Silver based Anti microbial finish

ABSTRACT:

            Textiles have function of second skin enabling human to living extreme conditions. At the same time consumers have increasingly aware of risk the garments  make cause to human health. The consciousness on the health among mankind increased urge for the developments of an antimicrobial finished textiles and infection free clothing. This articles has dealt with the impotence of silver based anti microbial finish, how it is done presently and merits & future scope of silver based antimicrobial finish.

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 uni-cellular organisms which grow very rapidly under warmth and moisture.

ANTI-MICROBIAL FOR GARMENTS:

The main reason for treating garments with antimicrobial control of perspiration odours. As the bacteria reproduced they give off gases which are familiar perspiration odour. Treating fabric with anti microbial means, that bacteria which have been transferred from the skin or the environment do not reproduce in the fabric. The reduction in bacteria means the volume of gas given off will be much smaller than an odour will not develop.

NECESSITY OF ANTIMICROBIAL FINISHES:

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

Ø  To avoid cross infection by pathogenic micro organisms;

Ø  To control the infestation by microbes;

Ø  To arrest metabolism in microbes in order to reduce the formation odour; and

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

SILVER BASED ANTI MICROBIAL:   

            Among the various antimicrobial agents used for the finishing of textile substrates, silver or silver ions have long been known to have strong inhibitory and bacterial effects as well as a broad spectrum of antimicrobial activities. The inhibitory effect of silver ion/ silver metal on bacteria has been attributed to the interaction of silver ion with thiol groups in bacteria as well as to the oxidative destruction of micro organism in aqueous medium. Silver ion based antimicrobial finishes have been developed by the interaction of a silver salt such as silver nitrate with anionic co polymer of styrene, ethyl acrylate , acrylic acid and divinyl benzene having at least support about 0.008 meter equal of carboxylic group per gram of polymer and ≥ 0.0009 mol of silver per gram of the polymer. The films of such polymeric finishes release anti bacterial and anti fungal silver ions slowly over a very long period of time.

In another patent, it is disclosed that a silver containing anti microbial agent that has affinity for textile fibres can be produced by treating cross- linked carboxyl methyl cellulose having greater than 0.4 carboxyl methyl group with silver nitrate. The anti microbial finishing agent may have 0.01 to 1 %  silver bound to the water resistant cross linked CMC (Ag.)

Milliken & company have developed a silver antimicrobial agent. That name is Alphasan™ by forming a complex of silver with zirconium phosphate. Other silver containing antimicrobial are silver substituted zeolite available from sinanen under the trade name Zeomic™ AJ, and silver subsisted glass available from the Ishizuka glass under the trade name Ionpore™. This compound can be applied on the fabrics by exhaustion with a dye solution. The antimicrobial fabric thus produced on finishing with and acrylic co polymer makes the antimicrobial finish more durable.

 Another method of producing durable silver containing antimicrobial finish is to encapsulate a silver compound is nano particle with a fibre reactive polymer. The resulting micro nano capsules when applied to a fabric, reactive with it and thus provide durable silver based anti microbial finish. The micro encapsulation of the nano particles may be carried out in different ways. For instance, for producing micro capsules of water soluble products, the product may first be dissolved in water and subsequently emulsified after adding an emulsifier and oil soluble encapsulating monomers or oligomer or polymers. On polymerization and cross-linking, the resulting shell encapsulate the water soluble product. One of the fibre reactive polymers used for this purpose is poly (styrene co –maliec anhydride).

Yang has patented the a process for preparing a silver nanoparticles containing functional microcapsule having the intrinsic antimicrobial and therapeutic functions of silver as well as additional functional of the products contained in the inner core of the capsule. Such microcapsule can be prepared by a two-step process. In the first step an emulsified solution of a perfume is encapsulated with melanin precondensate. The microcapsule so produced is treated with silver nanoparticle dispersed in water-soluble styrene maleic anhydride polymer solution before it fully dries. Thus microcapsules with duel function are produced. In these microcapsules, the silver nanoparticles are on the surface of the capsule (Fig. 1), Instead of a perfume, one can have a thermo sensitive pigment, thermal storage material or pharmaceutical preparation in the inner core.

Fig: 1 Structural view of a Silver nano particle containing functional microcapsule

(a). Microcapsule (b). Inner core contains functional substance such as perfume, a thermo sensitive pigment, thermal storage material or pharmaceutical preparation and (c). Inner shell.

In a chemical reduction method of producing highly concentrated stable dispersions of nano sized silver particles; silver nitrate is reduced with ascorbic acid to precipitate metallic silver in acidic solutions according to following reaction:

2Ag⁺ + C₆H₈O₆ ¬® 2Ag⁰ + C₆H₆O₆ + 2H⁺

Anti microbial fabrics made from cotton, linen, silk, wool, polyester, nylon, or their blends having nano silver particles can be produced by immersing them in nano silver particle- containing solution producing by reducing silver nitrate with glucose and drying at 120 0 to 160⁰C for about 40 – 60 min. The treated fabrics were yellow orange colour. Electron microscopic studies of the antimicrobial fabric indicate that the fabric samples contained nano silver particles which were evenly distributed and contained particles that were mostly bellow or about 10 nm size. Chemical testing indicated that the silver content in the fabrics was about 0.4-0.9 % by weight. The treated fabrics showed effect anti microbial activity against various bacteria, fungi, Chlamydia, that included.

