Abstract: A rheometer incorporates a blade (1) mounted for rotation about an axis (2). The blade is of twisted form such that it has first and second regions. A first region of the blade (1) substantially at the axis of rotation (2) has a first angle formed by its surface with respect to a plane perpendicular to the axis of rotation such that the surface of the blade in the first region extends substantially parallel to the axis of rotation. A second region of the blade spaced from the axis of rotation has a second angle, different to the first angle, formed by its surface with respect to the plane perpendicular to the axis of rotation.

Abstract: A rheometer for assessing characteristics of materials includes a vessel for containment of a material to be assessed, and a rotor which is, in use, passed through the material contained in the vessel, the rotor being comprised of a plurality of blades disposed at an angle relative to the axis of the rotor shaft. The vessel and rotor are constructed and adapted for rotation relative to one another about an axis and also for relative movement in the axial direction, and least one transducer is provided for determining the rotational and (optionally) axial forces that result from the relative motions(s) of the rotor and the material in order to thereby assess the characteristics of the material.