<p>Torsional oscillator for determining shear modulus of plastics has a first grip for holding one end of the plastics, a second grip for the other end, and connected to an oscillation body and a tempering chamber for the plastics. A transducer which produces an output dependent of the position of the body feeds a variable gain amplifier which in turn feeds a servo motor that pivots the first grip or a non-oscillating part of the transducer about the oscillation axis.</p>