Silver-containing antimicrobials have been incorporated into wound care devices and are rapidly gaining acceptance in the medical industry as a safe and effective means of controlling microbial growth in the wound bed, often resulting in improved healing. It is known that placing surface- available silver in contact with a wound allows the silver to enter the wound and become absorbed by undesirable bacteria and fungi that grow and prosper in the warm moist environment of the wound site. Once absorbed, the silver ions kill microbes , resulting in treatment of infected wounds or the prevention of infection in at risk wounds. Some of the commercial silver antimicrobial wound care products are Acticoat™, Actisorb™ And Silverlon™.

ADVANTAGE OF SILVER CONTAINING ANTI MICROBIAL

Generally silver based antimicrobial have more advantages compare to other antimicrobial agents, there are given bellow. Control of a wide range of bacteria perspiration by consumer as very safe able to withstand temperature of 400 to 500⁰ C for polymer applications;

Silver based antimicrobials works in three ways and a bacterial cell

                                                              i.      Reaction with thiol groups on proteins and enzyme

                                                            ii.      Interference with DNA & RNA functionality

                                                          iii.      Modification of the plasma membrane of the cell

Because there are three separate modes of activity, it is difficult for a bacterial cell to develop resistance to silver based antimicrobials. It is almost impossible for a cell to adapt to all three methods of attack.

CONCLUSION:

Generally silver based antimicrobial agents have more cost compare to other antimicrobial agents but it have more desirable properties like durability, very good  control of a wide range of bacteria perspiration and etc,  so now people are more considering about the quality rather than any other things like cost ,etc of the products, so these silver based anti-microbial finished materials will going to take very good place in future days.

REFERENCE:

1.     http://www.clinicalservicesjournal.com/Default.aspx

2. http://www.japoncorp.net/article.asp?art_ID=11589
3. ML Gulrajani / nano finishing /IJF&TR/ Pp197-199

THE ROLE ROBOTICS IN THE PACKING DEPARTMENT OF GARMENT INDUSTRY

THE ROLE ROBOTICS IN THE PACKING DEPARTMENT OF GARMENT INDUSTRY

             The packing of finished garments is done by man and machine. Even for machine packing manual labor is needed. The use of standard size templates is very common in today’s apparel industry. 

            The standard time for folding a full sleeve shirt in 14 seconds by using templates. To reduce the present time taken and to save one labor, it is thought fit to introduce the use of robots in the packing operations of a full sleeve shirt. The concepts of robotic were born in Japan with the sole purpose of reducing man power and saving in time in the manufacturing operations of any product.

 Robot has been defined by”The robot Institute of America as follows:-

“An industrial robot is a reprogrammable, multifunction manipulator”.

             It is a designed to move material, parts, tools or specialized devices, through variable programmed motions, to accomplish a variety of tasks. A robot must have the ability to adapt too many different kinds of jobs. 

General Description of Robot

Components of robot

Many industrial robot manufacturers are producing a variety of robot configurations with various capacities and capabilities. Robots have three common basic components.

a. Manipulator

Manipulators consist of mechanical linkages and joints, actuators, control values and feed back devices.

b. Controller

            The robot’s “brain” that directs movement of the manipulator

c. Power Supply

            The “heart” that provides regulation energy for the manipulator’s actuators.

d. Mechanical Arm

            The motion to the mechanical arm may be linear arm motion or rotational motion. 

1)    The combination of motions included in the arm will determine the type of arm geometry, which is present. 

2)    The basic geometries include rectangular, cylindrical, and spherical and joined spherical. 

3)    With a combination of these motions the arm can move to any required position within the work area.

External Power Source

            The power source required to operate a robot system includes the electricity to power the electronic controller and a hydraulic or pneumatic source to operate the arm motion and en-of arm tooling.

Classification of Robot

            There are many classification techniques available, out of which robot arm geometry classification divides robots into categories based on the shape of the work area produced by the robot arm.  Another technique divides robots into low, medium and high technology machines.

Classification of Robots is as Follows

1. Dedicated robot
2. Machine attending robot
3. Transport robot

The following operation using robotics will be by using the mechanical arm of the robot all actions done by human hands will be replaced by one pneumatic and electronically controlled arm. Similarly wrapping the folded shirts in polyethen / paper will be done by the robotic system.

By means of using Artificial Neural Network system and image processing analysis tools we can predict the actual and exact data’s that is any mis - alignment in the lay during packing with enough some Cv % tolerance.   

Textiles in Medical Science

Abstract:

             Globalization of world market has put a sufficient pressure of textiles manufacture to think about their survival. Changing scenario demands change in approach to diversification of product. Now textiles does not means only looking fashionable and covering body, but also it can be more functional and use for technical applications like agriculture , aerospace, geo textiles, medical textiles and etc,. The medical textiles are one part of technical textiles, it is an interdisciplinary field and it’s collaborated between medical and textile sectors.

          Medical science has become very advanced from last few decades. More and more techniques are invented to procure better health methods. Use of medical textiles for replacing damaged tissues or organs is the result of advanced medical invention. However substitute for defective body parts was used to be transplantation of that part or organ, but this is not always possible. Thus use of textiles as a substitute to replace and aid for damaged body parts is being utilized by the surgeons and physicians.

