Molecular aggregation in poly(vinyl chloride). III. Role of molecular structure

Abdel-Alim, A. H.

doi:10.1002/app.1975.070190811

Cited by 10 publications

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Diffusion and Thermodynamic Properties of Polyvinylchloride‐ and Polymethylmethacrylate‐Solutions

Roßkopf

Polawka

Rehage

et al. 1979

Ber Bunsenges Phys Chem

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Diffusion coefficients of different polyvinylchloride (PVC)‐samples have been measured in solvents of varying quality up to polymer concentrations which were still experimentally tractable. The samples differed by polymerization conditions and thus by the stereospecific microstructure. The thermodynamic factor of the diffusion coefficient was determined osmotically and the mobility of the polymer was calculated. In the semi‐dilute concentration range, the diffusion coefficient does no more depend on the molar mass of the polymer but is strongly influenced by the stereospecific microstructure of the PVC. The concentration dependence of the diffusion coefficients in all systems under investigation can be described by the relationship D ∼ ρα2. This was predicted by a new theory of De Gennes.

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Diffusion and Thermodynamic Properties of Polyvinylchloride‐ and Polymethylmethacrylate‐Solutions

Roßkopf

Polawka

Rehage

et al. 1979

Ber Bunsenges Phys Chem

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The measurement of the tacticity of poly(vinyl chloride) by ¹³C nuclear magnetic resonance spectroscopy

et al. 1983

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Fourier transform 'H-decoupled 13C NMR spectra were obtained on seven poly(viny1 chloride), (PVC), samples in solution in o-dichlorobenzene. Four of the polymers were of the commercial type and the others were prepared by suspension polymerisation at + 90 "C, + 5 "C, and -30 "C. Measurements of the spectra were used to assess the precision and accuracy with which information about the tacticity of PVC can be obtained from such spectra. The results show that the well-resolved a-carbon triad and b-carbon tetrad spectra obtained may be reliably analysed to give values of the probability of syndiotactic placement with a precision of about 0,005 for measurements on a single run on a single sample. The simplest and probably the most reliable method of measuring the areas under the peaks which correspond to specific triads ot tetrads is to use the spectrometer integrator, although results of slightly lower precision may be obtained by the use of a curve resolver. Consideration of possible systematic errors due to different T, relaxation times, unequal nuclear Overhauser enhancement (NOE) factors, and incomplete dissolution of the polymer has shown that the only one of these which is possibly significant is that due to NOE, which is almost certainly less than 0,008, so that the absolute accuracies of the P, values should be better than that. A more detailed study of the data shows that the polymers made at 5 "C and -30 "C are almost certainly non-Bernoullian and that firstoder Markov statistics can adequately describe the observed departures from Bernoullian statistics. These departures may have significant consequences for the physical properties of the polymers.

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X‐ray diffraction and infrared studies on annealed highly syndiotactic poly(vinyl chloride)

Baker

Maddams

Preedy

1977

J. Polym. Sci. Polym. Phys. Ed.

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X‐ray diffraction scans and infrared absorption spectra for the C‐CI stretching region were obtained for a highly syndiotactic poly(vinyl chloride) (PVC) sample made by the urea clathrate method. When the polymer was annealed at a series of increasing temperatures up to 180°C, x‐ray diffraction measurements showed that the crystallinity increases steadily with annealing temperature. Even at 50°C an increase above the original value of 63% was detectable and by 180°C it had reached 70% with a further increase to 78% after cooling to ambient temperature. There is a concurrent significant increase in the lateral crystallite dimensions. However, the infrared spectrum did not change, in agreement with the recent prediction of Moore and Krimm that there is no observable band splitting from interchain interaction in crystalline regions, thus indicating that these C‐CI bands cannot be used as a measure of crystallinity. The results from computer curve fitting of the spectra suggest that at least 85% of the polymer consists of long planar syndiotactic sequences and there is therefore substantial order along the chain direction. A mechanism for the increase in crystallinity on annealing, involving the lateral ordering of these regular chains, is discussed. Furthermore, as the temperature is raised some amorphous material is converted to a nematic phase, and this may crystallize during the subsequent cooling.

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Molecular aggregation in poly(vinyl chloride). III. Role of molecular structure

Cited by 10 publications

References 1 publication

Diffusion and Thermodynamic Properties of Polyvinylchloride‐ and Polymethylmethacrylate‐Solutions

Diffusion and Thermodynamic Properties of Polyvinylchloride‐ and Polymethylmethacrylate‐Solutions

The measurement of the tacticity of poly(vinyl chloride) by ¹³C nuclear magnetic resonance spectroscopy

X‐ray diffraction and infrared studies on annealed highly syndiotactic poly(vinyl chloride)

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Molecular aggregation in poly(vinyl chloride). III. Role of molecular structure

Cited by 10 publications

References 1 publication

Diffusion and Thermodynamic Properties of Polyvinylchloride‐ and Polymethylmethacrylate‐Solutions

Diffusion and Thermodynamic Properties of Polyvinylchloride‐ and Polymethylmethacrylate‐Solutions

The measurement of the tacticity of poly(vinyl chloride) by 13C nuclear magnetic resonance spectroscopy

X‐ray diffraction and infrared studies on annealed highly syndiotactic poly(vinyl chloride)

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Product

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The measurement of the tacticity of poly(vinyl chloride) by ¹³C nuclear magnetic resonance spectroscopy