Textiles in Automotive Engineering | Application of Textiles in Transportation

Transportation or automobile industry is the largest user of technical textiles with about 20 kg in each of the 45 million or so cars made every year world-wide.Textiles provide a means of decoration and a warm soft touch to surfaces that are necessary features for human well being and comfort, but textiles are also essential components of the more functional parts of all road vehicles, trains, aircraft and sea vessels. Textiles in transportation are classed as technical because of the very high performance specifications and special properties required. Seat coverings, for example, are not easily removable for cleaning and indeed in automobiles they are fixed in place and must last the lifetime of the car without ever being put in a washing machine. In trains, aircraft and passenger vessels they are exposed to much more rigorous use than domestic furniture. In addition they have to withstand much higher exposure to daylight and damaging ultraviolet radiation (UV) and because they are for public use they must satisfy stringent safety requirements such as flame retardant.

Application of Textiles in a Car or Vehicle

• Car seat fabrics
• Tyres
• Seat belts
• Door panel
• Headliner
• Sunvisor
• Parecel Self
• ABC Pillars
• Bootliners
• Air filter
• Airbags
• Heater hoses
• Battery separators
• Brake and clutch linings
• Gaskets
• Part of the suspension
• Gears
• Dash board
• Carpet
• Head board lining
• Part of the car body
• Crash Helmets

The most familiar technical textile in transportation is car seat fabric which is amongst the largest in volume and is growing annually in the developing world of the Pacific rim, Eastern Europe and South America Car seat fabric requires considerable technical input to produce both the aesthetic and also the very demanding durability requirements.The processes developed for car seat fabric and the technical specifications provide some indication of the requirements for seat materials in other transport applications.

Tyre:

Prime Fibers Used in Tire Making
Nylon 6,6
Nylon 6
Polyester
Rayon

 

Airbag
An airbag is a vehicle safety device. It is an occupant restraint system consisting of a flexible fabric envelope or cushion designed to inflate rapidly during an automobile collision. Its purpose is to cushion occupants during a crash and provide protection to their bodies when they strike interior objects such as the steering wheel or a window.

Air bags have been used in automobiles since the 1980s.The trend gathered momentum in the early and mid 1990s, during which major car manufacturers repeatedly boasted putting airbags in their new models for the driver. Beginning in 1998, driver-and passenger-side air bags have been required by law for all new cars in the United States.

When a car comes to a sudden stop, such as crash, the momentum of passengers depends on the speed of the car and the mass of the passenger. Because of the short time involved, the force required to stop the passengers can be very large. The goal of any supplemental restraint system is to help stop the passenger while doing as little damage to him or her as possible.

Typical Collision Force
Example:
A car travelling at 30 mph (48.6 km/h=13.5m/s) collided with another car travelling at the same speed from the opposite direction. Both cars stopped in 0.25 sec. Suppose the car weighs 2000kg.

Then the deceleration of the car is
(0-27.0)/0.25 = -108 m/s2
 

and the colliding force is
2000x108 = 216,000 N
 

If the passenger weighs 75kg, the inertia force on him/her is
75x108/2 =4,050 N

What happens to the air bag at a collision

The air bag system ignitesa solid propellant, which burns extremely rapidly to create a large volume of gas to inflate the bag. The bag then literally burstsfrom its storage site at up to 200 mph (322 kph).The gas quickly dissipates through tiny holes in the bag a second later, thus deflatingthe airbag.

The Airbag Mechanism
The bag itself is made of a thin, nylon fabric, which is folded into the steering wheel or dashboard or, more recently, the seat or door. The sensor is the device that tells the bag to inflate. Inflation happens when there is a collision force equal to running into a brick wall at 10 to 15 miles per hour (16 to 24 km per hour). A mechanical switch is flipped when there is a mass shift that closes an electrical contact, telling the sensors that a crash has occurred. The sensors receive information from an accelerometerbuilt into a microchip. The air bag's inflation systemreacts sodium azide (NaN3) with potassium nitrate (KNO3) to produce nitrogen gas. Hot blasts of the nitrogeninflate the airbag.

Generation of Nitrogen Gas
The main chemical component in the airbag is sodium azide (NaN3) together with KNO3and SiO2. In the gas generator a mixture of NaN3, KNO3, and SiO2is ignited through an electrical impulse and causes a relatively slow kind of detonation, called a "deflagration", that liberates a pre-calculated volume of nitrogen gas, which fills the air bag.

2 NaN3---> 2Na + 3N2
 

The sodium by-product of reaction 1, and the potassium nitrate generate additional nitrogen for the airbag in a second reaction
10 Na + 2 KNO3---> K20 + 5 Na2O + N2
 

These two reactions leave potassium oxide and sodium oxide to react with the third compound of the mixture, silicon dioxide, forming alkaline silicate ("glass"), which is a safe and stable, non-ignitable compound.
K2O + Na2O + SiO2---> alkaline silicate (glass)

Seat Belt 

Seat belts are multiple layer woven narrow fabrics in twill or satin construction from high tenacity polyester yarns, typically 320 ends of 1100dtex or 260 ends of 1670 dtex yarn. These constructions allow maximum yarn packing within a given area for maximum strength and the trend is to use coarser yarns for better abrasion resistance. For comfort they need to be softer and more flexible along the length, but rigidity is required across the width to enable them to slide easily between
buckles and to retract smoothly into housings. Edges need to be scuff resistant but not unpleasantly hard and the fabric must be resistant to microorganisms. Nylon was used in some early seat belts but because of its better UV degradation resistance, polyester is now used almost exclusively worldwide.


The use of seat belts is to prevent the forward movement of the wearer in a controlled manner during sudden deceleration of the vehicle.
Cars:lap and chest
Planes:lap
Racing cars:lap and shoulders

Seat fabrics 

Textile fabrics and leather are the main materials used for seat covering in the automotive industry. Fabrics have the advantage of being inexpensive and diversity for patterning. Car seat fabric design has been one of the main influences on new car buyers

The two most important technical factors governing the selection of fibres for car seat cover are the resistance to light (UV radiation) and abrasion. 

 

Fibres used include:

Nylon 6 and nylon 6,6 –rapid sunlight degradation Acrylic –low abrasion resistanceWool –expensivePolyester–good on both accounts, and occupying 90% of the market

Fabric types
Flat woven (200-400 g/m2)
Flat woven velvet (360-450 g/m2)
Warp knit tricot (piled surface, 160-340 g/m2)
Raschel double needle bar knitted (pile surface, 280-370 g/m2)
Circular knits (piled surface, 160-230 g/m2)

Manufacturing Processes
Manufacturing processesProcessing routes for the production of woven and knitted fabrics can be summarised as follows:

• Yarn, texturise, package dye, warp/beam, weave, scour, stenter/finish, laminate, cut/sew, fit to seat;
• Yarn, texturise, warp/beam, warp knit, brush/crop, stenter preset, scour/dye, stenter, brush, stenter finish, laminate, cut/sew, fit to seat;
• Yarn, texturise, package dye, cone, weft knit, shear, scour, stenter/finish, laminate, cut/sew, fit to seat;
• Yarn, texturise, package dye, cone, 3D knit, heat stabilise, fit to seat.

Composition of Car Seat Fabric
A typical car seat cover is composed of three laminated layers. The face layer is either woven or knitted

The middle layer, made from polyurethane, provides the softness of the seat cover and makes the seat cover crease free

 The backing layer, a warp knitted fabric from nylon or polyester, acts as a “slide aid” between the seat cover and the seat structure

New seat technology
The traditional way of seat making, involving cutting and sewing panels into a cover that is then pulled over the squab (seat back) and cushion (seat bottom), is time consuming and cumbersome in the modern age. Efforts have been made to develop alternative quicker and more efficient methods. Three-dimensional knitting is an option but this has had only limited usage so far.

Future development in automotive textiles
Car production was expected to remain generally static up to 2005 in the developed world, but is likely to expand considerably in the developing nations. Globally there are excellent opportunities for the multinational OEMs and their suppliers, especially those with the imagination and will to innovate new products and design features that will make car journeys more comfortable, safe and pleasant. The following paragraphs discuss the possibilities that are believed to exist. The largest growth area in automotive textiles will be in air bags as they become standard equipment in more cars. Development is needed to improve their safe functioning, however, legislation may spur on such developments in a similar way to the USA. The latest system is an air bag that deploys outwards from the occupant’s seat belt. Possible new applications for textiles within the car include the dashboard, sunvisor and seat pockets and circular knitted fabrics may be especially suited to these outlets.

