Textiles for protection is the fruit of a diverse body of talents, drawing together scientific and technical expertise from around the world, to produce an important source of current knowledge on textile materials and clothing, and their use in the protection of humans in hostile environments. It will be invaluable for all those working in the safety and protective fabrics industry and all concerned in health and safety in a wide variety of industries. It will also be an important work for health and safety workers in the ministry of defence, police and fire service.
Selection of protective cloths
The first step in selecting protective clothing is to determine the hazard, evaluate the potential for exposure and select the degree of protection required. The consequences of direct skin contact can range from minor diseases like dermatitis to systemic poisoning and cancer. There are different types of protective clothing and it can be divided into the following groups based on their end uses:
Ø Clothing against heat and flame
Ø Clothing against mechanical inputs
Ø Fireman's protective clothing
Ø Clothing against cold
Ø Clothing against foul weather (moisture, wind)
Ø Clothing against chemical substances (gases, liquids, particles)
Ø Clothing against radioactive contamination
Ø Protective clothing against electro static charges
Ø High visible warning clothing
Ø Projectile protection clothing
Ø Protective gloves against mechanical and thermal hazards
Selection factors for design of protective clothing:
o Clothing configuration o Components and options
o Sizes
o Ease of donning on and off
o Clothing Construction
o Accommodation of other selected ensemble equipment
o Comfort and restriction of mobility
Further, we have to consider the environment in/from which we want protection.
Thermal Protective Clothing
The thermal insulation provided by fibrous material is mainly due to the low thermal conductivity of the air entrapped in the fibre web. Thus fine and dimensionally stable fibres at work temperatures are used for the insulation of the building or a garment. Their construction design allows the air stability in order to limit the convection exchanges. For isothermal garments a polyester microfibre nonwoven filling, combined or not with an aluminised layer to reduce the radiation exchanges, is an efficient thermal protection material thus associated with comfort function derived from the impermeable breathable membrane.
Application:
a) Industrial oven
b) Aeronautics or aerospace
In the above applications ceramic fibres based on silica, alumina, and zirconium oxide are used. This fibre can withstand a temperature ranging from 1000ºC to 1400ºC.
Fire Protective Clothing
When flame resistance and safety are critical requirements in your garment, you need fabric solutions that offer outstanding quality and meet strict standards of performance. Good fire protection will be obtained through the use of thermo stable, fire resistant materials maintaining as long as possible the textile integrity and ensuring the certain degrees of freedom of comfort for the as in the case of fireman's suit.
This protective function may be obtained by using naturally thermo stable fibre or by treating this fibre with fire proofing or fire retardant agent before or after spinning on their own or in combination with the fibre ensuring a dimensional stability and mechanical resistance. The hybrid material is the answer to the functions demanded by the fireman, fire fighter and fighter plane pilot.
Commercially developed products for fire protection:
Carbon X@ R is a yarn from Chapman Innovations, created by spinning PAN (oxidised polyacrylonitile) fibre with an Aramid strengthening fibre. This formula results in a yarn with amazing flame resistant characteristics that can be used in a wide array of products and applications. The range includes:
· Knits for thermal defense that can be comfortably worn next to the skin (long underwear, socks, balaclavas and hoods)
· Nonwoven felts for insulation from severe conditions (thermal barriers, insulation, blankets)
· Wovens used in outerwear providing extreme protection
Those who must defend themselves against life-threatening forces on a daily basis need all the protection they can get. Introducing Glen Guard™ FR -- a revolutionary flame resistant fabric engineered to protect and serve workers who face the harsh environments of gas/oil refinery and electric utility industries.
The strength of our new fabric comes from the flame resistant, durable, comfortable and colorfast properties inherent in advanced, light weight Kermel® aramid fibres. Garments made of GlenGuard™ FR are UL certified, long-lasting and as comfortable as your day off.
Mechanical Protective Clothing
The mechanical performance of fibres have hybrid yarns in their interlacing mode of convey to the textile material, a personal protective function against different risk such as ballistic, blade cuts, puncture, projection of fragments, knives, slashing. Combined use of high performance material such as glass fibre, HT Polyethylene or Steel. Eg, anti-cut gloves. Current combat clothing systems are based upon the layer principle, where each layer performs a specific function in the combat soldier 95 assembly. This is a basic fighting system to which can be added other protective layers.
Functional Criteria For modern Military textile materials:
The functional criteria for military textiles are dealt with a range of direction.
Physical requirements -
· Light weight and low bulk
· High durability and dimensional stability
· Good handle and drape
· Low noise emission
Environmental Requirements -
· Water Repellant
· Water Proof
· Wind Proof and snow shedding
· Thermal Insulating
· Water vapour permeable
· Rot and UV Resistant
· Air permeable
· Biodegradable Camouflage, concealment and deception requirements -
· Visual Spectrum
· Ultraviolet
· Acoustic emissions
· Radar Spectrum
Requirements for flame, heat and flash protection -
· Flame retardance
· Heat and melt resistance/Low smoke emission
Chemical Protective Clothing
Many industrial sectors often use hazardous chemicals or gases products against which it is essential to be protected. This is more especially in case of chemical, photography, automotive, aeronautics and agricultural industry. It is also in case of military field and multiple examples have shown importance of having a most performing garments and gloves. The necessary performance level varied according to risk under gone. The equipment elements are therefore conceived with various shapes and material, efficiency level of which against chemical must be controlled, eg, fabric coated with Neoprene, PVC and Latex.
