By: Prof. T.K.Sinha, Yogita Agrawal, Rupa Mohanta
and Rupali Kapoor
As we enter 21st century, technical advances are dramatically influencing the world of fibers, fabrics and textiles. Today, technology can provide us with fabrics that imitate and actually improve upon nature's best fibers. In the next millennium, textiles will not just be an extension or simple alternatives to natural or synthetic fibers, but will provide superior functionality in broad and emerging sectors of the economy from space to super conductivity and agriculture to geotextile. This will be accomplished through modern business strategies for enhanced stakeholder value and highly efficient production schemes with no adverse impact on the environment and development of precisely specified molecules for new textile platforms.
We are living in a world in which technology is advancing at such an astonishing rate that most of us have difficulty comprehending the overall impact it has, and will continue to have, on our lives. Cloning of adult mammals, World Wide Web, smart materials, high-speed processors and wonder drugs continue to dazzle us almost on a daily basis. The textile industry has kept pace and technology today can provide fabrics that go well beyond the best that nature has to offer. It is, indeed, a narrow view to think of textiles as a fixed discipline of making "strings." It is much more diverse than that and most importantly; it is in a state of flux in response to changing needs of society and new innovations. The inherent characteristics of new textiles underpin the functional and aesthetic qualities of these many and varied applications from the world of fashion to agriculture, medical, aerospace, reinforced composites and architecture. There has been rapid growth in polymer, material, information and biological sciences. The advance, in these adjacent sciences and their inevitable interface, will catalyze the conceptualization of tomorrow's textiles. This concept of interdisciplinary research, development and product innovations will lead to new textile platforms for the next millennium.
Fibers that have ease of care and natural-like aesthetics have been major themes in recent decades, with high performance and specialty fibers taking on particular significance. Fiber and fabric tests, critical to product quality have relied largely on destructive, off-line methods. Advances in testing and quality control promise to have a major impact on first pass product yields and product quality.
DEVELOPMENTS OF NEW FIBERS
SOYABEAN PROTEIN FIBRE (SPF)
Soybean protein fiber (SPF) is a kind of regenerative plant fiber. It is made by means of wet spinning after extracting spherical protein from soybean residue with oil off biochemically and changing the space frame of the protein by adding functional agent. SPF is a kind of environment protecting product which dose no harm to the environment, atmosphere, water and human body during its process of production.
7. Electrical Properties
Low dielectric constant and loss tangent of polyethylene are of great importance in applications such as radar domes (radomes). Considering that the electrical properties do not change a great deal with molecular orientation and polymer morphology, the use of ultrastrong spectra fibers offers great potential for the development of structures in which structural rigidity, ballistic protection, and low dielectric constant are simultaneously required. Due to low dielectric constant and small loss tangent, the reflection of radar waves from polyethylene composites is smaller, and therefore the transmission is higher, than with glass fiber composites. In composites of spectra fiber/PE matrix, transmission is so high that it is practically transparent to the radar wave.
Advantages And Disadvantages Of Spectra Fibers:
Compared to other high performance fibers, spectra fibers have excellent specific properties and theoretical considerations indicate that their transverse-related properties, such as shear and compressive strengths, are equal to those of aramid fibers. Therefore, spectra fibers are good candidates for rigid structural composite applications. Exploratory spectra fibers exhibiting reduced creep offer promise to broaden the applicability of the fiber.
Spectra fibers can usually be processed very well on a variety of textile and composite manufacturing equipment. However, the unique combination of properties of this fiber may require that process and/or equipment modifications be made when utilizing conventional equipment.
For instance, it is essential to know that because of their unusually high strength, modulus, and amenability to high speed processing technology, Spectra fibers must be handled with maximum care. Operators unaccustomed to handling such fibers should be made aware of the potential danger of severe injuries if they are caught or entangled in a fast moving yarn.