Reference:

Handbook of Technical textiles (A R Horrocks and S C Anand)

Textiles in Automotive Engineering (Fung and Hardcastle)

Class Lecture Technical Textiles

Textiles in Automotive Engineering | Application of Textiles in Transportation

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Transportation or automobile industry is the largest user of technical textiles with about 20 kg in each of the 45 million or so cars made every year world-wide.Textiles provide a means of decoration and a warm soft touch to surfaces that are necessary features for human well being and comfort, but textiles are also essential components of the more functional parts of all road vehicles, trains, aircraft and sea vessels. Textiles in transportation are classed as technical because of the very high performance specifications and special properties required. Seat coverings, for example, are not easily removable for cleaning and indeed in automobiles they are fixed in place and must last the lifetime of the car without ever being put in a washing machine. In trains, aircraft and passenger vessels they are exposed to much more rigorous use than domestic furniture. In addition they have to withstand much higher exposure to daylight and damaging ultraviolet radiation (UV) and because they are for public use they must satisfy stringent safety requirements such as flame retardant.

Application of Textiles in a Car or Vehicle

• Car seat fabrics
• Tyres
• Seat belts
• Door panel
• Headliner
• Sunvisor
• Parecel Self
• ABC Pillars
• Bootliners
• Air filter
• Airbags
• Heater hoses
• Battery separators
• Brake and clutch linings
• Gaskets
• Part of the suspension
• Gears
• Dash board
• Carpet
• Head board lining
• Part of the car body
• Crash Helmets

The most familiar technical textile in transportation is car seat fabric which is amongst the largest in volume and is growing annually in the developing world of the Pacific rim, Eastern Europe and South America Car seat fabric requires considerable technical input to produce both the aesthetic and also the very demanding durability requirements.The processes developed for car seat fabric and the technical specifications provide some indication of the requirements for seat materials in other transport applications.

Tyre:

Prime Fibers Used in Tire Making
Nylon 6,6
Nylon 6
Polyester
Rayon

 

Airbag
An airbag is a vehicle safety device. It is an occupant restraint system consisting of a flexible fabric envelope or cushion designed to inflate rapidly during an automobile collision. Its purpose is to cushion occupants during a crash and provide protection to their bodies when they strike interior objects such as the steering wheel or a window.

Air bags have been used in automobiles since the 1980s.The trend gathered momentum in the early and mid 1990s, during which major car manufacturers repeatedly boasted putting airbags in their new models for the driver. Beginning in 1998, driver-and passenger-side air bags have been required by law for all new cars in the United States.

When a car comes to a sudden stop, such as crash, the momentum of passengers depends on the speed of the car and the mass of the passenger. Because of the short time involved, the force required to stop the passengers can be very large. The goal of any supplemental restraint system is to help stop the passenger while doing as little damage to him or her as possible.

Typical Collision Force
Example:
A car travelling at 30 mph (48.6 km/h=13.5m/s) collided with another car travelling at the same speed from the opposite direction. Both cars stopped in 0.25 sec. Suppose the car weighs 2000kg.

Then the deceleration of the car is
(0-27.0)/0.25 = -108 m/s2
 

and the colliding force is
2000x108 = 216,000 N
 

If the passenger weighs 75kg, the inertia force on him/her is
75x108/2 =4,050 N

What happens to the air bag at a collision

The air bag system ignitesa solid propellant, which burns extremely rapidly to create a large volume of gas to inflate the bag. The bag then literally burstsfrom its storage site at up to 200 mph (322 kph).The gas quickly dissipates through tiny holes in the bag a second later, thus deflatingthe airbag.

The Airbag Mechanism
The bag itself is made of a thin, nylon fabric, which is folded into the steering wheel or dashboard or, more recently, the seat or door. The sensor is the device that tells the bag to inflate. Inflation happens when there is a collision force equal to running into a brick wall at 10 to 15 miles per hour (16 to 24 km per hour). A mechanical switch is flipped when there is a mass shift that closes an electrical contact, telling the sensors that a crash has occurred. The sensors receive information from an accelerometerbuilt into a microchip. The air bag's inflation systemreacts sodium azide (NaN3) with potassium nitrate (KNO3) to produce nitrogen gas. Hot blasts of the nitrogeninflate the airbag.

Generation of Nitrogen Gas
The main chemical component in the airbag is sodium azide (NaN3) together with KNO3and SiO2. In the gas generator a mixture of NaN3, KNO3, and SiO2is ignited through an electrical impulse and causes a relatively slow kind of detonation, called a "deflagration", that liberates a pre-calculated volume of nitrogen gas, which fills the air bag.

2 NaN3---> 2Na + 3N2
 

The sodium by-product of reaction 1, and the potassium nitrate generate additional nitrogen for the airbag in a second reaction
10 Na + 2 KNO3---> K20 + 5 Na2O + N2
 

These two reactions leave potassium oxide and sodium oxide to react with the third compound of the mixture, silicon dioxide, forming alkaline silicate ("glass"), which is a safe and stable, non-ignitable compound.
K2O + Na2O + SiO2---> alkaline silicate (glass)

Seat Belt 

Seat belts are multiple layer woven narrow fabrics in twill or satin construction from high tenacity polyester yarns, typically 320 ends of 1100dtex or 260 ends of 1670 dtex yarn. These constructions allow maximum yarn packing within a given area for maximum strength and the trend is to use coarser yarns for better abrasion resistance. For comfort they need to be softer and more flexible along the length, but rigidity is required across the width to enable them to slide easily between
buckles and to retract smoothly into housings. Edges need to be scuff resistant but not unpleasantly hard and the fabric must be resistant to microorganisms. Nylon was used in some early seat belts but because of its better UV degradation resistance, polyester is now used almost exclusively worldwide.


The use of seat belts is to prevent the forward movement of the wearer in a controlled manner during sudden deceleration of the vehicle.
Cars:lap and chest
Planes:lap
Racing cars:lap and shoulders

Seat fabrics 

Textile fabrics and leather are the main materials used for seat covering in the automotive industry. Fabrics have the advantage of being inexpensive and diversity for patterning. Car seat fabric design has been one of the main influences on new car buyers

The two most important technical factors governing the selection of fibres for car seat cover are the resistance to light (UV radiation) and abrasion. 

 

Fibres used include:

Nylon 6 and nylon 6,6 –rapid sunlight degradation Acrylic –low abrasion resistanceWool –expensivePolyester–good on both accounts, and occupying 90% of the market

Fabric types
Flat woven (200-400 g/m2)
Flat woven velvet (360-450 g/m2)
Warp knit tricot (piled surface, 160-340 g/m2)
Raschel double needle bar knitted (pile surface, 280-370 g/m2)
Circular knits (piled surface, 160-230 g/m2)

Manufacturing Processes
Manufacturing processesProcessing routes for the production of woven and knitted fabrics can be summarised as follows:

• Yarn, texturise, package dye, warp/beam, weave, scour, stenter/finish, laminate, cut/sew, fit to seat;
• Yarn, texturise, warp/beam, warp knit, brush/crop, stenter preset, scour/dye, stenter, brush, stenter finish, laminate, cut/sew, fit to seat;
• Yarn, texturise, package dye, cone, weft knit, shear, scour, stenter/finish, laminate, cut/sew, fit to seat;
• Yarn, texturise, package dye, cone, 3D knit, heat stabilise, fit to seat.

Composition of Car Seat Fabric
A typical car seat cover is composed of three laminated layers. The face layer is either woven or knitted

The middle layer, made from polyurethane, provides the softness of the seat cover and makes the seat cover crease free

 The backing layer, a warp knitted fabric from nylon or polyester, acts as a “slide aid” between the seat cover and the seat structure

New seat technology
The traditional way of seat making, involving cutting and sewing panels into a cover that is then pulled over the squab (seat back) and cushion (seat bottom), is time consuming and cumbersome in the modern age. Efforts have been made to develop alternative quicker and more efficient methods. Three-dimensional knitting is an option but this has had only limited usage so far.

