Determination of Fiber Blend Composition of Polyester – Cotton


Fiber Blend Composition of Polyester – Cotton


This SOPS prescribes a method for quantitative chemical analysis of binary mixtures of polyester fibre and cotton or cellulose fibre in any form, yarn or fabric.

Cellulose Fibres
  • Cotton 
  • Viscose


  • Drying Oven – It shall be capable of maintaining a temp of 105 ± 3°C .
  • Analytical Balance – Capable of weighing an accuracy of 0.0002 g
  • Conical Flask – 250 ml
  • Desiccator
  • Sieve


  • Sulphuric Acid solution Reagent grade, 75 % (m/m) specific gravity 1.67 at 27°C.
  • Diluted Ammonia Solution – Adding 80 ml Concentrated Ammonia (Specific gravity 0.89 )  and making up to one litre with water.


  • Sample weighing about 2.0 to 3.0 g. Cut the yarn into pieces and dissect the cloth into yarn pieces of about 10 mm length.
  • Dry the sample in oven at 105 ± 3°C for 30 min.
  • Cool in a Desiccator and weight them 1 gm sample (W)
  • Treat the weighted out sample taken in a conical flask with 100 ml of 75% sulphuric acid solution.
  • Stopper the flask and shake it carefully to wet out the sample completely.
  • Maintain the flask at room temperature for 30 minutes.
  • Filter the content of the flask through a sieve.
  • wash the residue on the filter sieve with water, diluted ammonia solution and finally distilled water.
  • Dry the residue in the drying oven at 105 ± 3°C to constant weight,
  • Cool in a desiccator and weight them (W1)


Polyester fibre (%) =   W1*100 / W

  • W1 – Dry weight of residue
  • W   – Dry weight of sample

References – IS 3416-1: Methods for Quantitative Chemical
Analysis of Binary Mixtures of Polyester Fibres With Cotton or Regenerated
Cellulose, Part 1: Sulphuric Acid Method



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