A wave speed meter comprises a pair of relatively rotatable, concentric cylinders with a gap between the cylinders to define a chamber. A viscoelastic fluid is placed in the chamber, and one of the cylinders is suddenly rotationally displaced causing a shear induced wave to be propagated through the fluid filling the chamber between the cylinders. This wave is propagated toward the other cylinder and when the wave reaches the other cylinder the other cylinder moves. The transit time of the wave is determined by measuring the time between the displacement of the one cylinder and movement of the other cylinder as a result of the wave. The distance that the wave travels is known, so that the wave speed can be determined. In the form shown a counter is initiated at the time the one cylinder is displaced, and then disabled at the time when the other cylinder moves, using electro-optical techniques that are simple to utilize because mirrors can be mounted on the two cylinders and the motion of the cylinders can be amplified by properly locating the sensors that sense the beams reflected by the mirrors.
A rheological device suitable for measuring the rate of polymerization of ultraviolet sensitive polymers includes a part of open-ended cylindrical fixtures having removable quartz windows at one end. The upper fixture is adapted with a window which permits light to enter and impinge upon the surface of an elliptically-shaped mirror. Curing is monitored by measuring the elastic and viscous moduli during polymerization.
