Mechanical influence of static versus dynamic loadings on parametrical analysis of plasticized ethyl cellulose films.
The object of this study was to investigate the influence of static and dynamic forces on mechanical properties of the biocompatible polymer ethyl cellulose. Similar polymeric films containing 40% (w/w) of the plasticizer dibutyl sebacate were subjected to tensile forces at different velocities. The average Young's modulus and the variation of yield strength, strain, and strain energy at different velocities complied with the pre-established theories of dynamic loadings. The ultimate strength and the yield strength and/or strain displayed linearity with the velocity, though the ultimate strain and therefore, the plastic and/or ultimate working energies proved non-linear pseudo-Michaelis-Menten behavior. The speculation was that achieving the maximum displacement would probably be the most important cause of failure. Finally the most suitable velocity at which the data would obtain the most demonstrable stress-strain diagrams was selected: tensile forces at almost low velocities, best illustrated as static forces, proved immature failure of the specimens during or shortly after the yield; so that the specimen resembled as a brittle material. High velocities of loadings were also avoided since the strain would usually approach the plateau and would therefore disrupt the rational correlation between forces and displacements during the end region of the curve. Copyright © 2010 Elsevier B.V. All rights reserved.DOI: 10.1016/j.ijpharm.2010.11.031