A Novel Method for 13C-NMR Spectroscopy of Polymer in Emulsion: Quantitative Analysis of Microstructure of Crosslinked Polybutadiene in Latex

1999 ◽  
Vol 72 (5) ◽  
pp. 844-853 ◽  
Author(s):  
Seiichi Kawahara ◽  
Saori Bushimata ◽  
Takashi Sugiyama ◽  
Chihiro Hashimoto ◽  
Yasuyuki Tanaka

Abstract A novel analytical method using high resolution 13C-NMR spectroscopy to study polymer latex, which is a heterogeneous system comprising polymer dispersoid and water, is described. The appropriate concentrations of surfactant and dried rubber content of a polybutadiene latex, which give the best spectrum, were found to be 1 w/v % and 10%, respectively. The half-widths of resonance peaks for the latex sample were almost identical to the half-widths obtained in solution, which were about one-third the width of those obtained using a solid sample of either a crosslinked or soluble polybutadiene. Nevertheless, the signal to noise ratio for the latex sample was slightly smaller than that for the solution sample. The values of spin-lattice relaxation time, T1, for the latex sample were similar to those for the solid sample. These demonstrate that the latex state C-NMR spectroscopy will be a powerful technique for structural characterization of crosslinked gels in the dispersoid because it gives a high resolution spectrum comparable to solution state spectroscopy, showing short T1 values corresponding to those for solid state C-NMR spectroscopy. High resolution latex state 13C-NMR spectroscopy was used to determine the concentrations of the various isomers of the polybutadiene in the dispersoid.

1995 ◽  
Vol 28 (19) ◽  
pp. 6677-6679 ◽  
Author(s):  
Masatoshi Kobayashi ◽  
Isao Ando ◽  
Takahiro Ishii ◽  
Shigetoshi Amiya

The 31 P n. m. r. spectrum and spin–lattice relaxation time in polycrystalline P 4 S 3 have been measured between 77 and 500 K in the range 7 to 25 MHz. In phase II the 31 P n. m. r. spectra and second moments are dominated by the anisotropic chemical shift interactions. Close to the first-order phase transition at 314 K the spectra are narrowed by reorientation of the molecules about their triad axes. This motion also generates anisotropicshift spin-lattice relaxation notable for its absence of frequency dependence. The activation energy of this motion was found to be 34 kJ mol -1 . Nuclear dipolar interactions play only a minor role. In phase 1 the molecules exhibit rapid quasi-isotropic reorientation and diffusion. The anisotropic broadening interactions are averaged out and an AB 3 high-resolution spectrum of a doublet and quartet are resolved at 420 K, well below the melting point, 446 K. In this phase the spin–rotation interaction relaxation mechanism becomes dominant. Taking advantage of the remarkable motional narrowing in this compound we report the first solid-state n. m. r. J spectrum. This spectrum, recorded at 410 K, allowed the J coupling between apical and basal nuclei in solid P 4 S 3 to be measured accurately, 70.4 ± 0.5 Hz.


2007 ◽  
Vol 80 (5) ◽  
pp. 751-761 ◽  
Author(s):  
Seiichi Kawahara ◽  
Jinta Ukawa ◽  
Junichiro Sakai ◽  
Yoshimasa Yamamoto ◽  
Yoshinobu Isono

Abstract Crosslinking junctions of natural rubber vulcanizates were characterized by high-resolution latex-state 13C-NMR spectroscopy. Vulcanized natural rubber latex was prepared by two methods: i.e., vulcanization of the rubber latex and cryogenic crushing of a rubber sheet vulcanized on a hot press. High-resolution latex-state 13C-NMR spectroscopy was attained even after vulcanization of the rubber latex, as is evident from no background in spectrum and narrow half width of signals independent of vulcanization time. Small signals at 44 ppm and 57 ppm in the aliphatic carbon region were assigned by measurements of both Distortionless Enhancement by Polarization Transfer (DEPT) and Attached Proton Test (APT) to secondary and tertiary carbons of crosslinking points. The assignment was proved by high-resolution solution-state NMR spectroscopy of vulcanized liquid cis-1,4-polyisoprene as a model, in which DEPT, APT, 2-dimensional 1H-1H correlation (H-H COSY), 2-dimensional 1H-13C correlation (H-C COSY) and 2-dimensional heteronuclear multiple bond correlation (HMBC) measurements were applied.


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