Tensile hysteresis

Tensile hysteresis curve (ASTM D 4848). A complex load elongation or stress-strain curve obtained under either of two conditions ... 

Strain recovery curve See tensile hysteresis curve. 

Tensile hysteresis curve n. A complex load-elongation, or stress-strain curve obtained (1) when a specimen is successively subjected to the application of a load or stress less than that causing rupture and to the removal of the load or stress according to a predetermined procedure or (2) when a specimen is stretched less than the breaking elongation and allowed to relax by removal of the strain according to a predetermined procedure. 

Structural characterization of the polymers was obtained by FT-IR and NMR spectroscopy using a Nicolet MX-1 and Varian EM-390 spectrometer. The IR spectra for the oligomers and the copolymers were obtained from solution cast films on KBr discs. Dog-bone specimens were cut from the films for mechanical testing of the segmented copolymers. Mechanical measurements included stress-strain, stress relaxation, tensile hysteresis and permanent set behavior. All these tests were performed on an Instron. Model 1122 at room temperature. All stress-strain and hysteresis measurements were carried out at a strain rate of 200 per minute based on the initial sample length. 

Strain Recovery Curve See Tensile Hysteresis Curve. 

The morphological stracture was ejperimentally observed with multiple characterization techniques including DSC, TMA, tensile hysteresis and SAXS. The relationship between the morphological stracture and shape memory properties of the T -SMPUs was explored. In addition, the influences of thermomechanical conditiorts such as deformation amplitude, stress relaxation and pre-deformation on the shape memory behaviors are discussed. 

Tensile hysteresis of T -type shape memory polymers... 

Thus the hysteresis loop should close at a relative pressure determined by the tensile strength of the liquid adsorptive, no matter whether the pore system extends to finer pores than those characterized by or not. 

Fig. 3.24 Test of the tensile strength hysteresis of hysteresis (Everett and Burgess ). TjT, is plotted against — Tq/Po where is the critical temperature and p.. the critical pressure, of the bulk adsorptive Tq is the tensile strength calculated from the lower closure point of the hysteresis loop. C), benzene O. xenon , 2-2 dimethyl benzene . nitrogen , 2,2,4-trimethylpentane , carbon dioxide 4 n-hexane. The lowest line was calculated from the van der Waals equation, the middle line from the van der Waals equation as modified by Guggenheim, and the upper line from the Berthelot equation. (Courtesy Everett.)...

In formulating an explanation of this enhanced adsorption, there are several features to be accounted for the increase in adsorption occurs without hysteresis the amount of adsorbate involved is relatively small the Kelvin r -values are also small (e.g. for nitrogen, less than 17 A) and the effect is found in a region of relative pressures where, according to the simple tensile strength hypothesis, capillary condensate should be incapable of existence. 

AH three systems give similar tensile strength, elongation, and hardness properties. Hysteresis (heat buildup) measured by tan 5 shows an advantage for conventional and semi-EV systems and unaged fatigue follows the expected pattern. 

De Sarkar et al. [52] have reported a series of new TPEs from the blends of hydrogenated SBR and PE. These binary blends are prepared by melt mixing of the components in an internal mixer, such as Brabender Plasticorder. The tensile strength, elongation at break, modulus, set, and hysteresis loss of such TPEs are comparable to conventional rubbers and are excellent. At intermediate blend ratio, the set values show similarity to those typical of TPEs (Table 5.5). 

FIGURE 31.13 (a) Plot showing the stress-strain behavior of various irradiated rubbers, (b) Plot showing the variation of tensile strength and modulus of rubbers irradiated with different doses, (c) Plot showing the variation of hysteresis loss, set, and elongation at break of irradiated fluorocarbon rubbers. (From Banik, I. and Bhowmick, A.K., Radial. Phys. Chem., 54, 135, 1999. With permission.)... 

Fig. 8. Stress-strain hysteresis as a function of the number of number, measured in a tensile/compression fatigue test at 150 Hz and 0.13 % strain (SiC/SiC)...

Elastomers resulting from a series of organic reactions, e.g., a polyglycol ester of adipic acid reacted with an aromatic diisocyanate and cured with water, glycol or further reaction with an aromatic diisocyanate. These elastomers have high tensile strength, very high abrasion resistance, and lower hysteresis than natural rubber. A major use is in the manufacture of foamed polymers. 

A series of six stress-strain cycles with a crosshead rate of 600 mm/min was applied to specimens having a parallel length of 25 mm and a cross-section of 1 x 4 mm2 on a tensile testing machine. The samples were continuously stretched in six hysteresis cycles up to 60% of their elongation at break values, as shown in Fig. 47. This procedure is an established one and widely practiced for elastomeric composites reinforced with fillers such as carbon black and silica, which tend to build a strong filler-filler network [83]. 

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