Abstract
The effect of thermal history on yielding behavior of atactic polystyrene, isotactic polystyrene, polycarbonate, and polymethyl methacrylate was examined by correlating the deformed microstructure with measured density changes and compressive stress-strain studies. Electron micrographs of bulk polymers and thin films demonstrate the tendency for well-annealed materials to undergo localized shear deformation at 100–1000-Å interspacings, and density measurements show an over-all density increase of about 0.15% upon plastic deformation. Rapid cooling from the melt decreases both the material density (about−0.04%) and the tendency for plastic strain to localize into narrow bands. Compressive stress-strain studies in which the strain rate, test temperature, and thermal history were systematically varied show a semilogarithmic relationship between nominal strain rate and yield stress. These data were analyzed according to an Eyring-type exponential model where the ``shear activation volume'' and the ``activation energy'' were calculated and compared for the ranges of variables studied.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