Applications Of Spectra Fibers And Composites:
Spectra fibers and composites have gained rapid acceptance in a broad range of technologies; this is attributable to their mechanical properties; outstanding abrasion, fatigue and cut resistance; chemical inertness; and above all, unmatched damage tolerance. It has become clear that spectra fibers and composites will play major role in the rapidly expanding technology of survival. Specific applications are discussed in detail in the sections that follow.
1. Decelerator systems
Spectra is currently being used in decelerator system suspension lines. Equal load capabilities can be achieved at smaller diameters, there by reducing the pack volume and weight of system; also, in parachute reefing, the smaller line diameter enables use of smaller grommets or reefing rings.
When a parachute is open, lines passing through metal guides are exposed to severe amount of abrasion and must be frequently replaced due to abrasion damage. The advantages of spectra�s light weight strength go beyond tensile property, as it provides products with excellent abrasion properties. It has low frictional coefficient that is characteristic of polyethylene and as a result, even under abrasive circumstances, a relatively minimal amount of heat is generated. When the abrasion resistance of yarn to metal is evaluated, significantly greater strength retention can be found in the spectra fiber, the resistance of spectra is more than 20 times that of a comparable Kevlar braid.
Drawing was carried out either by stretching a gel fiber in a hot air oven and simultaneously removing the solvent to yield an essentially solvent free, highly oriented fiber or by drying the gel filaments at room temperature, then extracting traces of solvent with ethanol. The drawing experiments were carried out over a range of temperatures (70- 1430C) using either constant temperature or a temperature gradient.
The concentration of the polymer of the polymer as it was spun from solution and quenched into gel fibers appeared to be the most important process variable.
Properties of Spectra Fibers:
1. Tensile Properties
The tensile strength of spectra is higher than that of aramid fibers below ~ 1000C and falls below that of aramid fibers above this temperature. The capacity to withstand constant static tensile load also decrease rapidly when the temperature approaches 1000C, and it would be unwise to use spectra fibers at a temperature exceeding 80-900C in application s in which significant loads are applied for an appreciable length of time. Spectra show an outstanding retention of properties after prolonged heat treatments (annealing) to 1250C. It can be seen that, after cooling, the fibers almost completely retain their original room temperature strength unless the treatments exceed 1250C, although modulus decreases somewhat faster. It is well known that application of tension during annealing further decreases the strength decay of fibers.
2. Effect of Twist
Outstanding tensile properties and chemical inertness make spectra fibers promising candidates for use in cords for marine applications sail cloth, protective clothing, etc. Essential for these applications is the ability to withstand twisting without sacrificing strength. This, coupled with a very low coefficient of interfilament friction and outstanding resistance to flexural fatigue, makes spectra of great interest for users of cordage.
3. Creep Under Static Load
Spectra technology made important steps toward a dimensionally stable product, and these fibers are now successfully utilized in many industrial applications. Spectra�s tendency to creep under constant load is much higher than that of aramid fibers. In addition to modulus and strength, a major difference between spectra 900 and spectra 1000 is the greatly reduced creep of the 1000. Some development spectra fibers show even less creep than spectra 1000 at elevated temperatures. Any undesirable creep can be frequently be reduced by hybridization with a minor component of carbon or Kevlar fibers.
4. Retention of Properties in Various Solvents
Very high molecular weight and exceptionally high degree of molecular orientation and crystallinity contribute to outstanding solvent resistance. The chemical inertness of polyethylene and lack of hydrolysable bonds also contribute to this property.
5. Abrasion Resistance
In addition to outstanding tensile strength and low density, Spectra fibers exhibit superior abrasion resistance, a key requirement in many applications, especially for ropes. As a rule, the abrasion resistance decreases with fiber modulus, but in the case of ultrastrong polyethylene the trend is reversed, most likely because of its low coefficient of friction.
6. Drop Weight Impact
Because of the low glass transition temperature of polyethylene, which is placed between �800C and 1200 C, depending on the type of measurement, the thermoplastic Spectra fibers show by far the largest capability to withstand impact of all the high- performance fibers. As a result, spectra fibers retain their mechanical strength even at ballistic rates of deformation and very low temperatures. Depending on the construction, the impact resistance of spectra composites is 5 to 10 times higher than that of aramid.
