Performance fabrics are preferred for specialised industries to sustain the extreme working conditions in the industries. The performance fabrics are inherently coated or after -coated by specialised coatings which make them sustain the working conditions. They are manufactured for specific aaplications. For example, in goundry industry, the working conditions contain extreme heat, high temperature and metal splash.
The person working in this industry must be protected against such bizarre conditions. Hence, fabric material which can provide protection to the worker must be selected for this purpose. Fabric which can withstand high temperature, heat and metal splash need to be used.
Cotton fibers are natural hollow fibers; they are soft, cool, known as breathable fibers and absor-bent. Cotton fibers can hold water 24–27 times their own weight. They are strong, dye absorbent and can stand up against abraison wear and high tempertature. In one word, cotton is comfortable.
Cotton being strong and comfortable is used to produce industrial workwear. Cotton fabric is also cost effective. Genereally, cotton fabric with weight of 180-240 GSM is preferred in industrial workwear.
To improve the durability of cotton fabric, it is blended with other synthetic material such as polyester, nylon, etc. Cotton is otherwise treated to make it flame resistant, arc resistant and chemical retardent.
Polycot is a blend of cotton and polyester in variable proportion, may be 70:30, 60:40 or any other respectively. Mixing of polyester in the cotton fabric makes the fabric more durable and cost effective. There is one more reason for using polyester blend as polycots generate less wrinkles than pure cotton fabric.
Polycot being cost effective and durable but it is less breathable and less comfortable than pure cotton fabric. It is not preferred in hard work conditions and prolong wear. Hence, polycot is not a good option for industrial workwear but can be preferred for durability and cost.
Flame resistant (FR) and arc rated (AR) fabrics are used to manufacture FR clothing , which is worn by workers in many industries as the “last line of defense” against serious injury from arc flash, flash fire, molten metal, and combustible dust.
These fabrics are self-extinguishing ; they do not ignite and continue to burn once the heat source is removed, and they do not melt. Most FR fabrics fall into two categories: inherent and treated.
Inherently FR fabrics are knit or woven from fibers that have flame resistance built into their chemical structures. Interestingly, while the word inherent denotes a core property, or something that is innately and naturally a part of the whole, all inherent fibers in use today are engineered by humans. Because the FR engineering is done during creation of the fiber itself and is an inseparable part of the fiber, the flame resistance of garments manufactured from inherent fiber is permanent. Common and popular inherent fibers include aramids (Nomex®, Kevlar®, Glenguard and others), modacrylics (FRMC®, DH, DuPont MHP, Tecasafe®), and carbon fibers (Tecgen®).
Treated fabric begins as a product that is flammable (typically a cotton or a cotton rich blend) and then flame retardants are engineered into the fabric to create flame resistance. There are a number of different treated technologies being used in the world today, and the best of these technologies create a flame resistant polymer inside the hollow core of the cotton fibers—producing fabrics that are guaranteed FR for the life of the garment. Some of the brands include Mount Vernon Mills (MVM), Westex Ultrasoft®, iQ®, Indura® and True Comfort®, and PyroSafe by Antex®.
All FR fabrics (inherent and treated) are engineered to remove or reduce the presence of one or more of those components by interrupting the combustion process. Combustion is the chain reaction of heat breaking down material into fuel, which reacts with oxygen to create more heat, breaking down the material into more fuel, and so on. Depending on the type of FR fabric, this process can be interrupted by removing the fuel source , removing heat from impacting the fabric, or displacing oxygen. Most common FR fabrics char instead of burning, which acts to both remove fuel and block heat, and modacrylic fabrics also contain an active process that displaces oxygen. While the science of combustion and FR fabric is highly technical, understanding the properties of fire can provide the building blocks for greater insight into FR fabric technologies.
There are multiple technologies of inherent fibers, and each uses a different process to create flame resistant fabric. Some inherent fibers, like modacrylic, use a gas-phase technology. Gas-state technologies extinguish flame by forming a type of molecule called a free radical oxygen scavenger in the gas layer above the fabric and suffocating the fire, preventing further decomposition and creation of fuel. Other inherent fibers, such as aramids, are thermally stable and act in the solid phase—meaning their molecular structure resists decomposition to high temperatures, then forms a friable char. This interrupts combustion by preventing the creation of fuel.
Most modern types of treated FR fabric also act in the solid phase, causing the fabric to char instead of burning when exposed to heat—reducing the amount of fuel available and extinguishing the fire.
With the drastic improvements and innovations made in FR engineering over the years, differences between the durability of flame resistance and protective qualities of inherent and treated fabrics have essentially disappeared, at least among the major US manufacturers. A worker wearing FR clothing made from inherent or quality treated fabric will be well protected for the life of the garment. And, home laundering is easier than ever, as manufacturer recommendations are the same for both inherent and treated garments—no liquid chlorine bleach and no fabric softener. Nowadays, choosing between the two types of fabric most often comes down to worker preference—namely comfort, durability of the garment, and value.
Foundries are dangerous places where metal is handled at high temperatures. Therefore, workers must wear effective protection capable of resisting the impact of molten metal splashes at high temperatures. In addition, when trying to protect workers, the viscosity of each metal during the manufacturing process must be considered.
