Dr. V. K. KothariDepartment of Textile Technology, IIT, Delhi
Schematic of classifications of Protective Textiles
Flame retardant o Kermel® and Kermel® / Viscose
fabrics for flight suits, station wear and turnout gear.
o Nomex® for military applications o Molten Aluminum splash protective
fabric. o Electrical Arc
Ballistic protection o p – Aramid woven fabric for hard
and soft ballistic applications Lint free antistatic
o Continuous filament polyester / carbon fabrics
Medical textiles o Systemic and non systemic
antibacterial and antistatic fabrics for surgeons gowns, scrubs and warm up jackets.
Chemical protection o Liquid chemical protective fabrics
UV protection o Fabrics that offer a UPF rating for
the wearer. Industrial work wear
o Component fabrics for chain saw protection
o freezer suits o waterproof clothing
Military textiles o Uniformso Parachutes
Materials & Technologies
Processing technologies for specific protective clothing are different, the main processes generally include:
Material manufacturing or selection; Producing fabrics and other related items; Finishing, and Clothing engineering.
Schematic of materials and technologies for manufacturing protective textiles
Steps in selection of protective clothing materials
Step 1: Assess hazards
Type of hazard(s) Severity of the hazard
Step 2: Identify relevant standards, specifications, or guidelines
With well defined performance requirements Not well defined performance requirements
Steps in selection of protective clothing materials
Step 3 Screen materials based on protection performance of fabrics, e.g.
• Cold climate protection performance• Chemical protection performance• Biological protection performance• Flame and thermal protection performance• Mechanical protection performance
Step 4 Select materials based on other major factors
• Job performance• Comfort• Cost• Durability• Use, care & maintenance
AGENDALook at some aspects related to: Extreme old protection Chemical & Biological protection Radiation protection Electrical protection Heat & Flame protection Mechanical protection High visibility Protection
Extreme COLD PROTECTIVE CLOTHING
Hazards of Extreme Cold Climate Increased incidence of Arthritis,
Rheumatism and Bronchitis Cold metal injury Hypothermia - one of the serious
hazards of cold exposure Frostbite
Comfort & Survival Factors in Cold Protective Clothing
1. Physiological Factors – Metabolic heat output – Perspiration rate
2. Environmental Factors – “Wind Chill”– Relative Humidity or Dampness of the
Environment
3. Fabric Factors – Thermal insulation– Air permeability– Moisture vapour permeability
4. Design of the Fabric Assembly
The human heat balance equation
Appropriate protection against cold is provided when the human body is in heatbalance at acceptable levels of body temperatures (for example skin and coretemperatures).
This implies that heat losses are equal to metabolic heat production.
The following equation describes the heat balance.
where S is the rate of change in body heat content, M is the metabolic heat production, C is the convective heat exchange, R is the radiative heat exchange,E is the evaporative heat exchange,and RES is the respirative/airway heat loss, all in W/m2.
Thermal insulation
Evaporative resistance
Wind resistance
Water resistance
Measurements of clothing performance
Category of Fibres which provides Thermal Insulation
A. Heat Insulating - to entrap as much air as possible. - Low compressibility and high resilience - Conventional fibres, hollow fibres & high
bulk fibres
B. Heat Absorbing
- to maintain the microclimate inside the clothing
- Solar radiation absorbing fibre and fibres containing ceramic particles to absorb IR radiation
C. Heat Storing
- Phase change materials
Types of Layer- Combination Outer layer should provide adequate
resistance to wind penetration & should be water vapour permeable
Next-to-skin layer of the garment should wick the liquid sweat away from the body rapidly
Middle layer(s) should provide the main insulation. Body heat should be reflected back using a inner reflective layer.
Structural Model of a Cold Weather Protective Clothing
Laminates with Aluminum Film
Engineered Fibres• An unique polyester fibre such as Primaloft • Air pockets increases the thermal resistance and
help it to resist the passage of water while allowing body moisture in form of water vapour to escape
Insulation through Incorporation of Integrated Heating Panels
• Light weight, washable heating panels
powered by batteries are laminated in the fabric
Smart Polymeric Membranes
• Laminated fabrics made from monolithic breathable membrane which react to build up of heat and moisture
• As the microclimate temperature rises, the openings between the polymer molecules in the membrane expand, thereby increasing the fabric moisture permeability. As the temperature drops the pores in the fabric close, thereby trapping heat.