2. Commercial fishing
Performance advantages of spectra cited above related to decelerator systems are equally applicable to commercial fishing applications. In addition, Spectra products have a natural buoyancy and float, whereas polyesters and steel wire products do not.
Spectra�s superior strength greatly reduces bulk for rib lines. Head ropes, bridles, and other ropes traditionally made from polyesters or other synthetic fibers. Unlike wire rope, spectra will not corrode and damage netting materials over time. Also, regardless of their size, ropes made with spectra float, which significantly reduces the need for bulky and expensive flotation devices. Spectra winch lines, lifting slings and high strength chokers allow for easy handling and and greater safety when hauling back and unloading. Spectra provide the same strength as wire rope at only 20% of the weight. This reduces bodily strain when lifting and allows more crew efficiency, especially in emergency situations.
3. Damage-Tolerant Radar Domes
Radar domes, in addition to having demanding electrical requirements, must often exhibit a high degree of structural integrity. The composite structural properties have to be tailored to the specific application. For example, radomes may require high impact tolerance, a high degree of stiffness, and/or high tensile strength. The use of higher frequency radars (even into the millimetric band) has resulted in a growing interest in spectra systems. Three main factors, known as the radome parameters, control the microwave transparency: dielectric constant, loss tangent, and dielectric material thickness. The first two are properties inherent to main constituents of the radome (i.e., the main forcing fiber and the resin); the third is a geometric variable of the radome wall design.
The Emerging Paradigm The essence of new product development in fiber science during the 20th century has followed a relatively narrow and perhaps limited route of development. Fibers are made from either condensation or addition-type polymer platforms. The fiber may have polymer modifications, contain additives or be altered on the surface.
The next century, however, will demonstrate the seemingly unlimited power of the synergy of diverse disciplines as borders between material science, biological science and information science blur and erode Today the breadth of complementary technologies is far greater. In the future fiber molecules will be designed, engineered and produced more efficiently than ever before due to advances in combinatorial chemistry, robotics, nanotechnology, bioinformatics, spectroscopy, and high-throughput screening.
First of all we would like to express profound gratitude to the management of the institute, Administrative Officer Shri R.C.Parmar Principal Dr.Ing.V.P.Singh, Advisor Prof. Dr.H.V.S.Murthy and Head of the department Prof.Dr. Prabhakar Bhat for giving encouragement and guidance to work on FIBRES OF 21ST CENTURY.
� �New Fibres for 21st century�, Rijavec T. & Bukosek V., Tekstilec 2004, 47/102, 13-25. World Textile Abstract 2004.
� �Corn Fibres: Dawn of new Era in Eco Textiles�, N.Arun, Man-made Textiles in India, April 2003, 130-135.
� �Novel properties of PLA fibres�, Karthik T., Synthetic Fibres, 2004, 33/4, 5-10.
� �BioSteel � A future fibre�, Asian Textile Journal, December 2004, 83-90.
� �Spider Silk�, P. Madhavamoorthi, Synthetic Fibres, June 2004.
� �Speciality Fibres- Soybean Protein Fibre�, Dr. Manisha Mathur & Mrs. Manisha Hira, Man-made Textiles In India, October 2004, 365-369.
The authors are Lecturers in the Department of Textile Technology, Shri Vaishnav Institute of Technology and Science, Baroli (Indore-Sanwer Road), Distt: Indore (M.P), India, Pin-453331
E-Mail ID: email@example.com
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By adding antibiotic and ultraviolet absorbent during the process of spinning, we can get SPF with functions such as germ-resistance and ultraviolet-resistance. The fabrics made from SPF take on such features as soft luster of raw silk, moisture conductivity of cotton fiber and warm protection of cashmere. The development of SPF has successfully filled up the vacancy in this field of the world. From the year of 2000, initiated and in succession series of SPF shuttle weave and knit products according to fashion in vogue by adopting different line type combination of pure soybean protein yarn mixed with fibers such as wool, flax, silk and spandex or soybean protein yarn mixed with green dyeing agent and other functional agents.
