Donald J Plazek

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Three tests were used to obtain a basic understanding of the changes taking place in the physical properties of the Hygienic Ultrafil system. The materials studied were raw gutta-percha, gutta-percha points, and the two Ultrafil materials Blue (firm set) and White (regular set) gutta-percha. In the first test a differential scanning calorimeter was used to(More)
Interrupted shear measurements were used to follow the reentanglement kinetics and associated molecular weight dependence for solutions of near-monodisperse polybutadiene (PB). The timedependent recovery of the overshoot in the shear stress was measured for PB having weight-average molecular weights (Mw) equal to 61, 90, 107, and 167 kg/mol, corresponding(More)
Tissue engineering approaches are now being investigated for altering the course of intervertebral disc degeneration (IDD). Because the disease changes the mechanical properties of the load bearing tissues of the disc, viscoelastic tissue behavior is a key measure for comparing the efficacy of treatments. To investigate the basic viscoelastic behavior of(More)
The process of spin-coating to fabricate thin polymer films with high molecular weight can produce samples with entanglement concentrations that are far below the equilibrium value. It is not clear whether or not such low entanglement concentrations are responsible for the depression of the glass temperature in thin polymer films. In this work, we measure(More)
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