Apparatus for the Measurement of Shear Modulus and Internal Friction between 4.2 and 100°K

Abstract

An apparatus has been constructed to measure the shear modulus and logarithmic decrement of polymers from 4.2 to 100°K. The apparatus consists of a small torsion pendulum suspended on a rigid support at the bottom of a large glass Dewar vessel. After cooling to 4.2°K with liquid helium, the pendulum warms up at an initial rate of 0.1° per minute. Torsional oscillations of the pendulum are excited electrically and recorded photographically. The estimated accuracy of the modulus and logarithmic decrement is ±5.0%. Measurements of the shear modulus and logarithmic decrement have been made, from 4.2 to 100°K, on a series of tetrafluoroethylene‐hexafluoropropylene copolymers.