Underwear, baby outfit, towel and quilt of pure SPF, fashionable shirt and garment of SPF mixed with flax and spun silk, elastic close-fitting vest and skirt of SPF mixed with spandex, all sorts of jacquard and dyed scarf of SPF mixed with cashmere and spun silk, etc.
SPIDER SILK FIBRE
Spider silk is a bio polymer fibre, it's composition is a mix
of an amorphous polymer (which makes the fibre elastic) It is a fibrous protein secreted as a fluid, which hardens as it oozes out of the spinnerets which are mobile finger like projections. As the fluid oozes out, the protein molecules are aligned in such a way that they form a solid. The process is not yet well understood. The spider hauls out the silk with its legs, stretching, fluffing "it up or changing it in other ways. The silk is used by the spider for lot of different uses. Constructing their webs, the production of egg sacs, wrapping in their prey, as a lifeline when jumping or dropping to escape, from transferring the semen from the abdomen to the male palp, in draglines marked with pheromones, as a shelter in which it can retreat.
Properties Of Spider Silk:
- Unique combination of high strength & rupture elongation.
Strength = 1.75 Opa
Breaking elongation = over 26% ,
It is interesting to see spider silk as a mudel for the engineering of high-energy absorption fibres, because the fineness of spider silk is on the order of 4 nm.
Humans have, been making use of spider silk for thousands of years; The ancient Greeks used cobwebs to stop wounds from bleeding and the Aborigines used silk as fishing lines for small fish. More recently, silk was used as the crosshairs in optical targeting devices such as guns and telescopes until World War IT and people of the Solomon Islands still use silk as fish nets.
Current research in spider silk involves its potential use as an incredibly strong and versatile material. The interest in spider silk is mainly due to a combination of its mechanical properties and the non-polluting way in which it is� made. The production of modern man-made super-fibres such as Kevlar involves petrochemical processing, which contributes to pollution. Kevlar is also, drawn from concentrated sulphuric acid. In contrast, the production of spider silk is completely environmentally friendly. It is made by spiders at ambient temperature and pressure and is drawn from water. In addition, silk is completely biodegradable. If the production of spider silk ever becomes industrially viable, it could replace Kevlar and be used to make a diverse range of items such as
� Bulletproof clothing
� Wear-resistant lightweight clothing
� Ropes, nets, seat belts, parachutes.
� Rust-free panels on motor vehicles or boats
� Biodegradable bottles
� Bandages, surgical thread .
� Artificial tendons or ligaments, supp0l1s for weak blood vessels.
POLYLACTIC ACID FIBRES
PLA is composed of lactic acid, which is produced by converting cornstarch into sugar& then fermenting it to get lactic acid. The process involves direct condensation polymerization of lactic acid in solvents under high vacuum. More recently PLA was developed as an alternative binder for cellulosic nonwovens because of its easy hydrolytic degradability compared with polyvinyl acetate or ethylene-acrylic acid copolymers.
The process involves extracting sugars (mainly dextrose, but also glucose and saccharose) from corn starch, sugar beet or wheat starch and then fermenting it to lactic acid. Refined sugars are preferred to the cheaper molasses because purification after
fermentation is more expensive.
The lactic acid is converted into the dimer or lactide which is purified and polymerized (ring opening method) to polylactic acid without the need for solvents (Figure. 1). The family of polymers arises in part from the stereochemistry of lactic acid and its dimer. As fermented, lactic acid is 99.5% L-isomer and 0.5% D-isomer.
Figure 1. Direct and Dimer Routes to PLA 8
Conversion of this to the dimer can be controlled to give three forms, the L, D, and Mesolactides. (Figure. 2)
Figure.2.Three different lactides are possible 8
Polymerisation of the lactide to give polymers rich in the L-form gives crystalline products, whereas those rich in the D-form (>15%) are more amorphous. The enhanced control of the stereochemistry achieved in the dimer route accounts for the superiority of the products. The resulting PLA resin can be extruded like other thermoplastic resins to make fibres, films, spunbonds etc.