UV Protective Clothing
The UV radiation (UVR), a high energy constituent of the solar radiation is not only harmful to the living creatures; it is also responsible for deterioration in useful properties and service life of materials like textiles, furniture, electronic parts and construction materials. One possible solution to this problem is to carry out the outdoor activities under flexible textile structures, which can block the harmful UVR. The structure itself should have good service life and it should prevent the UVR from getting transmitted through the structure.
Hindered Amine Light Stabilisers (HALS) provides very good resistance against UVR while UV Absorbers provide good protection from UVR by absorbing it. In this study a suitable combination of HALS and UV absorbers has been incorporated in HDPE by melt mixing in different combinations and concentrations. The monofilaments have been tested for weatherablity to predict the service life and also evaluated for Sun Protection Factor (SPF) in film form. The results from these tests would be used to find the combination giving best UV stability and protection.
Cut Resistant Fabrics
It is very important to protect us from accidental injury from sharp metal, knives, and glass. From handling sheet metal and assembly operations to grinding small parts, the cut resistant fabrics keep us safe. Apart from the protection of human the cut resistant fabrics can be used as seat cover for public transport to prevent from frequent cut. These types of fabrics are also very useful as tarpaulin or covering of truck. The imported cut resistant fabrics are available, but the costs of these imported fabrics are very high. So, it was felt necessary to design and develop indigenously the different types of cut resistant fabrics for various technical applications.
Breathable Fabrics
Breathable fabrics come in three forms. The first one is not truly water-proof as it relies upon the close weave of the fabric to keep out water. The other two forms rely upon either the hydrophilic or microporous qualities of materials, which come as either a coating or a laminated film.
Methods of making the fabric breathable:
There are six basic ways of creating a waterproof/ breathable fabric. This mainly involves spraying a free fabric with layers of coating to form a waterproof coat. The more layers, the more waterproof (and often less "breathable"). Likewise a plate can be sprayed and the dried coating removed to create a film that can be laminated to a fabric.
The following are the brand names associated with specific water-proof methods:
§ Microporous coatings - Triple Point
§ Hydrophilic Coating - Miai Scantsx
§ Microporous laminates - Aquatex
§ Hydrophilic laminates - Sympatex
§ Bicomponent Coating - Entrant G2
§ Bicomponent laminate - Gore Tex
UV Resist, Water Repellant Breathable Fabric:
The demand for healthy lifestyles and comfort drives researchers to explore newer techniques to impart more functional properties in textiles. An attempt has been made to produce UV-resist, breathable fabrics for use in the cold regions of India as high-altitude fabrics. For UV-resist property, a dispersion of benzotrizol-type derivative and a silicone-based product are taken and perfluoro-alkyl-type fluorocarbon-based compound and fluorocarbon resin-type compound are used as water-repellent finishes. To estimate the performance of each finish on the fabric, these chemicals are applied separately with different concentrations. The finished fabrics are evaluated for their functional properties. It is found that the benzotriozol derivative for UV-resist and the fluorocarbon resin-type compound for water-repellent finish give best results. Both chemicals are applied sequentially and show good wash fastness.
Antistatic Protection
This is an example of a typical two-layer fabric construction constituting outer fabric, and liner of textiles to protect against electrostatic charges.
High visibility and weather protection
This is an example of a typical three layer fabric construction constituting outer fabric, membrane and liner of textiles to protect against extreme weather conditions.
Water Vapour Transport through Protective Textiles
Moisture accumulation in the breathable protective garments and in whole clothing systems is much smaller than in the non-breathable one. Additionally, the ratio of evaporated sweat to produced sweat E/P is much higher for breathable constructions. Differences are statistically significant at levels of p > 0.995 or higher. There is no indication of a temperature dependency of the water vapor resistance of hydrophilic membrane laminates, but results show that, especially at ambient temperatures far below the freezing point, such breathable foul weather protective textiles still offer a great benefit to wearers. Foul weather protective clothing for sports and occupational wear is extremely important to the textile industry throughout the world. However, feelings of uncertainty have been growing in the market about the function of so-called breathable (ie, water impermeable but water vapor permeable) materials at different climatic scenarios.
Conclusion
The protective clothing market is receptive to innovative new products. There is opportunity and need for functional and cost effective materials. But the market is fragmented and complex. Development and lead times are often long and expensive. Anyone contemplating entering the business must be prepared to spend significant sums on development and providing the products if these are to be accepted and widely used. But new needs are constantly emerging and the rewards often worth the risk.
References
The authors are with the Faculty of Textile Technology, SSM College of Engineering, Komarapalayam, Tamil Nadu 638 183. E-mail: parthi_mtech@yahoo.com.
copied from http://www.indiantextilejournal.com/articles/FAdetails.asp?id=321
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