Patent ID: 7526946

Claim:
A rheometric device for determining shear rate in an entangled polymer sample that is subject to a stick-slip transition, the device comprising: a tube having an open end, a closed end, an inside wall and an inside back-wall, wherein the tube comprises two members having semi-circular cross-sections divided along the longitudinal axis of the tube, wherein the tube is capable of receiving a piston at the tube's open end, while maintaining a gap between the inside wall of the tube and the piston, wherein the gap is capable of containing a molten polymer sample; a means for maintaining the polymer sample in a molten state; the piston having a first end and a second end, wherein the first end enters the tube before the second end, and wherein the position and/or speed of the piston is monitored; a means for driving the piston with a known constant force and speed into the tube while the tube contains a molten polymer sample; a means for recording piston speed and/or position as a function of time; and a means for recording the force applied to the piston.