PLA can be used for various materials similar to conventional synthetic fibres such as yarns, fabrics, knitted items, nonwoven fabrics, etc. It can be blended with cotton, rayon, wool, etc. to add values. This allows application to a variety of textile products, such as shirts, casual wear, uniforms, etc.
BANANA FIBRE AND PRODUCTS
Banana is an important crop in the Philippines and Ecuador, where its cultivation, harvesting and processing are major sources of employment. Before European textiles arrived in the Philippines, woven Manila hemp fibre was the chief source of clothing. In 1980 the Philippines and Ecuador expo11ed 87% (75,000 tonnes) and 12% (10,100 tonnes) respectively of the total world production of the fibre to a world-wide market, with 60% of the fibre being converted to pulp for specialized paper-making.
Raw Material: Banana pseudo stems and. Chemicals
The process involves splitting of the banana pseudo- stem into strips, digestion in open vats, washing and drying. The fibre is converted into various utility items using traditional techniques
For making coarse woven fabrics (hessian, sacking), ropes, twines, sand bags, tents, webbing canvas and screens, kit bags, tool bags, luggage covers. Banana fibre can also be blended with wool, cotton. and-Ilak for making blankets,
carpets and rags.
The first ideas / attempts to extrude continuous filaments (CF) from Basalt rocks were made in the USA and date back to 1923. The fibre is composed of 100% mineral continuous filaments. The focus is on the range of 9 to 13 J.tm for the filament diameters. These diameters give the best compromise between tenacity, suppleness and cost. They are also safely larger than the 5 J.tm limit for non-respirability. As the product presents no hazards to health and environment, it is suitable for asbestos replacement. The natural golden brown appearance of the resulting fabrics, incidentally can be covered for decorative purposes.
Forms Of Basalt
Continuous Basalt fibre is a unique product derived from volcanic mineral deposits. Basalt fibres are superior to other fibres in terms of thermal stability; heat and sound insulation properties; vibration resistance and durability.
Basalt Twisted Yarn
The main advantages of Basalt continuous fibre, roving and yam, are higher operating temperature, young's modulus and chemical resistance as compared to fiberglass. It possesses high temperature resistance and excellent mechanical properties.
Basalt woven fabrics
The Basalt fabrics have the width of 100cm with deviation +2/-1 % from the norms. The fabrics can be produced with the width up to 200cm.
General Properties Of Basalt
1) Mechanical Properties
� Specific tenacity of CF Basalt fibres exceeds that of steel fibres.
� Basalt is roughly 5%denser than glass.
� The tensile modulus of CF Basalt fibres is higher than the one of E glass fibres.
� This makes CF Basalt fibres & fabrics attractive for the reinforcement of composites.
� The low elongation perfectly elastic up till rupture- results in dimensionally
� very stable fabrics.
� Basalt textiles show sufficient suppleness and drapeability.
� They exhibit good fatigue resistance.
2) Chemical Properties
� They have good acid and solvent resistances.
� They have better resistance to alkalis. .
� The inert basic material possesses, in addition to its corrosion resistance, good resistances to UV -light and biological contamination.
� In pure form, it is free of odour and has low soiling sensitivity.
� Absorption of humidity comes to Jess than 0.1 % at 65% relative air humidity
and room temperature.
� They show excellent "wet ability"
3) Thermal Properties
� They show good resistances against low and high temperatures.
� It is a non-combustible and explosion proof.
� They have excellent resistance to fire.
Fields And Applications Of Basalt
1) Surface & air transportation
� Fire protected seats in planes, trains, ships, subways,.....
� Airplane life jacket pouches.
2) Specialty furniture
� Fire proof mattresses (for hospitals, hotels,etc.).
� Fire proof seating.
� Fire proof curtains and partitions for indoors and outdoors.
� Fire protective clothing
� Fire resistant floor coverings: backing, reinforcement.
4) Environmental safety
� Basalt carbon heaters for clothes, rooms etc.
� Fire proofing and heat protection working cloth.
