Wednesday, November 14, 2018
FABRIC PROPERTIES PART - III
13 - Fabric pilling: when the fabric is used for garment, flat sheet, fitted sheet, car sheeting, table linen etc, it passes under various kinds of situations like rubbing, stretching, lighting, raining etc. the rubbing of the fabric badly affect the fabric surface. This rubbing situation generates balls on the fabric surface. Thus we can say that the formation of the balls on the fabric surface during fabric wear due to the entanglement of protruding fibres is termed as pilling. These balls on the fabric surface form due to rubbing. The pilling of the fabric is always a major fabric quality issue because it directly affects the fabric surface. Some factors influencing fabric pilling are given below:
Yarn quality: the quality of yarn to be used in the fabric has a major impact on pilling. The yarn having low hairiness always poses better pilling resistance. The combed or compact yarn helps to improve the pilling resistance of the fabric. The yarn spun from fine and long-staple fibres always give high pilling resistance. The spun yarn always poses better pilling resistance than continuous filament yarn.
Type of material: natural fibres have better pilling resistance than man-made fibres. The re-generated fibres also pose poor pilling resistance.
The degree of twist of yarn: the optimum amount of twist present in the yarn helps to improve the pilling resistance of the fabric because the degree of twist helps to hold the fibres together in the yarn and they do not come out of the yarn during rubbing of the fabric surface.
Weave of the fabric: the weave of the fabric has little impact on the pilling resistance of the fabric. The weave having more interlacing points shows better pilling resistance of the fabric. The plain weave poses better pilling resistance than twill or satin weave because the short float length prevents to come out the fibres on the fabric surface. The weaves having a longer float length always result in the form of poor pilling resistance.
Count and construction of the fabric: the effect of the count and construction of the fabric can be understood by bellow example:
Suppose that two fabrics have identical warp and weft counts. In this case, the fabric having more E.P.I. and P.P.I. will show better pilling resistance because of the firmness of the fabric.
Suppose that two fabrics have identical E.P.I and P.P.I.
In this case, the fabric having a coarser warp count and weft count will show improved pilling resistance in the fabric.
14 - Drape coefficient of the fabric: it is a very important characteristic of the fabric. It prescribes the fabric deformation by gravity when it is allowed to hang under its own weight. It is the ratio of the difference between the area of the draped sample and supporting disk to the difference between the area of the specimen and the supporting disk. Its value becomes always less than one. The low value of the drape coefficient shows the good draping properties of the fabric. Some factors affecting the drape coefficient of the fabric are given below:
The weight per square unit of fabric: the weight per square unit of the fabric has a direct impact on the drape coefficient of the fabric. The fabric has a lower weight per square unit always poses better draping properties.
Count and construction of fabric: if the count of the yarn is the same for two fabrics, the fabric having higher threads count per square inch shows poor draping properties.
If the threads count per square inch is the same for two fabrics, the fabric having a coarser yarn count gives poor draping properties.
Type of material: type of material to be used in the fabric has a direct impact on the fabric. Cotton fibre gives better draping properties than flax fibre. The soft material always shows better draping properties.
Weave of the fabric: the loose weave or the weave having low interlacing points give improved draping properties. The plain weave shows poor draping properties than satin or twill weave because of short float length.
15 - Moisture absorbency: the moisture absorbency of fabric is a very important property of the fabric because it is directly associated with other properties of the fabric. The ability of a fabric to pick up moisture. When a fabric comes into direct contact with moisture, it starts to absorb moisture. The rate of pick up the moisture and amount of absorbed moisture differ for different fabrics. The consumer can compare the moisture absorbency of two different fabrics as follows:
Take two fabric swatches of the same size and weight. Take a beaker and fill it with distilled water. Drop the first fabric swatch in the beaker and record the time when the fabric gets completely wet. As the fabric starts to dip into the water record the time again. Now repeat this process with another fabric swatch. Now make a comparison between the two fabrics. The fabric, which is taking less wetting and dipping time, will show better moisture absorbency.
The factors affecting the moisture absorbency are given below:
The degree of yarn twist: the amount of the yarn twist plays a very important role in the moisture absorbency of the fabric. A low twist yarn always has more air space in it. As the amount of twist increases, the yarn becomes more compacted and the airspace in the yarn is also decreased. Due to the reduction of airspace in the yarn, the moisture absorbency was also reduced. Thus we can say that the moisture absorbency of the fabric is inversely proportional to the degree of yarn twist.
