Comparison and evaluation of the thermooxidative stability of medical natural rubber latex products prepared with a sulfur vulcanization system and a peroxide vulcanization system

Abstract

This article deals with our study of the thermooxidative degradation of medical natural rubber latex tubes prepared with sulfur-prevulcanized latex (sample I) and peroxide-prevulcanized latex (sample II) in a dynamic air atmosphere by the use of the thermogravimetry/differential thermogravimetry method as well as the evaluation of the thermooxidative stability of these two samples. The test results showed that an oxygen-absorption mass-gain process occurred after a slight mass loss; the mass-gain rate decreased with an increase in the temperature rising rate (␤), and this was more prominent in sample II than in sample I. The maximum mass-gain rate of sample II was 1.43% when ␤ was 5°C/min, which was 5.02 times that of sample I; the thermooxidative stability of sample II was also lower than that of sample I. Because the oxygen absorption of sample II clearly caused serious oxidation, the balanced initial temperature, the temperature of the balanced degradation peak, and the balanced final temperature of sample II in the first reaction stage were obviously lower than those of sample I. The apparent activation energy (E o ϭ 143.6 kJ/mol) of sample I was significantly higher than that of sample II, and the stability of sample I was also higher than that of sample II. The temperature of the balanced degradation peak of sample II in the second reaction stage was higher than that of sample I, and E o (154.0 kJ/mol) of sample II was significantly higher than that of sample I; the stability of sample II was also higher. Thermogravimetry curves of the two samples at various ␤ values intercrossed each other, and the temperature at the crosspoint and the degradation rate increased linearly as ␤ increased. On the temperature segment from the initial temperature to the crosspoint, the degradation rate of sample II was higher than that of sample I when the temperature of the two samples was the same, but on the segment from the crosspoint to the final temperature, the degradation rate of sample II was lower than that of sample I when the temperature of the two samples was the same. The degradation rate of the samples at 600°C was 99.2-99.5%.

A Combined Experimental and Molecular Simulation Study of Factors Influencing the Selection of Antioxidants in Butadiene Rubber

“…Figure shows that the absorption peak intensities increase with α until α reaches approximately 70%, corresponding to the thermal-oxidative degradation of BR. The subsequent decrease of the absorption peak intensities corresponds to the further degradation of the thermal-oxidative aging products of BR . We focus our attention on the first part and summarize the characteristics of the absorption peaks in Table for reference. , …”

“…The subsequent decrease of the absorption peak intensities corresponds to the further degradation of the thermal-oxidative aging products of BR. 38 We focus our attention on the first part and summarize the characteristics of the absorption peaks in Table 2 for reference. 39,40 The basically stable absorption bands for CH stretching vibrations indicate that BR sample P basically retains the structural characteristics of butadiene.…”

Effects of lanthanum complex on the thermo-oxidative aging of natural rubber

“…In the air atmosphere, the DTG curves exhibit two peaks; therefore, the thermo-oxidative degradation reaction can be considered as a two-stage reaction [15]. As the weight loss at about 350e425 C in the air atmosphere is lower than that in the N 2 atmosphere, the first decomposition stage is considered to be the thermo-oxidative decomposition of NR chain.…”

A method based on thermogravimetry/differential scanning calorimetry for the forensic differentiation of latex gloves

“…examples of thermograms. Three main steps were observed in most of the samples [19][20][21]. One was located between about 200 and 400 8C followed by a further mass loss between 400 and 500 8C.…”