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M. Ashraf and S. Riaz
weave structure the textile surface texture could be controlled. The roughness can be
adjusted at submicron level by maneuvering the fiber numbers and composition, yarn
diameter, and weaving mechanism. Thus, due to this micro roughness, hydrophobic characteristics could be granted by application of organic repellents. Until now
different water and oil repellents have been introduced like paraffin waxes, stearic
acid-melamine, silicon and fluorocarbon based repelling agents. Surface energy can
be lowered by different ways like the mechanical incorporation of repellents into
fibrous structure or onto fabric surface filling the fiber and yarn interstices. The
paraffin repellents are integrated in this way. Then chemical reaction of repellent
with textile is another approach to impart superhydrophobicity such as stearic acid.
Silicon and fluorocarbon based repelling agents have been applied in the form of thin
film on fiber surface [24].
These repelling agents could impart hydrophobicity by lowering the surface free
energy of textiles depending upon their chemical composition. A study was conducted in which polyester fabric was coated with siloxane by conventional pad-dry
and cure method. The polyester fabric with 2 μm yarn diameter upon coating with
repellent agent showed superhydrophobicity with WCA 170° and contact angle hysteresis of below 5°. This research was done to validate the claim that microfiberous
textile surface without having nanoroughness can exhibit superhydrophobic properties, because the air trapped inside microfibers was large enough that water droplets
could not be absorbed and rolled off easily at the surface [25].
Paraffin Repellents
The paraffin waxes; known as earliest repellent agents, have been used to make textile
hydrophobic and various researches have been conducted in this regards [26, 27].
These repellents are usually emulsions that contain aluminium, barium, or zirconium
salts of fatty acid normally stearic acid. Because these finishes are making polarnonpolar junction with textile therefore their adhesion could be increased. In this
finishing mixture of repellent the paraffinic part is attracted towards the hydrophobic
region and the polar end is attracted towards the fiber surface. These emulsions have
been applied on textile by padding or exhaustion techniques. Though this finishing make the textile repellent in cost effective way but it increases the problem of
inflammability and also less durable.
Stearic Acid–Melamine Repellents
Another primitive class of repellents that were more durable to laundering without
having much effect on hand feel are mainly prepared by reaction of stearic acid
with formaldehyde and melamine. In these repellent finishes, inherent hydrophobic
nature of stearic acid provides the water repellency to the substrate finished with
these repellants, and the durability of them is due to the N-methylol groups that reacts
with cellulose for permanent binding [28]. Though these repellent agents give durable
M. Ashraf and S. Riaz
weave structure the textile surface texture could be controlled. The roughness can be
adjusted at submicron level by maneuvering the fiber numbers and composition, yarn
diameter, and weaving mechanism. Thus, due to this micro roughness, hydrophobic characteristics could be granted by application of organic repellents. Until now
different water and oil repellents have been introduced like paraffin waxes, stearic
acid-melamine, silicon and fluorocarbon based repelling agents. Surface energy can
be lowered by different ways like the mechanical incorporation of repellents into
fibrous structure or onto fabric surface filling the fiber and yarn interstices. The
paraffin repellents are integrated in this way. Then chemical reaction of repellent
with textile is another approach to impart superhydrophobicity such as stearic acid.
Silicon and fluorocarbon based repelling agents have been applied in the form of thin
film on fiber surface [24].
These repelling agents could impart hydrophobicity by lowering the surface free
energy of textiles depending upon their chemical composition. A study was conducted in which polyester fabric was coated with siloxane by conventional pad-dry
and cure method. The polyester fabric with 2 μm yarn diameter upon coating with
repellent agent showed superhydrophobicity with WCA 170° and contact angle hysteresis of below 5°. This research was done to validate the claim that microfiberous
textile surface without having nanoroughness can exhibit superhydrophobic properties, because the air trapped inside microfibers was large enough that water droplets
could not be absorbed and rolled off easily at the surface [25].
Paraffin Repellents
The paraffin waxes; known as earliest repellent agents, have been used to make textile
hydrophobic and various researches have been conducted in this regards [26, 27].
These repellents are usually emulsions that contain aluminium, barium, or zirconium
salts of fatty acid normally stearic acid. Because these finishes are making polarnonpolar junction with textile therefore their adhesion could be increased. In this
finishing mixture of repellent the paraffinic part is attracted towards the hydrophobic
region and the polar end is attracted towards the fiber surface. These emulsions have
been applied on textile by padding or exhaustion techniques. Though this finishing make the textile repellent in cost effective way but it increases the problem of
inflammability and also less durable.
Stearic Acid–Melamine Repellents
Another primitive class of repellents that were more durable to laundering without
having much effect on hand feel are mainly prepared by reaction of stearic acid
with formaldehyde and melamine. In these repellent finishes, inherent hydrophobic
nature of stearic acid provides the water repellency to the substrate finished with
these repellants, and the durability of them is due to the N-methylol groups that reacts
with cellulose for permanent binding [28]. Though these repellent agents give durable