Wool from Sheep

 

Wool Fibre from Sheep

The Merino is an economically influential breed of sheep prized for its wool. Merinos are regarded as having some of the finest and softest wool of any sheep.

Following are the common breeds of Merino Sheep:

• Booroola Merino
• Delaine Merino
• Fonthill Merino
• German Mutton Merino
• Medium-Wool Merino
• Merinolandschaf
• Poll Merino
• South African Merino

The sheep was one of the first animals to be domesticated over 8000 years ago. Sheep were usually seen with humans on the move because they could be herded easily and they provided humans with their basic needs – food, clothing, and shelter. For the early Stone Age hunter, the fleece served as a tunic or sleeveless shirt, worn just as it came from the animal’s back. The first weavers used reeds, threads or grass to make baskets and nets. By Neolithic times, a simple loom had been invented and the art of weaving was well on its way.

As early as 4000 B.C. wool clothing was worn in Babylon, Babylon means “Land of Wool”. Fifteen hundred years later, nations of the East began to trade wool, thus making it one of the early items of international trade.

From Fiber to Fabric

Once each year the sheep can give us the coats off their backs. The wool is removed with shears similar to those a barber uses. This process of shearing does not hurt the sheep. In about five minutes the wool is shorn from the sheep in a single piece, called the fleece. The fleece is carefully rolled and tied for bagging. Most shearing is done between February and June, just before lambing. Most shearers move from ranch to ranch. A good shearer can shear from 80 to 125 head of sheep a day. A highly trained expert can shear up to 225 head of sheep in one day.

Fleeces are rolled up and tied, then packed into sacks. These sacks hold between 20 and 35 fleeces (of 4-12 lbs each) and weigh an average of 200 to 400 pounds. From this step, the processing of the wool begins.

The wool is washed by moving it gently with rakes through a series of tubs containing a soap and water solution heated to about 140°F. It is then rinsed. During the washing, process wool loses 30 to 70 percent of its weight when natural grease (lanolin) and soil are removed. After washing, the wool is passed through a series of squeeze rollers and finally dried. The purified lanolin by-product is used in face creams, soaps, and other ointments.

Wool can be dyed at several stages in the processing – after it has been washed, in which case it is called stock-dyed wool; after spinning, when it is referred to as yarn-dyed wool; or after weaving or knitting when it is called piece-dyed. Because wool is a porous fiber, color tints are absorbed right into its core to give rich and lasting hues.

Carding blends wool fibers remove vegetable matter and straighten the fibers so they will lie in the same direction. This is done by passing the wool through a system of rollers covered with wire teeth which form the fibers into a thin web. If the wool fibers are to be made into fabric, the web is divided into strips which are rubbed together gently to form the “roving” or “sliver.”

Spinning draws strips of roving through small rollers, applying a twist that gives the resulting yarn strength and size. The difference in size, twist, and ply give the woven fabric different texture which is part of fabric design.

Woven fabrics are made on looms by interlacing at least two sets of yarn at right angles to each other (put another way, weaving involves two pieces of yarn running in different directions, one up and down, and one across). The lengthwise (or up and down) yarn is the warp. Yarn running crosswise in the loom is called weft or filling. As warp yarn passes through the loom it is raised and lowered by a wire eyelet through which it is threaded. To form the woven fabric, filling yarn is pushed through openings created in the warp.

As the fabric comes from the loom it has a loose texture. Fulling or milling by the application of moisture, heat, and friction causes the material to shrink and thus tighten the weave. The fabric can then be napped by a metal brushing process, or sheared to give a smooth, uniform appearance

Processes in the Wool Industry

BY-PRODUCT – something produced in addition to the main product. In the case of sheep, wool and meat are the major products. Other products that come from the sheep are lanolin for cosmetics; hides and skins for leather goods; gelatin for photographic film; animal fat for soap and special glues and medicines – to name only a few.

CARDING – blending and straightening out the wool fibers.

DYEING – to impart color to something.

FLEECE – coat or wool covering a sheep.

FULLING – applying moisture, heat, and friction to wool fabric to cause the weave to tighten. 

