Determination of Fibers Composition in a Blended Fabric

Last Updated on 24/11/2021

Name of the Experiment:
Determination of different fibers composition in a blended fabric

Objective:

  1. Determination the composition of different fibers in the given sample (blended material).

Theory:
To determine the composition of different fibers in a blended fabric we have to apply chemical test. Because there may consist of both thermoplastic and non-thermoplastic fibers. So we cannot different them by physical test such as burning etc. But in chemical test if it dissolves in a specific chemical we can identify that fiber portion of fabric. Now if we weight the sample before dissolving in chemical and after dissolving in chemical we can easily find out the composition of them in the fabric sample.

Determination of Fibers Composition

At last we will apply chemical for the rest fibers to identify it. Suppose the total weight of the fabric sample = a and after dissolving one portion we find the rest weight = b. Then we can find the composition as follow:

…………………………………………………….a – b
Fiber composition of 1st portion = ————– x 100%
………………………………………………-……..a

……………………………………………………..b
Fiber composition of 2nd portion = ————– x 100%
……………………………………………………..a

Atmospheric condition:

  1. Wet condition: 26°C. & Dry condition: 30°C.
  2. Difference between wet and dry bulb = 30°C – 26°C.  = 4°C
  3. So, relative humidity (RH) = 67 %

Working Procedure:

1. At first cut the fabric into equal size of samples.

2. Then take weight of them.

3. Now test with chemicals as follow:

Sample no.   Chemical           Behavior            Remark
      1.     Phenol     Dissolve one portion          Polyester
      2.     H2SO4     Dissolve one portion          Polyester
      3.     HNO3     Dissolve one portion          Polyester

4. Again take weight of the residual samples and test with chemicals as follow:

Sample no.   Chemical              Behavior               Remark
       1.     H2SO4    Dissolve residual portion                Cotton
       2.     HNO3    Dissolve residual portion                Cotton

Calculation:

Total weight of fabric sample = 210 mg

Weight after dissolving one portion = 90 mg

Weight of residual portion = 210-90 = 120 mg

…………………………………………120
Composition of Cotton = ————- x 100%
…………………………………………210

= 57.14%

…………………………………….90
Composition of polyester = ————- x 100%
……………………………………210

= 42.86%

OR,

For Example,

A fabric Wt = 10 gm, (Before Residue),

B Fabric Wt = 2 gm (After Residue)

—————————————–(First Weight – Second Weight)
Composition of Cotton = —————————————————— x 100%
————————————————–(First Weight)

= {(10-2)/10} x 100%

= 80% (Cotton)

———————————————Second Weight
Composition of Polyester = ————————————————— x 100%
———————————————(First Weight)

= 2/10 x 100%

= 20%

Result:
The blended fabric consists of cotton and polyester. Here polyester is 42.86% and cotton is 57.14%.

Conclusion:
I would like to thank our respected teacher for the important instructions. I am also grateful to our lab assistants for their kind help. This experiment helps me to know about the fibers composition in a polyester cotton blended fabric that is very important for textile testing. I think this will be very helpful in my future life.

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3 thoughts on “Determination of Fibers Composition in a Blended Fabric”

  1. Dear Sir / Reader
    You can also apply below formula and example. Below mentioned Formula is right is per the calculation below example,

    For Example,
    A fabric Wt = 10 gm, (Before Residue),
    B Fabric Wt = 2 gm (After Residue)
    (First Weight – Second Weight)
    Composition of Cotton = ——————-———————- x 100%
    (First Weight)
    = (10-2)/10*100%
    = 80 % ( Cotton)

    Second Weight
    Composition of Polyester = ——————-———————- x 100%
    (First Weight)
    = 2/10*100%
    = 20%

    Please Confirm your formulas for blend.

    Reply
  2. Is there any tolerance in this method of calculating the blend composition of the fabric ?
    I have to match 58% Wool out of 100% as mentioned in some document but after this method I am getting 56% Wool out 100% , Is it okay or Am i performing this method wrongly ?

    Reply

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