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A nuclear magnetic resonance study of poly(ether ether ketone) and poly(polyphenylene sulfide)

University of British Columbia

Poly(ether ether ketone), PEEK, and poly(phenylene sulfide), PPS, are both polymers of commercial importance on account of their application as matrix materials for composites. Amorphous and crystalline forms of both plastics have been studied by nuclear magnetic resonance spectroscopy: high resolution ¹³C CP/MAS and wide-line PMR. The high resolution ¹³C spectra of the polymers were assigned with the aid of the dipolar dephasing technique. The width of the resonance lines of the CP/MAS spectra were seen to be proportional to the crystal-Unity of the sample, with the fully amorphous spectra being the widest. The variable-contact-time experiment for PEEK indicated that the optimum contact time for the amorphous form is shorter than that of the crystalline. Variable temperature ¹H linewidth and spin-lattice relaxation measurements were made on both the crystalline and amorphous forms of the polymers. The temperature range was ambient to 440K. The proton spectra appeared as a broad line with a narrow component superimposed. Except in the case of PPS above the T[sub g], the broad line was by far the more intense. Partially relaxed spectra below T[sub g] indicated separate relaxation times for the two components. Linewidth measurements were made on the broad line: at all temperatures the crystalline spectra were broader than the amorphous. The amorphous linewidths showed abrupt narrowing at the glass transition temperature. All samples displayed maximum relaxation times in the glass transition region. Differential scanning calorimetry was employed to complement the NMR data. The melting, glass transition and crystallization temperatures were measured by DSC. An attempt was made to correlate the results of the study with the morphology and molecular motional behaviour of the two polymers.

Text

2010-06-20

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http://hdl.handle.net/2429/25863

Chemistry

University of British Columbia

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