A Proposed Method of Improving the Process of Manufacture of Smokeless Powder

Linus Pauling, Pasadena, California, November 10, 1940

Judith Rooks

1. Smokeless powder grains sometimes crack, causing increase in the rate of burning of the powder charge and consequent error in the path of the projectile. X-ray diffraction photographs of powder grains show a rather high degree of orientation of crystallites, and hence of the long nitrocellulose molecules. This would be expected to lead to longitudinal checking and cracking.

A Method of Improving the Process of Manufacture of Smokeless Powder

Linus Pauling, Pasadena, California (3500 E. Fairpoint St.), Sunday, November 10, 1940

1. I learned from the N.D.R.C. meeting in Washington which I attended, from Dr. Farnumat [?] Indian head, and from books (Worden, Marshall, etc.) that sometimes smokeless powder grains crack, causing increase in rate of burning of the powder charge and consequent error in the path of the projectile. X-ray photographs of powder grains made by Dr. R.B. Corey at my request showed a rather high degree of orientation of crystallites, and hence of the long-chain molecules. This would be expected to lead to longitudinal checking and cracking.

2. I have invented an improvement in the process of manufacture of smokeless powder rains and in similar manufacturing processes designed to increase the resistance of the grains to checking and cracking by the production of grains in which the orientation of crystallites and long-chain molecules is such as to give the grains suitable mechanical properties.

3. This improvement in the process of manufacture may be achieved, for example, by rotating the press head (the nozzle) or a portion of the press head during the extrusion of the colloid in the form of a rope. The rotation may be continuous, in one direction, or oscillatory, first in one direction and then in the other. The rate of rotation should be such as to lead to the desired orientation.

[Figure 1. Diagram of device described in bullet point 4.]

4. A device to do this is shown in Figure 1. This figure represents the head (the nozzle) of a press for extruding the smokeless powder rope. A is a perforated plate through which the colloid is forced by pressure, emerging on the right side as strings. B is the nozzle tube. This is to be rotated by an applied torque (through a mechanism which is not shown in the drawing) at such a rate that the extruded strings are coiled so that their longitudinal axes are no longer essentially parallel to the axis of the nozzle.

5. If difficulty is experienced through the forcing of colloid into the space at E between the press A and the rotating nozzle B, some lubricant or suitable substance (alcohol) might be applied under suitable pressure so as to prevent the entrance of the colloid into this space.

6. In order that the system of rods C which produce longitudinal holes in the rope may rotate to the desired extent with the rotating nozzle B, this system might be attached to A by a support D with a bearing permitting rotation at the point F or at some other suitable place. This would eliminate the disadvantage of attaching the system C directly to the nozzle B by structures which might so influence the colloid being extruded as to give it unsatisfactory mechanical properties.

7. The system of rods C might be attached to A by a support D with such properties as to permit the rotation of C relative to A by a suitable amount. The device would then be operated by causing B to undergo rotational oscillation, rotating first through a suitable angular range in one direction, then through the same range in the opposite direction, and so on.