1. SOLIDS CONTENT IN DEHYDRATED NITROCELLULOSE

1.1 PREPARATION OF SAMPLE

A representative sample of nitrocellulose is spread out on an aluminum tray and any aggregates are broken by rubbing the sample gently between the hands. The speed of handling is essential to avoid evaporation of the damping medium.

1.2 PROCEDURE

Thirty to forty gm of the prepared sample are weighed into a tared aluminum dish with close fitting lid. The lid is removed and the dish is placed in a water jacketed oven maintained at 75-80^oC. After 4 hours the dish is cooled in a dessicator, the lid fitted and the whole is weighed. The heating cycle is continued until constant weight is attained.

The dry nitrocellulose after test should be immediately wetted with water and destroyed.

2. WATER IN DEHYDRATED NITROCELLULOSE

2.1 PROCEDURE

In a dry tared weighing bottle 1.0-1.5 gm of prepared sample is taken and weighed accurately. 5 ml of anhydrous methanol is added using a 5ml pipette. The bottle is fitted in the Karl Fisher titration assembly and the mix is titrated with K.F. reagent. A blank titration is also carried out with 5 mi anhydrous methanol without the sample.

Where f is the factor for the K.F.reagent.

2.2 DETERMINATION OF FACTOR FOR K.F. REAGENT

In a tared weighing bottle 0.10-0.15 gm of sodium acetate is taken and weighed accurately. Titrate it with K.F. reagent until a first permanent reddish tinge is observed.

3. ACIDITY IN NITROCELLULOSE

3.1 PROCEDURE

2 gm of dried Nitrocellulose (following the procedure given in 1.2) are weighed accurately and taken in a clean, dry 250 ml stoppered conical flask. To this, 90 ml of acetone is added, the stopper returned and the flask is agitated till Nitrocellulose dissolves. 10 ml of distilled water is added and the flask is shaken to dissolve any precipitated Nitrocellulose. To the solution, 0.5 ml of mixed indicator (neutral red and bromocresol green) is added and the solution is titrated with 0.01 N NaOH until a green colour appears. A blank titration is carried out using 90 ml of acetone, 10 ml of distilled water and 0.5 ml of the indicator.

Where f= Factor of 0.01 N NaOH used.

4. NITROGEN CONTENT IN NIROCELLULOSE

4.1 APPARATUS

There are several methods for the determination of the nitrogen contents, but it is usually done using lunge nitrometer. For details of the apparatus refer to IS 1091- 1976, ‘Specification for nitrocellulose'.

4.2 PROCEDURE

About 0.56-0.62 gm of the dried sample (following the procedure given in 1.2) is taken in a tared weighing bottle. The sample is further dried for 4 hrs. in a water oven maintained at 75-80 ^oC. The weighing bottle with the sample is then cooled in a dessicator over calcium chloride and weighed accurately. The difference gives the mass of the material. 5ml of Analar sulphuric acid (94.5%) is added into the weighing bottle & the mass is made into slurry with a glass rod. The slurry is transferred into the cup of the Nitrometer & drawn into the Nitrometer by operating the stopcock taking care to avoid sucking air into the reaction tube. The weighing bottle & the cup of the Nitrometer are rinsed several times with 94.5% sulphuric acid using a total of 15ml for dissolving and rinsing. The reaction mixture is allowed to stand in Nitrometer arm for 15 minutes & then shaken vigorously for 2 to 3 minutes. The gas generated is allowed to cool to room temperature & the volume is measured under atmospheric pressure by adjusting the leveling tube .

where V = volume of gas in ml.
          P = corrected barometric pressure in mm of mercury.
          t = room temperature in ^oC.
          W = weight of the dried material taken.

5. BERGMANN & JUNK TEST FOR STABILITY OF NITROCELLULOSE

5.1 APPARATUS
For details of B&J bath & reaction tubes assembly refer to IS: 1091-1976, ‘Specification for Nitrocellulose’.

5.2 PROCEDURE

The bath is filled with glycerine water mixture (adjusted to boiling to point of 132± 0.2^oC ) & the copper tubes with liquid paraffin to the level 50mm below the top of the cover plate when reaction tubes are inserted to a depth of 15cm. The bath is heated and maintained at 132± 0.2^oC.

About 10 gm of prepared sample (as given in 1.1) are dried for 4 hrs at 65-70^oC in a water oven & cooled in a dessicator over calcium chloride. 2gm each of dried sample are weighted accurately in two portions & transferred into the reaction tubes, brushing down any material adhering to the sides. The samples are compacted gently by pressing to 5cm height. A third reaction tube is set apart as blank. In each of the head –pieces, 15 ml of water is filled & these are fitted to the reaction tubes using 3-in–1 oil at the joints. The reaction tubes are then lowered into the bath with suitable holders. After two hours the tubes are raised up & allowed to cool for about 1 hr. Water in each cup is transferred into a conical flask, then rinsed with 25 ml distilled water & rinsing added to the flask. 20ml of standard 0.1 N hydrochloric acid is added to each reaction tube and to the blank. The tubes are stoppered and shaken vigorously to from uniform slurry. The content of the tubes are transferred to the corresponding flask with the rinsings. To each of the conical flasks 25ml of 0.1 N sodium hydroxide is added and the excess alkali is titrated with 0.1 N HCI using methyl red methylene blue mixed indicator.

where f = factor of 0.1 N HCI

6. VISCOSITY OF SOLUTIONS OF NITROCELLULOSE IN 95% V/V AQUEOUS ACETONE

The viscosity of Nitrocellulose solution is determined by the failing –sphere method using a steel ball of 1.58±0.01 mm diameter.

6.1 APPARATUS

The details of the viscometer have been given in IS: 1091-1976, 'Specification for Nitrocellulose’.

6.2 PROCEDURE

A solution of the requisite concentration is prepared by adding a fixed weight of dried Nirtrocellulose (see table below) in 100 ml of 95% v/v aqueous acetone (relative density 0.8097 at 20^oC) taken in a glass tube 45 cm long & 2.5cm internal diameter. The tube is securely stoppered, shaken by hand to prevent the caking of the Nitrocellulose into a hard mass than rotated on a wheel untill the number is homogenous and free from any lumps. The solution is transferred to the viscometer, which is stoppered and in a vertical position in a thermostat maintained at 20±0.1^oC. The solution is allowed to stand until quite free from air bubbles and it has attained the temperature of 20±.1^oC. The stopper of the viscometer is then replaced by the one carrying the release tube and the steel ball introduced into the solution through this device. (The time of fall of the through 15 cm is noted).

Similar determination is made using castor oil of known viscosity in place of nitrocellulose solution.

6.3 CALCULATION

where T= Time of fall (in seconds) in the nitrocellulose solution

          T₁ = Time of fall in the castor oil
          S  = Density of steel ball
          S₁ = Density of Nitrocellulose Solution at 20^oC
          S₂ = Density Of Castor Oil (Viscosity of Castor Oil at 20^oC =9.65 Poise)

SAMPLE SIZE FOR FALLING SPHERE METHOD OF VISCOSITY DTERMINATION