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STUDENT NAME -ANKIT KUMAR BHATT

INTRODUCTION

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Flame-retardant finishes provide textiles with an important

performance characteristic that is it stopped the propagation of

fiber when it comes in contact with fire.

NEEDS OF FLAME RETARDANTS

Protection of consumers from unsafe apparel

Firefighters and emergency personnel require protection

Floor coverings, upholstery and drapery protection

The military

the airline industry

Types of F.R. Fabric In Industry

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Fabric which has to be padded with F.R.

chemical

Fabric which is made flame retardant at the

time of manufacturing of yarn

HISTORY

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About 450 BC EGYPTIANS used ALUM to reduce

flammability of wood

In 1638 clay & gypsum used for theater curtains.

1821 GAY-LUSSAC mixture of borax & ammonium salt of

phosphoric acid for linen

1913 Perkin gives FR treatment for cotton by using so.

Stannite & ammo. Sulphate.

Mechanisms of flame retardancy

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Combustion:

is an exothermic process that requires three components,

Heat

oxygen

suitable fuel.

Mechanisms of flame retardancy

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Pyrolysis temperature, TP,

At this temperature, the fiber undergoes irreversible chemical changes, producing

non-flammable gases (carbon dioxide, water vapor and the higher oxides of nitrogen and sulfur),

carbonaceous char,

tars (liquid condensates) and

flammable gases (carbon monoxide, hydrogen and many ox disable organic molecules).

Mechanisms of flame retardancy

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the combustion temperature, TC, At this point, the flammable gases combine with

oxygen in the process called combustion, which is a series of gas phase free radical reactions.

These reactions are highly exothermic and produce large amounts of heat and light.

Some combustion Cycle Disruption Techniques

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1. Heat Sink on / in the fiber

2. Insulating Layer

3. Condensed Phase: reaction to produce less flammable volatiles and more residual char.

Combustion Cycle Disruption Techniques

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1. Heat Sink on / in the fiber

by use of materials that thermally decompose through strongly endothermic reactions.

If enough heat can be absorbed by these reactions, the pyrolysis temperature of the fiber is not reached and no combustion takes place.

Examples of this method are

the use of aluminum hydroxide or ‘alumina rehydrate’

and calcium carbonate as fillers in polymers and coatings

Combustion Cycle Disruption Techniques

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2. Insulating Layer to apply a material that forms an insulating layer around thefiber at temperatures below the fiber pyrolysis temperature.

Boric acid and its hydrated salts function in this capacity. When heated, these low melting compounds release water vapor and produce a foamed glassy surface on the fiber,insulating the fiber from the applied heat and oxygen.

Combustion Cycle Disruption Techniques

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Condensed Phase: reaction to produce less flammable volatiles and more residual char.

This ‘condensed phase' mechanism can be seen in the action of phosphorous-containing flame retardants

which, after having produced phosphoric acid

through thermal decomposition,

crosslink with hydroxyl-containing polymers thereby altering the pyrolysis to yield less flammable by-product.

Combustion Cycle Disruption Techniques

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The ‘condensed phase’ strategy includes the described mechanism

of removal of heat and the enhancement of the decomposition temperature as in heat resistant fibers.

Testing of flame retardants The visual timing test- vertically

The 45 degree test – 5 inch distance at such angle

Hoop test- semi circular frame

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LOI LIMITED OXYGEN INDEX is give us some

information about flame retardancy

It is the minimum % of oxygen in oxy- nitro atmosphere require to sustain combustion

L.O.I. = (O2)/(O2+N2)* 100

HIGHER THE LOI MEANS MORE THE FLAME RETARDENT

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Factor affecting the f. resistance Fiber content

Fabric structure

weight

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Problems with flame retardantToxicity

Irritated towards skin

Durability

Flexibility

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Protective clothing for fire fighter (APPLICATION)NATIONAL FIRE PROTECTION ASSOSIATION has set

a fundamental requirement that it’s TPP value must be 35 minimum.

According to NFPA each far. cloth ,, contain three component –

Outer shell

Moisture barrier

Thermal barrier

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Protective clothing for fire fighter As an example LOS ANGELOUS fire department

used-

outer shell –nomex/kevlar in a rip stop weave

Thermal insulator

Moisture barrier

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