Low strain rate deformation

Following the procedures used by Bucknall et ah (6,7,8) for analyzing low strain rate deformation mechanisms, toughening in three ABS... 

It is well known that at low strain rate, deformation and fracture are controlled by thermally activated mechanism, and in at high strain rate. 

When polymer thin films are deformed under certain conditions (usually low strain rates and temperatures higher than those at which only CSCs are ob-... 

Relevant and complementary information about the damage process of polymers can be obtained among others by the analysis of the force-displacement curves, by the observation of the fracture surfaces (cf. Sects. 3.2.5 and 5.4) and, as will be shown in Sect. 6.2.2, by the determination of the amount of voids in a sample during and/or after deformation. However, a complete elucidation of the deformation mechanisms is only possible by their direct observation at the sub-micron level. Transmission electron microscopy is often used for this purpose. For convenience, the tests (which require experience and touch) are generally carried out at room temperature and at a low strain rate. 

The existence of tie molecules and/or tie fibrils was initially demonstrated by Keith and Padden (19, 20) via electron microscopy. The relationship of these morphological structures to the mechanical strength and deformation behavior of polymers has been demonstrated by Peterlin (21) and by Becht, DeVries, and Kausch (22). Fracture during low strain rate tensile failure can be expected to occur along a path of mini-... 

If a solid is stressed beyond its elastic limit, it will acquire a permanent deformation. The deformation can be either brittle or ductile depending on (i) the material, (ii) the hydrostatic pressure, (iii) the temperature, and (iv) the strain rate. In general, a solid is more likely to deform in a brittle manner at low hydrostatic pressures, low temperatures, and at high strain-rates. Convesely, high hydrostatic pressures and temperatures and low strain-rates favor ductile deformation. 

Fig. 1 Spectrum of deformation of liquid (viscous) and solid (elastic) matter first described by Newton and Hooke, and further developed by Navier and Stokes. Semisolid matter behaves viscoelastic, i.e., viscous at low strain rates and elastic at high strain rates.

The contribution of crazing to ten e deformation increases with stress, and therefore with strain rate. This point is illustrated in Fig. 3, which ows changes in mechanism with stress and strain in ABS and in tcai ened epoxy resin. The data are taken from creep tests in which the strain rate increased with time under load, so that the values quoted for low strains are also for low strain rate. The changes in... 

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