Strain unit

Chemical shift imaging (CSI) was used to monitor the oil volume fraction during the mixing process. Figure 4.5.13 shows normalized volume fraction profiles along the vertical center-line (see Figure 4.5.3) at different times. The mixing time is expressed in strain units as y = tV/(R0 - i)> where t is the time. One revolution of the outer cylinder corresponds to 9.83 strain units. The initial condition (y = 0)... 

Here vq is the measured tangential velocity profile at time t and (ve,steady) is the value at steady-state. Both intensity indices have a value of unity at f = 0, and approach zero as t approaches infinity. Figure 4.5.15 shows the variation of the intensity indices with average strain, for an outer cylinder velocity of 0.05 cm s 1. These plots indicate that the mixing process occurs in two stages, where the velocity profile develops only after the droplet concentration profile is essentially uniform. It can be seen that 1 decays to zero at approximately 100 strain units, whereas Iv shows that the steady-state velocity profile is reached only when y ps 400. From Figure 4.5.14 it can be seen that when y = 115, flow is detected... 

After 1000 strain units, the recorded viscosity was fitted to give... 

Strain (units/liter) (units/liter) (units/liter) (units/liter) (units/liter)... 

Figure 6.25 Shear stress as a function of shear strain for a polyamide 6 filled with 30% by weight glass fibers of different aspect ratios, where the fibers were initially oriented in the velocity-gradient direction. The shear was interrupted after about 7 strain units, and the stress was allowed to relax. The shecir was then restarted the shear stress quickly returned to the value it had before cessation of shearing, showing that fiber orientation only changes during shearing. (From Laun 1984b, reprinted with permission from Steinkopff Publishers.)...

Figure 10.15 Damping of shear stress and reversal of damping as a function of time after startup of shearing in a cone-and-plate rheometer at y = 8 seer for a tumbling nematic, 8CB. In (a) the shearing direction is reversed after imposition of 170 strain units the damping of the stress nscillatinns is rp.vp.rsed. In (h), shear reversal occurs after imposition of 480 strain iiniK fhp damping is not reversed. (From Gu et al. 1993, with permission from the Journal of Rheology.)...

Figure 2. Extrudate shrinkage (In Hencky strain units) vs. composition of polypropylene/low density polyethylene blends. (Adapted from ref. 38.)...

The intra- and intermolecular interaction between cationic center and tt-electron system have attracted many chemists and much knowledge on the interaction has been accumulated (1). In 1975, we intended to apply such a kind of interaction to cyclopolymerization. Thus, it is expected that the transition state leading to a strained cyclic unit in the polymerization could be stabilized by the intramolecular attractive interaction between cationic growing-end and ir-system There had been few examples of cyclopolymerizations giving strained units. A paracyclophane unit was employed as a strained cyclic unit in the polymer main chain. In Table I are summarized some cyclophanes with their strain energies. 

The first occurs almost instantaneously (less than 2 strain units) on the start up of flow while the second peak occurs at much higher strains (40 to 50 units). The double peak behavior is not necessarily... 

In Figure 4 we have plotted values of the primary normal stress difference (N ) versus time. Here we observe that a single overshoot peak is observed in N. The peak stress occurs at strains of the order of 40 to 6o strain units which is similar to the range observed for the appearance of the second peak in the shear stress. Whereas the shear stress rises rapidly at the start up of flow, the normal stresses rise gradually. It should be pointed out that this is exactly the behavior predicted by the corotational Jeffrey s model. ... 

The shear stress growth on the inception of shear flow may reflect the orientation of the liquid crystalline domains. Orientation seems to occur within less than 2 strain units in shear flow. This primary normal stress difference can exhibit different phenomena from the shear stress response. In particular for the 60 mole % PHB/PET system, values of N are positive and rise gradually to the equilibrium values whereas the 80 mole % PHB/PET system can exhibit negative values of N. Ericksen s transversely isotropic fluid theory can qualitatively handle some of the observed phenomena. Further studies which couple the transient flow behavior to the orientation and morphology need to be carried out. 

As an interesting detail of these investigaticns an isosbestic point diaractaistic of the equilibrium established between the relaxed and strained units at different stress levels could be detected in the region of the 5(CH2) absorption bands (Fig. 27). This experimental result suggests that equivalent converaon one modification into the other takes place with no possibility left for an intermediate variety forming ... 

The time needed to reach the stationary state, tsu varies inversely with the shear rate, indicating that whatever 7, steady state is reached after a constant deformation. For both CPCl/Hex and SDS/Dec this deformation was of the order of 300 strain units [284,301]. Nematic surfactant solutions of micelles can be considered to have forgotten their shear history after having been sheared for more than a few hundreds strain units. 

The incremental energy (SL/J for an incremental volume element (SV) of the sphere is given by A/ /AV = o-r/2, where T is the strain of the sphere. Since the sphere is uniformly polarized, it is also uniformly strained and the strain energy will be given by = o-rW2. The T is an intensive property of the sphere, therefore we identify the strain of the sphere with the strain/unit. This quantity is also proportional to the total moment of the sphere per unit. In other words ... 

The strain F(f) is an intensive property of the sphere, therefore, we identify the strain of the sphere with the strain/unit and is proportional to the total dipole moment of the sphere per unit. In other words. 

Figure 13.3. Vectra B observed under crossed polarizers after shearing at a stress of 500 Pa for 500 strain units. Reprinted from E. G. Kim, M.S. thesis, U. California, Berkeley, 1996.

The rheology experiments were performed on a Bohlin VOR (dynamic modulus and viscosity measurements) and a Rheometrics Dynamic Stress rheometo (viscosity measurements) using cone and plate fixtures with 2.S cone. To insure that the flow transient had been surpassed, the sample was pre-sheared for 200 strain units prior to collecting steady viscosity data, or prior to flow cessation in those experiments where evolution of the moduli was monitored. The sample chamber was sealed to prevent solvent loss at long times. The dynamic modulus was obtained using a 1.3% strain at 1 Hz. 

Figure 9.58 gives plots of cr+(r, y) versus yt to shear startup for the first 200 strain units and to reversal flow for the next 200 strain units for PSHQIO at 160°C and at two different shear rates 0.1 and 0.5 s T In Figure 9.58 we observe that upon shear... 

Figure 9.58 Plots of y) versus yt at 160 °C, upon shear startup followed by flow reversal, for as-cast PSHQIO specimens at two different shear rates (s ) ( ) 0.1 and (O) 0.5. Flow reversal began after 200 strain units upon shear startup. Note that is 179 °C for PSHQIO. (Reprinted from Mather et al., Macmtnolecules 33 7594. Copyright 2000, with permission from the American Chemical Society.)...

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