Multiple-Pulse Nuclear Magnetic Resonance Experiments on Some Crystalline Polymers

Fujimoto, Kunihiko; Nishi, Toshio; Kado, Ryoichi

doi:10.1295/polymj.3.448

Cited by 60 publications

(21 citation statements)

References 23 publications

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“…Figure 8 shows the 13 C DD/MAS NMR spectra of MA or PMA at various reaction times at 55˚C. The carbon peaks belonging to the residual monomers or polymers can be observed separately, which qualitatively offers a spectroscopic view on the cross-section of the polymerization progress.…”

Section: Dd/mas Nmr Spectroscopymentioning

confidence: 94%

“…The results were considered in conjunction with that of 13 C DD/MAS NMR measurements and the polymer yield.…”

Section: Introductionmentioning

confidence: 99%

“…13 C dipolar decoupling (DD)/magic angle spinning (MAS) NMR spectra were measured by a Bruker DMX 500 spectrometer operating at a carbon frequency of 125 MHz. Another experiment concerning the polymerization was also performed under the same experimental conditions as mentioned above to calculate the polymer yield and to carry out 13 C DD/MAS NMR measurements. The reaction temperatures were regulated within ±0.5˚C by an air-flow thermostat.…”

Section: Introductionmentioning

confidence: 99%

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Pulsed NMR Study of Network Formation in the Course of Bulk Polymerization of Methyl Acrylate

et al. 2005

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Pulsed NMR can be used to elucidate certain aspects of the polymer structure and those properties that are affected by the molecular mobility. The spin-spin relaxation time (T2), which is primarily determined by the relatively slow motion of the polymer chain in the fluid state, was found to be useful for investigating the polymer structural order, chain entanglement and their presence as permanent cross-links. 1-3 Short polymer chains in a liquid state or at high temperature in the molten state will give rise to a single exponential T2 decay. When the molecular weight exceeds a critical value, the spin-spin relaxation deviates from the single exponential behavior. This is explained by the presence of higher molecular weights of molecular entanglements sufficient in number to provide a three dimensional network. 4 The entanglement of a polymer chain restricts the chain mobility. Since this long-range chain motion affects the NMR relaxation times, the studying T2 can provide a sensitive probe with which to investigate the effect of intermolecular coupling on the mobility.Most of molecular motion studies, however, have focused on polymers in a static state, such as cross-linked rubbers, 5 polymer melts with non-disperse molecular weight. 3 From a molecular motional point of view, bulk polymerization is also one of the most interesting targets for pulsed NMR spectroscopy. The reaction is followed by a liquid-to-solid transition accompanied by a change in the polymer structure, the molecular weight distribution and the density. The molecular motion during the course of the reaction is, therefore, continuously influenced particularly by the propagation process, where the entanglement occurs along with a rapid increase in the degree of polymerization. Under such circumstances, samples consist of a mixture of high-polymer, low-molecular weight polymer, oligomers, and a residual monomer where high molecular weight entangled (network structure) molecules co-exist with low molecular weight "free molecules". The constituents' fractions also continuously change during the reaction. In terms of the molecular motion, studying the network formation by a pulsed NMR method in a kinetic process, such as bulk polymerization, is therefore of interest and worth investigating as well as that by the gravimetric method, 6-9 because the pulsed NMR method provides such a different perspective on the kinetic process of the reaction in real time.In the present work, the proton spin-spin relaxation time of poly(methyl acrylate) (PMA) was measured in order to study network formation as a function of the reaction time at various temperatures by the pulsed NMR method. The results were considered in conjunction with that of 13 C DD/MAS NMR measurements and the polymer yield. ExperimentalPulsed NMR measurements were carried out with a JEOL Mu-25 spectrometer operating at a frequency of 25 MHz. The proton spin-spin relaxation time (T2) was obtained from the free induction decay (FID), which follows a 90˚ pulse. 10 The pulse interval time was 10 s...

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Section: Dd/mas Nmr Spectroscopymentioning

confidence: 94%

“…The results were considered in conjunction with that of 13 C DD/MAS NMR measurements and the polymer yield.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Pulsed NMR Study of Network Formation in the Course of Bulk Polymerization of Methyl Acrylate

et al. 2005

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“…Pulsed NMR can generally be used to elucidate certain aspects of polymer structure, and those properties that are affected by the molecular mobility. [10][11][12] The spin-lattice relaxation time, T1, and the spin-spin relaxation time, T2, which are primarily determined by the relatively slow motion of a polymer chain in a liquid state, are found to be useful for investigating the polymer structure order, chain entanglement and their presence as permanent cross-links. 13,14 The entanglement of a polymer chain (network structure), especially like in a curing process of epoxy resin, restricts the chain mobility, because the epoxy resin reacts with the curing agent to form "a permanent network structure" by chemical bonding between them.…”

Section: Introductionmentioning

confidence: 99%

Pulsed NMR Study of the Curing Process of Epoxy Resin

et al. 2008

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“…The mobile region of low-density polyethyelene is a typical example. 4 The discreteness of the time constants also appears in the highresolution NMR spectrum of the polymer solution. In a trans-decalin solution of a polypropylene the PRFT (partially relaxed Fourier transform) 13 C NMR spectrum, there are many peaks corresponding to chemical groups and stereochemical configurations.…”

mentioning

confidence: 99%

Application of Catastrophe Theory to Draw Resonance

Chûjô

Tsuyama

1979

Polym J

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ABSTRACT:Catastrophe theory was successfully applied to the analysis of draw resonance phenomena. It was shown that the potential of cusp catastrophe was appropriate to the analysis of oscillating viscoelasticity appearing in the above-mentioned phenemena. Moreover, basic behavior such as stress relaxation is discussed in regard to this potential. In these analyses, no relaxation spectrum is introduced. However, an apparent spectrum can be obtained if the results of stress relaxation are analyzed by a procedure similar to that used in the analysis of linear viscoelasticity. But a spectrum may not always exist even if derived analytically.

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Multiple-Pulse Nuclear Magnetic Resonance Experiments on Some Crystalline Polymers

Cited by 60 publications

References 23 publications

Pulsed NMR Study of Network Formation in the Course of Bulk Polymerization of Methyl Acrylate

Pulsed NMR Study of Network Formation in the Course of Bulk Polymerization of Methyl Acrylate

Pulsed NMR Study of the Curing Process of Epoxy Resin

Application of Catastrophe Theory to Draw Resonance

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