PLA (CORN) FIBRE
PLA is composed of lactic acid, which is produced by converting corn starch into sugar & then fermenting it to get lactic acid.
Lactic acid can be considered a commodity chemical sleeping giant, with advantages including
a) It can be made from biomass
b) It has both an hydroxyl group and a carboxylic acid group
c) It is optically active
The lactic acid exists in two optical isomers L-isomer & D-L isomer. The polymer produced from D-L isomer by using direct condensation requires solvent under high pressure & high vacuum. Hence L isomer is used. Lactic acid firstly condensed to transform it into short chain PLA. It is then converted into lactic acid by using vacuum distillation. No solvent is required during distillation. The final stage is ring-opening polymerization.
Flow of Manufacturing:
►Corn → Starch → Undefined Dextrose → Fermentation → Lactic acid → Direct polymerization → PLA → Melt spinning → PLA fibre.
►Corn → Starch → Undefined Dextrose → Fermentation → Lactic acid → Vacuum distillation → Condensation → PLA → Melt spinning → PLA fibre.
Lactron (Corn) circulation system in nature:
Microbiological breakdown shows that these products, after their use, can be used as soil conditioner, composted material etc. & the yielded material such as co2 & water again utilized by corn plant for its growth. Hence the fibre is totally eco friendly.
Physical and Mechanical Properties:
PLA can be used for various materials similar to conventional synthetic fibres such as yarns, fabrics, knitted items, nonwoven fabrics, etc. It can be blended with cotton, rayon, wool, etc. to add values. This allows application to a variety of textile products, such as shirts, casual wear, uniforms, etc.
For agriculture: Seeding pots, animal prevention nets, weed prevention bags, etc.
For construction/civil engg. Material: Curing sheet, slope vegetation nets, etc.
For food packaging: Trays, fast- food containers, etc.
For daily sundry products: Garbage pail bags, strainer bags, etc.
SPIDER SILK (BIOSTEEL) FIBRE
Spider, small animal, often less than a millimeter across can make a substance that we humans with all our technology are unable to reproduce, a substance that is tough, stronger and more flexible than anything else we can make is surely a humble reminder of the fact that Nature created us and not the other way around..
What is spider silk made of?
Spider silk is a bio polymer fibre, its composition is a mix of an amorphous polymer (which makes the fibre elastic) It is a fibrous protein secreted as a fluid, which hardens as it oozes out of the spinnerets which are mobile finger like projections. As the fluid oozes out, the protein molecules are aligned in such a way that they form a solid. The process is not yet well understood. The spider hauls out the silk with its legs, stretching, fluffing it up or changing it in other ways.
Nexia Biotechnologies Inc in Montreal, Canada has inserted silk genes into goats to produce silk proteins in their milk. This is hoped to be a better method because protein from bacteria is not as strong due to faulty crosslinking of the proteins and hard white lumps can form. Milk production in mammary glands is similar to silk protein production in spiders so it is thought that proper protein crosslinking could occur in goats. Scientists have injected the spider�s gene into a goat named Willow. Willow�s milk will be processed so the protein can be used. This silk thus produced biologically is called �BioSteel�
Properties of Spider Silk:
Unique combination of high strength & rupture elongation.
Strength = 1.75 Gpa
Breaking elongation = over 26%
It is interesting to see spider silk as a model for the engineering of high-energy absorption fibres, because the fineness of spider silk is on the order of 4 nm
Current research in spider silk involves its potential use as an incredibly strong and versatile material. The interest in spider silk is mainly due to a combination of its mechanical properties and the non-polluting way in which it is made. The production of modern man-made super-fibres such as Kevlar involves petrochemical processing, which contributes to pollution. Kevlar is also drawn from concentrated sulphuric acid. In contrast, the production of spider silk is completely environmentally friendly. It is made by spiders at ambient temperature and pressure and is drawn from water. In addition, silk is completely biodegradable.
