Abstract: A rheometer includes a holder assembly for coupling a test specimen to a motor assembly to effect rotational strain in the test specimen while enabling the determination of axial displacement effected by the test specimen normal to the direction of the rotational strain, the holder assembly having a first member coupled to the test specimen, a second member coupled to the motor assembly, and a suspension arrangement coupling the first member with the second member for simultaneous maximum resistance to relative rotational displacement between the first and second members and minimum resistance to relative axial displacement between the first and second members.

Abstract: A rheometer includes a holder assembly for coupling a test specimen to a motor assembly to effect rotational strain in the test specimen while enabling the determination of axial displacement effected by the test specimen normal to the direction of the rotational strain, the holder assembly having a first member coupled to the test specimen, a second member coupled to the motor assembly, and a suspension arrangement coupling the first member with the second member for simultaneous maximum resistance to relative rotational displacement between the first and second members and minimum resistance to relative axial displacement between the first and second members.

Abstract: On-line rheological measurements are made on a process flowing material, such as a polymer melt, utilizing a rheometer of the type in which an inlet pump delivers a relatively large volumetric flow of diverted process material from a process main stream to an inlet site located in very close proximity to the entrance of a capillary passage, and a metering pump draws a smaller portion of the volumetric flow of the diverted material from the inlet site through the capillary passage for return to the process main stream. The viscosity of the diverted material is measured as a function of the rate of flow of the material through the capillary passage and the pressure drop between spaced apart locations along the capillary passage.

Abstract: On-line rheological measurements are made utilizing a rheometer of the type in which a first metering pump delivers diverted melt from a process main stream to a capillary passage and a second metering pump returns the diverted melt from the capillary passage to the process main stream and the viscosity of the diverted melt is measured by controlling the rate of flow of the melt through the capillary passage to maintain constant the pressure drop between spaced apart locations along the capillary passage and measuring the temperature of the melt in the capillary passage. The measurements may be made while controlling the speed of the second metering pump independent of the speed of the first metering pump to maintain the pressure at the exit of the capillary passage essentially constant.