Mitsuhiko Morimoto

Gel permeation chromatography—Fourier transform infrared study of some synthetic polymers : II. Instrumentation for the characterization of polyethylene

Abstract A high-temperature gel permeation chromatography—Fourier transform infrared (GPC—FT-IR) system was developed to characterize commercially available polyethylene. High-temperature transfer tubing was used to connect the high-temperature flow cell of an FT-IR spectrophotometer and a high-temperature GPC system. The GPC—FT-IR system was calibrated to determine the molecular weight distribution (MWD) and the short-chain branching (SCB) for high-density polyethlene (HDPE) and linear low-density polyethylene (LLLDPE). The MWD and SCB of a commercial LLDPE determined using the present GPC—FT-IR system compared favourably with those measured with a solvent gradient elution fractionation technique where 13 C NMR spectrometry was employed to determine the SCB for the same PE.

Nondestructive quantitative analysis of ethylene-propylene blend polymer by the NIR/ATR/FT-IR method

The attenuated total reflectance Fourier transform infrared (ATR/FT-IR) method in the near-infrared region was found to provide a novel opportunity for nondestructive analysis of ethylene-propylene (EP) blend polymer. The absorption due to the overtone of the C-H stretching vibration at ∼5900 cm−1 was utilized to determine the ratio of two monomer units, the ethylene and propylene units, of the blend polymer, since the overlapping of CH3- and -CH2- is not so prohibitive as in the case of the fundamental C-H stretching vibration at ∼2900 cm−1. The well-known disadvantage of the weak intensity of the overtone absorption, however, was overcome by the choice of the high-sensitivity FT-IR technique.

IN SITU FT-IR STUDY OF POLYNUCLEAR PEROXO COMPLEXES FORMED IN A H2O2-CERIUM(IV) DECATUNGSTATE ANION (CEW10O368-) REACTING SYSTEM

Isopoly and heteropoly molybdenum- and tungstenpolyoxometalates have been widely applied to the syntheses of epoxides from olefins and of carbonium compounds from alcohols with the use of H2O2 as a very selective catalyst, Some of the formed peroxo complexes have generally been believed to play an important role in the reacting process as a key species, and thus many investigators have tried to determine their structures and behaviors using various kinds of in situ spectroscopic techniques. Recently, we have found an interesting catalytic activity of the sodium lanthanidedecatungstates, Ce(IV)-, Nd(III)-, and Sm(III)-W10O36n- (LnW10), for the H2O2 decomposition and H2O2 oxidation of cyclohexanol. In the H2O2-cerium(IV) decatungstate (CeW10) reacting system, the formation of the peroxo complex and its reversible behaviors have been successfully observed with the use of in situ FT-Raman spectroscopy, and its unique catalytic activity for the H2O2 oxidation of various primary and secondary alcohols has been elucidated, In an effort to obtain more information about the structural features of the peroxo complex, in situ spectroscopic measurements, FT-IR and 183W-NMR, were used under the H2O2-CeW10 reaction conditions. Here we wish to report a novel and unique structure of the peroxo complex and its reversible behavior as deduced from such measurements.