Future development in automotive textiles
Car production was expected to remain generally static up to 2005 in the developed world, but is likely to expand considerably in the developing nations. Globally there are excellent opportunities for the multinational OEMs and their suppliers, especially those with the imagination and will to innovate new products and design features that will make car journeys more comfortable, safe and pleasant. The following paragraphs discuss the possibilities that are believed to exist. The largest growth area in automotive textiles will be in air bags as they become standard equipment in more cars. Development is needed to improve their safe functioning, however, legislation may spur on such developments in a similar way to the USA. The latest system is an air bag that deploys outwards from the occupant’s seat belt. Possible new applications for textiles within the car include the dashboard, sunvisor and seat pockets and circular knitted fabrics may be especially suited to these outlets.

Reference:

Handbook of Technical textiles (A R Horrocks and S C Anand)

Textiles in Automotive Engineering (Fung and Hardcastle)

Class Lecture Technical Textiles

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Medical Textile | Use of Technical Textiles in Health and Hygiene Products

Medical Textile a general term which describes a textile structure which has been designed and produced for use in any of a variety of medical applications, including implantable applications.

An important and growing part of the textile industry is medical, hygiene and health sector. The extent of growth is due to the development and improvement of knowledge in both textile as well as medical sector.

The engineering approach to develop textile products that will be suitable for medical and surgical application should possess a combination of the following properties

e.g. strength, flexibility, and sometimes moisture and air permeability.

Materials include natural fibre, mono-filament as well as multifilament yarns. 

 

The number of application is huge and diverse, ranging from a single thread suture to the complex composite structures for bone replacement, and from the simple cleaning wipe to advanced barrier fabrics used in operation rooms. Thus the textiles used in medical and surgical purposes can be classified as follows;

1.    Nonplantable materials-Wound dressing, bandages, plasters etc.
2.    Extracorporeal devices- artificial kidney, liver, and lung
3.    Implantable materials-suture, vascular grafts, artificial ligaments, artificial joints, etc.
4.    Healthcare/hygine products-bedding, clothing, surgical gowns, cloths, wipes etc.

The majority of the healthcare products are disposable while some are reused. The medical product based on textiles is around $ 76 billion in the year 2000.

Fibres used:

Fibres used in medical application may be classified as follows;

1. According to source of origin:

i.    Natural- Cotton and silk most widely used
ii.    Synthetic- Viscose, polyester, polyamide, polytetrafluoroethylene (PTFE), polypropylene, carbon, glass, and so on.


2. According to biological resistance:
  

Biodegradable- Fibres which are absorbed by the body within 2-3 months time after implantation and include Cotton, Viscose rayon, polyamide, polyurathene, collagen, and alginate, polycaprolactone, polypropiolactone.

 Non biodegradable-Fibres that are absorbed by the body slowly and take more than six months time to degrade are considered as non biodegradable. Non-biodegradable fibres and include polyester (e.g. Dacron), polypropylene, PTFE and carbon.

Fibre used in medical textiles must full fill the following criterion

•  the fibres must be nontoxic
• must be non-allergenic
• must be non-carcinogenic
• must be able to be sterilised without impairing any change in their physical or chemical characteristics.
• where necessary biodegradable
• where necessary non biodegradable

Traditionally cotton, silk and viscose have long been used for medical and surgical purposes. One such area of application is wound care, where moisture and liquid exude from the wound is absorbed by the fibrous structure to promote healing in relatively dry conditions.

However upon healing small fibrous elements protruding from the wound dressing are usually trapped in the pores of the newly formed tissues which make their removal distressing to the patients.

Research show that wound under moist condition would in fact heal better and faster, which would also remove the problem of fibres being trapped in the healing wound.

The concept of moist healing has since been responsible for the development of many fibres which have vastly improved wound management techniques and patient care.
A variety of polymers such as collagen, alginate, chitin, chitosan have been used to be essential materials for modern wound dressings.

Collagen which has been obtained from bovine skin is used to produce biodegradable fibres used as suture which is as strong as silk.

The fibre can also be converted to transparent gel like film structure used as contact lens which has very good oxygen permeability.

Alginate (obtained from sea weeds) and chitin (obtained from shrimp shells) are widely used for treatment of wound healing.  Chitin nonwoven fabric is used as artificial skin.


A. Nonplantable materials:
These materials are used for external application on the body and may or may not make contact with skin.

The following table illustrates a range of materials used as non-implantable madical textiles.

(i) Wound care products– The purpose of these products are to provide protection against infection, absorb blood and exudates, promote healing and in some instances apply medication into the wound.

Common wound dressings are composite materials consisting of an absorbent layer held between a wound contact layer and a flexible base material.

The absorbent pad absorbs blood or liquids and provides cushioning effect to protect the wound.

The wound contact layer should prevent adherence of the dressing to the wound and be easily removed without disturbing new tissue growth. The base materials are normally coated with acrylic adhesive to provide the means by which the dressing is applied to the wound.

The use of collagen, alginate, and chitin fibres contribute significantly to the healing process.

When alginate fiber is used as wound contact layer the interaction between the alginate and the exuding wound creates a sodium alginate gel which is hydrophilic and permeable to oxygen and impermeable to the bacteria and contribute to the formation pf new tissue.

(ii) Gauze: It is an open weave absorbent fabric, when coated with paraffin wax is used for the treatment of burns and scalds. In surgical application gauze serves as an absorbent material.

(iii) Lint:  It is a plain weave cotton fabric that is used as protective dressing for first aid and mild burn application.
(iv) Wadding:  It is a highly absorbent material that is covered with a nonwoven fabric to prevent wound adhesion or fibre loss.

(v) Bandages: Bandages are designed to perform a whole variety of specific functions depending upon the final medical requirements.

They can be 

         -woven,
         -knitted,
         -or nonwoven and are
         -either elastic or nonelastic.

the most common application of bandages is to hold the dressing in place over wound.

These are light weight knitted or woven fabrics made of cotton or viscose –scoured, bleached and sterilized.

Elasticized yarns are incorporated to the structure to impart support and conforming characteristics. 

Knitted bandages are produced either in weft knitting machine to produce tubular fabric of varying diameter or in warp knitting machine.

Woven light support fabrics are used in the management of sprains or strains and the elasticated properties are obtained by weaving crepe yarns having a very high twist.

Similar properties can also be obtained by weaving fabric from two warp beam one in low tension and the other in high tension.

Compression bandages are used for the treatment and prevention of deep vein thrombosis, leg ulceration, and varicose veins and are designed to exert a required amount of compression on leg when applied at a constant tension.

Compression bandages are classified by the amount of compression they can exert at the ankle and include extra –high, high, moderate and light compression can be either woven and contain cotton and elastomeric yarns or warp and weft knitted in both tubular or fully fashioned forms.

Orthopedic cushion bandages are used under plaster casts and compression bandages to provide padding and prevent discomfort.

Non-woven orthopedic cushion bandages are produced from polyurethane foam, polyester, or polypropylene fibres and contain blends of natural or synthetic fibres.

Non woven bandages are lightly needle punched to maintain bulk and loft. 
      

B. Extra-corporeal devices:

These are mechanical organs that are used for blood purification and include the artificial kidney (dialyser), the artificial liver, mechanical lung. The function and performances of these devices benefit from fibre and textile.

The function of artificial kidney is achieved by circulating the blood through a membrane, which may be either a flat sheet or a bundle of hollow regenerated cellulose fibres in the form of cellophane that retain the unwanted waste materials.

Multilayred filters composed of numerous layers of needle punched fabrics with varying densities may also be used and are designed to remove the waste materials rapidly and efficiently.

The artificial liver utilizes hollow fibres or membranes similar to those used in artificial kidney to perform high permeability to gases but low permeability to liquids and function in the same manner as in the natural lung allowing oxygen to come into contact with the patient’s blood.



C. Implantable materials:
These materials are used in effecting repair to the body whether it be wound closure (Sutures) or replacement surgery (Vascular grafts, artificial ligaments etc.). Table 15.3 show the list of implantable materials.

Bio-compatibility is of prime importance if the textile materials are to be accepted by the body and four key factors will determine how the body reacts to the implant, these are as follows

1.    The most important factor is porosity which determines the rate at which human tissue will grow and encapsulate the implant.
2.    Small circular fibres are better encapsulated with human tissue than larger fibres with irregular cross section.
3.    Toxic substances must not be released by the fibre polymer, and the fibres should be free from surface contaminations such as lubricants and sizing agents.
4.    The properties of the polymer will influence the success of the implantation in terms of its biodegradability.

