Apparatus for Measuring the Dynamic Mechanical Properties of Polymeric Materials between 4° and 300°K

An apparatus to measure the dynamic mechanical behavior of polymeric materials from 4°K to room temperature and at frequencies in the mid-audio range is described. The specimen is driven in its fundamental longitudinal mode of vibration by a transducer which is coupled to the sample by a glass fiber. The lower end of the sample, which hangs vertically, is coated with a thin layer of iron filings. A small permanent magnet is rigidly supported close to and directly below the lower end of the specimen, and a pickup coil detects the motion of the latter. This apparatus uses either the free decay or bandwidth method of determining the internal friction Q−1 and values as low as 6×10−6 have been obtained. Measurements from 8° to 300°K for lead and from 20° to 130°K for polystyrene are reported.