Elastomer stress-strain diagram

Figure 15.4 gives the stress-strain diagrams for a typical fiber, plastic, and elastomer and the average properties for each. The approximate relative area under the curve is fiber, 1 elastomers, 15 thermoplastics, 150. Coatings and adhesives, the two other types of end-uses for polymers, will vary considerably in their tensile properties, but many have moduli generally between elastomers and plastics. They must have some elongation and are usually of low crystallinity. 

Figure 5.77 Comparison of idealized stress-strain diagrams for metals, amorphous polymers, and elastomers.

Fig. 6. Stress-strain diagrams of standard test samples consisting of PMMA and 0, 10, 25, and 100 wt. % (graphs 1-4) of PMMA grafted silicone elastomer particles (powder from Fig. 3a)...

The Vc and Me values for crosslinked polymer networks can also be evaluated from stress-strain diagrams on the basis of theories for the rubber elasticity of polymeric networks. In the relaxed state the polymer chains of an elastomer form random coils. On extension, the chains are stretched out, and their conformational entropy is reduced. When the stress is released, this reduced entropy makes the long polymer chains snap back into their original positions entropy elasticity). Classical statistical models of entropy elasticity affine or phantom network model [39]) derive the following simple relation for the experimentally measured stress cr ... 

Figure 2-47. Stress-strain diagram of an elongation-recovery cycle of the reference elastomer at 27 "C.

Fig. 3. Schematic diagram of a typical apparatus used to measure elastomer stress as a function of strain (21). T = Temperature.

Figure 11-14. Schematic representation of the tensile stress aw as a function of strain e at constant temperature for an elastomer E, a partially crystalline thermoplast T, and a hard-elastic thermoplast HT. The ductile region is la-II-III. The necking effect shown below the diagram is typical of normal thermoplasts, but does not occur with elastomers or hard-elastic thermpolasts. The diagram is not drawn to scale for example, elastomers show a much larger elongation at break than do thermoplasts.

Figure 11 Schematic diagram of a typical apparatus used to measure the uniaxial stress as a function of strain for an elastomer (reproduced by permission of Wiley from J. E. Mark, J. Polym. ScL, Macromol. Rev.y 1976,11, 135)...

---