Polyamide is the most reactive material losing its overall strength after only two years as a result of biodegradation. PTFE is the least reactive with polypropylene and polyester is in between



SUTURES:

Sutures are used for closure of wounds. They are either monofilament or multifilament. Nonbiodegradable sutures are used for closure of external wounds and after healing of the wounds, they are removed. Biodegradable sutures are used for closure of internal wounds; these sutures are gradually absorbed by the body.

SOFT TISSUE IMPLANTS:
Textile materials are used for constructive and corrective surgery of tendons ligaments and cartilage.

Artificial tendons are woven or braided porous meshes or tapes surrounded by a silicone sheath. During implantation the natural tendon can be looped through artificial tendon and then sutured to itself in order to connect the muscle to the bone.

Textile materials used for artificial knee ligaments should not only possess biocompatibility properties but must also have the physical characteristics needed for such a demanding application.

Artificial ligaments are braided composite materials containing carbon and polyester filaments.

There are two types of cartilages found in the human body e.g-(i) Hayline cartilages- these are dense and hard and used where rigidity is needed. (ii) Elastic cartilage- are soft

Low density polyethylene is used to replace facial, nose, ear and throat cartilage.

Carbon fibre reinforced composites structures are used for hay-line cartilage. 



Orthopedics implants:
Orthopedic implants are those materials that are used for hard tissue applications to replace bones and joints. Fiber-reinforced composite materials may be designed with the required high structural strength and bio-compatibility properties needed for these applications and are now replacing metal implants for artificial joints and bones.

To promote tissue in-growths around the implant a non-woven
mat made from graphite and PTFE (e.g. Teflon) is used, which acts as an interface between the implant and the adjacent hard and soft tissue. Composite structures composed of poly (d, l-lactide urethane) and reinforced with polyglycolic acid have excellent physical properties.

The composite can be formed into shape during surgery at a temperature of 60 °C and is used for both hard and soft tissue applications. Braided surgical cables composed of steel filaments ranging from 13–130mm are used to stabilize fractured bones or to secure orthopedic implants to the skeleton.

Cardiovascular implants:
Vascular grafts are used in surgery to replace damaged thick arteries or veins 6mm, 8mm, or 1 cm in diameter. Commercially available vascular grafts are produced from polyester (e.g. Dacron) or PTFE (e.g. Teflon) with either woven or knitted structures.

Straight or branched grafts are possible by using either weft or warp knitting technology. Polyester vascular grafts can be heat set into a crimped configuration that improves the handling characteristics.

During implantation the surgeon can bend and adjust the length of the graft, which, owing to the crimp, allows the graft to retain its circular cross-section.

Knitted vascular grafts have a porous structure which allows the graft to become encapsulated with new tissue but the porosity can be disadvantageous since blood leakage (hemorrhage) can occur through the interstices directly after implantation.

This effect can be reduced by using woven grafts but the lower porosity of these grafts hinders tissue ingrowths; in addition, woven grafts are also generally stiffer than the knitted equivalents.

In an attempt to reduce the risk of hemorrhage, knitted grafts have been developed with internal and external velour surfaces in order to fill the interstices of the graft. Another method is to seal or preclot the graft with the patient’s blood during implantation.

This is a time-consuming process and its effectiveness is dependent upon the patient’s blood chemistry and the skill of the surgeon.

Presealed grafts have zero porosity when implanted but become porous allowing tissue ingrowths to occur. The graft is impregnated with either collagen or gelatin that, after a period of 14 days, degrades to allow tissue encapsulation. Artificial blood vessels with an inner diameter of 1.5 mm have been developed using porous PTFE tubes. The tube consists of an inner layer of collagen and heparin to prevent blood clot formation and an outer biocompatible layer of collagen with the tube itself providing strength.

Artificial heart valves, which are caged ball valves with metal struts, are
covered with polyester (e.g. Dacron) fabrics in order to provide a means of suturing the valve to the surrounding tissue.



D. Healthcare/hygiene products:
Healthcare and hygiene products are an important sector in the field of medicine
and surgery. The range of products available is vast but typically they are used either in the operating theatre or on the hospital ward for the hygiene, care, and safety of staff and patients. Table 15.4 illustrates the range of products used in this category and includes the fibre materials used and the method of manufacture.



Alginate Wound Dressings
Alginates  are naturally occurring substances formed only in brown sea weed. Among the many species of brown sea weed the most widely used are the species of

1. Laminaria (British isles,France,N.America & Japan).
2. Macocystics (USA)&
3. Asco phylum (British isles)

Alginate is a copolymer of a two epimer units.

(a)    α –L guluronic acid (G)

• Mainly instems.
• Binding Calcium ions more firmly.
• Fibre swelling only slightly.
• Forming a stronger gel

(b)  β-D Mannuronic acid (M)

• Mainly in leaves.
• Binding Calcium ions Less firmly.
• Fibre swelling enormously.
• Forming a softer gel.

Likely combinations are – GG,MM,MG at various lengths and proportions.

Making of alginate fibres:

Sodium alginate solutions.(water soluble)
Extruding solution into a calcium chloride bath (ion exchange)
Calcium alginate filament (water ionsoluble)
Washiong.
Drafting.
Drying.
Crimping.
Cutting.

Alginate properties: The wide spread use of alginate fibres in the production of

High tech wound dressing:

• Sodium ion in wound exudates.
• Calcium ion in calcium alginate fibre.
• Fibre becoming partial sodium partial calcium.
• Water soluble sodium alginate fibers show small effect on ion exdchange.
• High M alginate fibres swells enormously at the result of the exchange.

Alginate Dressings:

• To prevent strike.
• To keep wound in a dry and clean condition.
• Gauze used as the main wound dressing material.

General Requirements for the High tech wound dressings:

• To remove excess exudates and toxic component.
• To maintain a high humidity at wound dressing interface.
• To allow gaseous exchange.
• To provide thermal insulation.
• To offer protection against secondary infection.
• To be free from particulate or toxic contaminants.
• To allow removal without trauma at dressing change.

Structure of alginate dressing:

• Primarily non woven pads of different sizes.
• Also considered for particular properties.
• Woven.
• Knitted
• Braided structures.

Problem of the non woven alginate dressing:

• High M alginate dressing lacking integrity when wetted.
• Difficult to remove as one piece.
• Warm saline solution used to wash away dressing.(This action may cause pain when damage new tissue or contaminant the wound)
• High G alginate better but less absorbent.

Reinforced dressings: Woven structures:

When dressing is wetted the filaments forms a woven web within the gel therefore making dressing easy to remove.
For absorbency thicker yarns used suitably high densities is used to maximize absorbency.
Zs contact layer thinner yarns is used to remove layer of alginate gel.

Braided structures:

• Useful for cavity wound.
• Braidede tubes.
• Braided tubes with alginate sliver as core

Knitted Structures:  Circular dressings.

Medical Textile | Use of Technical Textiles in Health and Hygiene Products

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Medical Textile a general term which describes a textile structure which has been designed and produced for use in any of a variety of medical applications, including implantable applications.

An important and growing part of the textile industry is medical, hygiene and health sector. The extent of growth is due to the development and improvement of knowledge in both textile as well as medical sector.

The engineering approach to develop textile products that will be suitable for medical and surgical application should possess a combination of the following properties

e.g. strength, flexibility, and sometimes moisture and air permeability.

Materials include natural fibre, mono-filament as well as multifilament yarns. 

 

The number of application is huge and diverse, ranging from a single thread suture to the complex composite structures for bone replacement, and from the simple cleaning wipe to advanced barrier fabrics used in operation rooms. Thus the textiles used in medical and surgical purposes can be classified as follows;

1.    Nonplantable materials-Wound dressing, bandages, plasters etc.
2.    Extracorporeal devices- artificial kidney, liver, and lung
3.    Implantable materials-suture, vascular grafts, artificial ligaments, artificial joints, etc.
4.    Healthcare/hygine products-bedding, clothing, surgical gowns, cloths, wipes etc.

The majority of the healthcare products are disposable while some are reused. The medical product based on textiles is around $ 76 billion in the year 2000.