In the case of aluminum, the high level of viscosity reached at 700 °C may be extremely dangerous due to the ease with which it sticks to fabric, causing serious burns.
Common and popular inherent fibers include 100% wool, DuPont MHP and Coats Flame Pro Flash protection fabrics. DuPont, Coats and Solvay are the major manufacturers of Metal splash resistant fabric.
By using a range of specific molten metal splash protection fabric for different types of foundries (aluminum, steel or iron, zinc, glass, cement works, etc.), textile offers protection from large masses of molten metal, high temperature , electrical discharges and radiant heat. In addition, these fabrics may be made in high visibility colors for monochrome areas.
Antistatic fiber is a conductive material and polyester fibers formed by joining a microconductive function of synthetic fibers. Antistatic fabric is usually a blend of anti-static fiber and polyester yarn. Through the composite fiber spinning technology, can be given in the fiber surface conductive material, and through the core layer of pure polyester fiber strength of the backbone support, is a significant antistatic performance of the fiber. They are used in petro-chemical industry precision industry, painting room, conveyor belt safety shoes and fire service, need to strictly control the static electricity industry.
The performance of most antistatic finishes depends on the kind of fibre and sometimes also on the kind of fabric (anisotropic behaviour, for example, different in warp and weft directions). Although wool is a hydrophilic fibre, wool fabrics often are highly charged, caused by the strong friction between the wool scales
When applying antistatic finishes to fabrics, uniform fabric penetration is important for optimal performance. The use of wetting agents in the finish formulation is recommended. Pad, spray and kiss-roll applications are favoured . Some of the potential side effects of the use of antistatic finishes include wear comfort (no clinging and a pleasant skin contact caused by hydrophilicity), soil-release properties, increased soiling with dry soil, yellowing after exposure to heat and impaired crockfastness of textiles dyed or printed with disperse dyes. The permanence of antistatic finishing effects to repeated washings, even at only 40°C, is limited, as the mechanical stress of the washing process decreases the antistatic performance significantly. So the washing and the abrasion resistances of anti-static finishes are crucial.
Combination of textile technology and medical sciences has resulted into a new field called medical textiles. New areas of application for medical textiles have been identified with the development of new fibers and manufacturing technologies for yarns and fabrics. Development in the field of textiles, either natural or manmade textiles, normally aimed at how they enhance the comfort to the users.
Development of medical textiles can be considered as one such development which is really meant for converting the painful days of patients into the comfortable days
The major requirements for biomedical polymers:
Health care fabrics are further classified into Non-woven and Lminated fabric.
Fabric broadly defined as a sheet or web structure bonded together by entangling medical fibers or filaments (and by perforating films) mechanically, thermally or chemically. They are flat, porous sheets that are made directly from separate fibers or from molten plastic or plastic film.
The fibers in a non-woven may be oriented in one direction or randomly throughout the fabric.
Multiple layers can be combined to acheive desired strength, elongation and other mechanical
properties. Porosity can be controlled by varying fiber diameter, fibre density, fiber orientation
and additional mechanical processing.
Key characteristics of non-woven fabrics include:
Non-woven fabrics are further classified based on layers - SSMMS, SMMS, SMS and SS fab-rics (S-spun bond, M- melt blown). The weight of fabric used in medical apparels is from 20-90 GSM. Masks are made of 20GSM material while surgical or medical gowns are manufac-tured from 35-50 GSM material. The PPE coveralls are produced from 60-70 GSM material.
Laminating fabrics is similar to laminating printing, glass, and other materials. A premade film is bonded on the fabric via thermal, or adhesive propertis. Fibrous material such as yarns fabric that are woven, and knit or non-woven fabrics can be laminated. The laminated fabrics are further classified based on the lamination technique into Thermal bonded and overlay. Thermal bonding is the most popular method of bonding used in non-wovens manufacture. It offers high production rates because bonding is accomplished at high speed with heated calendar rolls or ovens.
Where the chemical hazard results in a high level of skin protection required, appropriate chemical resistant apparel which provides an effective barrier between the chemicals used and the
area of the body to be protected must be worn. It is important to note that no single material
will protect against all chemicals, and that no material is totally impermeable. Materials only
temporarily resist chemical breakthrough; even the most chemically resistant material will
breakdown after repeated chemical exposures. Selecting the clothing material which best
protects against a particular chemical must be based on chemical resistance performance
upon contact with the chemical. Appropriate chemical resistant clothing must demonstrate no
penetration, no significant degradation, a breakthrough time greater than the duration of the
task, and a low permeation rate upon contact with the chemicals used:
1) Penetration occurs when a chemical leaks through seams, zippers, pinholes and other
imperfections in the clothing.
2) Degradation is the physical deterioration of a material due to contact with a chemical.
This may cause the material to soften, swell, shrink, stretch, dissolve, or to become hard and
brittle. Materials having good to excellent rating against degradation should be selected.
3) Permeation is the process by which a specific chemical diffuses through a material at the
molecular level, from the outside to the inside surface of the material. Chemical permeation
frequently occurs with no obvious signs of physical degradation of the material. The rate of
permeation is affected by factors such as the type of chemical, chemical concentration, material thickness, humidity, temperature and pressure.
