Stretch-hold technique

Figure 16.9. Oriented PP films in tensile tests. Comparison between SAXS patterns /(sij.Ss) recorded during continuous straining (top row, f lCf s ) and patterns from an experiment in stretch-hold technique (bottom row). Straining direction and meridian is vertical (S3). Equator (s,2) is horizontal ( Reproduced [50] with permission of Wiley Interscience)...

Stribeck N, Ndchel U, Funari S S and Schubert T (2008) Tensile tests of polypropylene monitored by SAXS. Comparing the stretch-hold technique to the dynamic technique, J Polym Sci Part B Polym Phys 46 721-726. 

Studies of deformation by X-ray scattering are presently experiencing a change from the so-called stretch-hold technique [1] to an in situ study of nanostructure evolution during dynamical tensile tests. Thus, here the new perspectives, their technical foundations, and first results are discussed in com-... 

Only a few years ago, dynamic experiments with a good signal-to-noise (S/N) ratio of the scattermg patterns were not possible. Therefore many of the studies listed in this chapter have been performed by means of the older stretch-hold technique. A recent comparative study [61] imexpectedly revealed pronounced differences after switching from stretch-hold to a slow dynamic experiment. Consequently, results on the nanostructme evolution retrieved in stretch-hold studies may be used only with a lot of cautiousness to explain the dynamic loading process that is relevant in practical applications. 

Throughout the years, quasi-dynamical studies employing the stretch-hold principle [1] represent the predominant part of all the investigations on the nanostructure evolution of composite materials [6,16-35]. Since this technique means that the sample is held at a constant elongation until a low-noise scattering pattern has been exposed, the data can, in principle, be analyzed by quantitative evaluation, although most of the published papers do not proceed far beyond a presentation and interpretation of the accumulated images. 

A new approach to investigating interactions directed at the carboxamide is the use of resonance Raman spectroscopy. Callender and co-workers have found significant alterations in the carbonyl stretching frequencies attributed to the carboxamide of NADH on binding (36). Thus this technique holds promise for analyzing in detail the interactions directed toward the side chain and pos-... 

UFT Two strips ofgoid card (cardboard) are slotted together m a manner similar to variation It of the Trellis technique, then bent into a circle to create the star effect. A rubber band holds We construction m shape. When flattened, the band stretches. If the pressure on the flat card is released, the band ccmtracts and the card spnngs dramaticslly into shape. 

As the discs rotate, the web is stretched in the cross direction. At some point around the discs, the belt holding the web to the perimeter is peeled away and the transverse-oriented film continues down the process line (Fig. 7). If the forces required to stretch the film are quite large, this technique may not work. The film may be pulled out from under the belt. 

A pendant drop occasionally breaks loose.. This occurs when its weight W exceeds the capillary forc i that holds it in place (Tate s law). The capillary force is at most equal to 27tR7, where R is the inner radius of the tube. In principle, one could determine the value of 7 simply by weighing a drop that has fallen off. While the technique appears extremely straightforward at first blush, its practical implementation runs into a numb[Pg.58]

Securing Thermocouples Adhesive Tapes. Tape should be avoided for holding the thermocouple bead to the board as it is known to be an unreliable technique. Problems arise as the tape heats up and stretches, expands, or even releases from the board, allowing the thermocouple bead to float off its measurement target. The tape also shields the thermocouple and target solder j oint from the oven ambient, which is contrary to the task at hand— measming the effect of the oven environment on the intended solder-joint location. 

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