Fibres used:

Fibres used in medical application may be classified as follows;

1. According to source of origin:

i.    Natural- Cotton and silk most widely used
ii.    Synthetic- Viscose, polyester, polyamide, polytetrafluoroethylene (PTFE), polypropylene, carbon, glass, and so on.


2. According to biological resistance:
  

Biodegradable- Fibres which are absorbed by the body within 2-3 months time after implantation and include Cotton, Viscose rayon, polyamide, polyurathene, collagen, and alginate, polycaprolactone, polypropiolactone.

 Non biodegradable-Fibres that are absorbed by the body slowly and take more than six months time to degrade are considered as non biodegradable. Non-biodegradable fibres and include polyester (e.g. Dacron), polypropylene, PTFE and carbon.

Fibre used in medical textiles must full fill the following criterion

•  the fibres must be nontoxic
• must be non-allergenic
• must be non-carcinogenic
• must be able to be sterilised without impairing any change in their physical or chemical characteristics.
• where necessary biodegradable
• where necessary non biodegradable

Traditionally cotton, silk and viscose have long been used for medical and surgical purposes. One such area of application is wound care, where moisture and liquid exude from the wound is absorbed by the fibrous structure to promote healing in relatively dry conditions.

However upon healing small fibrous elements protruding from the wound dressing are usually trapped in the pores of the newly formed tissues which make their removal distressing to the patients.

Research show that wound under moist condition would in fact heal better and faster, which would also remove the problem of fibres being trapped in the healing wound.

The concept of moist healing has since been responsible for the development of many fibres which have vastly improved wound management techniques and patient care.
A variety of polymers such as collagen, alginate, chitin, chitosan have been used to be essential materials for modern wound dressings.

Collagen which has been obtained from bovine skin is used to produce biodegradable fibres used as suture which is as strong as silk.

The fibre can also be converted to transparent gel like film structure used as contact lens which has very good oxygen permeability.

Alginate (obtained from sea weeds) and chitin (obtained from shrimp shells) are widely used for treatment of wound healing.  Chitin nonwoven fabric is used as artificial skin.


A. Nonplantable materials:
These materials are used for external application on the body and may or may not make contact with skin.

The following table illustrates a range of materials used as non-implantable madical textiles.

(i) Wound care products– The purpose of these products are to provide protection against infection, absorb blood and exudates, promote healing and in some instances apply medication into the wound.

Common wound dressings are composite materials consisting of an absorbent layer held between a wound contact layer and a flexible base material.

The absorbent pad absorbs blood or liquids and provides cushioning effect to protect the wound.

The wound contact layer should prevent adherence of the dressing to the wound and be easily removed without disturbing new tissue growth. The base materials are normally coated with acrylic adhesive to provide the means by which the dressing is applied to the wound.

The use of collagen, alginate, and chitin fibres contribute significantly to the healing process.

When alginate fiber is used as wound contact layer the interaction between the alginate and the exuding wound creates a sodium alginate gel which is hydrophilic and permeable to oxygen and impermeable to the bacteria and contribute to the formation pf new tissue.

(ii) Gauze: It is an open weave absorbent fabric, when coated with paraffin wax is used for the treatment of burns and scalds. In surgical application gauze serves as an absorbent material.

(iii) Lint:  It is a plain weave cotton fabric that is used as protective dressing for first aid and mild burn application.
(iv) Wadding:  It is a highly absorbent material that is covered with a nonwoven fabric to prevent wound adhesion or fibre loss.

(v) Bandages: Bandages are designed to perform a whole variety of specific functions depending upon the final medical requirements.

They can be 

         -woven,
         -knitted,
         -or nonwoven and are
         -either elastic or nonelastic.

the most common application of bandages is to hold the dressing in place over wound.

These are light weight knitted or woven fabrics made of cotton or viscose –scoured, bleached and sterilized.

Elasticized yarns are incorporated to the structure to impart support and conforming characteristics. 

Knitted bandages are produced either in weft knitting machine to produce tubular fabric of varying diameter or in warp knitting machine.

Woven light support fabrics are used in the management of sprains or strains and the elasticated properties are obtained by weaving crepe yarns having a very high twist.

Similar properties can also be obtained by weaving fabric from two warp beam one in low tension and the other in high tension.

Compression bandages are used for the treatment and prevention of deep vein thrombosis, leg ulceration, and varicose veins and are designed to exert a required amount of compression on leg when applied at a constant tension.

Compression bandages are classified by the amount of compression they can exert at the ankle and include extra –high, high, moderate and light compression can be either woven and contain cotton and elastomeric yarns or warp and weft knitted in both tubular or fully fashioned forms.

Orthopedic cushion bandages are used under plaster casts and compression bandages to provide padding and prevent discomfort.

Non-woven orthopedic cushion bandages are produced from polyurethane foam, polyester, or polypropylene fibres and contain blends of natural or synthetic fibres.

Non woven bandages are lightly needle punched to maintain bulk and loft. 
      

B. Extra-corporeal devices:

These are mechanical organs that are used for blood purification and include the artificial kidney (dialyser), the artificial liver, mechanical lung. The function and performances of these devices benefit from fibre and textile.

The function of artificial kidney is achieved by circulating the blood through a membrane, which may be either a flat sheet or a bundle of hollow regenerated cellulose fibres in the form of cellophane that retain the unwanted waste materials.

Multilayred filters composed of numerous layers of needle punched fabrics with varying densities may also be used and are designed to remove the waste materials rapidly and efficiently.

The artificial liver utilizes hollow fibres or membranes similar to those used in artificial kidney to perform high permeability to gases but low permeability to liquids and function in the same manner as in the natural lung allowing oxygen to come into contact with the patient’s blood.



C. Implantable materials:
These materials are used in effecting repair to the body whether it be wound closure (Sutures) or replacement surgery (Vascular grafts, artificial ligaments etc.). Table 15.3 show the list of implantable materials.

Bio-compatibility is of prime importance if the textile materials are to be accepted by the body and four key factors will determine how the body reacts to the implant, these are as follows

1.    The most important factor is porosity which determines the rate at which human tissue will grow and encapsulate the implant.
2.    Small circular fibres are better encapsulated with human tissue than larger fibres with irregular cross section.
3.    Toxic substances must not be released by the fibre polymer, and the fibres should be free from surface contaminations such as lubricants and sizing agents.
4.    The properties of the polymer will influence the success of the implantation in terms of its biodegradability.

Polyamide is the most reactive material losing its overall strength after only two years as a result of biodegradation. PTFE is the least reactive with polypropylene and polyester is in between



SUTURES:

Sutures are used for closure of wounds. They are either monofilament or multifilament. Nonbiodegradable sutures are used for closure of external wounds and after healing of the wounds, they are removed. Biodegradable sutures are used for closure of internal wounds; these sutures are gradually absorbed by the body.

SOFT TISSUE IMPLANTS:
Textile materials are used for constructive and corrective surgery of tendons ligaments and cartilage.

Artificial tendons are woven or braided porous meshes or tapes surrounded by a silicone sheath. During implantation the natural tendon can be looped through artificial tendon and then sutured to itself in order to connect the muscle to the bone.

Textile materials used for artificial knee ligaments should not only possess biocompatibility properties but must also have the physical characteristics needed for such a demanding application.

Artificial ligaments are braided composite materials containing carbon and polyester filaments.

There are two types of cartilages found in the human body e.g-(i) Hayline cartilages- these are dense and hard and used where rigidity is needed. (ii) Elastic cartilage- are soft

Low density polyethylene is used to replace facial, nose, ear and throat cartilage.

Carbon fibre reinforced composites structures are used for hay-line cartilage. 



Orthopedics implants:
Orthopedic implants are those materials that are used for hard tissue applications to replace bones and joints. Fiber-reinforced composite materials may be designed with the required high structural strength and bio-compatibility properties needed for these applications and are now replacing metal implants for artificial joints and bones.

To promote tissue in-growths around the implant a non-woven
mat made from graphite and PTFE (e.g. Teflon) is used, which acts as an interface between the implant and the adjacent hard and soft tissue. Composite structures composed of poly (d, l-lactide urethane) and reinforced with polyglycolic acid have excellent physical properties.

The composite can be formed into shape during surgery at a temperature of 60 °C and is used for both hard and soft tissue applications. Braided surgical cables composed of steel filaments ranging from 13–130mm are used to stabilize fractured bones or to secure orthopedic implants to the skeleton.

