APPENDIX B
PRACTICAL PLASTOMETRY
The measurement of the flow of plastic substances resembles
that of viscous substances in most respects, but since plastic
substances do not drain like liquids, it is convenient to measure
the volume (or weight) of substance extruded. For this purpose
the plastometer, shown in Fig. 30, p. 77, has been designed to
replace the viscometer. It consists of a top A, container 5, and
base C with capillary D and receiver E. The top consists of a
square plate of brass, through which the pressure is admitted by
means of a copper tube F, which is enlarged at the end to make it
convenient to connect with the pressure. The rubber gaskets H
and / enable one to make the apparatus gastight, when the
thumb-screws are screwed down. A brass pin K, brazed into the
top, passes through the rubber gasket and into a hole in the body
of the container. On the opposite side of the container, a small
copper tube passes through the top, through the rubber gasket,
and into a hole which extends all of the length of the container,
and into the lower end of which a short piece of hollow copper
tubing is affixed. This tube in turn passes through the second
rubber gasket J leading into the base C, thus affording a connec-
tion between the atmosphere and the receiver while the plas-
tometer is immersed in the bath.
The receiver is made of glass and with a flat bottom so that it
will sit upright. It is held in position by means of the rubber
collar M. The rod G is attached to the container in order that
the plastometer may be supported by the frame shown in Fig. 89.
Through the base, there extends the capillary tube D, whose
ends have been ground off flat and whose dimensions are known.
To cement the capillary in position it is cleaned carefully with
chromic acid mixture and dried without touching the part to be
soldered. It is "tinned over" in the usual manner and soldered
in place, the space N being filled with the alloy. Two parts
bismuth, two parts lead and one part tin has been found satis-
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