        In this paper, discussed about the application of textiles in various medical fields namely, health care, hygiene products, extra corporeal devices and surgical textiles, Non implantable and implantable materials, Phase Change Materials and Super Absorbent Fibers in these felids.

Introduction:

The term “medical textiles” literally means textiles used for medical purposes. Textile apart from being a vital part of human life are since long been used in medical field, though the tern has been coined very recently. Textile materials have a range of properties such as flexibility, elasticity, strength, etc. based on these properties research work has been going on rapidly around the world towards the application of textiles in medical field. Specialist from physicians to textile chemists and textile engineers are ready to devote themselves unitedly to apply these broad ranges of properties of textile material in medical technology ^(1).

Categories of Medical Textiles

Surgical Sutures ⁽²⁾

Fibers are also used as sutures in surgery. Sutures are sterile filaments which are used to hold tissues together until they heal adequately or to join tissues implanted prosthetic devices., Sutures are either braided or monofilament are mostly used to close wounds and approximate tissues. The textile materials have generated considerable interest in medical technology where materials in the form of monofilament, multifilament, woven and nonwoven structures are being used for bio and medical applications. The major requirement of the textile materials is the bioreceptivity and biocompatibility at the application site in human being. The medical textile group in the Department of Textile Technology at IIT Delhi has been working on the development of antimicrobial biocompatible sutures and scaffolds for tissue engineering. Because of the lack of proper post-surgical care, the bacterial infection in stitched wounds is prevalent in many of the cases.   

                                                                     

The development of an antimicrobial suture based on Nylon and Polypropylene monofilaments is being pursued in the Medical Textile group. The surface functionalization of the suture is carried out in such a way that the inherent characteristics, such as mechanical and knot strength of the suture are not affected. Both the high energy gamma radiation and the plasma irradiation are being used to activate the materials for the surface functionalization. An antimicrobial drug is immobilized on the suture surface which subsequently is released slowly into tissues surrounding the stitch and prevents the microbial invasion. The tissue compatibility of these sutures is excellent and no adverse reaction has been observed against these sutures.             Fig: 1 Surgical Suture Process

Barbed Sutures

Recently a bi-directional barbed suture has been developed which obviates the necessity to tie a knot. It has ability to put tension in the tissues with less suture slippage in the wound, as well as to more evenly distribute the holding forces there by reducing tissue distortion. The barbed suture with a steeper cutangle and a median cut depth have a higher tissue holding capacity than those with a moderate cutangle and a nominal cut depth.                                    Fig: 2 Barbed Suture Needle

GELATIN COATED SUTURES

Gelatin coated sutures are having a superior handling characteristics. The gelatin coating given to the suture material improves the surface smoothness and reduces the fraying characteristics. It can be obtained by means of treating the suture with that of aqueous solution of gelatin to coat the suture and it is made to have a contact with that of fixative agent to crosslink gelatin. This process includes the step of contacting the coated suture with that of buffer solution and heats it to 50⁰C for a particular period of time interval. Usually heating can be carried out for about 1-20hrs. Sometimes plasticizers can be incorporated into the gelatin solution. The plasticisers used are triethyl citrate, glycerin or other poly hydric alcohols. The plasticiser used is mainly to enhance the benefits of the gelatin coating. The fixative solution used in the process is a cross linking agent. The preferred cross linking agent is preferably a dialdehyde such as glyoxal, which may be used alone or in conjunction with formaldehyde or other aldehyde.

Dressing Materials ^{(3 &4)}
Calcium Alginate Fibers

The raw material for the production of this fibre is alginic acid, a compound obtained from the marine brown algae. It has a variety of properties, including the ability to stabilize viscous suspension, to form film layers, and to turn into gels. When the dressing made of this fibre is applied to wound, the reverse ion exchange take place, and this fibre is placed on the wound in dry state and begins to absorb the exudates. The calcium ions are then gradually exchange against sodium ions that are present in the blood and wound exudates.

The fiber absorbs large amounts of secretion, starts to swell and in the presence turns into a moist gel that fills and securely covers the wound. Both the extent and the rate of gel formation depend on the available amount of secretions. The more exudates present the more rapid gel formation occur. Addition of excess sodium ion causes further dissolution of the gel, so that calcium alginate fibres remaining in the wound can be resorbed. If necessary, but mayh also without problems be rinsed out with physiological saline solution.

Sorbalgon

It is a supple, non-woven dressing made from high quality calcium alginate fibre with excellent gel forming properties. The dressing offers number of practical therapeutic advantages for wound healing over any other commonly uses textiles. A Sorbalgon dressing absorbs approximately 10ml exudates per gram dry weight and thus provide with an absorption capacity. They in addition differ from textile dressings with respect to applied mechanism of absorption. It takes wound secretion directly into the fibres i.e., using intra capillary forces.                                                            

Super Absorbable Polymer

Super absorbents are swell able cross linked polymer, which have the ability to absorb and store 400-600 times there own weight of aqueous liquid by forming a gel. The liquid is then retained and not released, even under pressure. The absorption rate of the polymers differs according to their mechanism used for preparation. SAP cannot dissolve because of their 3-D polymeric network structure of the many different types of polymers, only a few can be made into useful fibers. This is because a polymer must meet certain requirements before it can be successfully and efficiently converted into a fibrous product. Some of the most important of these requirements are:

·  Polymer chains should be linear, long, and flexible. Side groups should be simple, small, or polar.

