Helical barrel rheometer

A rheometer for measuring at least one rheological property of a composition comprising:

• a. a tubular housing member having an inner surface and an outer surface;
• b. a helical flange disposed on the inner surface of said housing member;
• c. a rotor disposed concentrically within said helical flange and abutting said helical flange while maintaining sliding contact with said flange, wherein said rotor and said helical flange define a helical channel therebetween, said helical channel having an entrance, an exit, and at least one flight therebetween;
• d. means for rotating said rotor;
• e. means for introducing said composition into said entrance o f said channel;
• f. means for removing said composition from said exit of said channel:
• g. means for measuring a pressure difference of said composition between an upstream location and a downstream location in said channel, situated at least one flight apart within said helical channel, wherein said upstream location is disposed downstream of said entrance of said helical channel, and wherein said downstream location is disposed upstream of said exit of said helical channel;
• h. means for measuring temperature of said composition at a point between said entrance and said exit of said helical channel;
• and
• i. means for controlling a temperature of said composition.

A method of measuring at least one rheological property of a composition comprising the following steps:

• a. placing said composition in contact with a rotating surface;
• b. dragging said composition in contact with said rotating surface along an enclosed helical path which is defined by said rotating surface and a stationary helical weir, thereby transporting said composition simultaneously in a rotational and an axial direction, whereby said composition is transported from an entrance to an exit of said helical path;
• and
• c. restraining the transport of said composition in the axial direction at said exit of said helical path while simultaneously measuring a pressure difference between an upstream and a downstream location in said helical path, wherein said upstream location is disposed downstream of said entrance of said helical path, and wherein said downstream location is disposed upstream of said exit of said helical path.