Density Measurement for Fiber

 Equipment and Reagent:-

ð  10 ML graduated cylinder and either 100 ml graduated cylinder or six 20 ml beakers.

ð  Two liquids of known densities which are miscible in all proportions and, which will, when correctly mixed, give a range of densities from 1.0 to 1.60.

ð  Suggested liquids are

• Carbon tetrachloride (sp. gr. 1.60) and xylene (sp. gr. 0.87)
• Carbon tetrachloride (sp. gr. 1.60) and n-heptane (sp. gr. 1.10)
• Perchloroethylene (sp. gr. 1.63) and xylene (sp. gr. 0.87)

Manipulation:-

ð  Fiber density can be determined in two ways: by using density gradient tube or graduated series of liquids of known densities.

ð  Density Gradient Tube:-

·    It is prepared using 10 ml graduated cylinder, prepare the mixture of carbon tetrachloride and xylene respectively; 90/10, 80/20, 70/30, 60/40, 50/50, 40/60, 30/70, 20/80, 10/90 ml/ml; add carefully 10 ml carbon tetrachloride in to 100 ml of xylene.

·     Add above nine mixtures and pour 10 ml of xylene on top.

·    The mixtures should be added in such a way that one mixture will not penetrate more than depth of 12 ml into previous mixture. 

·     The cylinder will now have a column of liquid, the density of which varies continuously down its length from 1.6 at the bottom to 0.87 at the top.

·    Now, wet out the fibers in warm xylene, dry them, and cut them into very short lengths (1mm).

·     Place them on a sheet of paper and tease them apart so that no fiber is adhering to any other.

·      Then lay them on the surface of the liquid in the cylinder. With a stirring rod, shove the fibers under the surface of the liquid and allow them to seek their level of density.

·       After 10 – 15 minutes, read off the levels at which the fibers float and identify them by referring to the below table.

Table:- Densities of Fibers

Fiber	Density (g/cc)
Cotton	1.50
Viscose	1.52
Wool	1.32
Silk	1.33
Nylon 66	1.14
Nylon 6	1.14
Polyester	1.38