History of Manmade Fiber

 

Manmade Fiber at a glance 

A useful filament was not produced until the last part of the 19th century when Swann and de Chardonnet extruded a solution of cellulose nitrate (collodion) through small holes (spinnerets). These pioneer manmade fibers were replaced by rayon fibers which were spun from an alkaline cellulose xanthate solution (viscose), which were in turn supplemented by cellulose acetate and many synthetic fibers.

History  of Manmade Fibers

Year	Description
1664	English naturalist Robert Hooke first suggested the possibility of producing a fiber that would be “if not fully as good, nay better” than silk.
1855	The first patent for “artificial silk” was granted in England in 1855 to a Swiss chemist named Audemars. He dissolved the fibrous inner bark of a mulberry tree, chemically modifying it to produce cellulose. He formed threads by dipping needles into this solution and drawing them out – but it never occurred to him to emulate the silkworm by extruding the cellulosic liquid through a small hole.
Early 1880’s	Sir Joseph W. Swan, an English chemist and electrician, inspired by Thomas Edison’s new incandescent electric lamp. He experimented with forcing a liquid similar to Audemars solution through fine holes into a coagulating bath. His fibers worked like carbon filament, and they found early use in Edison’s invention. In 1885 he exhibited in London some fabrics crocheted by his wife from his new fiber, but he focused on electric lamps and abandoned work on textiles.
1889	French chemist Count Hilaire deChardonnet displayed fabric “artificial silk” in the Paris Exhibition.
1890	Count Hilarie deChardonnet built the first commercial rayon plant at Besancon, France and secured his fame as the father of the rayon industry.
1893	Arthur D. Little of Boston, invented cellulosic acetate and developed it as a film.
1910	The American Viscose Company, formed by Samuel Courtaulds and Co., Ltd., began production of rayon.
By 1910	Camille and Henry Dreyfus were making acetate motion picture film and toilet articles in Basel, Switzerland. During World War I, they built a plant in England to produce cellulose acetate dope for airplane wings and other commercial products. Upon entering the War, the United States government invited the Dreyfus brothers to build a plant in Maryland to make the product for American warplanes.
1924	First commercial textile uses for acetate in fiber form were developed by the Celanese Company.
Mid-1920’s	Textile manufacturers could purchase the rayon and acetate fibers for half the price of raw silk, and so began manufactured fibers’ gradual conquest of the American fiber market. This modest start in the 1920’s grew to nearly 70% of the national market for fiber by the last decade of the century.
1931	American chemist Wallace Carothers reported on research carried out in the laboratories of the DuPont Company on “giant” molecules called polymers. He focused his work on a fiber referred to simply as “66,” a number derived from its molecular structure. Nylon, the “miracle fiber,” was born. The Chemical Heritage Foundation is currently featuring an exhibit on the history of nylon.
1938	Paul Schlack of the I.G. Farben Company in Germany, polymerized caprolactam and created a different form of the polymer, identified simply as nylon “6.” Nylon’s advent created a revolution in the fiber industry. Rayon and acetate had been derived from plant cellulose, but nylon was synthesized completely from petrochemicals. It established the basis for the ensuing discovery of an entirely new world of manufactured fibers.
1939	Vinyon was first produced in 1939 by American Viscose, now FMC Corporation.
1939	Vinyon was first produced in 1939 by American Viscose, now FMC Corporation.
1939	DuPont began commercial production of nylon. The first experimental testing used nylon as sewing thread, in parachute fabric, and in women’s hosiery. Nylon stockings were shown in February 1939 at the San Francisco Exposition and the most exciting fashion innovation of the age was underway. American women had only a sampling of the beauty and durability of their first pairs of nylon hose when their romance with the new fabric was cut short when the United States entered World War II.
1941	The War Production Board allocated all production of nylon for military use. During the War, nylon replaced Asian silk in parachutes. It also found use in tires, tents, ropes, ponchos, and other military supplies, and even was used in the production of a high-grade paper for U.S. currency. At the outset of the War, cotton was king of fibers, accounting for more than 80% of all fibers used. Manufactured and wool fibers shared the remaining 20%.
August 1945	By the end of the war cotton stood at 75% of the fiber market. Manufactured fibers had risen to 15%. After the war, GI’s came home, families were reunited, industrial America gathered its peacetime forces, and economic growth surged. The conversion of nylon production to civilian uses started and when the first small quantities of postwar nylon stockings were advertised, thousands of frenzied women lined up at New York department stores to buy. In the immediate post-war period, most nylon production was used to satisfy this enormous pent-up demand for hosiery.