Cardiovascular implants:
Vascular grafts are used in surgery to replace damaged thick arteries or veins 6mm, 8mm, or 1 cm in diameter. Commercially available vascular grafts are produced from polyester (e.g. Dacron) or PTFE (e.g. Teflon) with either woven or knitted structures.

Straight or branched grafts are possible by using either weft or warp knitting technology. Polyester vascular grafts can be heat set into a crimped configuration that improves the handling characteristics.

During implantation the surgeon can bend and adjust the length of the graft, which, owing to the crimp, allows the graft to retain its circular cross-section.

Knitted vascular grafts have a porous structure which allows the graft to become encapsulated with new tissue but the porosity can be disadvantageous since blood leakage (hemorrhage) can occur through the interstices directly after implantation.

This effect can be reduced by using woven grafts but the lower porosity of these grafts hinders tissue ingrowths; in addition, woven grafts are also generally stiffer than the knitted equivalents.

In an attempt to reduce the risk of hemorrhage, knitted grafts have been developed with internal and external velour surfaces in order to fill the interstices of the graft. Another method is to seal or preclot the graft with the patient’s blood during implantation.

This is a time-consuming process and its effectiveness is dependent upon the patient’s blood chemistry and the skill of the surgeon.

Presealed grafts have zero porosity when implanted but become porous allowing tissue ingrowths to occur. The graft is impregnated with either collagen or gelatin that, after a period of 14 days, degrades to allow tissue encapsulation. Artificial blood vessels with an inner diameter of 1.5 mm have been developed using porous PTFE tubes. The tube consists of an inner layer of collagen and heparin to prevent blood clot formation and an outer biocompatible layer of collagen with the tube itself providing strength.

Artificial heart valves, which are caged ball valves with metal struts, are
covered with polyester (e.g. Dacron) fabrics in order to provide a means of suturing the valve to the surrounding tissue.



D. Healthcare/hygiene products:
Healthcare and hygiene products are an important sector in the field of medicine
and surgery. The range of products available is vast but typically they are used either in the operating theatre or on the hospital ward for the hygiene, care, and safety of staff and patients. Table 15.4 illustrates the range of products used in this category and includes the fibre materials used and the method of manufacture.



Alginate Wound Dressings
Alginates  are naturally occurring substances formed only in brown sea weed. Among the many species of brown sea weed the most widely used are the species of

1. Laminaria (British isles,France,N.America & Japan).
2. Macocystics (USA)&
3. Asco phylum (British isles)

Alginate is a copolymer of a two epimer units.

(a)    α –L guluronic acid (G)

• Mainly instems.
• Binding Calcium ions more firmly.
• Fibre swelling only slightly.
• Forming a stronger gel

(b)  β-D Mannuronic acid (M)

• Mainly in leaves.
• Binding Calcium ions Less firmly.
• Fibre swelling enormously.
• Forming a softer gel.

Likely combinations are – GG,MM,MG at various lengths and proportions.

Making of alginate fibres:

Sodium alginate solutions.(water soluble)
Extruding solution into a calcium chloride bath (ion exchange)
Calcium alginate filament (water ionsoluble)
Washiong.
Drafting.
Drying.
Crimping.
Cutting.

Alginate properties: The wide spread use of alginate fibres in the production of

High tech wound dressing:

• Sodium ion in wound exudates.
• Calcium ion in calcium alginate fibre.
• Fibre becoming partial sodium partial calcium.
• Water soluble sodium alginate fibers show small effect on ion exdchange.
• High M alginate fibres swells enormously at the result of the exchange.

Alginate Dressings:

• To prevent strike.
• To keep wound in a dry and clean condition.
• Gauze used as the main wound dressing material.

General Requirements for the High tech wound dressings:

• To remove excess exudates and toxic component.
• To maintain a high humidity at wound dressing interface.
• To allow gaseous exchange.
• To provide thermal insulation.
• To offer protection against secondary infection.
• To be free from particulate or toxic contaminants.
• To allow removal without trauma at dressing change.

Structure of alginate dressing:

• Primarily non woven pads of different sizes.
• Also considered for particular properties.
• Woven.
• Knitted
• Braided structures.

Problem of the non woven alginate dressing:

• High M alginate dressing lacking integrity when wetted.
• Difficult to remove as one piece.
• Warm saline solution used to wash away dressing.(This action may cause pain when damage new tissue or contaminant the wound)
• High G alginate better but less absorbent.

Reinforced dressings: Woven structures:

When dressing is wetted the filaments forms a woven web within the gel therefore making dressing easy to remove.
For absorbency thicker yarns used suitably high densities is used to maximize absorbency.
Zs contact layer thinner yarns is used to remove layer of alginate gel.

Braided structures:

• Useful for cavity wound.
• Braidede tubes.
• Braided tubes with alginate sliver as core

Knitted Structures:  Circular dressings.

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Technical Textile | Application and Milestone of Technical Textile

 Technical Textiles: Textile materials & products manufactured primarily for their technical & performance properties rather than their esthetic or decorative characteristics.

A technical textile is a textile product manufactured for non-aesthetic purposes, where function is the primary criterion. Now a days, it is a large and growing sector and supports a vast array of other industries.

According textile terms & definition- Industrial textiles is now more often viewed as a subgroup of wider category of technical textiles, referring specially to those textile products-

   -used in the course of manufacturing operations (e.g. filters, machine clothing, conveyor belts, abrasive substrates)

   -incorporated into other industrial products (e.g. electrical component & cable, flexible seals & acoustic & thermal insulation)

Technical textiles include textiles for automotive applications, medical textile (e.g. implants), geo textiles (e.g. reinforcement of embankments), agrotextiles (textiles for crop protection), industrial textile and protective clothing.

Best alternative name of technical textile-

• Industrial textile
• Performance textile
• Functional textile
• Engineering textile
• Hi-Tech textile

Product Group of Technical Textile:

Coated Textiles: Laminated textiles, tent/canvas materials, packaging, materials, sacking, tarpaulin fabric, covering & accessories, awning materials.

Composite Textiles: Reinforcement textiles, fiber reinforced composites, textile reinforced plastic & concrete components.

Bond Tech Textiles: Finishing technologies, including sealing, bonding and coating.

Application Area of Technical Textile:

Summery of technical textile applications:

• agrotech: agriculture, aquaculture, horticulture and forestry
• buildtech: building and construction
• clothtech: technical components of footwear and clothing
• geotech: geotextiles and civil engineering
• hometech: technical components of furniture, household textiles and
  floorcoverings
• indutech: filtration, conveying, cleaning and other industrial uses
• medtech: hygiene and medical
• mobiltech: automobiles, shipping, railways and aerospace
• oekotech: environmental protection
• packtech: packaging
• protech: personal and property protection
• sporttech: sport and leisure.

Transport textiles
Transport applications (cars, lorries, buses, trains, ships and aerospace) represent the largest single end-use area for technical textiles, accounting for some 20% of the total. Products range from carpeting and seating (regarded as technical rather than furnishing textiles because of the very stringent performance characteristics which they must fulfil), through tyre, belt and hose reinforcement, safety belts and air bags, to composite reinforcements for automotive bodies, civil and military aircraft bodies, wings and engine components, and many other uses. The fact that volume and value growth rates in these applications appear to be amongst the lowest of any application area needs to be interpreted with caution. The automotive industry (which accounts for a high proportion of all transport textiles) is certainly one of the most mature in market terms.

Industrial products and components
Set to rival transport textiles for first place by the year 2005 or shortly thereafterm(in volume terms, although not yet in value) is the diverse field of ‘industrial’ textiles. As now more precisely defined, this includes textiles used directly in industrial processes or incorporated into industrial products such as filters, conveyor belts and abrasive belts, as well as reinforcements for printed circuit boards, seals and gaskets, and other industrial equipment.

Growth rates are generally well above average in most areas. Because of the universal nature of many industrial requirements, some large companies have emerged with worldwide manufacturing and distribution to dominate markets for industrial textile products. They include companies such as Scapa (UK) and Albany (US), leaders in papermaking felts and related product areas, Milliken (USA) in textiles for rubber reinforcement and other industrial applications and BWF (Germany) in filtration.

