Stereoregularity of polyacrylonitrile determined by NMR

Abstract

synopsisThe NMR spectrum of polyacrylonitrile is interpreted and the tacticity of three polyacrylonitrile samples prepared at dserent temperatures in the range from -78 to 120OC. determined. The ratio between isotactic and syndiotactic units is about 50:50 for all the three samples examined. 2875 Some ZusammenfassungMan gibt eine Deutung des Polyacrylonitril NMRSpectrums. Auf Grund dieser Deutung bestimmt man die Taktizitiit von drei Polyacrylonitril-Proben, die bei verschiedenen Temperaturen, -78 bis +12OoC, hergestellt wurden. Das Verhiiltnis zwischen iso-und syndiotaktischen Monomereinheiten ist ungefahr 50:50 fur die drei gepriiften Proben.

Zeolite Inclusion Chemistry

“…The polymer recovered from the zeolite hosts is identical to bulk PAN as shown by NMR spectroscopy. 90 The NMR spectra show two bands at a ratio of 2 to 1, one at 2.0 ppm corresponding to the methylenic group in the polymer, and the other at 3.1 ppm confirming a methine group. The 13 C NMR data of the zeoliteextracted PAN show CH2 (27.5 ppm), CH (32.7 ppm ), and -CN (120.1 ppm), identical to the bulk material.…”

Kinetics and Mechanism of Radical Polymerization

“…In a well stirred reactor the conversion/time curves follow the same course as with homogeneously initiated bulk polymerization, except that induction periods occur whose length is proportional to [S];o. 5 .…”

“…Radical polymerization is characterized by the high reactivity of the active polymeric radica1,s combined with a pronounced non-specificity of reaction : they react both with molecules and with other radicals, by addition and by substitution. In polymer chemistry these reactions are known as: chain propagation (2), chain transfer (3), disproportionating termination (4), and combinational termination ( 5 ) ; R* corresponds to a polymer radical, e. g. *CHX--CH,fCHX-CH2$;; H.…”

“…(77)for C = 1 -([M]/[M]o). This integrated rate equation (77) permits a very good description of the experimental results.Y Versus t plots of the experimental data are straight lines whose intersections with the ordinate are proportional to [S]g 5. and whose slopes are proportional to [S];.'…”

Investigation of gel-spun PAN fiber morphology by membrane technology techniques

“…A lot of data concerning the molecular structure of acrylic fibers has been generated over the years covering both intrachain and interchain organizations [4][5][6][7][8][9]. The view appears to be that PAN, and its copolymer relatives adopt an irregular helical configuration with the C≡N dipoles arranged so as to minimize repulsion between near neighbours.…”