Chemical Protection
Chemical Hazard
• Affects human based on its characteristics and mode of entry
• Chemicals present a variety of hazards such as toxicity, corrosiveness, flammability, reactivity, and oxygen deficiency
• Routes of chemical entry into the human body are oral, respiratory, and dermal
• Dermal exposure considered primary mechanism of chemical entry through human body
Chemical Resistant Clothing
• It provides an effective barrier between the chemicals used & area of the body to be protected• No single material will protect against all chemicals
Appropriate chemical resistant clothing must demonstrate:
No penetration
No significant degradation
Low permeation rate
Chemical/Biological (CB) warfare agents and their effects
To design and to fabricate effective CB protective clothing, it is necessary tohave an understanding of the hazardous threats that must be prevented fromreaching the wearer.
CWAs are defined as natural or synthesized chemical substances, whethergaseous, liquid or solid, which might be employed because of their direct toxiceffects on man, animals and plants. BWAs are microorganisms (viruses and bacteria) or toxins derived fromliving organisms.
They are used to produce death, or incapacitation in humans, animals, or plants. Typical effects of selected CWAs are listed in Table given in the next slide.
Chemical and biological protection
Typical effects of toxic chemicals, microorganisms, and toxins
There are basically four different types of CB Protective Materials. Figure illustrates the differences in their protective capabilities.
Different types of protective materials
Examples of Chemical Protective Clothing
Three layers outer fabric, sorptive layer and inner layer
Layers of Protective Clothing
• Outer shell is water repellent layer protecting from liquid chemicals• Sorptive layer is soul of protective clothing absorbing liquid & air borne chemicals• Inner layer provides comfort to the wearer
Development of Chemical Protective Clothing
Polyester fabricCotton NonwovenActivated carbon Cotton NonwovenCotton fabric
• Formed by five layers• Outer shell made of polyester as it has low absorption of 2% & provides good strength to the fabric and polyester has a good resistance to lab grade chemicals• Inner layer is made up of cotton fabric as it gives good absorbency and comfort• Middle layer comprises of activated carbon sandwiched in cotton nonwoven
Chemical Protective Clothing
CPC Garment materials
• Textiles
• Unsupported rubber or plastics
• Microporous film basics
• Adsorbent-based fabrics
• Coated fabrics
• Plastic laminates
• Combinations
The use of excellent protective materials, effective closures, and ergonomic survival equipment for an individual will be meaningless and unproductive without proper garment designs.
There are different garment designs given as follows:
Coverall or one-piece garments
Two-piece garments
Undergarments
Multilayered garments
Closure system, components, and systems
Clothing system designs
UV exposure and human skin
Effect of UV rays on different types of skin
Radiation Protection
Ultraviolet radiation band
UVA(320 to 400 nm)
UVB(290 to 320 nm)
UVC(200 to 290 nm)
Causes little visible reaction on skin but decrease immunological response of skin cells
Responsible for development of skin cancers
Totally absorbed by atmosphere & doesn’t reach the earth
Radiation Protection
Fabric's ability to block UVR dependent on several parameters:
Principal Parameters
Fiber Chemistry Fabric Construction Moisture content Wet Processing History
WeightThicknessPorosity
Dye Concentration
FluorescentWhitening Agents
UV-absorbers
Textiles as protection from ultraviolet radiation
Schematic representation of a textile as a barrier to UV radiation
Electrostatic Protection
The term `electrostatic' or `static electricity' refers to the phenomenon associated with the build up of electrical charges generated, for example, by contact and/or rubbing of two objects. Static electricity is generated by unbalancing the molecular configuration of relatively non-conductive materials.
Discharge of static electricity
In principle, there are three methods for neutralizing charges on insulators:
conductance through the bulk of the material conductance along the surface of the material the attraction of oppositely charged ions from the air
Measurement techniques
There have been two main approaches to assessing the electrostatic propensity of textile materials.
One is to measure the charge built up on a clothed person or the electrical capacitance of a body (human-body model)
The second is to measure some electrostatic characteristics of textiles (e.g., surface resistivity, charge decay rate, peak potential, etc.) in small-scale tests.
The most common way to confer anti-static properties on a fabric is to incorporate conductive fibres/yarns.
Common conductive elements used in
fabrics include carbon, copper, silver, stainless steel or metallic salts.
The choice of conductive product will
partly depend on the end use and the required level of static protection.
Modern ESD-textiles
• Many ESD-garments are made of heterogenous composite fabrics where a grid or stripes of conductive threads are present inside an insulating matrix of cotton, polyester or mixtures of these materials.
• The conductive threads are more and more frequently made by composites, i.e. by a mixture of conductive and insulating fibres.
• There are several variations in both fabric and thread structures.
Gore-tex: Antistatic
Source: AVANTEX 2000