water repellency of fabrics

Welcome to our presentation

Md. Yousuf HossainID:131-23-3294

TopicWater repellency of fabric

Definition• water repellent fabrics are those which resist being

wetted by water, water drops will roll off the fabric.

A fabric’s resistance to water will depend on • the nature of the fiber surface, • the porosity of the fabric • the dynamic force behind the impacting water spray.

Distinguish between water-repellent and water-proof fabrics

water-repellent fabrics water-proof fabricsi. Water Repellent Fabrics have open pores and are permeable to air and water vapour.

i. Water-Proof Fabrics have fewer open pores and are less permeable to the passage of air and water vapour.

ii. Water-repellent fabrics will permit the passage of liquid water once hydro-static pressure is high.

ii. Water-Proof Fabrics are resistant to the penetration of water under much higher hydrostatic pressure.

iii. A fabric is made water-repellent by depositing a hydrophobic material on the fibre’s surface.

iii. however. Waterproofing requires filling the pores as well as depositing a hydrophobic material on the fibre’s surface.

Water-repellent fabrics water-proof fabrics

necessity of water repellency property in fabrics

Md. Shamim HossainId: 131-23-3328

Water repellent finishes

• Water repellents are chemical finishes• Resist the penetration of water into the fabric• Permits the passage of moisture or air through the fabric• There are three types of water repellent finishes:

non-durable finishes semi-durable finishes durable finishes

Non-durable finishes• This type of water repellent finish is usually based on

paraffin wax-aluminum acetate emulsion.• non-durable finishes are easily removed in laundering or

dry-cleaning.• non-durable finishes do not provide satisfactory

resistance to liquids.• Examples:

Aquarol AX,Aridex WP,Dryon,Repelex etc

Semi-durable finishes

• These are wax or salt solutions.• They are emulsified off the fabric in laundering.• They ate resistant to dry-cleaning.• Examples:

Bishopel,Dryon A-B,Nalan W etc

Durable finishes• There are several types of durable water repellents, such

as

1. Pyridinium compounds

It is Applied to cotton, linen & viscose rayon fabrics.

It also endures repeated washings as well as dry-cleaning.

It improves the fabric’s appearance.

2. Melamine resins & stearamides compounds

It is used on cotton, rayon etc.

These have excellent repellency and good tolerance to laundering.

3. Silicone compounds

These are excellent water repellents.

The finish is usually more resistance to dry cleaning than to laundering.

Examples: Aerotex, Hydro-Pruf, Zelan, Zepel etc.

Md. Jowel MiahId: 131-23-3377

Several test methods of water repellency of fabrics

AATCC TM22: Water Repellency-Spray Test

AATCC TM35: Water Resistance: Rain Test

AATCC TM42: Water Resistance: Impact Penetration Test

AATCC TM70: Water Repellency-Tumble Jar Dynamic Absorption Test

AATCC TM127: Water Resistance: Hydrostatic Pressure Test

Working procedure of spray test method

• Step-1: The sample fabric is mounted on a metal hoop.


• Step-2: Then the metal hoop attached with sample fabric is fixed on the instrument at 45ᵒ angle.


• Step-3: Now the beaker is filled with 250 cc water.


• Step-4: pour the distilled water into the funnel.


• Step-5: spray the whole quantity of water on the test specimen for a period of 25 - 30 sec.


• Step-6: After spraying has finished the sample holder is removed and the surplus water removed by tapping the frame 6 times against a solid object.

Assessment technique

water repellency of fabrics

Engineering