If the production of spider silk ever becomes industrially viable, it could replace Kevlar and be used to make a diverse range of items such as : Bulletproof clothing, Wear-resistant lightweight clothing, Ropes, nets, seat belts, parachutes, Rust-free panels on motor vehicles or boats, Biodegradable bottles, Bandages, surgical thread & Artificial tendons or ligaments, supports for weak blood vessels.
Imagine stretching elastic and seeing it get fatter rather than thinner. It may sound bizarre, but this property is what makes auxetic materials potentially so useful. An auxetic material, which has a negative Poisson ratio so that it has the property of expanding or contracting transversely to a direction in which it is extended or compressed, is made in filamentary or fibrous form. A suitable process involves cohering and extruding heated polymer powder so that the cohesion and extrusion is effected with spinning to produce auxetic filaments. Typically the powder is heated to a temperature sufficient to allow some degree of surface melting yet not high enough to enable bulk melting.
A conventional polymer processing technique (melt spinning) is the basis of this technique, with novel modifications. The process flow of manufacturing typical polypropylene auxteic fibre is illustrated below:
Auxetic fibres can be used as fibre reinforcements in composite materials e.g. polyolefin auxetic fibres in a polyolefin matrix. The auxetic fibres improve resistance to fibre pull out and fibre fracture toughness, and give enhanced energy absorption properties. Sonic, ultrasonic and impact energy can be absorbed enabling superior composites to be made for sound insulation of walls of buildings, body parts for submarines or other vehicles, etc, bumpers for cars, etc.
Auxetic fibres can be used alone or in combination with other materials for personal protective clothing or equipment as a consequence of the superior energy absorption and impact resistance properties. Crash helmets and body armour (e.g. bullet proof vests) are examples of applications.
It may be desirable to make the protective material in the form of an auxetic macrostructure made from auxetic fibres (i.e. a hierarchical auxetic material). These properties should also lead to enhanced sports protective clothing, e.g. shin pads, knee pads, batting gloves etc. The possibility exists of producing protective clothing made from auxetic fibres which have equivalent protective performance to those made from non-auxetic fibres but which are lighter and/or thinner due to the benefits associated with the auxetic property.
Auxetic materials have pore size/shape and permeability variations leading to superior filtration/separation performance in several ways when compared to non-auxetic materials. Application of an applied tensile load on a non-auxetic porous material causes the pores to elongate in the direction of the applied load, which would tend to increase the filter porosity. Benefits for auxetic filter materials, therefore, include release of entrapped particulates (e.g. drug-release materials) and self-regulating filters to compensate for pressure build-up due to filter fouling.
In this world very rapid developments are taking place in every field. Then how the field of textiles can remain untouched with it. Recently developed spectra fiber is one of the world�s strongest and lightest fibers. A bright white polyethylene, it is, pound-for-pound, ten times stronger than steel, more durable than polyester and has a specific strength that is 40 percent greater than aramid fiber. Spectra is best known as the super-fiber used in the Small Arms Protective Insert (SAPI) plates protecting American soldiers in Iraq and Afghanistan. Spectra fiber is used in numerous high-performance applications, including police and military ballistic-resistant vests, helmets, armored vehicles, sailcloth, fishing lines, marine cordage, lifting slings, and cut-resistant gloves and apparel..
Production (Spinning Process):
A process for making polymer filaments, which have a high tensile strength and a high modulas by stretching a polymer filamentwhich, contains a substantial amount e.g., at least 25 wt% of polymer solvent, at a temperature between the swelling point and the melting point of polymer. A solution of the polymer may be spun to a filament through a spinning aperture and the spun filament cooled to below the dissolution temperature of the polymer without substantial evaporation of solvent from the filament and then brought to a temperature between the swelling point and the melting point of the polymer and stretched.
Polymer solutions were prepared by dissolving the polymers in paraffin oil, decalin, or dodecane under a nitrogen atmosphere and in the presence of an antioxidant. The solutions were spun using the experimental setup. The extrusion temperature varied from 130 to 1750C for dilute solutions and was fixed at 1200C for concentrated solutions. The spun filaments were then quenched in cold water to form gel fibers and collected on a winder.