Behavior hysteresis

T = 140 °C. Here, during solidification, the H increase from 140 °C down to about 100 °C is the result of a double contribution of (a) the crystallization of the fraction of molten crystals and (b) the thermal contraction of the nonpolar phase crystals. The hysteresis behavior is also found in other mechanical properties (dynamic modulus) derived from micromechanical spectroscopy [66, 67], where it is shown that the hysteresis cycle shifts to lower temperatures if the samples are irradiated with electrons. It has also been pointed out that the samples remain in the paraelectric phase, when cooling, if the irradiation dose is larger than 100 Mrad. 

In conclusion, it appears that microhardness yields information about paraelectric to ferroelectric phase changes in VF2/F3E copolymers which can be discussed in the light of the changes in the lattice spacings of the different phases and in variations of the crystallinity value. 

---

The model describes the characteristic stress softening via the prestrain-dependent amplification factor X in Equation 22.22. It also considers the hysteresis behavior of reinforced mbbers, since the sum in Equation 22.23 has taken over the stretching directions with ds/dt > 0, only, implying that up and down cycles are described differently. An example showing a fit of various hysteresis cycles of silica-filled ethylene-propylene-diene monomer (EPDM) mbber in the medium-strain regime up to 50% is depicted in Figure 22.12. It must be noted that the topological constraint modulus Gg has... 

It was the objective of this work to investigate the effect of variation in block architecture (number and the order of the blocks) on the crystallinity level, morphology, the stress-strain and hysteresis behavior of this series of polymers. In addition, the composition ratio of the two block types is expected to play a crucial role in determining the bulk material properties of the block copolymers. This is related to the fact that the mechanical properties of block copolymer are typically influenced more substantially by the behavior of the continuous phase, as will be demonstrated.(1,22)... 

Mechanical Properties. The stress-strain and the hysteresis behavior of the polymers were measured on a Model 1122 Instron using dog-bone samples of 0.28 cm width and 1.0 cm effective length. The strain was measured using the displacement of the crosshead. In the calculation of the strain it was assumed that... 

Hysteresis Behavior. The hysteresis behavior of the HBIB triblock copolymers are given in Figure 13A and of that of the inverted HIBI block copolymer is given in Figure 13B. The difference in the behavior of these two series of block copolymers is tremendous. The origin of these differences are again directly related to the morphology and the architecture of the polymers. 

Similar observations have been made with respect to the hysteresis behavior in segmented urethanes as a function of composition and domain morphology. 

The hysteresis behavior of the HIBI series is shown in Figure 13B. All of the samples have much higher hysteresis than the corresponding member (with respect to composition) of the HBIB series. Although there is a noticeable decrease in the percent hysteresis with an increase in rubbery HI content, the hysteresis does not fall below 55% at high extensions. 

The hysteresis behavior of the diblock copolymer HBI-50 is not shown but is very similar to that of HIBI-49. In summary then, the difference in hysteresis behavior of the HBIB series to that of HIBI and HBI is related to the ability of the members of the first series to form permanent entanglements, by entrapment of the end blocks in the semicrystalline domains, whereas no such arrangment is possible for neither HIBI nor HBI series. The permanent entanglement serves as a physical crosslink which promotes recovery of the polymer after the deforming stress has been removed. At the same time, much less energy is lost as heat. 

But contrary to HBIB polymers, they do not show any strain hardening and are very weak materials. The hysteresis behavior of HIBI and HBI polymers is also very different from that of the HBIB polymer. The former polymers show tremendously higher energy loss during cyclic deformations, and these differences are again inter-... 

Figure 3.32 Hysteresis behavior of the magnetization of a ferromagnetic crystal or polarization of a ferroelectric crystal with respect to the applied magnetic or electric switching field.

Further reduction of manganese ions and the generation of oxygen vacancies could take place only after all metal vacancies are consumed under cathodic polarization. However, the oxygen vacancy formation and the removal of cation vacancies may not be the only explanation for the hysteresis behavior as shown recently by Wang and Jiang [35],... 

In previous literature, the type B hysteresis was ascribed to a lamellar-like structure that commonly observed in the pillared materials.[13,14] Here its existence in our mesoporous materials is associated with some internal defects in the channels. To further understand such hysteresis behavior, we compared the microtomed ultra-thin sections TEM micrographs of these two samples. In Fig. 2A, B, we show the typical parallel channels of MCM-41 and the well-ordered hexagonal mesoporous in pure silica sample(I). However in Fig. 2 C, D, one can obviously find the aluminosilicate(II) possessing the normal well-aligned MCM-41 nanochannels with extensive voids interspersed. The white void parts were attributed to the structural defects. These structural defects are not the lamellar form but the irregularly shaped defects. The size of the defects is not uniform and distributes between 5.0-30.0 nm. nanometers. Therefore, these aluminosilicate mesoporous materials were composed of structural defects-within-well-ordered hexagonal nanochannels matrix. 

The synthesis and characterization of the structural defects within aluminosilicate mesoporous materials were provided. We further discussed the fascinating adsorption-desorption hysteresis behaviors and the influencing factors in the formation of the structural defects. However, mesoporous MCM-41 can act as catalyst support for many catalytic reactions, especially involve bulk oiganic molecules, due to its large surface area and pore size. The ability to synthetically control the connectivity of the mesoporous materials may have important applications in catalysis. 

Fig. 11. Hysteresis behavior of the flow discontinuity in LPE, indicating that the shear rate range covered by the negative-slope line is not experimentally accessible under controlled pressure. The separation (oh-Gi) depends on the rate of the pressure variation...

Fig. 6.11 Changes in the hysteresis behavior during the fatigue of unidirectional SiCf/CAS-II. The number of cycles (in thousands) is shown above each curve. Note that the average modulus, area of the hysteresis loops, and the permanent strain offset all change during fatigue. Failure took place at 3.21 x 106 cycles. After Holmes and Cho.12...

Sorption and desorption of water by starch exhibits hysteresis behavior. In maize starch, the sorption branch of the hysteresis loop corresponding to moisture contents above 16% displays exponential kinetics386 ... 

An extremely unusual power dependence has been observed in the cooperative upconversion luminescence of Yb -doped Cs3Lu2Br9 and related systems [57-61]. As illustrated by the 7.5 K power-dependence data in Fig. 14a, b, increasing the excitation power from the low-power excitation limit results in a sharp jump in both VIS and NIR luminescence intensities at a certain critical power. Reversing the direction of the power sweep also results in a sharp jump on the return path, but this jump occurs at a lower power than the forward jump, resulting in a hysteresis behavior with a distinct region of bistability. Monitoring the transmission of the laser beam shows that the absorption of the sample also increases and decreases at these same critical powers (Fig. 14a, inset) [62]. The properties of this jump are clearly dependent upon temperature, with smaller jumps observed at lower excitation powers as the temperature is elevated (Fig. 14). 

Fig. 14 a, b. Power and temperature dependence of a the visible cooperative luminescence b the NIR downconversion luminescence in 10% Yb + Cs3Lu2Br9 excited at 10,591 cm plotted on linear axes. These data show distinct hystereses, the properties of which are temperature dependent. Inset 10 K laser transmission, which also shows hysteresis behavior. Adapted from [62]... 

---