Raman shift factors
Polymer and Materials Science
Wiley InterScience Backfile Collection 1832-2000
Chemistry and Pharmacology
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
A series of diacetylene-containing polyesters with number-average molar masses (GPC) in the range 900-4200 g mol-1 were prepared from terephthaloyl chloride and hexa-2,4-diyne-1,6-diol using benzoyl chloride as a monofunctional reactant for control of molar mass. Degrees of crystallinity were estimated from WAXD to be up to 29%. Correlations between molar mass, melting behaviour, degree of crystallinity and thermal cross-polymerisation of diacetylene-containing polyesters have been established using hot-stage microscopy, DSC and resonance Raman spectroscopy. The polyester with M̄n of 1264 g mol-1 gave the best balance between processability and the ability to cross-polymerise efficiently. Its degree of crystallinity before cross-polymerisation was estimated from WAXD measurments to be 24%, a value coincident with the percentage conversion of diacetylene units to polydiacetylene chains measured by 13C solid-state NMR. The optimum conditions for compression moulding the polyester to produce a material with a strong Raman spectrum involved heating under vacuum at 120°C for 6h after an initial 3 h heat-up period. The material thus produced gave an intense Raman C=C stretching band, which upon tensile deformation shifted linearly with strain to lower wavenumber by 12.0 cm-1 %-1. The potential use of the diacetylene-containing polyesters in the preparation of model blends for use in quantitative micromechanics studies of stress transfer between phases is briefly discussed.
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