by materials scientists who see the potential in their amazing stiffness, strength, thermal conductivity, electrical properties and high surface area. However, CNTs have yet to make significant impacts in products produced by the textile industry. But this could change, as new methods to produce high aspect ratio carbon nanotubes, and nonwoven fabrics directly from them, are emerging.

    What are carbon nanotubes and how are they currently used in the textile industry?
    Carbon nanotubes are tubular fibrous structures composed entirely of graphitic carbon planes. The carbon-carbon bonds form a hexagon shape within the lamellar graphite planes that resembles common chicken wire. A common analogy to describe the structure of a CNT is to picture the same sheet of chicken wire rolled up into a cylinder. The orientation of the graphite planes, parallel to the fiber axis, along with the seamless nature of the tube structure, enables their extreme mechanical properties. The diameter of carbon nanotubes can vary, usually from 1-50 nanometers, which is significantly smaller than fibers produced by meltblowing or optimized electrospinning processes.

    Dry CNT fabric formation processes
    One major requirement for producing fabrics directly from CNTs is that the CNTs should have an extremely high aspect ratio. CNT lengths in the range of hundreds of microns to millimeters should be used. While this length would be considered very short in the case of traditional staple textile fibers, in this case the nanoscale CNT diameter means the aspect ratios are in the hundreds of thousands. This is important because the surface of CNTs are smooth with no chemical functional groups, so the fabrics made from them are held together by the weak secondary interactions among tubes. Increasing the length of the CNTs allows for more of these interactions to “add up” along their length to allow for the creation of stable fabrics.

    Where it could lead
    Fabrics made entirely of carbon nanotubes have many potential applications. One of the most attractive is in high-strength composite materials. Fabrics with long, aligned, individualized CNTs can be used to produce resin pre-impregnated fabrics and high-fiber volume fraction composite materials with morphologies that resemble traditional carbon fiber materials.

    With the multifunctional properties they would provide, CNT fabrics and composites produced from them may fill needs not met by carbon fiber composites in defense, aerospace, automotive and consumer markets. Their high specific surface area, chemical stability and thermal stability make them a great candidate for battery electrodes, catalyst supports, thermoelectric materials, and air and water filtration.

    43
    Textile Engineering / Textile fibre in tumour & cancer cell surgery
    « on: July 18, 2014, 10:24:39 PM »
    Endovascular embolization is a medical procedure to treat abnormal blood vessels in the brain and other parts of the body. It is an alternative to open surgery.
    This procedure cuts off the blood supply to a certain part of the body.

    Particles of PVA (poly vinyl alcohol) are injected slowly with X-ray guidance to prohibit the supply of nutrition to some kind of cell, such as- a cancer cell , tumour, fibroid etc.
    The iodinated PVA fibrils can be used as an embolic fiber for biomedical applications, owing to their-
    high fineness,
    good biocompatibility, and
    good binding property.



    Disadvantage of conventional metallic coil-shaped embolic materials-
    Expensive
    Problems during operation because of the sharpness of their cut faces

    Advantages of PVA microfibril-
    More effective
    Comparatively superior properties
    Less expensive
    enhanced biocompatibility
    less risk of scratching

    Radiopacity is a very important characteristic for embolic materials for the minute positioning control of materials in human organs.
    It is necessary to endow radiopacity to PVA fibrils by iodination to be used as embolic material.


    44
    Textile Engineering / Antimicrobial finish in textiles
    « on: July 18, 2014, 07:03:17 AM »
    The consumers are now increasingly aware of the hygienic life style and there is a necessity and expectation for a wide range of textile products finished with antimicrobial properties.
    The inherent properties of the textile fibres provide room for the growth of micro organisms. Besides, the structure of the substrates and the chemical processes may induce the growth of microbes. Humid and warm environment still aggravate the problem. Infestation by microbes cause cross infection by pathogens and development odour where the fabric is worn next to skin. In addition, the staining and loss of the performance properties of textile substrates are the results of microbial attack. Basically, with a view to protect the wearer and the textile substrate itself antimicrobial finish is applied to textile materials.

    What are microbes?
    Microbes are the tiniest creatures not seen by the naked eye. They include a variety of micro organisms like bacteria, fungi, algae and viruses. Bacteria are unicellular organisms, which grow very rapidly under warmth and moisture. Further, sub divisions in the bacteria family are Gram positive (Staphylococcus aureus), Gram negative (E-Coli), spore bearing or non-spore bearing type.

    Necessity of antimicrobial finishes

    Antimicrobial treatment for textile materials is necessary to fulfill the following objectives:

    To avoid cross infection by pathogenic micro organisms.

    To control the infestation by microbes.

    To arrest metabolism in microbes in order to reduce the formation odour.

    To safeguard the textile products from staining, discolouration and quality deterioration.

    Antimicrobial textiles
    The antimicrobial textiles can be classified into two categories, namely, passive and active based on their activity against micro organisms. Passive materials do not contain any active substances but their surface structure (Lotus effect) produces negative effect on the living conditions of micro organisms (Anti-adhesive effect). Materials containing active antimicrobial substances act upon either in or on the cell.
    Actigard finishes from Clariant are used in carpets to combat action of bacteria, house dust mites and mould fungi. Avecia.s Purista-branded products treated with Reputex 20 which is based on poly (hexamethylene) biguanide hydrochloride (PHMB) claimed to posses a low mammalian toxicity and broad spectrum of antimicrobial activity. PHMB is particularly suitable for cotton and cellulosic textiles and can be applied to blends of cotton with polyester and nylon.

