Characterization of Semicrystalline Polymers Using Pulsed 1H-NMR

Characterization of Semicrystalline Polymers Using Pulsed 1H-NMR

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Morphology is responsible for physical - mechanical properties of semicrystalline polymer. Generally, crystallinity is parameter that characterizes polymer morphology. The following conventional analyses are used for assessment of polymer's crystallinity: i) Differential Scanning Calorimetry, ii) X-ray spectroscopy, iii) Infrared spectroscopy, iiii) Density. Each of these methods gives a different value of crystallinity, based on the physical principle. It is known, crystallinity is semiquantitative comparative parameter and it depends on method of assessment. In this present paper, the crystallinity of semicrystalline polymers is characterized via pulsed 1H-NMR. This method distinguishes sequences of macromolecules with different relaxation behavior. A large difference in mobility of the strongly coupled proton pairs within the two phases is expected. The content of faster relaxing phase - so called Solid Phase Content (SPC) - has been determined instead of crystallinity. A direct fitting of the observed FID signal determines the SPC. An effort has been made to examine different analytical functions to fit the FID signal. The SPC has been correlated with physical - mechanical properties. Chemopetrol Litvínov supplied polymer samples for all measurements reported in this work. The main object of this presentation is to emphasize the potential use of the pulsed 1H-NMR technique to characterize semicrystalline polymers.

Morphology is responsible for physical - mechanical properties of semicrystalline polymer. Generally, crystallinity is parameter that characterizes polymer morphology. The following conventional analyses are used for assessment of polymer's crystallinity: i) Differential Scanning Calorimetry, ii) X-ray spectroscopy, iii) Infrared spectroscopy, iiii) Density. Each of these methods gives a different value of crystallinity, based on the physical principle. It is known, crystallinity is semiquantitative comparative parameter and it depends on method of assessment. In this present paper, the crystallinity of semicrystalline polymers is characterized via pulsed 1H-NMR. This method distinguishes sequences of macromolecules with different relaxation behavior. A large difference in mobility of the strongly coupled proton pairs within the two phases is expected. The content of faster relaxing phase - so called Solid Phase Content (SPC) - has been determined instead of crystallinity. A direct fitting of the observed FID signal determines the SPC. An effort has been made to examine different analytical functions to fit the FID signal. The SPC has been correlated with physical - mechanical properties. Chemopetrol Litvínov supplied polymer samples for all measurements reported in this work. The main object of this presentation is to emphasize the potential use of the pulsed 1H-NMR technique to characterize semicrystalline polymers.

pulsed 1H-NMR, semi-crystalline polymers, solid phase content

pulsed 1H-NMR, semi-crystalline polymers, solid phase content

VILČ, L.; KRATOCHVÍLA, J.

27.09.2006

Halle