Tensile creep modulus, creep lateral contraction ratio and torsional creep measurements on small nonrigid specimens

A torsional creep apparatus incorporating a novel linear bearing to permit simultaneous application of axial and torsional creep stresses to small nonrigid specimens is described. The results of a detailed examination of the capabilities of this apparatus and a comparison of shear creep and recovery compliance data is made (as measured direct in torsion and calculated from the axial and lateral strain data in tension). The measurements were made on isotropic and oriented sheets of low-density polyethylene and the use of oriented, as well as the more usual isotropic, material in such trials is illustrated.