Count and construction of the fabric: the effect of the count and construction of the fabric can be understood with the help of the following examples:
Suppose that there are two fabrics A and B.
And both have been woven with a similar count.
Fabric A has greater threads per square inch (EPI and PPI) than fabric B.
In this case, fabric A poses poor moisture absorbency because airspace in this fabric is decreased.
If two fabrics have similar threads per square inch (EPI and PPI), then the fabric woven with fine count yarn shows better moisture absorbency because the airspace in this fabric is increased.
Note: now these days, spinners have developed air rich yarn, which gives improved moisture absorbency of the fabric. This yarn is also known as hollow yarn.
The weaver can improve the moisture absorbency of the fabric without changing the count and construction of the fabric with the help of this air rich yarn.
Type of material used: the type of material also plays a decisive role in the moisture absorbency of the fabric. Since we know the synthetic materials are hydrophobic in character, therefore synthetic material always poses poor moisture absorbency. The yarn made of long-staple and fine fibres poses better moisture absorbency of the fabric. The fabric made of spun yarn has better moisture absorbency than filament yarn because of the much air space present in the spun yarn. The multifilaments yarn has better moisture absorbency than monofilament yarn.
Weave: the weave of the fabric also has a high impact on the moisture absorbency of the fabric. Since we know that the plain weave has minimum airspace due to short float length, therefore it gives poor moisture absorbency. The satin and twill weaves show improved moisture absorbency due to bigger float length and airspace.
16 - Water repellency: The water repellency of the fabric is the ability to resist the fabric to absorb moisture. The factors affecting the water repellency are given below:
GSM, yarn count and construction of the fabric: The fabric having higher GSM does not always repel more water than lighter GSM fabric. The water repellency of fabric is directly associated with the airspace present in the fabric. The higher GSM fabric having the lowest possible airspace poses better water repellency. If the heavyweight fabric has more air space than lightweight fabric, the lightweight fabric will show better water repellency because of the lowest air space present in it. Generally, in heavyweight fabrics, the end to end or pick to pick gap minimizes up to the lowest possible level, hence the heavyweight fabric shows better water repellency.
The water repellency of fabric has great concern with the yarn count and construction of the fabric.
If the two fabrics have equal threads per square inch, then the fabric woven with a coarser count will show improved water repellency. If two fabrics have similar warp and weft counts, then the fabric having more threads per square inch will show better water repellency. This thing happens due to the airspace present in the fabric. Thus we can say that the water repellency of the fabric is inversely proportional to the airspace present in the fabric.
Type of material used: the material having hydrophobic nature always shows better water repellency. Synthetic fibres have better water repellency than natural fibres. The continuous filament yarn shows improved water repellency in comparison to synthetic spun yarn. The monofilament yarn always poses better water repellency than multifilament yarn.
The degree of yarn twist: the degree of yarn twist also influences the water repellency of the fabric. As the amount of twist increases, the airspace also decreases in the yarn. Now the yarn becomes more compact. In this way, the increased degree of yarn twist helps to improve the water repellency of the fabric.
Weave: the weave of the fabric has a great impact on the water repellency of a fabric. If two fabric has all fabric parameters except weave, then the fabric having plain weave will show better water repellency than satin or twill weave because of minimum possible air space present in the plain weave fabric.
17 - Thermal conductivity of the fabric: The ability of the fabric to transfer the heat from the higher temperature to the lower temperature surface by conduction is termed the thermal conductivity of the fabric. The thermal conductivity of a fabric is the ratio of the heat energy transferred per second per unit surface area of the fabric to the temperature difference. It is measured in watts per second per square metre. It mainly depends upon the following factors:
GSM, yarn count and construction of the fabric: Since we know that the GSM, yarn count and construction of the fabric directly affect the airspace present in the fabric, therefore the fabric having minimum space poses poor thermal conductivity of fabric because the lowest air space prevents to transfer the heat from higher temperature to the lower temperature.
Type of the material used: the type of material used also has a great concern with the type of material used. The fabric made of good heat conductor material always gives a better thermal conductivity of the fabric. The cotton fibre shows better thermal conductivity than wool fibre. The fabric made of continuous filament yarn shows better thermal conductivity than staple yarn. The man-made fibres show better thermal conductivity than natural fibres.
18 - Light permeability of the fabric: The ability of the fabric to allow the degree of light to pass through the fabric is called light permeability of the fabric. It depends upon the construction of the fabric, type of material of the fabric etc. the fabric having more airspace always give better light permeability.
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