Solid state carbon and proton line shapes for the characterization of phenylene group motion in polycarbonates

Inglefield, Paul T.; Amici, Robert M.; O’Gara, John F.; Hung, Chi Cheng; Jones, Alan A.

doi:10.1021/ma00243a028

Cited by 50 publications

(25 citation statements)

References 2 publications

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“…At 160 K the fully relaxed spectrum does not show any motionally narrowed contribution, whereas the partially relaxed spectrum in Figure 4 proves that even at this low temperature phenylene groups with correlation rates greater than 105 Hz are present. From a line shape analysis the primary motional mechanism could be determined as 180 ~ flip about the C1C4 axis, which has been since confirmed by 13C NMR measurements [11,12]. For simplicity additional small angle fluctuation were neglected in our line shape calculations in the low temperature region presented here, vide infra.…”

Section: Phenylene Motion In Pcmentioning

confidence: 63%

Phenylene motion in polycarbonate and polycarbonate/additive mixtures

Wehrle

Hellmann

Spiess

1987

Colloid & Polymer Sci

133

102

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Pulsed deuteron NMR line shapes have been analysed to characterize type and time scale of the phenylene group motion in glassy bisphenol-A polycarbonate. The motional mechanism involves ~z-flips about the CIC4 axis augmented by small angle fulctuations about the same axis, reaching arms amplitude of _+ 35 ~ at 380 K. The distribution of correlation times for the n-flips is heterogeneous in nature and can be described either by a log-Gaussian or an asymmetric distribution with a more rapid decay at high correlation times comparable to the Williams-Watts distribution. From both distributions essentailly the same mean activation energy of 37 kJ/mol is obtained, whereas the temperature dependent width of the highly asymmetric distribution is somewhat smaller compared to the log-Gaussian distribution. Time scale and activation energy of the n-flip motion are correlated to secondary mechanical relaxations. Low molecular mass additives, which suppress the mechanical relaxation, also hinder the phenylene motion for a substantial fraction of phenylene groups. The effect of additives is not only to shift the mean value of the distribution of correlation times to higher values but also to increase drastically the width of the distribution. The results of this work strongly suggest that the secondary mechanical relaxation and the large amplitude motions of the phenylene groups in polycarbonate are related.

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Section: Phenylene Motion In Pcmentioning

confidence: 63%

Phenylene motion in polycarbonate and polycarbonate/additive mixtures

Wehrle

Hellmann

Spiess

1987

Colloid & Polymer Sci

133

102

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“…2. In fact, as demonstrated by extensive 2H and I3C NMR experiments on the phenylene motion of bisphenol-A polycarbonate, in addition to the n-flips, small angle fluctuations about the flip axis may also have to be taken into account at low temperatures [16,18,22, 23% Indeed, such oscillations have been detected in the present H NMR experiments at higher temperatures. The corresponding activation energy is 79 kJ/mol.…”

Section: *€I Nmr Investigationmentioning

confidence: 80%

Local dynamics in a thermotropic terpolyester as revealed by dynamic mechanical analysis, ²H NMR and dielectric spectroscopy

et al. 1996

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+t Dynamic mechanical, 'H NMR and dielectric spectroscopy techniques were used to identify the nature of the local motions involved in the secondary relaxations of a thermotropic aromatic terpolyester prepared from para-hydroxybenzoic acid, hydroquinone and isophthalic acid. Three secondary relaxations, denoted B, y, arid 6, were detected. A B relaxation, pointed out by dynamic mechanical measurements, is quite close to the large amplitude x-flip processes observed by 'H NMR. Correlated motions of the para-substituted rings and adjacent carbonyl groups may also participate in the /?process. Then, at lower temperatures, a y process is detected by both dielectric and dynamic mechanical experiments. It is assigned to small amplitude oscillations of the isophthalic acid units of the HBA33 polymer. At high temperatures, a heavy overlap ofbroad rate distributions for the /? and y processes observed in the measurements precludes a more detailed analysis. A dielectric relaxation, denoted 6 relaxation, is observed at very low temperatures. It likely comes from motions of a very small number of water molecules trapped in the structure of the terpolyester.

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“…This is a common pattern found in both polymer materials and glass formers. The secondary process is even more depleted in linear polymers that contain the dipole moment rigidly attached to the main chain, such as poly(vinyl chloride) [16] and polycarbonate [17][18][19]. T /ºC Fig.…”

Section: β Relaxationmentioning

confidence: 99%

Molecular dynamics in polymeric systems

2004

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It is well known that the properties of polymeric materials depend strongly upon their chemical structure. Other more specific factors that may be related to the chemical structure also determine the macroscopic behaviour of such materials, namely the relative position of the different segments of the polymeric chain, the molecular architecture (molecular weight distribution, branching, copolymer organisation, cross-linking extent, etc.), the crystalline environment and the pressure/temperature conditions. All these factors have a common impact in the material: they are strongly correlated to the mobility on the molecular level. That is why a huge amount of work has been devoted to the study of translational/rotational mobility that occurs within the polymeric chains. This review is intended to provide a brief survey on such kinds of mobilities, how they can be studied and what are their main characteristics. Examples on systems studied in our groups will be provided, obtained by dielectric and mechanical spectroscopies and differential scanning calorimetry. It will be mainly focused on molecular motions that occur in the solid phase (i.e., to temperatures up to the rubbery plateau). The dynamics in blends or copolymers will be avoided here, as they would deserve a special discussion in their own context. Special attention will be paid to the glass transition and the mobility that occurs below and above it. The dynamics that are observed in peculiar systems, such as semi-crystalline or liquid crystalline polymers, will be addressed.

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Solid state carbon and proton line shapes for the characterization of phenylene group motion in polycarbonates

Cited by 50 publications

References 2 publications

Phenylene motion in polycarbonate and polycarbonate/additive mixtures

Phenylene motion in polycarbonate and polycarbonate/additive mixtures

Local dynamics in a thermotropic terpolyester as revealed by dynamic mechanical analysis, ²H NMR and dielectric spectroscopy

Molecular dynamics in polymeric systems

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Solid state carbon and proton line shapes for the characterization of phenylene group motion in polycarbonates

Cited by 50 publications

References 2 publications

Phenylene motion in polycarbonate and polycarbonate/additive mixtures

Phenylene motion in polycarbonate and polycarbonate/additive mixtures

Local dynamics in a thermotropic terpolyester as revealed by dynamic mechanical analysis, 2H NMR and dielectric spectroscopy

Molecular dynamics in polymeric systems

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Local dynamics in a thermotropic terpolyester as revealed by dynamic mechanical analysis, ²H NMR and dielectric spectroscopy