Shigeru Takayama

Determination of the ring concentration in polyoctenamer

Abstract The ring concentration was determined for trans-polyoctenamer (TOR) by GPC/RI (differential refractive index detector), GPC/LALLS (low angle laser light scattering detector) and 13C-NMR methods. While the difference between the M w by GPC/RI and GPC/LALLS suggested that almost all molecules are cyclic, the difference between the end-group contents by GPC/RI and 13C-NMR indicated that about 50% of all molecules were cyclic and that not only oligomers, but at least 30% of high polymer molecules had ring structures.

Spectroscopic studies of the oxidation of poly(2,6-dimethyl-1,4-phenylene ether) as a function of molecular weight

Abstract The oxidation of poly(2,6-dimethyl-1,4-phenylene ether) (PPE) during polymerization has been examined as a function of molecular weight, using spectroscopic techniques. The visible light absorption and the IR absorption at 1660cm−1 increased as the molecular weight decreased. A most probable chromophore may have a xanthone-like structure and be present near the polymer chain-end. The 13C-NMR spectra for fractions of various molecular weights from a PPE sample indicate that the increase in chain mobility around the chain-end is a major reason for the higher activity in the oxidation.