Medical and hygiene textiles
The fact that medical and hygiene textiles are expected to show below average growth in volume but above average growth in value reflects the contrasting prospects of at least two main areas of the market. The largest use of textiles is for hygiene applications such as wipes, babies’ diapers (nappies) and adult sanitary and incontinence products.With the possible exception of the last of these, all are relatively mature markets whose volume growth has peaked. Manufacturers and converters now seek to develop them further by adding value to increasingly sophisticated products. Nonwovens dominate these applications which account for over 23% of all nonwoven use, the largest proportion of any of the 12 major markets for technical textiles.

The other side of the medical and hygiene market is a rather smaller but higher value market for medical and surgical products such as operating gowns and drapes, sterilisation packs, dressings, sutures and orthopaedic pads.At the highest value end of this segment are relatively tiny volumes of extremely sophisticated textiles for uses such as artificial ligaments, veins and arteries, skin replacement, hollow fibres for dialysis machines and so on. Growth prospects in these areas are potentially considerable although the proving and widespread introduction of new life-criticalproducts takes time.

Home textiles
Nonwovens and composite reinforcements, over 35% of the total weight of fibres and textiles in that category, lies in the field of household textiles and furnishing and especially in the use of loose fibres in wadding and fibrefill applications. Hollow fibres with excellent insulating properties are widely used in bedding and sleeping bags.Other types of fibre are increasingly being used to replace foams in furniture because of concern over the fire and health hazards posed by such materials. Woven fabrics are still used to a significant extent as carpet and furniture backings and in some smaller, more specialised areas such as curtain header tapes. However, nonwovens such as spunbondeds have made significant inroads into these larger markets while various drylaid and hydroentangled products are now widely used in household cleaning applications in place of traditional mops and dusters.

Clothing components
This category includes fibres, yarns and textiles used as technical components in the manufacture of clothing such as sewing threads, interlinings, waddings and insulation; it does not include the main outer and lining fabrics of garments, nor does it cover protective clothing. As for home textile applications, this is a major market for fibrefill products.Some of the latest and most sophisticated developments have seen the incorporation of temperature phase change materials into such insulation products to provide an additional degree of control and resistance to sudden extremes of temperature, be they hot or cold.

Agriculture, horticulture and fishing
Textiles have always been used extensively in the course of food production, most notably by the fishing industry in the form of nets, ropes and lines but also by agriculture and horticulture for a variety of covering, protection and containment applications. Although future volume growth rates appear to be relatively modest, this is partly due to the replacement of heavier weight traditional textiles, including jute and sisal sacking and twine, by lighter, longer lasting synthetic substitutes, especially polypropylene.Lightweight spunbonded fleeces are now used for shading, thermal insulation and weed suppression. Heavier nonwoven, knitted and woven constructions are employed for wind and hail protection. Capillary nonwoven matting is used in horticulture to distribute moisture to growing plants.

At sea, fish farming is a growing industry which uses specialised netting and other textile products. High performance fibres such as HMPE (High Modulus Poly Ethylene) are finding their way into the fishing industry for the manufacture of lightweight, ultra-strong lines and nets.

Construction – building and roofing
Textiles are employed in many ways in the construction of buildings, both permanent and temporary, dams, bridges, tunnels and roads.A closely related but distinct area of use is in geotextiles by the civil engineering sector. Temporary structures such as tents, marquees and awnings are some of the most
obvious and visible applications of textiles.Where these used to be exclusively made from proofed heavy cotton, a variety of lighter, stronger, rot-, sunlight- and weatherproof (also often fireproof) synthetic materials are now increasingly required.

A relatively new category of ‘architectural membrane’ is coming to prominence in the construction of semipermanent structures such as sports stadia, exhibition centres and other modern buildings. Nonwoven glass and polyester fabrics are already widely used in roofing applications while other textiles are used as breathable membranes to prevent moisture penetration of walls. Fibres and textiles also have a major role to play in building and equipment insulation.

Packaging and containment
Important uses of textiles include the manufacturing of bags and sacks, traditionally from cotton, flax and jute but increasingly from polypropylene. Tea and coffee bags use wet-laid nonwovens. Meats, vegetables and fruits are now frequently packed with a nonwoven insert to absorb liquids. Other fruits and vegetable products are supplied in knitted net packaging.

Sport and leisure
Even excluding the very considerable use of textiles in performance clothing and footwear, there are plenty of opportunities for the use of technical textiles throughout the sports and leisure market

Geotextiles in civil engineering
The geosynthetics market (comprising geotextiles, geogrids and geomembranes) is nevertheless expected to show some of the highest growth rates of any sector over the foreseeable future. The economic and environmental advantages of using textiles to reinforce, stabilise, separate, drain and filter are already well proven. Geotextiles allow the building of railway and road cuttings and embankments with steeper sides, reducing the land required and disturbance to the local environment. Nonwovens already account for up to 80% of geotextile applications. Current interest is in ‘composite’ fabrics which combine the advantages of different textile constructions such as woven, knitted, nonwoven and membrane materials.To supply the diversity of fabrics needed for the many different applications of geotextiles, leading specialist manufacturers are beginning to assemble a wide range of complementary capabilities by acquisition and other means.

Protective and safety clothing and textiles
Textiles for protective clothing and other related applications are another important growth area which has attracted attention and interest somewhat out of proportion to the size and value of the existing market. As in the case of sports textiles, a number of relatively high value and performance critical product areas have proved to be an ideal launch pad for a new generation of high performance fibres, most notably the aramids, but including many other speciality materials. The variety of protective functions that needs to be provided by different textile products is considerable and diverse. It includes protection against cuts, abrasion, ballistic and other types of severe impact including stab wounds and explosions, fire and extreme heat, hazardous dust and particles, nuclear, biological and chemical hazards, high voltages and static electricity, foul weather, extreme cold and poor visibility.

Ecological protection textiles
Technical textiles can contribute towards the environment in almost every sphere of their use, for example by reducing weight in transport and construction and thereby saving materials and energy. Improved recycleability is becoming an important issue not only for packaging but also for products such as cars.

Milestones of Technical textiles:

Natural Fibers: Cotton, flax, jute, hemp, sisal used for heavy canvas rope with limited resistance to water or fungal attack & poor flame retardency.

Viscose Rayon: Developed in 1910 used as reinforcement to tires and other rubber goods ( drive belt, conveyors and hoses) for their tenacity & modulus and heat resistance. Absorbency led to the use in paper making, non woven for cleaning & hygiene.

Nylon and Polyester: Nylon developed in 1939, high strength & abrasion resistance, good elasticity, excellent energy absorption used for climbing ropes, parachute fabrics, sails and tire cords.- Polyester developed in 1950 which is low cost & used as alternative to viscose & poly-amide in technical applications.

Technical Textile | Application and Milestone of Technical Textile

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 Technical Textiles: Textile materials & products manufactured primarily for their technical & performance properties rather than their esthetic or decorative characteristics.

A technical textile is a textile product manufactured for non-aesthetic purposes, where function is the primary criterion. Now a days, it is a large and growing sector and supports a vast array of other industries.

According textile terms & definition- Industrial textiles is now more often viewed as a subgroup of wider category of technical textiles, referring specially to those textile products-

   -used in the course of manufacturing operations (e.g. filters, machine clothing, conveyor belts, abrasive substrates)

   -incorporated into other industrial products (e.g. electrical component & cable, flexible seals & acoustic & thermal insulation)

Technical textiles include textiles for automotive applications, medical textile (e.g. implants), geo textiles (e.g. reinforcement of embankments), agrotextiles (textiles for crop protection), industrial textile and protective clothing.

Best alternative name of technical textile-

• Industrial textile
• Performance textile
• Functional textile
• Engineering textile
• Hi-Tech textile

Product Group of Technical Textile:

Coated Textiles: Laminated textiles, tent/canvas materials, packaging, materials, sacking, tarpaulin fabric, covering & accessories, awning materials.

Composite Textiles: Reinforcement textiles, fiber reinforced composites, textile reinforced plastic & concrete components.

Bond Tech Textiles: Finishing technologies, including sealing, bonding and coating.

Application Area of Technical Textile:

Summery of technical textile applications:

• agrotech: agriculture, aquaculture, horticulture and forestry
• buildtech: building and construction
• clothtech: technical components of footwear and clothing
• geotech: geotextiles and civil engineering
• hometech: technical components of furniture, household textiles and
  floorcoverings
• indutech: filtration, conveying, cleaning and other industrial uses
• medtech: hygiene and medical
• mobiltech: automobiles, shipping, railways and aerospace
• oekotech: environmental protection
• packtech: packaging
• protech: personal and property protection
• sporttech: sport and leisure.

