In both the waxes and the slurries employed in investment casting, the control mechanismsinvolved in the contention between kinetically and thermodynamically driven processes are ofjoint scientific and practical interest. Particularly during the injection of a wax, the temperaturethe material experiences and changes in temperature profile during the injection process can haveeffects on the flow and dimensional characteristics of a wax. An understanding of thesemechanisms allows strategies to be developed that lead to improved process control and surfacedefinition of wax patterns. Controlled stress rheometry and dynamic mechanical analysis (DMA)have been employed to study the behavior of waxes at the onset of congealing under flowconditions in an attempt to measure these effects. Characterization of the wax using controlledstress rheometry reveals phase changes that occur along with linear viscoelastic behaviour.Temperature modulated DMA allows for the investigation of reversible and non-reversiblephenomena in the melting and crystallization region of waxes. Temperature modulated DMAalso provides high sensitivity for small and slow changes in crystallinity, e.g. during recrystallization.The combination of controlled stress rheometry and DMA yields new informationabout local processes at the surface of polymer crystallites.
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