Deformation-at-break

The limiting local deformation at break 6 is markedly lower (e = 0.3) in networks than in linear polymers (for PS e > 1 87>). 

Table 18 shows values of strength at break, Ob, deformation at break, 8b, and elasticity coefficient, E, of studied polymer networks. The data indicate that substitution of methyl groups by phenyl ones and variation of the distance between chain branching centers is accompanied by a significant chan-ge of deformation and strength properties of studied polymers. Note that substitution of both methyl groups by phenyl ones is accompanied by the... 

ISO 4600 details a ball or pin impression method for determining the ESCR. In this procedure, a hole of specified diameter is drilled in the plastic. An oversized ball or pin is inserted into the hole, and the polymer is exposed to a stress cracking agent. The applied deformation, given by the diameter of the ball or pin, is constant. The test is multiaxial, relatively easy to perform, and with not very well-defined specimens, and the influence of the surface is limited. Drawbacks are the small testing surface and the undefined stress state. After exposure, tensile or flexural tests may be performed on the specimens. This leads to the determination of either the residual tensile strength or the residual deformation at break. 

PDMS Initial chain mass [g mol ] Elasticity domain [%] Deformation at break [%] Young s modulus [MPa]... 

For plastics, reinforcement results in an increase in modulus and hardness. The effect of particulate fillers is quite clear— they replace a part of the matrix. So modulus becomes higher, but deformation at break decreases in the same time. 

The situation is very different for elastomers the use of reinforcing fillers induces a simultaneous increase modulus and deformation at break. Curiously, the replacement of a part of the deformable matrix by solid objects doesn t reduce its deformability. The increase of these two antagonistic properties characterizes elastomer reinforcement. This fascinating paradox, despite not being fully understood, explains the ability of reinforced elastomers to provide... 

The specimens are placed in a water bath at 60 C 1 C for 30 to 40 min before testing using the Marshall apparatus (Figure 5.3). The Marshall apparatus compresses diametrically the specimen at a constant rate (50.8 mm/min) until breaking occurs. The applied load at breaking, measured in kilonewtons (or pounds) is the Marshall stability. The resulting deformation at breaking, measured in millimetres (or inches), is the flow. 

SO modulus becomes higher, but deformation at break decreases in the same time. 

Fig. 17.13. Phase diagram of iPP showing the region of stability of the different poljrmorphic forms as a function of deformation e e = 100(L/ — Lo)/Lo) and stereoregularity, defined as concentration of the fuUy isotactic pentads mmmm. The values of critical strains corresponding to the boundary hues between the various crystalline forms have been determined from the X-ray fiber diffraction patterns of Figs. 17.8—17.11. The concentration of rr triad defect is indicated in the upper scale. The deformation at break is also indicated dashed line)...

As it s shown, the durability of all polymer mixes based on different acrylic dispersions decreases with time in water. Though the deformation at break increases in 3-5 times. So, we can say about plasticizing influence of water for these polymers. 

Polymer-polymer MECs also show better deformation ability when compared to common PP composites. While the deformation at break of the MFCs is about 80% [45], that of the PP, reinforced with 30% (by wt) GF, is only 3 to 5% [91]. 

The mechanical properties of protein-based films can be markedly improved by adding fibres (i.e., composite materials). Mechanical properties are always highly dependent on the temperature and RH of the protein material (Figure 11.9). This modification, (i.e., sharp increase in deformation at break and decrease in mechanical strength), occurs suddenly when the material crosses the Tg range [174]. 

Sample Tensile Modulus, (MPa) Stress at break,o (MPa) Deformation at break. 

Figure 2 Influence of cross-linking physical (thermal or UV treatments) or chemical (pre- or post-treatments by formaldehyde) treatments on the mechanical properties (i.e. strength and deformation at break) of wheat gluten...

Many other important impact design parameters such as yield stress, energy to yield, initial modulus, and deformation at break can be measured with high-speed tension tests (38). In spite of the capability of high-rate tension tests to provide stress at strain rates that simulate actual service, the tests have not been popular because the delivered stress is uniaxial. Normally, the real-life impact stress is multiaxial. 

Fig. 3. Young s modulus and deformation at break ofPHB in dependence on plasticizer content (triacetine)...

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