·  Polymers should be dissolvable or melt able for extrusion.

·  Chains should be capable of being oriented and crystallized.

Common fiber-forming polymers include cellulosic (linen, cotton, rayon, acetate), proteins (wool, silk), polyamides, polyester (PET), olefins, vinyls, acrylics, polytetrafluoroethylene (PTFE), polyphenylene sulfide (PPS), aramids (Kevlar, Nomex), and polyurethanes (Lycra, Pellethane, Biomer). Each of these materials is unique in chemical structure and potential properties. For example, among the polyurethanes is an elastomeric material with high elongation and elastic recovery, whose properties nearly match those of elastin tissue fibers. This material when extruded into fiber, fibrillar, or fabric form derives its high elongation and elasticity from alternating patterns of crystalline hard units and noncrystalline soft units. Although several of the materials mentioned above are used in traditional textile as well as medical applications, various polymeric materials both absorbable and nonabsorbable have been developed specifically for use in medical products.

The reactivity of tissues in contact with fibrous structures varies among materials and is governed by both chemical and physical characteristics. Absorbable materials typically excite greater tissue reaction, a result of the nature of the absorption process itself. Among the available materials, some are absorbed faster (e.g., polyglycolic acid, polyglactin acid) and others more slowly (e.g., polyglyconate). Semiabsorbable materials such as cotton and silk generally cause less reaction, although the tissue response may continue for an extended time. Nonabsorbable materials (e.g., nylon, polyester, and polypropylene) tend to be inert and to provoke the least reaction. To minimize tissue reaction, the use of catalysts and additives is carefully controlled in medical-grade products ^(5).

Water Absorbent Polymer

Water absorbent polymers are known as hydro-gel, water crystal, super absorbent polymers etc., are simply a type of plastic that possesses some unique water absorbing qualities. This is due to the presence of sodium or potassium molecules that form bridges between the long hydro carbon chains. These bridges are known as cross linking, which enables the polymer to form into a huge single super molecule, including its ability to degrade in the environment and breakdown into simpler molecules, and hold significant amount of water. When water comes in contact with super absorbent an electrical repulsion takes with in the particles. When this happens, water is drawn into the particles resulting in swelling of each particle. At maximum absorption capacity each particle will expand to over 30 times its original volume. When water evaporates it shrinks, returning to unswollen state.

Spider Silk

Modified goat milk will contain web protein .A goat that produces spider's web protein is about to revolutionist the materials industry. It is Stronger and more flexible than steel, spider silk offers a lightweight alternative to carbon fibre. Up to now it has been impossible to produce "spider fibre" on a commercial scale. Unlike silk worms, spiders are too anti-social to farm successfully.                                              Fig: 4 Spider silk (Spinners)          

 Now a Canadian company claims to be on the verge of producing unlimited quantities of spider silk - in goat's milk. Using techniques similar to those used to produce Dolly the sheep, scientists at Nexia Biotechnologies in Quebec have bred goats with spider genes. New kids on the block Called Webster and Pete, the worlds first "web kids" cannot dangle from the ceiling, nor do they have a taste for flies. In fact they look like any other goat. But when they mate, it is hoped they will sire nanny goats that produce milk that contains the spider silk protein. This "silk milk" will be used to produce a web-like material called Biosteel. Naturally occurring spider silk is widely recognized as the strongest, toughest fibre known to man.                                                                                 

Its tensile strength is greater than steel and it is 25 percent lighter than synthetic, petroleum-based polymers. These qualities will allow Biosteel to be used in applications where strength and lightness are essential, such as aircraft, racing vehicles and bullet-proof clothing. Kind to humans another advantage of spider silk is that it is compatible with the human body. That means Biosteel could be used for strong, tough artificial tendons, ligaments and limbs. The new material could also be used to help tissue repair, wound healing and to create super-thin, biodegradable sutures for eye-or neurosurgery ^(6).

Antimicrobial Fiber

Antibacterial fiber is produced by entrapping the metal ion with a cation exchange fibre having a sulphonic or carboxyl group through an ion exchange reaction. The antibacterial metal ion is silver or silver in combination with either copper or zinc. The great advantage of this material is that those are not to react with tissue. Flexible products such as sponges and textile wites, which have protracted antimicrobial effect. The wipes are impregnated with biocides by spra8ying, dipping or soaking for use in medical field.

Acticoat Dressing

It provides broader and faster protection against fungal infection than conventional antimicrobial products. The dressings are layered with mono crystalline silver known to have antimicrobial and antifungal properties, creating a protective barrier as silver ions are consumed. Acticoat has the faster kill rate and was effective against more fungal species. The product can be applied to variety of wounds including graft and donor sites and surgical wounds.

Antimicrobial Wound Dressing

Kerlix AMD is pure cotton treated with anecia's polyhexamethylene biguandine agent. These antimicrobial agents resist bacterial growth with in the dressing as well as reducing bacterial penetration through the product. Wound covering, is made of a hydrophobic bacteria-adsorbing material which comprises the antimicrobial active component which is not released into wounds, it is preferably made of mixture of hydrophobic fibres and fibre comprising antimicrobial property ^(7).

