Study on hot air aging and thermooxidative degradation of peroxide prevulcanized natural rubber latex film

Abstract

AbstractThe air‐aging process at 120°C and the thermooxidative degradation of peroxide prevulcanized natural rubber latex (PPVL) film were studied with FTIR and thermal gravity (TG) and differential thermal gravity (DTG) analysis, respectively. The result of FTIR shows that the OH and COOH absorption of the rubber molecules at IR spectrum 3600–3200 cm−1, the CO absorption at 1708 cm−1, and the COH absorption of alcohol at 1105 and 1060 cm−1 increased continuously with extension of the aging time, but the CH3 absorption of saturated hydrocarbon at 2966 and 2868 cm−1, the CH3 absorption at 1447 and 1378 cm−1, and the CC absorption at 835 cm−1 decreased gradually. The result of TG‐DTG shows that the thermal degradation reaction of PPVL film in air atmosphere is a two‐stage reaction. The reaction order (n) of the first stage of thermooxidation reaction is 1.5; the activation energy of reaction (E) increases linearly with the increment of the heating rate, and the apparent activation energy (E0) is 191.6 kJ mol−1. The temperature at 5% weight loss (T0.05), the temperature at maximum rate of weight loss (Tp), and the temperature at final weight loss (Tf) in the first stage of degradation reaction move toward the high temperature side as the heating rate quickened. The weight loss rate increases significantly with increment of heating rate; the correlation between the weight loss rate (αp) of DTG peak and the heating rate is not obvious. The weight loss rate in the first stage (αf1) rises as the heating rate increases. The final weight loss rate in second stage (αf2) has no reference to heating rate; the weight loss rate of the rubber film is 99.9% at that time. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3196–3200, 2004