| This thesis involves the design, fabrication and use of an instrument to characterize polymeric materials at high speed. The work comprises a study in the field of mechatronics. Mechatronics is the synergistic combination of precision mechanical engineering, electronics, control systems and computers. Each of these components was required for a different aspect of the instrument; it was only through their synergy that the goal of high-speed operation was achieved. Indicative of a mechatronics approach, the mechanical design included a direct drive actuator, a hardy, simple means of obtaining precision motion. Inertia had to be minimized. The structural integrity of the design had to be analyzed and verified. Wideband, low noise, electronics were used in the feedback control loop and for the sensors that measured various mechanical variables. A linear feedback control system gave the instrument, the reference signal tracking, disturbance rejection and robustness to unmodeled dynamics required for its operation. This control system, therefore, provided the system functionality for the mechanical components. Finally, a computer system was used for data acquisition, parameter model determination and reference signal generation. The whole instrument was clearly more than the sum of its component parts.; The primary scientific advance from this work comes from the fact that this instrument enables a high-speed characterization of polymers with a precision not previously available. The instrument subjects the polymer to squeezing flow, a type of flow pattern more complex than shearing flow and characteristic of many engineering processes. The instrument measures the viscoelastic rheological properties of the polymer under this flow regime at high system speeds (high rates of strain). Further, the instrument characterizes the cohesive properties of the polymer under high-speed transient extension. Finally, the instrument measures the adhesive properties of the polymer in compressive contact with various substrates on very short time scales. |