    With advent of new technologies, the growing needs of the consumer in the wake of health and hygiene can be fulfilled without compromising the issues related to safety, human health and environment. Taping new potential antimicrobial substances, such as, Chitosan from nature can considerably minimise the undesirable activities of the antimicrobial products.
    Scientists all over the globe are working in the area and a few of them reported to have used antimicrobial finishes and fluoro chemicals to make the fabric having antimicrobial as well as blood repellant properties. Chitosan and fluoro polymers are reported to be most suitable finishing agents for medical wears with barriers against micro organisms and blood. To carve a niche for textile materials, this kind of value adding finishes are the need of the hour.


    45
    Textile Engineering / Aroma Textiles
    « on: July 18, 2014, 06:53:53 AM »
    We may choose various products such as fi­bres, fabrics, non-fabrics and garments to enjoy the pharmaceutical and emotional effects of aromatherapic textiles. We believe that aromatherapy and aroma­therapic textiles are the first choice for people who want to keep healthy in their daily life, and these textiles will become a fashion in the near future.

    Aroma Textiles:
    An ‘aroma compound’ also known as aroma or fragrance is a chemical compound that has a pleasant smell or odor. Any chemical compound has smell or odor when two conditions are met:

    1. The compound needs to be volatile so that it can be transported to the olfactory system in the upper part of the nose,

    2. The compound needs to be sufficiently high in concentration so that it can interact with the olfactory receptors present in the upper part of the nose which in turn transmit the stimuli to the olfactory centre in the brain where it is perceived as a pleasant or unpleasant odor.

    Aroma finish is a process by which textile material is treated with the pleasant odour producing essential oils and aromatic compounds so that the wearer gets beneficial effects. Various essential oils like lavender, rosemary, and jasmine were used in this finish.

    Need for Aroma Textiles:
    Home textiles such as bed linens, pillow covers, bed sheets do not remain fresh due to everyday use. Also, among apparels, intimate garments and sportswear- sports t-shirts, socks and sports shoes are constantly exposed to human sweat which contains a lot of micro-organisms that give off bad odour. Hence, by some technological means, if textile materials used for the above purposes are made aroma textiles, it adds a lot of value to the product. Also, aroma compounds infuse a feeling of well-being and freshness in the wearer.
    Aroma fabrics fabrics have several uses fields of medicine and alternative healing.

    The sedative effects/or emotion of essential oils:

    Anxiety:
    Benzoin, Lemon, Chamomile. Rose, Cardamom, Clove, Jasmine

    Lament:
    Rose

    Stimulation:
    Camphor, Balm oil

    Anger:
    Chamomile, Balm oil. Rose, Ylangylang

    Wretchedness:
    Basil, Cypress, Mint, Patchouli

    Allergy:
    Chamomile, Jasmine, Balm oil

    Distrustfulness:
    Lavender

    Tension:
    Camphor, Cypress, Vanilla. Jasmine. Balm oil. Lavender, Sandalwood

    Melancholy:
    Basil, Lemon, Chamomile, Vanilla, Jasmine, Lavender, Mint, Rose

    Hysteria:
    Chamomile, Balm oil, Lavender, Jasmine

    Mania:
    Basil, Jasmine, Pine

    Irritability:
    Chamomile, Camphor, Cypress, Lavender

    Desolation:
    Jasmine, Pine, Patchouli, Rosemary


    Microcapsules and Aromatherapy in Textiles:
    Microencapsulation can be defined as a micro packaging technique wherein an active core material is encapsulated in a polymer shell of limited permeability. The objective of this technology is either to protect the active core material from the external environment till required or to affect the controlled release of the active-core to achieve desired delay until the right stimulus is encountered.

    Market Potential of Aroma Textiles:
    Fashion retailer’s interest in fragrance infused fabrics dates back to the 1960s when Kanebo, a Japanese consumer products company, manufactured women’s scented tights. In fact, hosiery and intimate apparel have been the more widely explored product categories to apply scent infused fabric technology. More recently, international companies such as Woolmark™ have formed joint ventures with the International Fragrances and Flavors association to delve into R&D initiatives with mills around the world. Woolmark™ calls its use of microencapsulation as Sensory Perception Technology™ fabrics. Woolmark™ is applying this technology to hosiery, lingerie, underwear, socks, outdoor clothing, carpeting and other interior textiles. In 2005, the Invista Company, owner of fiber brands such as LYCRA®, TACTEL® and SUPPLEX®, launched the LYCRA® Body Care Collection. The Body Care Collection includes moisturizing and fragrance features in the yarns to enhance the wearer’s sense of well being in the intimate apparel category. The micro-beads which are built into the fibers release their contents when the elastane content fabrics are stretched during wear. The Olga clothing brand launched a collection utilizing LYCRA® Body Care Collection in April 2005. The Nike clothing brand has\ also explored encapsulation methods to a limited extent. Associates have estimated that fragrance infused fabric technology, such as the one seen in the Nike Precoo System running shirt, is less than 5% of their total buy.

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