Spin-probe investigation of the dynamic behavior of low molecule additive in polyvinylchloride

The three kinds of TEMPO radical derivatives (TEMPO (-H), TEMPOL (-OH), TEM POAM (-NH2)) having different substituents in the molecule as the spin prob e agents were added to the poly(vinyl chloride) (PVC) including dioctyl pht halate (DOP) as plasticizer, and the rotational correlation times tau(c)((m )) of the radical derivatives were obtained in the temperature range of 90- 180 degrees C by the ESR measurement. The values of tau(c)((m)) for each ra dical decreased by increasing the quantity of DOP added to PVC. Similarly, the values of tau(c)((m)) decreased by increasing the temperature. The decr ease of tau(c)((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. ft has been cleared t hat the value of tau(c)((m)) varies depending on the kinds of functional gr oups (-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 we re 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 fa st rotation motion in PVC resin.