Determination of Water Soluble Matter – Textile materials

Water  Soluble Matter 

SCOPE

PRINCIPLE

APPARATUS

1. Desiccator.
2. Reflux Condenser
3. Oven  – 105° to 110°C
4. Flat Bottom Flask- 250 ml
5. Heating element.
6. Filtration assembly

REAGENTS

1. Distilled water.

CONDITIONING OF TEST SPECIMEN

Prior to test, test specimens shall be conditioned for 24 hours to moisture equilibrium in a standard atmosphere at 65±2 percent relative humidity and 27°± 2°C temperature

PROCEDURE

Preparation of evaporating dish:-

1. Heat the evaporating dish at 110°C in Hot air oven for one hour.
2. Remove the dish and cool in Desiccator.
3. Weigh quickly and note the dry weight of dish

Determination

• Condition the rest specimens to moisture equilibrium in the standard atmosphere and weigh accurately 1 or 2 g of test specimen.
• Put the specimen in the flask and add water to make the liquor to material ratio of 20:1(i.e. 20 ml of water for 1 g of test specimen) for all textiles, except wool.
• If the test specimen is wool, the liquor to material ratio should be, 50: 1
• Connect the flask to condenser and rapidly bring to boiling.
• Continue to boil the liquor under reflux for 60 minutes.
• After one hour, disconnect and remove the flask while liquor is still boiling.
• Immediately close the flask with glass stopper.
• Rapidly cool the flask and its content to room temperature (27±2°C).
• Filter the extracted liquid and wash the residue with amount of water.
• Take the filtrate and washings in previously weighed evaporating dish and evaporate the extract to dryness on a hot plate or steam bath.
• After evaporation, shift the evaporating dish into a hot air oven and dry the residue at 110°C for two hours.
• Cool the dish in a Desiccator and weigh quickly.
• Repeat the process of drying in oven till the weight change between two successive weighing is less than 0.005 gm.

CALCULATION

Calculate the total water soluble matter as follows 

Permissible Error