Solid state 13C n.m.r, was used to study the phase heterogeneity of poly(phenylene sulphide), PPS, at room temperature. Relative fractions of crystal, rigid amorphous and liquid-like amorphous phases were determined from X-ray and thermal analyses. Samples containing very different fractions were examined using cross-polarization contact time and spin-lattice relaxation measurements. The optimum carbon/proton contact time for cross-polarization/magic angle spinning studies was found to be ~ 1000 #s. Peak intensity of the protonated carbons was studied as a function of delay time. A pronounced amorphous halo exists in the n.m.r, spectrum of PPS films containing a large fraction of liquid-like amorphous phase, and the halo decreases significantly with increasing delay time. A very insignificant halo exists in the n.m.r. spectrum of PPS containing a large fraction of rigid amorphous phase. We conclude that this halo is from the most mobile, liquid-like amorphous phase. Using spin-lattice relaxation measurements, we studied the dynamic heterogeneous phase behaviour of PPS. Here we find that from the standpoint of spin-lattice relaxation time, T1, 100% amorphous PPS shows phase heterogeneity at room temperature. The longest T1 is ~45s, corresponding to a mass fraction of 0.57. In semicrystalline PPS, spin-lattice relaxation measurements show a much larger amount of the material possesses longer relaxation time. The 7"1 of semicrystalline PPS ranges from 150 to 200 s, corresponding to mass fractions of 0.91-0.94. This indicates that semicrystaUine PPS is more nearly homogeneous: the crystals and most of the amorphous phase are very 'rigid' at temperatures far below the glass transition of PPS.
Посилання на статтю:
13C n.m.r, study of phase heterogeneity in poly(phenylene sulphide) / Peter Pengtao Huo and Peggy Cebe* // Polymer. – 1992. – Vol 33. – P. 4913-4919.
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