Late 1940’s	Nylon was also being used in carpeting and automobile upholstery. At the same time, three new generic manufactured fibers started production. Dow Badische Company (today, BASF Corporation) introduced metalized fibers; Union Carbide Corporation developed modacrylic fiber; and Hercules, Inc. added olefin fiber.
By the 1950’s	The industry was supplying more than 20% of the fiber needs of textile mills. A new fiber, “acrylic,” was added to the list of generic names, as DuPont began production of this wool-like product. Meanwhile, polyester, first examined as part of the Wallace Carothers early research, was attracting new interest at the Calico Printers Association in Great Britain. There, J. T. Dickson and J. R. Whinfield produced a polyester fiber by condensation polymerization of ethylene glycol with terephthalic acid. DuPont subsequently acquired the patent rights for the United States and Imperial Chemical Industries for the rest of the world. A host of other producers soon joined in.
Summer 1952	“Wash-and-wear” was coined to describe a new blend of cotton and acrylic. The term eventually was applied to a wide variety of manufactured fiber blends. Commercial production of polyester fiber transformed the wash-and-wear novelty into a revolution in textile product performance.
1953	Polyester’s commercialization was accompanied by the introduction of triacetate. The majority of the 20th century’s basic manufactured fibers now had been discovered, and the industry’s engineers turned to refining their chemical and physical properties to extend their use across the American economy.
Early 1960’s	Manufactured fiber accounted for nearly 30% of American textile mill consumption.
By 1965	The manufactured fiber industry was providing over 40% of the nation’s fiber needs.
1960’s	Manufactured fiber production accelerated as it was spurred on by continuous fiber innovation. The revolutionary new fibers were modified to offer greater comfort, provide flame resistance, reduce clinging, release soil, achieve greater whiteness, special dullness or luster, easier dyeability, and better blending qualities. New fiber shapes and thicknesses were introduced to meet special needs. Spandex, a stretchable fiber; aramid, a high-temperature-resistant polyamide; and para-aramid, with outstanding strength-to-weight properties, were introduced into the marketplace. Consumers bought more and more clothing made of polyester. Clotheslines were replaced by electric dryers, and the “wash and wear” garments they dried emerged wrinkle free. Ironing began to shrink away from the daily list of household chores. Fabrics became more durable and color more permanent. New dyeing effects were being achieved and shape-retaining knits offered new comfort and style.
Late 1960’s	One dramatic new set of uses for manufactured fibers came with the establishment of the U.S. space program. The industry provided special fiber for uses ranging from clothing for the astronauts to spaceship nose cones. When Neil Armstrong took “One small step for man, one giant leap for mankind,” on the moon on July 20, 1969, his lunar space suit included multi-layers of nylon and aramid fabrics. The flag he planted was made of nylon. Today, the exhaust nozzles of the two large booster rockets that lift the space shuttle into orbit contain 30,000 pounds of carbonized rayon. Carbon fiber composites are used in as structural components in the latest commercial aircraft, adding strength and lowering weight and fuel costs.
Early 1970’s	A wave of consumer protection demands emerged, most notably one for a mandated Federal flammability standard for children’s sleepwear. The manufactured fiber industry spent $20 million on flammability research and development in 1972 and 1973 and manufactured fiber fabrics became predominant in this market. Flammability standards were also issued for carpet and other products. In the U.S. carpet market, 99% of all surface fibers are now manufactured fibers.
Late 1973	When the U.S. was struck by a severe energy crisis, the manufactured fiber industry reduced the energy required to produce a pound of fiber by 26%. By then, the industry was using but 1% of the Nation’s petroleum supply to provide two-thirds of all fibers used by American textile mills. Innovation is the hallmark of the manufactured fiber industry. Fibers more numerous and diverse than any found in nature, are now routinely created in the industry’s laboratories.
1990’s	Nylon variants, polyester, and olefin are used to produce carpets that easily can be rinsed clean even 24 hours after they’ve been stained. Stretchable spandex and machine-washable, silk-like polyesters occupy solid places in the U.S. apparel market. The finest microfibers are remaking the world of fashion.
Late 1990’s	Increased environmental awareness further encourages manufacturers to become green manufacturers, reducing energy consumption, cleaning up or eliminating air and water pollution, and recycling production supplies and finding environmentally safe uses for fabric waste.
2001	Cargill Dow introduces the first completely renewable fiber made of plant dextrose from cornstarch, polylactide (PLA) and markets it as InGeo. It competes in durability with the petrochemicals and can be disposed of safely as completely biodegradable end-use products. PLA has application in interior design materials and carpeting, apparel, packaging, and industry.
Today	Fiber research and improvement continues. As they always have, manufactured fibers continue to mean, “life made better.”