Phase Change Materials (PCM):

Phase change technology in textiles means incorporating micro capsules into textile structures. Phase change materials (pcm) are used in health care applications for faster recovery of patients. These are the material that possesses the ability to change their physical state from solid to liquid or vice- versa, within a certain range of temperature. The energy required for breaking the bonds and changing from solid to liquid is absorbed from the surroundings. During the entire phase change the temperature of the surrounding substrate and the pcm remains constant. These pcm’s can be used in micro encapsulated form for surgical clothing, bedding material and intensive care material purposes. Microfibres, non woven and their composites are used in drapes, gowns, caps, mask, etc. due to their dispesability, barrier properties, breathability, drapeability, strength, softness and comfortability. A British company has developed a special bra, called “mamo test bra”, which can detect breast cancer at a very early stage. The black bra is coated with thermochrombic liquid crystal ink, which changes color with the amount of heat. It is subjected to the cancerous tumours are warmer than the adjacent areas and can be detected by different color patterns ⁽⁸⁾.

Disposable Products:

Absorbent disposable products, such as diapers, sanitary napkins, tempons, incontinence products, panty shields, wipe, etc. are mostly single use items and are designed to receive, absorb and retain body fluids and solid waste. The disposable diaper for baby care was first marketed in Sweden in the late 1930’s. and the present all-in-one diaper consists of multilayer components with an enhanced facility to collect urine and faucal waste and incorporates a super absorbent polymer as an absorbent component.

A modern breathable disposable feminine product consists of three layers, of which the inner top layer is made of a blend of hydrophobic (polyester), low density fibres (polyethylene) and is liquid and water permeable. The core layer, packed with wood- pulp as other absorbent materials, is highly absorbent and the third layer consists of a multi layer barrier, that is water vapour permeable, but resistant to liquid water. It is of interested to note that fibers obtained from gellan gum are utilized for making tempons. The gum is obtained from the culture of pseudomonas elodeabacterium by fermentation. A washable or disposable nursing pad has been developed to absorb breast milk leaking from a nursing mother into her outer garments, principally during the night.

 A modern incontinence product also consist of three layers, a cover stock, that is permeable and diffuses the liquid laterally, a highly absorbent core, and a barrier polyethylene or polyvinyl chloride film that helps the patient clothes or bedding to keep dry ⁽⁹⁾.

Smart Textiles for Health Care:

Intelligent or ‘smart’ textile is an emerging field in textile research, where the material is designed to sense and react to different stimuli or environmental conditions. The extent of intelligence can be divided in three sub- groups; passive smart, active smart and very smart textiles. An important development applicable to the medical field is the ‘wearable computer system’. For example, a smart t- shirt with conductive fibers capable

Fig: 4 Schematic of an embedded network of processing element in a textile fabric for health monitoring

Of feeding sensor signals into a small transmitter has been manufactured. Such apparel capable of recording, analyzing, storing, sending and displaying biofunctional data including internet connectivity can be used to monitor the health status of the wearer. The first textile material that, in retroaction, was labeled as a ‘smart textiles’ was silk thread having a shape memory.

Smart t-shirt was originally designed for combat soldiers in the military to detect the location and severity of wounds and subsequently to monitor their physiological state, and to transmit the information to remote medical sites. The concept was later extended to medical applications in which the transmission of data from such a’ wearable computer’ enables the remote monitoring of heart beat, blood oxygen level, respiration and body temperature to start with. The health status can also be interpreted and transmitted to a doctor’s office or to a hospital monitoring system as required. Such a’ smart’ system can also be used for monitoring babies considered at risk for sudden infant death syndrome. Keeping watch on post- surgical geriatric patients at home, remote monitoring of stroke patients in bed , tightness of pressure garments, heat stress suffered by fire fighters and three dimensional scanning and medical imaging of patients.

The concept of smart textiles is also being extended to new finishes, for example, to provide vitamins to the body through garments, termed as ‘wearable vitamins’. Fuji spinning has developed a finish to fix pro-vitamins to fibres in a staple manner. A finished t-shirt, containing vitamin C and also E now, has been developed ^(10).

Compression Bandages

The basic function of bandages is compression, retention and support. This is obtained by properties intrinsic to the component and further enhanced and re-enforced supportively by the process of weaving and finishing relevant to the required end use. The regulation of the blood flow and prevention of swelling is closely interlinked with this property and there by enhancing improved healing healing process. It provides necessary support to restrict movement and speed up the healing process ^(11).

Conclusion:

Thus the application of textile in high performance and specialized fields are increasing day by day. There will be an increasing role for medical textile in future. Thus the textile will be used in all extra corporal devices, external or implanted materials, healthcare and hygienic products. Textile materials continue to serve an important function in the development of a range of medical and surgical products. The introduction of new materials, the improvement in production techniques and fiber properties, and the use of more accurate and comprehensive testing have all had significant influence on advancing fibers and fabrics for medical applications. As more is understood about medical textiles, there is every reason to believe that a host of valuable and innovative products will emerge; in future many more developments will happen in medical textiles particularly Phase Change Materials and Super Absorbent Fibers.

