Reorientational correlation functions small-amplitude

Fig. 14. Effects of small-amplitude reorientation on 2H NMR experiments, as calculated by means of RW simulations. In the model, C-2H bonds (<5 = 2n 125 kHz, rj = 0) perform rotational random jumps on the surface of a cone with a full opening angle % = 6°. (a) 2H NMR spectra for various solid-echo delays tp (tj = t = 30 pis), and (b) 2H NMR correlation functions Fcos(tm) for various evolution times tp (tj = t = 10ms). (Adapted from Ref. 76.)...

Dynamic mechanical analysis coupled with polarised step-scan FTIR transmission and two-dimensional correlation analysis was used to monitor the submolecular orientational responses of the components of a semicrystalline 50/50 blend of LDPE with perdeuterated HDPE to a small amplitude uniaxial 23.47 Hz sinusoidal mechanical strain. Perdeuteration of the HDPE component allowed the distinction of its response from that of the LDPE in the blend samples. Experiments were carried out at room temp. Analysis of the data indicated that the crystalline parts of the two components reorient at different rates, with the functional groups of the high density portion reorienting faster, in general, than those of the LDPE in response to the mechanical strain. 29 refs. USA... 

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