Hysteresis peaks intensity

Dipole reorientation under the influence of an electric field was investigated in oriented nylon 11 films with polarised IR spectroscopy for the amide A (N-H stretching) and amide I (carbonyl stretching) bands. Butterfly-shaped hysteresis loops were obtained from peak intensity versus applied electric field strength. Least-squares Gaussian... 

A second clear result from the present work is the influence of phase separation on the constitutive response. Evidence for some phase separation was seen in SAXS for all the materials studied. But in the PTHF-based materials it was particularly pronounced (as evidenced by SAXS peak intensity). Inelasticity as measured by hysteresis and unrecovered strain was reduced by increased phase separation. 

The glass transition curve usually shows an enthalpy relaxation or hysteresis peak as well. The intensity of the hysteresis peak can be greatly increased if one anneals the glass just below the glass transition temperature or if the material was slowly cooled (see Section 2.7, on phase transitions in thermoplastic polymers). TTiis poses two problems (1) obtaining a comparative glass transition temperature and (2) evaluating the hysteresis behavior. 

Distinct and different peak profiles of X-ray powder diffraction on [Fe(4,7-(CH3)2-phen)2(NCS)2] have been observed for the 5T2 and A, phases, respectively183). The intensities of the lines show the same temperature dependence and the same hysteresis behaviour as the area fractions of the HS and the LS quadrupole doublets, respectively, of the Mossbauer spectra. These studies183) provide clear evidence for a simultaneous change of the electronic spin state and of the crystallographic properties. 

Figure 2(A) shows the SAXS profiles of water-adsorbed PlT-5 (u) = 0.8iim) iis a fuiict ion of (p. The SAXS profiles for all relative pressures had no peak and the scattering intensities deciease wit h the incre iso of s over the whole. s region. The soli. The s< atler-ings on desorption are overlapped to those of adsor )-tion process, corresponding to absence of adsorption hysteresis.

Figure 2, top, shows the T-dependent integrated intensity of the 451 peak. This peak is fee forbidden, and its intensity is therefore proportional to the square of the sc order parameter. Abut half the 0-K intensity is lost in a continuous precursor extending from 0 to Tc the remainder disappears much more abruptly at Tc 249 1 K. There is no measurable hysteresis, and no measurable cell volume change at Tc. These observations are all consistent with weakly first-order behavior. Scans of the range 2.7 A <4.5 A" at 230 and... 

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