Transport textiles
Transport applications (cars, lorries, buses, trains, ships and aerospace) represent the largest single end-use area for technical textiles, accounting for some 20% of the total. Products range from carpeting and seating (regarded as technical rather than furnishing textiles because of the very stringent performance characteristics which they must fulfil), through tyre, belt and hose reinforcement, safety belts and air bags, to composite reinforcements for automotive bodies, civil and military aircraft bodies, wings and engine components, and many other uses. The fact that volume and value growth rates in these applications appear to be amongst the lowest of any application area needs to be interpreted with caution. The automotive industry (which accounts for a high proportion of all transport textiles) is certainly one of the most mature in market terms.

Industrial products and components
Set to rival transport textiles for first place by the year 2005 or shortly thereafterm(in volume terms, although not yet in value) is the diverse field of ‘industrial’ textiles. As now more precisely defined, this includes textiles used directly in industrial processes or incorporated into industrial products such as filters, conveyor belts and abrasive belts, as well as reinforcements for printed circuit boards, seals and gaskets, and other industrial equipment.

Growth rates are generally well above average in most areas. Because of the universal nature of many industrial requirements, some large companies have emerged with worldwide manufacturing and distribution to dominate markets for industrial textile products. They include companies such as Scapa (UK) and Albany (US), leaders in papermaking felts and related product areas, Milliken (USA) in textiles for rubber reinforcement and other industrial applications and BWF (Germany) in filtration.

Medical and hygiene textiles
The fact that medical and hygiene textiles are expected to show below average growth in volume but above average growth in value reflects the contrasting prospects of at least two main areas of the market. The largest use of textiles is for hygiene applications such as wipes, babies’ diapers (nappies) and adult sanitary and incontinence products.With the possible exception of the last of these, all are relatively mature markets whose volume growth has peaked. Manufacturers and converters now seek to develop them further by adding value to increasingly sophisticated products. Nonwovens dominate these applications which account for over 23% of all nonwoven use, the largest proportion of any of the 12 major markets for technical textiles.

The other side of the medical and hygiene market is a rather smaller but higher value market for medical and surgical products such as operating gowns and drapes, sterilisation packs, dressings, sutures and orthopaedic pads.At the highest value end of this segment are relatively tiny volumes of extremely sophisticated textiles for uses such as artificial ligaments, veins and arteries, skin replacement, hollow fibres for dialysis machines and so on. Growth prospects in these areas are potentially considerable although the proving and widespread introduction of new life-criticalproducts takes time.

Home textiles
Nonwovens and composite reinforcements, over 35% of the total weight of fibres and textiles in that category, lies in the field of household textiles and furnishing and especially in the use of loose fibres in wadding and fibrefill applications. Hollow fibres with excellent insulating properties are widely used in bedding and sleeping bags.Other types of fibre are increasingly being used to replace foams in furniture because of concern over the fire and health hazards posed by such materials. Woven fabrics are still used to a significant extent as carpet and furniture backings and in some smaller, more specialised areas such as curtain header tapes. However, nonwovens such as spunbondeds have made significant inroads into these larger markets while various drylaid and hydroentangled products are now widely used in household cleaning applications in place of traditional mops and dusters.

Clothing components
This category includes fibres, yarns and textiles used as technical components in the manufacture of clothing such as sewing threads, interlinings, waddings and insulation; it does not include the main outer and lining fabrics of garments, nor does it cover protective clothing. As for home textile applications, this is a major market for fibrefill products.Some of the latest and most sophisticated developments have seen the incorporation of temperature phase change materials into such insulation products to provide an additional degree of control and resistance to sudden extremes of temperature, be they hot or cold.

Agriculture, horticulture and fishing
Textiles have always been used extensively in the course of food production, most notably by the fishing industry in the form of nets, ropes and lines but also by agriculture and horticulture for a variety of covering, protection and containment applications. Although future volume growth rates appear to be relatively modest, this is partly due to the replacement of heavier weight traditional textiles, including jute and sisal sacking and twine, by lighter, longer lasting synthetic substitutes, especially polypropylene.Lightweight spunbonded fleeces are now used for shading, thermal insulation and weed suppression. Heavier nonwoven, knitted and woven constructions are employed for wind and hail protection. Capillary nonwoven matting is used in horticulture to distribute moisture to growing plants.

At sea, fish farming is a growing industry which uses specialised netting and other textile products. High performance fibres such as HMPE (High Modulus Poly Ethylene) are finding their way into the fishing industry for the manufacture of lightweight, ultra-strong lines and nets.

Construction – building and roofing
Textiles are employed in many ways in the construction of buildings, both permanent and temporary, dams, bridges, tunnels and roads.A closely related but distinct area of use is in geotextiles by the civil engineering sector. Temporary structures such as tents, marquees and awnings are some of the most
obvious and visible applications of textiles.Where these used to be exclusively made from proofed heavy cotton, a variety of lighter, stronger, rot-, sunlight- and weatherproof (also often fireproof) synthetic materials are now increasingly required.

A relatively new category of ‘architectural membrane’ is coming to prominence in the construction of semipermanent structures such as sports stadia, exhibition centres and other modern buildings. Nonwoven glass and polyester fabrics are already widely used in roofing applications while other textiles are used as breathable membranes to prevent moisture penetration of walls. Fibres and textiles also have a major role to play in building and equipment insulation.

Packaging and containment
Important uses of textiles include the manufacturing of bags and sacks, traditionally from cotton, flax and jute but increasingly from polypropylene. Tea and coffee bags use wet-laid nonwovens. Meats, vegetables and fruits are now frequently packed with a nonwoven insert to absorb liquids. Other fruits and vegetable products are supplied in knitted net packaging.

Sport and leisure
Even excluding the very considerable use of textiles in performance clothing and footwear, there are plenty of opportunities for the use of technical textiles throughout the sports and leisure market

Geotextiles in civil engineering
The geosynthetics market (comprising geotextiles, geogrids and geomembranes) is nevertheless expected to show some of the highest growth rates of any sector over the foreseeable future. The economic and environmental advantages of using textiles to reinforce, stabilise, separate, drain and filter are already well proven. Geotextiles allow the building of railway and road cuttings and embankments with steeper sides, reducing the land required and disturbance to the local environment. Nonwovens already account for up to 80% of geotextile applications. Current interest is in ‘composite’ fabrics which combine the advantages of different textile constructions such as woven, knitted, nonwoven and membrane materials.To supply the diversity of fabrics needed for the many different applications of geotextiles, leading specialist manufacturers are beginning to assemble a wide range of complementary capabilities by acquisition and other means.

Protective and safety clothing and textiles
Textiles for protective clothing and other related applications are another important growth area which has attracted attention and interest somewhat out of proportion to the size and value of the existing market. As in the case of sports textiles, a number of relatively high value and performance critical product areas have proved to be an ideal launch pad for a new generation of high performance fibres, most notably the aramids, but including many other speciality materials. The variety of protective functions that needs to be provided by different textile products is considerable and diverse. It includes protection against cuts, abrasion, ballistic and other types of severe impact including stab wounds and explosions, fire and extreme heat, hazardous dust and particles, nuclear, biological and chemical hazards, high voltages and static electricity, foul weather, extreme cold and poor visibility.

Ecological protection textiles
Technical textiles can contribute towards the environment in almost every sphere of their use, for example by reducing weight in transport and construction and thereby saving materials and energy. Improved recycleability is becoming an important issue not only for packaging but also for products such as cars.

Milestones of Technical textiles:

Natural Fibers: Cotton, flax, jute, hemp, sisal used for heavy canvas rope with limited resistance to water or fungal attack & poor flame retardency.

Viscose Rayon: Developed in 1910 used as reinforcement to tires and other rubber goods ( drive belt, conveyors and hoses) for their tenacity & modulus and heat resistance. Absorbency led to the use in paper making, non woven for cleaning & hygiene.

Nylon and Polyester: Nylon developed in 1939, high strength & abrasion resistance, good elasticity, excellent energy absorption used for climbing ropes, parachute fabrics, sails and tire cords.- Polyester developed in 1950 which is low cost & used as alternative to viscose & poly-amide in technical applications.

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