Man-made /Artificial fibers

 

Man-made /Artificial fiber

Man-made fibers are fibers in which either the basic chemical units have been formed by chemical synthesis followed by fiber formation or the polymers from natural sources have been dissolved and regenerated after passage through a spinneret to form fibers. This fiber came to success when the researchers obtained a product by condensation of molecules presenting two reactive aminic groups with molecules characterized by two carboxylic reactive groups.

The fiber came to success when the researchers obtained a product (polymerized amide, from which the name polyamide) by condensation of molecules presenting two reactive aminic groups (hexamethylenediamine) with molecules characterized by two carboxylic reactive groups (adipic acid). In order to be differentiated from other polymers belonging to the same chemical class, this polymer was marked with the acronym 6.6 which indicates the number of carbon atoms (that is 6) in the two molecules forming the repetitive polymer unit.

Polyester fiber

This is the most important man-made fiber, with a production of 22 million tons in 2003 (58% continuous filament/42% staple fiber), which since some years overcame cotton production. The number of plants installed in the world is estimated already now at more than 500.

Another aspect of considerable importance under the geographic-economic point of view is the fact that 75% of the production is located in Asia. Polyester wrung the record of most produced synthetic fiber out from the polyamide fiber already in 1972 when it reached a share of 65% in the synthetic fiber market. Its success is due to its particular characteristics, to its versatility in the various application sectors and to the relatively low raw materials and production costs.

Acrylic fiber

The production of this fiber is estimated at 2,6 million tons (2003) and West Europe is still today the area with the highest production (30%).

This fiber found its main use in the traditional wool sectors and is being produced in practice only in form of discontinuous or staple fiber.

It shows negligible production increases and consequently, its share in the man-made fiber market fell from 20% in 1970 to 9% in 2002.

Polypropylene fiber

This is the last-born man-made fiber and, as it is used also in near sectors (as in the plastic industry), its importance in the textile sector was not always adequately monitored. In fact, even excluding such sectors, the production for merely textile uses (carpeting, clothing, technical uses) can be estimated at 3,0 million tons and shows steady growth rates. The most significant producer areas are Europe and USA.

Other man-made fibers

Within the group of fibers with high-tech performance, the elastane fiber (spandex) stands out for its characteristics of elongation and elasticity: its consumption in 2001 has been estimated at 160.000 tons.

Aramid fibers are appreciated for their mechanical and fireproof properties (consumption estimate in 2001: 33.000 tons), while carbon fibers are used in composite materials for hi-tech applications estimated consumption in 2001: 13.000 tons).

Polyester Fibers

 

Polyester Fiber

Polyesters are those fibers containing at least 85% of a polymeric ester of a substituted aromatic carboxylic acid including but not restricted to terephthalic acid and f-hydroxybenzoic acid.

Polyesters are those fibers containing at least 85% of a polymeric ester of a substituted aromatic carboxylic acid including but not restricted to terephthalic acid and f-hydroxybenzoic acid. The major polyester in commerce is polyethylene terephthalate, an ester formed by step-growth polymerization of terephthalic acid and the diethylene glycol.