References:

1. A.A.Desai, “Biomedical Textiles” Journal of Textile Association  Jan –Feb 2004
2. Indian Journal of Fiber and Textile Research, Vol. 31, Pp 215-229.
3. Somasundram D &Kothari V K (2007) “Textile Materials in Implantable Medical Surgeries” Indian Textile Journal July Pp 73.
4. Krishnabala S. & Thangeswaran P. (2005) “Biomaterials in Medical Applications” Asian Textile Journal, Vol. 14/6, Pp 57-61.
5. Hayavadana J et. al, “Biomedical Textiles” Asian Textile Journal, February (2004), Pp 93-98.
6. I.V. Walker,  proceedings of Medical Textile Conference., 1999, Bolton  Institute, U.K., Publishing Co., Cambridge, Pp 12- 19
7. Rigby A.J et. al, Medical Textiles, Textile Horizon March 1999
8. S. Anand, ‘Medical Textiles’, Wood head publishing Ltd, Abington, 2001.
9. Opportunities for healthcare and medical textiles growth’, Technical Textiles Inter­national, 2003
10. Alistan. et. al, Hand book of Technical Textiles, Wood head Publishing Limited – England PP 412.
11. M.R. Ten Breteler et. al “ Textile Slow-Release Systems With Medical Applications” Autex Research Journal, Vol. 2, No4, December 2002

Self Cleaning Textiles

ABSTRACT

       Now a day’s people are very busy in their work that they do not have time for clean their daily wear cloths also people who are working in kitchens having headek to wash their garments. Also military peoples have to survive in such drastic condition that they cannot wash their cloths. Nanotechnology provides a new concept self cleaning textiles which gives self cleaning as well as fresh cloths every day.

        Water and soil repellency has been one of the major targets for fiber and textile scientists and manufacturers for centuries. Combinations of new materials for fiber production with a variety of surface treatments have been developed to reach the condition of limited wet ability. This paper gives the concept behind the self cleaning textiles, different surface treatments based on nano technology, application of  self cleaning textiles problems and limitations of  self cleaning textiles.

INTRODUCTION:-

       Finishes that repel water, oil and dry dirt are important in all parts of the textile market – for clothing, home and technical textiles. Water repellency is achieved using different product groups, but oil repellency is attained only with fluorocarbon polymers. They are modified to have a wide range of properties to fit the different demands of the users and the intended purpose. This is one of the most interesting new developments of chemical finishing.

       The oldest repellent finish is to repel water. The purpose of this finish is self evident. Drops of water should not spread on the surface of the textile and should not wet the fabric. The drops should stay on the surface and easily drip off. Similarly, oil repellent finishes should prevent oily fluids from wetting treated textiles. In a similar manner, soil-repellent finishes should protect textiles from both dry and wet soils. In all cases, the air permeability of the finished fabric should not be significantly reduced.  

       In addition to the desired repellency effects, other undesirable fabric properties are often found with repellent finishes. These include problems with static electricity, poor soil removal in aqueous laundering, stiffer fabric hand, greying (soil redeposition) during aqueous laundering and increased flammability. Some fabric properties that are often improved by repellent finishes include better durable press properties, more rapid drying and ironing, and increased resistance to acids, bases and other chemicals.

Mechanisms of repellency

       Repellent finishes achieve their properties by reducing the free energy at fibre surfaces. If the adhesive interactions between a fibre and a drop of liquid placed on the fibre are greater than the internal cohesive interactions within the liquid, the drop will spread. If the adhesive interactions between the fibre and the liquid are less than the internal cohesive interactions within the liquid, the drop will not spread. Surfaces that exhibit low interactions with liquids are referred to as low energy surfaces. Their critical surface energy or surface tension γC must be lower than the surface tension of the liquid γL (the internal cohesive interaction) that is repelled. γL of water, at 73 mN m–1, is two to three times greater than γL of oils (20– 35 mN m–1). Therefore, oil repellency finishes with fluorocarbons (γC = 10–20 mN m–1) always achieve water repellency, but fluorine-free products, for example silicones (γC = 24–30 mN m–1) will not repel oil.7 Low energy surfaces also provide a measure of dry soil repellency by preventing soil particles from strongly adhering to fibre surfaces. This low interaction allows the soil particles to be easily dislodged and removed by mechanical action.

WHAT IS SELF CLEANING TEXTILES:

           The self-cleaning fabrics have a nano film coating of titanium dioxide nanoparticles  which can break down dirt molecules, pollutants, and microorganisms when exposed to visible and UV light. Clothes made this way could be cleaned by simply exposing them to sunlight. Scientists have developed a method for applying the thin film of titanium dioxide to cotton easily and inexpensively. With their method, self-cleaning fabrics could be produced commercially and for public use. The anothes method of manufacturing self cleaning textiles is application of silver nano particals on the besis of lotus leave surface structure.   The scientists note that self-cleaning fabrics could be especially useful for people who don't have the time or means for washing their clothes, such as military personnel or hikers

The Lotus Effect: biomimetic ultraphobic surfaces

       Biomimetics mimics naturally occurring biological mechanisms with modification, to produce useful imitative synthetic items using conventional methods available to science and technology. The Lotus Effect has been named after the unusual properties of the leaf surfaces of the lotus plant, which are remarkably water-repellent and soil-repellent. The surface of the lotus leaf is covered by a thin extracuticellular membrane termed the cuticle, which is covered by waxes forming characteristic microstructures due to self-organisation. On smooth wax layers (surface area contact 10%) the contact angle of water may reach 110°, but because of the surface roughness of the wax layer, whose dimensions can be measured in micrometres, a very pronounced super hydrophobicity is generated with contact angles up to 170° and surface area contact as low as 7%. (As an analogy, imagine a mercury droplet lying on a bed of nails or a pimple rubber mat.) As a result, the area for adhesion of water is markedly diminished and air is enclosed between the droplets and the wax crystals.

