Spin-Probe Investigation of the Dynamic Behavior of Low Molecule Additive in Polyvinylchloride

Kouhei SAWADA*†††, Show ONODERA, Hiroyuki ENOMOTO,
Shin-ichi NAGAOKA†† and Kazuo MUKAI††

Oleochemical Research Laboratory, NOF Co. Ltd.; Ohama-cho 1-56,
Amagasaki-shi 660-0095 Japan
††Department of Chemistry, Faculty of Science, Ehime University;
Bunkyo-cho 2-5, Matsuyama-shi 790-8577 Japan

The three kinds of TEMPO radical derivatives (TEMPO (-H), TEMPOL (-OH), TEMPOAM (-NH2)) having different substituents in the molecule as the spin probe agents were added to the poly(vinyl chloride) (PVC) including dioctyl phthalate (DOP) as plasticizer, and the rotational correlation times τC(m) of the radical derivatives were obtained in the temperature range of 90--180 °C by the ESR measurement. The values of τC(m) for each radical decreased by increasing the quantity of DOP added to PVC. Similarly, the values of τC(m) decreased by increasing the temperature. The decrease of τC(m) may be explained by the decrease of the density of the PVC resin and, thus, the decrease of the viscosity of PVC resin, due to the addition of DOP and the increase of the temperature. It has been cleared that the value of τC(m) varies depending on the kinds of functional groups (-H, -OH, -NH2) in TEMPO radical derivatives, indicating the existence of the interaction between the PVC molecule and the functional groups (-H, -OH, -NH2) in TEMPO derivatives. The energies of the above interactions were calculated with the UHF-PM3 method by using the MOPAC 93 program. TEMPO derivatives and DOP increases in the order of TEMPO<TEMPOL=DOP<TEMPOAM. Low stabilization energy was obtained for the TEMPO derivatives, which show fast rotation motion in PVC resin.

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