ma60078a052_cookieSet=1 - Macromolecules 1 980,13,...

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Macromolecules 1980,13, 1647-1650 1647 The relaxation times Ti,,REV and Ti, of the crystalline fraction in the temperature region around 20 "C are gov- erned by the same motional process. However, the dom- inant interaction for these relaxation times is the dipolar interaction. Again, for this relaxation mechanism we have the two correlation times T~ = 1/D and T~ = 1/40, Since the main contribution to the fluctuating dipolar interaction comes from the two 19F nuclei within a CF2 group whose internuclear vector is nearly perpendicular to the axis of rotation, it is T~ that dominates TixzREV and Tip. In other words, TiZzm reaches a minimum when r2 = 0.6 X 3.6 pat3 which corresponds to D = 18 kHz. Extrapolation of the data plotted in Figure 9 predicts that this would occur at 35 "C. Similarly, the Tip minimum is expected, where 2401~2 = 1 or D = l/2W1. For a spin-lock field of 60 kHz this would be at 37 "C, where the diffusion rate is 30 kHz. References and Notes (1) Wilson, C. W.; Pake, G. E. J. Chem. Phys. 1957,27, 115. (2) Slichter, W. P. J. Polym. Sci. 1957, 24, 173. (3) Hyndman, D.; Origlio, G. F. J. Appl. Phys. 1960, 31, 1849. (4) McCall, D. W.; Douglass, D. C.; Falcone, D. R. J. Phys. Chem. 1967, 71, 998. (5) McBrierty, V. J.; McCall, D. W.; Douglass, D. C.; Falcone, D. R. Macromolecules 1971. 4. 584. (6) Ellett, D.; Haeberlen, U.;Waugh, J. S. J. Polym. Sci., Polym. Lett. Ed. 1969, 7, 71. (7) Garroway, A. N.; Stalker, D. C.; Mansfield, P. Polymer 1975, lfi. 171. I (8) Mehring, M.; Griffin, R. G.; Waugh, J. S. J. Chem. Phys. 1971, 55,746. (a) Schaefer, Stejskal, E. 0.; Buchdahl, R. Macro- molecules 1975,8, 291. (b) Ibid. 1977,10,384. (9) English, A. D.; Vega, A. J. Macromolecules 1979, 12, 353. (10) Pembleton, R. G.; Wilson, R. C.; Gerstein, B. C. J. Chem. Phys. 1977, 66, 5133. (11) Binsch, G. J. Am. Chem. SOC. 1969, 91, 1304. (12) (a) Mehring, M. NMR. 1976 1976, 11. (b) Haeberlen, U. Adv. Magn. Reson., Suppl. 1 1976. (13) Vega, A. Vaughan, R. W. Chem. Phys. 1978, 68, 1958. (14) English, A. D.; Garza, 0. T. Macromolecules 1979, 12, 351. (15) Rhim, W.-K.; Elleman, D. D.; Vaughan, R. W. J. Chem. Phys. 1973,59,3740. (16) Rhim, W.-K.; Elleman, D. D.; Schreiber, L. B.; Vaughan, R. W. Chem. Phys. 1974, 60,4595. (17) Eby, R. K.; Sinnott, K. M. J. Appl. Phys. 1961,32, 1765. (18) Sperati, C. A.; Starkweather, H. W. Fortschr. Hochpolym. (19) Ryland, A. L. J. Chem. Educ. 1958, 35,80. (20) McBrierty, V. Polymer 1974, 15, 503. (21) Vega, A. English, A. D. J. Magn. Reson. 1980, 37, 107. (22) McCrum, N. G.; Read, B. E.; Williams, G. "Anelastic and Di- electric Effects in Polymeric Solids"; Wiley: New York, 1967. Also see ref 4. (23) Starkweather, H. W., unpublished review. (24) Bunn, C. W.; Howells, E. R. Nature (London) 1954,174,549. (25) Spin-lattice relaxation times were measured and semiquanti- tatively agree with those reported in ref There is no indi- cation that the a relaxation is detectable with TI measure- menta. Forsch. 1961,2, 465. (26) Diehl, P.; Khetrapol, C. L. NMR. 1969 1969, 1. (27) Petersen, N. 0.; Chan, S. I. Biochemistry 1977, 16, 2657. (28) Bocian, D. F.; Chan, S. I. Annu. Rev. Phys. Chem. 1978,29, (29) Bates, T. W.; Stockmayer, W. H. Macromolecules 1968, I, 12, (30) Brown, R. G. J. Chem. Phys. 1964,40, 2900. (31) Martin, G. M.; Eby, R. K. J. Res. Natl. Bur. Stand., Sect. A (32) Clark, E. S. J. Macromol. Sci.-Phys. 1967, Bl (4), 795. (33) Rabolt, F.; Piermarini, G.; Block, S. J. Chem. Phys. 1978, 69, 2872. (34) (a) Rabolt, F.; Fanconi, B. Polymer 1977, 18, 1258.
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This note was uploaded on 09/30/2010 for the course MANAGEMENT MG2432 taught by Professor Muhammadadeel during the Spring '10 term at École Normale Supérieure.

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