       A similar situation holds true for particles that are located on the surface of the lotus plant leaf. The contact angle between the particle and the surface is minimised, which results in the adhesion of particles to the water surface  Independent of their size and chemical nature, contaminants are removed from such optimised surfaces with only a small amount of water.

       This remarkable self-cleaning effect is currently being harnessed to transfer the Lotus Effect into products with bio mimetic self-cleaning surfaces. A façade paint suitable as an ‘anti-graffiti’ surface has already been devised and roof tiles and wood paints are currently under development. It is conceivable that within the next decade the application of the Lotus Effect using nanotechnology, precision engineered polymers and suitable application methods could be used to provide a new generation of fabrics with ultraphobic surfaces. These would undoubtedly be expensive but would possess very high levels of water- and oil-repellency and outstanding soil- and stain-repellency properties. However, the adhesion of such polymers to the fibre surface and their durability to abrasion, wear, laundering and dry-cleaning would have to be appropriate for the end-use.

Self Cleaning Using Nano Technology:-

       There are basically two types of self-cleaning surfaces involving nanotechnology. In the first place extremely water repellent, microscopically rough surfaces: dirt particles can hardly get a hold on them and are, therefore, removed by rain or by a simple rinse in water .The second example is given by photo-catalytic layers: due to a layer of nanocrystalline titanium oxide, fouling organic material is destroyed by solar irradiation.  Self-cleaning, deodorant and anti-VOC (volatile organic compounds) effects are possible when modifying the surface of textiles before anchoring them on TiO_2. Physical methods like RF-plasma and vacuum-UV have been used to introduce carboxylic groups in wool-polyamide5 and cotton6. The TiO₂ forms a complex with the -COOH groups retaining their oxidative action under solar irradiation in the presence of water vapor and air. This leads to self-cleaning effects and to the destruction of organic compounds like wine, coffee, make up, grease etc. Chemical spacers have also been used to attach TiO₂ to fabrics, anchoring this semiconductor on one carboxyl and condensing the surface -TiOH with the second carboxyl-group.

       Dirt adheres to the fibers of most fabrics. To clean the fabrics, people typically put them in the washer or send them to the dry cleaners. But the water-repellency of fabrics made with the new coating is superior and makes it easier to keep dirt from accumulating, because water that is applied to the garment rolls off and takes the dirt with it. Suits made with the new coating could simply be sprayed clean or wiped with a damp cloth to remove the dirt, the researcher says. If desired, the fabric can still be cleaned by conventional means, including washing as well as dry cleaning, without harming the coating, he notes. In addition to suits, the new coating could be applied to hospital garments, sportswear, military uniforms and rain coats. Other possible applications include awning material for outdoor campers, fabrics for lawn furniture and convertible tops for cars.

Application of photo catalytic layer of titanium di oxide

        The fabric is coated with a thin layer of titanium dioxide particles that measure only 20 nanometers in diameter. When this semi-conductive layer is exposed to light, photons with energy equal to or greater than the band gap of the titanium dioxide excite electrons up to the conduction band. The excited electrons within the crystal structure react with oxygen atoms in the air, creating free-radical oxygen. These oxygen atoms are powerful oxidizing agents, which can break down most carbon-based compounds through oxidation-reduction reactions. In these reactions, the organic compounds (i.e. dirt, pollutants, and micro organisms) are broken down into substances such as carbon dioxide and water. Since the titanium dioxide only acts as a catalyst to the reactions, it is never used up. This allows the coating to continue breaking down stains over and over.

       TiO₂ is acts as photo catalyst layer which destructs the dirt particles photo catalytically. The durability of this nano layer is very good up to 40-50 washing cycles.    The simple process sequence for applying the nano layer of Tio2 film is as

Pad                   dry                 cure

Working of self cleaning photo catalytic layer:

 

       The self-cleaning fabrics work using the photocatalytic properties of titanium dioxide, compound used in many new nanotechnology solar cell applications.   The fabric is coated with a thin layer of titanium dioxide particles that measure only 20 nanometers in diameter. When this semi-conductive layer is exposed to light, photons with energy equal to or greater than the band gap of the titanium dioxide excite electrons up to the conduction band. The excited electrons within the crystal structure react with oxygen atoms in the air, creating free-radical oxygen. These oxygen atoms are powerful oxidizing agents, which can break down most carbon-based compounds through oxidation-reduction reactions. In these reactions, the organic compounds (i.e. dirt, pollutants, and micro organisms) are broken down into substances such as carbon dioxide and water. Since the titanium dioxide only acts as a catalyst to the reactions, it is never used up. This allows the coating to continue breaking down stains over and over.

Reactions taking place during self cleaning:

          Titanium dioxide is a photocatalyst; when it is illuminated by light of energy higher than its band gap, electrons in TiO₂ will jump from the valence band to the conduction band, and the electron (e–) and electric hole (h+) pairs will form on the surface of the photocatalyst. The negative electrons and oxygen will combine to form O₂ –. radical ions, whereas the positive electric holes and water will generate hydroxyl radicals OH.. Since both products are unstable chemical entities.  The following reactions show the photo catalysis of the titanium di oxide treated fabric.

