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Rynhart Research Limited

The Provost, Fellows and Scholars of the College of the Holy and

Gerald E Wardell

Vincent J McBrierty

A method for measuring the AC electrical conductance of a polymeric composite to determine homogeneity of dispersion of a filler is disclosed. The method comprises the steps of applying two spaced apart capacitor plate electrodes closely adjacent to, or onto the surface of the polymeric composite; applying an AC voltage between the electrodes; and measuring the AC current which flows through the polymeric composite from one electrode to the other electrode. The electrodes have a sufficiently large surface area for providing a coupling into the polymeric composite. The coupling shunts the contact resistance of the polymeric composite.

Method for measuring the AC electrical conductance of a polymeric

An apparatus for capacitance or dampness measurement is provided. The apparatus is particularly suitable for continuous determination of dampness over substantially flat surfaces such as roofs, floors, pavements and walls. The apparatus essentially includes a pair of substantially elongate electrodes attached to a casing which has a pair of removable surface engaging wheels a handle for pushing and steering, a pair of grip handles for carrying and maneuvering, and two recesses, one for a power supply and the other for an electronic monitoring apparatus combined with a read-out display means. The electrodes are separated by a gap of approximately 5 cm and are retained on the casing so as not to be taut but to be slightly floppy so as to permit good contact between the electrodes and the surface to be tested. The value of capacitance/unit area of the electrodes in air is preferably in the range 50 pFm.sup.-2 -150 pFm.sup.-2. In use, following the calibration, the apparatus is propelled systematically over the surface to be tested as a manually propelled vehicle. Capacitance readings are taken by observation of the dials of the electronic monitoring apparatus through the opening. When used on walls, the wheels are removed to provide improved contact between the electodes and the wall. In another embodiment, the electrodes also function as tracks, (which are electrically insulated from each other and the casing) for a tracked vehicle. A roller pair for each track, which is endless, is provided.

Apparatus for capacitance or dampness measurements

An NMR test method is provided for determining the homogeneity of dispersion of a filler substance such as carbon black in an elastomer composition such as a rubber, either on an arbitrary scale or by reference to a standard dispersion of optimum homogeneity which is given the value 1.0 on a linear scale. The method involves measuring the intensity of the short component and the total intensity of the proton free induction decay, of a sample of the dispersion deriving the ratio P.sub.t of said intensities, and optionally deriving a second similar ratio P.sub.s from the standard dispersion to permit a value P.sub.t /P.sub.s on said linear scale to be derived.

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Killaloe, Ireland

Gerald E Wardell