Pulsed NMR Investigation on the Polymerization of Methyl Methacrylate

Kurotu, Takuzo

doi:10.1295/polymj.18.859

Cited by 10 publications

(6 citation statements)

References 24 publications

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“…FS at each temperature increases sharply at a certain reaction time and reaches a saturated value. 15,21 This increase occurs at shorter times as the reaction temperature rises. Figure 5 shows the reaction time dependence of the polymer yield at various temperatures.…”

Section: Reaction Time Dependence Of the Spin-spin Relaxation Timesmentioning

confidence: 99%

“…As we have pointed out, FS corresponds to the amount of a tight entanglement of polymer chains, and FM corresponds to the amounts of polymers whose molecular weight is lower (more mobile) than that belonging to FS. 15 The latter does not form a spectroscopically tight entanglement by itself, or a loosely entanglement. The onset of the gel effect corresponds to the occurrence of entanglement.…”

Section: Reaction Time Dependence Of the Spin-spin Relaxation Timesmentioning

confidence: 99%

“…The polymer chains propagate and begin to interpenetrate each other to form a tight entanglement of polymer chains (transient 3D network structure), which caused the motion of the polymer chain to be constrained. [1][2][3] In the previous work, 15 we also investigated the bulk polymerization process of MMA (methyl methacrylate) by pulsed NMR. The time course of the reaction proceeded in a similar manner to that of MA.…”

Section: Reaction Time Dependence Of the Spin-spin Relaxation Timesmentioning

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: Reaction Time Dependence Of the Spin-spin Relaxation Timesmentioning

confidence: 99%

Section: Reaction Time Dependence Of the Spin-spin Relaxation Timesmentioning

confidence: 99%

Section: Reaction Time Dependence Of the Spin-spin Relaxation Timesmentioning

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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“…12 Since this relatively short-range chain motion affects the NMR relaxation times, studying T1 and T2 can provide a sensitive probe by which to investigate the effect of intermolecular coupling on the mobility, such a kinetic process, like a bulk polymerization or the curing process of epoxy resin. [15][16][17][18] In the present work, we demonstrated that pulsed NMR was sufficiently sensitive to changes in the material properties of epoxy resin and could be used for a non-destructive state assessment of the curing process of epoxy resin. Our results in this study also substantiate the perspective to conduct a hardening process or lifetime predictions of epoxy resin, or other polymers in situ in real time on the basis of laboratory reference data.…”

Section: Introductionmentioning

confidence: 99%

“…These kinetic behaviors of the components were also observed in a bulk polymerization, where a gel effect generally occurs. [15][16][17][18] PS observed in the polymerization is, therefore, associated with the existence of polymer chain entanglements, of which the motion is severely restricted (~20 ms). The time course of these components explains in regard to the proton motion how the curing process with a gel effect proceeds by the formation of three dimensional polymer chain networks.…”

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confidence: 99%

Pulsed NMR Study of the Curing Process of Epoxy Resin

et al. 2008

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An NMR study of the electron beam‐induced polymerization of trimethylolpropane triacrylate and trimethylolpropane trimethacrylate

Harrell¹,

Choudhury²,

Ahuja³

et al. 1991

J Polym Sci B Polym Phys

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Electron beam‐induced polymerization of trimethylolpropane triacrylate (TMPTA) and its methacrylate analog (TMPTMA) was studied using nuclear magnetic resonance (NMR) relaxation time measurements. Free induction decays (FID) of partially polymerized samples consist of a short Gaussian component and a longer component comprised of a distribution of simple exponentials. The relative intensity of the Gaussian component increases with radiation dose. T1 and T1ρ values were measured as a function of temperature and radiation dose. The relaxation is due primarily to methyl group reorientation at low temperatures, ethyl group reorientation at intermediate temperatures, and whole‐molecule reorientation at high temperatures. In both compounds, the T1 and T1ρ values at the high temperature minima increase with increasing dose, and the minima values can be used to estimate the degree of polymerization. The temperature at which the T1ρ minimum occurs increases with dose, suggesting an increase in the glass transition temperature, Tg, with polymerization. The polymerization appears to have very little effect on the low temperature CH3 reorientation in TMPTA. In TMPTMA the polymerization appears to reduce the mobility of the methacrylate methyl groups.

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Pulsed NMR Investigation on the Polymerization of Methyl Methacrylate

Cited by 10 publications

References 24 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

An NMR study of the electron beam‐induced polymerization of trimethylolpropane triacrylate and trimethylolpropane trimethacrylate

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