AbstractIn the investigation of the rheological properties of viscoelastic material, a variety of instruments may be employed. The investigation may be concerned either with mechanical properties under “steady‐state” or dynamic conditions or with optical properties such as are determined by flow birefringence techniques. This paper describes representative instrumentation (available at the Franklin Institute Laboratories) suitable for making the above types of determinations. The types of instruments are: (1) a coni‐cylindrical rotational viscometer, (2) a high‐pressure capillary tube viscometer; (3) the Weissenberg rheogoniometer, (4) a jet extrusion instrument, (5) a vibration tester, (6) a torsion crystal instrument, and (7) a flow birefringence instrument. The fundamental principles underlying the instruments which have not been described previously, are
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