POLYETHYLENE TEREPHTHALATE

Polyethylene terephthalate polyester is the leading man-made fiber in production volume and owes its popularity to its versatility alone or as a blended fiber in textile structures. When the term “polyester” is used, it refers to this generic type. It is used extensively in woven and knitted apparel, home furnishings, and industrial applications. Modification of the molecular structure of the fiber through texturizing and or chemical finishing extends its usefulness in various applications.

POLY-l,4-CYCLOHEXYLENEDIMETHYLENE TEREPHTHALATE

The cyclo hexylene group within this fiber provides additional rigidity to the molecular chains, but the packing of adjacent polymer chains may be more difficult due to the complex structure, As a result, the fiber has a lower tenacity than polyethylene terephthalate.

Poly-p-ethyleneoxybenzoate

The properties of this fiber were not sufficiently different from other
polyesters to achieve reasonable market penetration, and the fiber has been
discontinued.

Modified Terephthalate Polyesters

Poor dyeabi1ity and the moderate flammabi1ity of polyester have resulted in the formulation of modified terephthalate esters to improve the dyeability and the flame retardant properties of the fiber.

Polyamide Fiber

 

Polyamide Fiber

The polyamide fibers include the nylons and the Aramid fibers. Both fiber types are formed from polymers of long-chain polyamides.

Synthetic man-made account for the largest part of the raw material used in manufacturing nonwoven bonded fabrics. In this group of synthetic nonwoven bonded fabrics, polyamide fibers are the not only the oldest ones used in production, they also increase the serviceability of the product. This improved quality is of importance for various purposes, e.g.:

• where nonwoven bonded fabrics are subjected to frequent folding, as in the case of paper reinforced with synthetic fibers
• where exceptional resistance to abrasion is required, as is the case with needled floor coverings

The polyamide fibers include the nylons and the aramid fibers. Both fiber types are formed from polymers of long-chain polyamides. The nylons generally are tough, strong, durable fibers useful in a wide range of textile applications.

The fully aromatic aramid fibers have high-temperature resistance, exceptionally high strength, and dimensional stability.

The number of carbon atoms in each monomer or comonomer unit is commonly designated for the nylons. Therefore the nylon with six carbon atoms in the repeating unit would be nylon 6 and the nylon with 6 carbons in each of the monomer units would be nylon 6,6.

A group of fully synthetic fiber materials, which are manufactured in a melt spinning process. Characteristics: highly elastic, tear and abrasion-free, low humidity absorption capability, fast drying, no loss of solidity in a wet condition, crease-free, rot and seawater proof.

Application: fine stockings (for example nylon), outer sporting and motorcycle garments (for example Tactel, Cordura), female underclothes (for example Perlon), parachutes.

In the middle of the 1930s nylon, a polyamide was brought to the market by the American chemical company DuPont. It was the first material fully obtained from basic chemical elements. A sure sign for the economic breakthrough of synthetic fine chemical fibers was the triumph of nylon stockings at the beginning of the 1950s.

The textile industry concentrated above all on space research and during the years of the Cold War on equipment for soldiers. At the end of this, the industry had to look for new sales markets.

During the last ten years, a series of new synthetic textiles and techniques for processing textiles have been developed, in which war and space technology has been matched with innovative novelties from design laboratories. A milestone: the active breathing microfibers (such as Gore-Tex).

Type of Polyamides

The two main types of fiber are polyamide 6, usually known as Perlon, and polyamide 6.6, which is generally called Nylon to distinguish it from Perlon. The number or numbers after the word ‘polyamide’ indicate how many carbon atoms there are in each molecule making up the polyamide. The fact that there is only one number in one instance and two in the other shows that polyamide 6 contains only one basic module and polyamide 6.6 contains two, with six carbon atoms in each molecule.

Nylon 6 and 6.6
Polyamide 6 is made from caprolactam and polyamide 6.6 from hexamethylenediamine and adipic acid. For fiber production, the resulting polyamide has to have the capacity to be spun into filaments, i.e.

·         it must have the capacity to be melted without decomposing and to be forced through a jet.

·         the molten mass must be such that the filaments that are still ductile when formed do not break during cooling. Certain conditions must be met, one of them being a minimum prescribed length for the macromolecule.