Application of silver nano particals for self cleaning :

                 Application of silver nano particles on textile surface is working as a phenomenon of lotus leaf which does not absorb the water as well as do not adhere the organic matter on its surface Similarly silver nano particals can be applied on the surface of textile. These particals canbe applied on the surface with plymer film (polyglycidyle methycrylate) which ensures that silver nano particals are get fixed on textile surface. These silver particals can be applied to silk, cotton, viscose etc. but the concept is same as that of lotus plant. The nano particals are applied on to the surface of textile by using simple finishing method pad-dry-cure. The following diagram shows applied nano particles on the textile surface

                              

Lotus leaf and a SEM image of its surface                       silver nano particals applied on textile material

Working of textile surface treated with silver nano particals :

      A highly water-repellant coating made of silver nanoparticles that can be used to produce suits and other clothing items that offer superior resistance to dirt as well as water and require much less cleaning than conventional fabrics. Nano-Tex improves the water-repellent property of fabrics by creating nanowhiskers, which are made of hydrocarbons and have about 1/1000 of the size of a typical cotton fiber. They are added to the fabric to create a peach fuzz effect without lowering the strength of cotton.

        Untreated surface                       Treated surface                                                               

                           

       The diagram shows that the two textile surface one which is treated with silver nano particals and other is not treated with silver nano particals.

The untreated surface having dust particals, when water droplates rolls over it do not get washed off because dust particals are adhere by textile surface. While treated textile surface do not adheres the dust particals hnce when water particals rolls over it dust get washed off. In fig. (b) Silver nano particals treated surface shows self cleaning property.

 Self cleaning textile in sport wear:

       Muddy sports kit, the bane of parents with active children, may be heading for the laundry. Scientists have produced a coating that could make shirts and football shorts self cleaning means which can either washed easily or do not allow to develop the bacteria’s on fiber surface as shown in figure .   The "self-cleaning" process makes fabrics repel water, resist stains and even kill off the bacteria that grow in sweat and make clothes smell. As a result, kit could be worn repeatedly between washes, the distinctive aroma of kit bags gone for ever – even performance on the field could be enhanced.

       Scientists working for the US Air Force have already produced T-shirts and underwear that can be worn for weeks at a time without washing, and the technology has now been licensed to a London company, Alexium, to develop for civilian applications

Limitations of self cleaning fabric:

       Breakthroughs in nanotechnology have made self-cleaning fabrics both practical and economical. With commercial production making the technology readily available to the masses, will washing machines and laundry detergent become obsolete? 

       There are several factors limiting how quickly current self cleaning fabric would be able to break down organic compounds. Sunlight is the best source of light for activating the self-cleaning process. A ketchup-stained shirt would have to be left outside in the sun for at least a day in order to remove the stain. However, for military persons or hikers, who are outside in the sun for long periods of time without the time or means to clean their clothes, self-cleaning fabric would be ideal. It's also important to note that the newly developed method for producing self-cleaning fabric has only been developed for cotton.  Further research would be required to test ways of applying titanium dioxide nanofilms to other textiles.

Problems with Self-Cleaning Fabric :

            The main reasons that self-cleaning fabrics require a lot of time to break down stains is because titanium dioxide is very inefficient at using energy from sunlight. The titanium dioxide serves as a catalyst for the break down of dirt molecules by providing electrons that oxidize oxygen molecules in the surrounding air. The electrons are freed from the titanium dioxide via the photoelectric effect. But because of titanium dioxide's high band gap energy, only high energy blue and UV light photons have enough energy to excite electrons to the conduction band. High energy blue and UV light only make up 3% of the solar spectrum, so titanium dioxide can only use a very small portion of the sun's energy to break down stains.
             Excitation of electrons to the conduction band is only the beginning of the cleaning process. These electrons must then react with oxygen atoms, which then react with the dirt particles. All of these reactions are limited by access to and the amount of freed electrons in the titanium dioxide. So for a large stain, a lot of light energy is needed before the fabric can fully break it down.

CONCLUSION

       The realization of self-cleaning properties on textile surfaces by using the nanotechnology includes a vast potential for the development of new materials or new products and applications for known materials. The opening of new application fields for textiles will lead to a new growth stage. For the growing market of technical textiles a further increase in production volume, sales and application fields can be expected by successful transfer of the self cleaning effect on textile materials. Structure based soil and water-repellent properties lead to an efficient use of materials and are therefore in agreement with the principles of sustainable development. The economic significance of the self cleaning   textiles can be outlined as follows:

1.   Ease of maintenance and environmental protection because of reduced cleaning efforts

2.   Time, material, energy reduction and consequently cost-efficiency during       production

3.   Reduced requirements regarding static properties by weight reduction at construction textiles

4.   Fuel savings through weight reduction in the field of transport

5.   Improved ageing behavior by extended surface purity effect.

REFRENCES

1. A new dimension to textiles/garments - Pradeep Kaira,
2. http://www.snaimpex.com/a_new_dimension_to_textiles.htm.
3. Hatch KL: Making a claim that a garment is UV protective.
4. AATCC Review,3, (2003),23-26.
5. Development of New Textile Processing Technology Based on Nano-
6. Technology-Nano-Scale Coating Made Possible on Monofilament                                                                                                                                                                                                                           Surface,                                
7. http://www.toray.com/news/fiber/nr041022.html
8. Selected Applications of Nanotechnology in Textiles, Y. W. H. Wong, etal..AUTEX Research Journal, Vol. 6, No 1, March 2006.