The frequency master curves of thermoset and thermoplastic glassy polymers were determined by dynamic mechanical analysis, and the results were simulated by sinusoidal response of the standard viscoelastic model. The elastic and viscous elements of the model were determined and correlated with struc
The viscoelastic behavior of notched glassy polymers
โ Scribed by R.A. Crook; Alan Letton
- Publisher
- Elsevier Science
- Year
- 1993
- Tongue
- English
- Weight
- 515 KB
- Volume
- 44
- Category
- Article
- ISSN
- 0013-7944
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โฆ Synopsis
In the bulk, glassy polymers exhibit a nonlinear viscoelastic response during deformation. Stress or strain induced damage (i.e. crazing, microshear banding) results in the production of nonrecoverable work and observed nonlinearity. Stress or strain dependent shift factors have been used to mathematically model the mechanical behavior of these polymers. Glassy polymers that have been notched, may exhibit very different load displacement response compared to the same material under bulk defo~ation. If a sharp notch is inbox into the body then loaded, the load displacement trace may appear to be sing&valued in the absence of viscoelasticity and crack growth. This suggests the volume of damaged material is small compared to the overall dimensions of the specimen. The ability to produce a single-valued load-load-line displacement trace through the use of the Correspondence Principle may prove to be useful for fracture of viscoelastic materials.
๐ SIMILAR VOLUMES
The yield stress of amorphous glassy polymers depends strongly on the strain rate, temperature, and hydrostatic pressure. On the other hand, the yield criteria, valid for metals, do not describe this behavior. Therefore, the yield phenomenon of the polymeric glassy state must be mainly a nonlinear v