Ultimate elongation elastomers

The strength and extensibility of a noncrystallizable elastomer depend on its viscoelastic properties (28,29), even when the stress remains in equilibrium with the strain until macroscopic fracture occurs. In theory, such elastomers have a time- or rate-independent strength and ultimate elongation, but such threshold quantities apparently have not been measured, though rough estimates have been made (28,30). 

Figure 4 shows stress-strain curves measured at an extension rate of 94% per minute on the TIPA elastomer at 30°, —30°, and —40°C. With a decrease in temperature from 30° to -40°C, the ultimate elongation increases from 170% to 600%. The modulus Ecr(l), evaluated from a one-minute stress-strain isochrone, obtained from plots like shown in Figure 1, increases from 1.29 MPa at 30°C to only 1.95 MPa at —40°C. This small increase in the modulus and the large increase in the engineering stress and elongation at fracture results from viscoelastic processes. 

Of prime interest are the tensile properties summarized in Table 4, and typical of stress-strain curves exhibited by thermoplastic elastomers. The elongation and strength at break were measured above 1000% and 50 MPA, respectively. Both the tensile modulus and the stress at yield increased by increasing the PCL relative content whereas, as expected, the ultimate elongation at break slightly decreased. 

Elastomers. In the Investigation of the effects of methanol/ gasoline blends on elastomers [2] we established that the ultimate stress and the ultimate elongation In swelled elastomers are linearly related to the volume of rubber Vj. In the swelled network, I.e.,... 

Linear Regression Analysis of Tensile Strength (o.) and Ultimate Elongation (Ej ) Versus Volume of Elastomer In Ethanol Swelled Network... 

Linear Regression Analysis of Elastomers Tensile Strength Versus Swelled In Ethanol and Ultimate Elongation for MTBE ... 

Elongation at break Parameter indicating the elongation in relation to the original length (in %) of a material up to its fracture. In the case of elastomers also called ultimate elongation. 

It is pointed out in the thermal degradation of polymer that as the radical concentration increases with passing the aging time, crosslinking reaction increases by the recombination of the radicals. A certain type of radiation induced degradation of elastomer may have the same tendency. Figure 9 shows the other types of modulus-ultimate elongation relationship. Irradiation raised... 

Considering the evaluation of the life time of elastomer, Samay et al. pointed out that tensile strength has the same importance as ultimate elongation has. They proposed Braking Energy (BE) to estimate the life time of elastomer (J). Equation 1 defined BE. 

Previously, it was shown that elastomers based on non-crystallising polyols such as ultra-low monol PPG have twice the ultimate elongation of crystallising polyols such as PTMEG. The next experiments were aimed at determining how much ultra-low monol PPG it would take to eliminate the stress crystallisability of PTMEG [19]. A series of 80 Shore A elastomers... 

All low-acid-value 10/90 SINs yielded before failure, and had the highest ultimate elongation. Such behavior was observed to depend on the acid value of the elastomer prepolymer (as noted in the cases of morphology and Tg behavior) Table 7 illustrates this re- sponse for 10/90 crambe/PS SINs. The higher acid value (low RPVF) SINs exhibit less toughness (smaller area under the stress-strain curves) than those with low acid values (high RPVF). 

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