Strain properties

Fig. 2. Typical stress—strain properties of staple fibers at 65% rh and 21°C. Rate of elongation is 50%/min. To convert N/tex to gf/den, multiply by 11.3.

Post-Curing. Whenever production techniques or economics permit, it is recommended that compounds based on terpolymer grades be post-cured. Relatively short press cures can be continued with an oven cure in order to develop full physical properties and maximum resistance to compression set. Various combinations of time and temperature may be used, but a cycle of 4 h at 175°C is the most common. The post-cure increases modulus, gready improves compresson set performance, and stabilizes the initial stress/strain properties, as chemically the polymer goes from an amide formation to a more stable imide formation. Peroxide-cured dipolymer compounds need not be post-cured. 

B 1,481.2 1,4-Polybutadiene (low vinyl) 1,2-Polybutadiene (high vinyl) Polyethylene Polybutylene Improved material stress-strain properties... 

Average viscosity (poise) (4°C) Stress-strain properties 7400 3800 3800 3800 90 165... 

Both tear resistance and hysteresis increase on incorporation of silica, but the effect is less pronounced as compared to the stress-strain properties. Tension set of the ZnO-neutralized m-EPDM system is low (around 20%) and incorporation of filler causes only a marginal increase in set due to chain slippage over the filler surface, as previously discussed. Measurement of physical properties reveal that there occurs an interaction between the filler surface and the polymer. Results of dynamic mechanical studies, subsequently discussed, support the conclusions derived from other physical properties. 

This effect was estimated from the experimental comparison of the stress-strain properties in three sample series which were brought to different phase contents by means of heat treatment. All samples were hydrogen-alloyed to a = 0.35 at T = 1053 K, then furnace cooled. Before straining, samples of the first series were maintained at the test temperature for 0.5 h. Series 2 samples were heated to the j9-phase, T = 1163 K, for 15 min, then cooled to the test temperature and treated like series 1 samples. The phase content in the third series was equilibrated by heating to 1163 K and slow cooling to 903 K before the test temperature was fixed. 

The high-pressure study on the Ti-H alloys showed stress-strain properties are not the only ones which are affected by pressure, but phase equilibria are also strongly dependent on this parameter . A new ( -phase and a corresponding single phase region in the isobaric T — C section of the T — P — C phase diagram appear in the... 

E.G. Ponyatovsky, O.N. Senkov, and I.O. Bashkin, Str s-strain properties of the Ti-6A1-2Zr-1.5V-Mo alloy with the various grain structures and hydrogen contents, Phys. Met. Metall. 72 194 (1991). 

The table data show that the stress/strain properties of compositions are improved by additional dispersion (mixing). Ultrasonic analysis is sufficiently reliable and informative as a means of mixing quality assessment. The very small change of the characteristics for filled compositions (chalk + kaolin) can be due to the fact that these fillers are readily distributed in the matrix as they are. 

Reliable data in the literature for the stress versus strain properties of composite propints are exceedingly difficult to find. Since the binder chemical properties and curing additions are susceptible in many cases to hydrolytic degradation, the exact formulations under test should be specified. Additionally, the binder to oxidizer adhesion properties are dependent upon particle size distribution used in the pro-pint. This should be specified and in almost all literature sources unearthed, it remained unknown. As some of these data show, the manner of conducting the test and control of such... 

In TPE, the hard domains can act both as filler and intermolecular tie points thus, the toughness results from the inhibition of catastrophic failure from slow crack growth. Hard domains are effective fillers above a volume fraction of 0.2 and a size <100 nm [200]. The fracture energy of TPE is characteristic of the materials and independent of the test methods as observed for rubbers. It is, however, not a single-valued property and depends on the rate of tearing and test temperature [201]. The stress-strain properties of most TPEs have been described by the empirical Mooney-Rivlin equation... 

Pedemonte E., Alfonso G.C., Dondero G., De C.F., and Araimo L. Correlation between morphology and stress strain properties of three block copolymers. 2. The hardening effect of the second deformation. Polymer, 18, 191, 1977. 

Stress-strain properties (Cure 160°C/t9o) Hardness, Shore A 70 69 70 66... 

FE simulations of the stress-strain properties of fiUer-reinforced elastomers are an important tool for predicting the service live performance of mbber goods. Typical examples are the evaluation of rolling resistance of tires due to hysteresis energy losses, mainly in the tire tread or the adjustment of engine mounts in automotive applications. 

Most mechanical and civil engineering applications involving elastomers use the elastomer in compression and/or shear. In compression, a parameter known as shape factor (S—the ratio of one loaded area to the total force-free area) is required as well as the material modulus to predict the stress versus strain properties. In most cases, elastomer components are bonded to metal-constraining plates, so that the shape factor S remains essentially constant during and after compression. For example, the compression modulus E. for a squat block will be... 

Figure 8. Comparison of the stress-strain properties of the press-quenched films of HBIB to those from the homopolymers HB and HI. Composition of each polymer is denoted by the butadiene content next to the graph.

There are various test methods, one being the De Mattia Flex Test method which is suitable for rubbers that have reasonably stable stress-strain properties, at least after a period of cycling, and do not show undue stress softening or set, or highly viscous behaviour. The results obtained for some thermoplastic rubber should be treated with caution if the elongation at break is below,... 

Stress-strain diagram, 27 721 Stress-strain instrument, 27 744 Stress-strain properties, of styrene plastics, 23 359-362... 

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