These nylon polymers form strong, tough, and durable fibers useful in a wide variety of textile applications. The major differences in the fibers are that nylon 6,6 dyes lighter, has a higher melting point, and a slightly harsher hand than nylon 6

Aramid Fibers

The aramid polyamide fibers are formed from a long chain of synthetic polyamides in which at least 85% of the amide linkages are attached to aromatic rings. These essentially fully aromatic polyamides are characteristically high melting and have excellent property retention at high temperatures and excellent durability. They are unaffected by moisture and most chemicals and are inherently flame retardant. The fibers have high strength and can be used in a number of unique high-strength applications.

Common trade names for aramid fibers include Nomex and Kevlar (DuPont). Aramid fibers are extremely strong and heat resistant. Fabrics from the aramids have a high luster with a fair hand and adequate draping properties.

The fibers are light yellow unless bleached and exhibit moderate moisture absorption characteristics. The fibers recover readily from stretching and bending deformation and are extremely abrasion resistant. They do tend to pill due to the high strength of the fiber.

Other Polyamides

Several other polyamides have been introduced for use as fibers in specialty applications where certain combinations of properties are desired. The major specialty nylons include Qiana, nylon 4, nylon 11, nylon 6,10, and biconstituent nylon-polyester.

Manufacturing of Polyamide Filaments

The molten mass is forced through the holes in the spinneret by pressure pumps and metering pumps, after which it is pulled off in the form of filaments. They cool rapidly in the (air) blasting chamber and are then either baled or wound onto bobbins at a constant speed.

The macromolecules are still randomly distributed in the filaments, which is why they are stretched so that molecules are more longitudinally oriented.

Once they have this orientation, the filaments take on their characteristic physical properties and can be cut to the lengths needed to make the fibers. Then the filaments of staples are prepared to ensure that they retain their processing properties.

Application of Textile as Hygiene Products

 

Application of Textile as Hygiene Products 

Healthcare/Hygiene Products: These products are related to daily uses in hospitals and health care industries. These include bedding, clothing, surgical gowns, cloths wipes and so on. All fibers are used in this product must be non-toxic, non-allergenic, noncarcinogenic and must be able to be sterilised without imparting any change in their physical or chemical characteristics. The range of this products available is vast but typically they are used in the operating room theatre or on the hospital ward for the hygiene, care and safety of staff and patients. Production of hygiene and medical textiles is on increase, as is the variety of applications in this important sector. By 2005, hygiene and medical textiles valued at US$4.1 billion, almost 12% of the global technical textiles market.

Surgical Gowns:  Surgical gowns used to help prevent the gown wearer from contaminating vulnerable patients, such as those with weakened immune systems.  Gowns are one part of an infection-control strategy. Disposable nonwoven surgical gowns have been adopted to prevent the release of pollutant particles into the air which is a probable source of contamination to the patient. Surgical gowns are composed of nonwoven fabrics and polyethylene films in weight range of 30–45 g/m2.

Surgical Masks:  Surgical mask is intended to be worn by health professionals during surgery and during nursing to catch the bacteria shed in liquid droplets and aerosols from the wearer’s mouth and nose. Simple surgical masks protect wearers from being splashed in the mouth with body fluids, and prevent transmission of body fluids from the wearer to others, e.g. the patient. Surgical masks are popularly worn by the general public in East Asian countries to reduce the chance of spreading airborne diseases.

Surgical Drapes, Cloths:  These are also called scurbs. Scrubs are the sanitary clothing worn by surgeons, nurses, physicians and other workers involved in patient care in hospitals. Originally designed for use by surgeons and other operating room personnel. In many operating rooms, it is forbidden to wear any exposed clothing, such as a t-shirt, beneath scrubs. As scrubs are designed to promote a clean environment, the wearing of outside clothing is thought to introduce unwanted pathogens.

Surgical Cap:  Surgical cap an accompaniment to the surgical gown (below) which covers the head, and sometimes facial hair, of members of the surgical team; the object is to avoid contamination of the wound. The surgical cap is in place to prevent hazardous bodily fluids from splashing onto the doctor or nurse’s hair and head. They are also used to prevent hair from affecting the vision of the medical professionals. On the other hand of the spectrum, loose hair or even other contaminants like hair products or dandruff is dangerous to the patient. 

