Rotors deformable

Shifting of parts due to plastie deformation of rotor parts... 

The term plastic is not a definitive one. Metals, for instance, are also permanently deformable and are therefore plastic. How else could roll aluminum be made into foil for kitchen use, or tungsten wire be drawn into a filament for an incandescent, light bulb, or a 100 ton ingot of steel be forged into a rotor for a generator. Likewise the different glasses, which contain compounds of metals and nonmetals, can be permanently shaped at high temperatures. These cousins to polymers and plastics are not considered plastics within the plastic industry or context of this book. 

In order to avoid having to shut down the whole vacuum system each time the cryostat is vented after an experiment, it is advisable to place a small slide or butterfly valve between the turbopump and the expander port. When the system is reevacuated, the turbopump must be stopped before opening the valve, otherwise the ambient pressure shock wave that results might deform the delicate rotor and... 

This fact and the results of several experimental and theoretical studies suggest that the nuclei around A = 100 change their shapes rapidly but that they have complex potential energy surfaces. In particular, these nuclei are supposed to be soft with respect to y deformations. However, recent investigations on odd-mass nuclei revealed properties of classical symmetric rotors. A good example is Y6q, the isotone of 98Sr and 100Zr,... 

The properties of 99Y suggest that this nucleus is a classical symmetric rotor. Thus, configurations can be assigned to all the bands in accordance with the predictions of the Nilsson model for A 100 and a deformation of e - 0.3. Also the mixing ratios 6 for the AI = 1 members of the bands can be accounted for in the classical picture of rotational nuclei. The half-life of the isomer at 2142 keV is obviously due to K forbiddenness. 

Since so little was known about the single particle structure of deformed A=100 nuclei, our approach in [VDH85] was to use a textbook version of the particle-rotor model, as outlined by [BUN71], that had been systematically used to study deformed rare earths. 

In polymer processing, compaction is an important and necessary step in order to reduce the interparticle, unoccupied spaces and thus eliminate air. It is essential for melting in both single-screw extruders as well as for twin-rotor processors, as we shall see in Chapters 5 and 10. In twin-rotor devices, such as Co-TSEs, for example, the large and repeated deformation of compacted particulates by the kneading elements, which induces large plastic deformation of particulates, is the dominant melting mechanism. 

Plastic energy dissipation and frictional energy dissipation, in that order of importance, where compacted polymer particulates are relentlessly deformed by twin rotor devices, which rapidly raise their temperature and create regions of melts. 

After the first e = 1 deformation, the initial sample temperature (26°C) will increase by 37°C to (260 + 37 °) = 63 °C. After the second deformation, the new sample temperature will be 630 + 340 = 97 °C. It is striking that only two successive compressive e = 1 deformations are capable of raising the PS sample temperature very close to Tg. The conclusion from such experimental findings, which we will discuss further in connection with twin rotor devices in Chapter 10, is that PED is a very powerful melting mechanism for PS. 

Production. Recognition that the shish-kebab fibers produced by the surface-growth procedure result from the deformation of a gel-like entangled network layer at the rotor surface led to the development of gel-spun polyethylene fibers. The fiber is made by the solution spinning method. The polymer is... 

Numerical solutions of (6.1.48) show that already for moderate microwave field strengths the smooth straight line phase-space orbits shown in Fig. 6.3 start to deform. At higher field strengths they break up entirely. This scenario strongly resembles the analogous scenario already encountered in Chapter 5 in connection with the kicked rotor. Once the... 

Fig. 1. Shear stress versus deformation time when the rotor rpm is 0,05-0 3 min ...

Figures 1,2 show typical curves of shear stress versus deformation time of aminoplastic at 120 °C for different r.p.m. of the plastometer rotor, from 2 = 0.05 to 50 min (i.e. for shear rates from 1.4 x 10 to 1.5 x 10 s ).

Curve 1 in Fig. 1 under low rotor r.p.m. corresponds to the case when the rate of the stress buildup under the effect of deformation is commensurate with the rate of their relaxation. The development of time-delayed elastic deformations determines the final rate of attainment of the steady-state regime of viscous flow, under which the stationary value of the shear stress is recorded. Starting with the moment of time t, the stress will increase and the period of the viscous-plastic state comes to an end. 

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