Diaper:  A diaper or a nappy is a type of underwear that allows the wearer to defecate or urinate without the use of a toilet, by absorbing or containing waste products to prevent soiling of outer clothing or the external environment. Diapers are made of cloth or synthetic disposable materials. Cloth diapers are composed of layers of fabric such as cotton, hemp, bamboo, microfiber, or even plastic fibers such as PLA or PU. Disposable diapers contain absorbent chemicals and are thrown away after use. Cloth diapers are reusable and can be made from natural fibers, synthetic materials, or a combination of both 

Medical textiles are located at the interfaces between technical disciplines and life sciences. Prospects for medical textiles are rather better, especially for nonwoven materials and disposable medical textiles used in surgical rooms. Combination of textile and its application in medical sciences has been proof that the painful days of patients and surgeons converting into the comfortable days.

Implantable Medical Textiles:

 

Implantable Medical Textiles

Implantable products are biomaterials which are used for wound closure (e.g. suture), replacement surgery (e.g. vascular graft, artificial ligaments etc.) Another important category of implantable products is soft-tissue implants.

These are flexible strong materials commonly used to replace tendons, ligaments and cartilage in both reconstructive and corrective surgery. Suspensors and reinforcing surgical meshes are used in plastic surgery for repairing defects of the abdominal wall.

Artificial Ligament:

Artificial ligament is used for joining two joints of a human body. It is a one kind of medical device. In adult skeleton there are 400 joints which are joined by the ligaments. The ligament is a short band of tough, flexible, fibrous connective tissue that connects two bones. Artificial Ligament is a multilayered or tubular woven structure having intra-particular region, at least one bend region and end regions.

Example: DACRON, LEEDS-KEIO ARTIFICIAL LIGAMENT

A prosthetic ligament should have following characteristics:

1. Extensive tough
2. Stiffness to match the compliance of normal ACL (Anterior Cruciate Ligament)
3. Durability to withstand against high tensile load for million of cycles without wear
4. Perfectly tolerable to host

Artificial skin:

The characteristics of human skin are heavily dependent on the hydration of the tissue – in simple terms, the water content. This also changes its interaction with textiles. Artificial skin is a substitute for human skin produced in the laboratory, typically used to treat severe burns. The skin’s basic functions, which include protecting against moisture and infection and regulating body heat.

Skin is primarily made of two layers: the uppermost layer, the epidermis, which serves as a barrier against the environment; and the dermis. The dermis also contains the proteins collagen and elastin, which help give the skin its mechanical structure and flexibility. Artificial skins work because they close wounds, which prevents bacterial infection and water loss and helps the damaged skin to heal. Artificial skins mimic either the epidermis or dermis, or both epidermis and dermis in a “full-thickness” skin replacement.

For example, one commonly used artificial skin, Integra, consists of an “epidermis” made of silicone and prevents bacterial infection and water loss, and a “dermis” based on bovine collagen and glycosaminoglycan.

Some Manufacturer of Artificial Skin:

1. Human Bio Sciences Incorporated (India)
2. Delhi Dressing and Surgicals (India)
3. Intercytex Ltd. (UK) 

Vascular Graft:

Vascular grafts are used for the blood vessels, including the arteries and veins. Synthetic materials have been employed in vascular graft design for a variety of reasons, mainly due to the ease and flexibility of tailoring their mechanical properties. One such example is ePTFE, a porous polymer with an electronegative luminal surface that is not degradable. However, only 45% of standard ePTFE grafts are patent as femoropopliteal bypass grafts at 5 years, while autologous vein grafts display a 60–80% patency.

Textiles produced in the form of a tube have been used as implants to repair the damaged arteries and veins. Typical diameters of such tubes are 6mm, 8mm, and 10mm. Vascular grafts are either made from polyester or PTFE fibre, woven or knitted. The knitted tube has the advantage of good tissue encapsulation, but less satisfactory in preventing blood leakage, because of the loose structure of the knitted materials. On the other hand, the woven tube is good at preventing blood leakage, but is not so good for tissue growth, due to its relatively tight structure.