Effect of atmosphere on the thermal decomposition of chlorinated natural rubber from latex

Abstract

ABSTRACT:The kinetics of the thermal decompositions of chlorinated natural rubber (CNR) from latex under both air and nitrogen atmospheres were studied with thermogravimetric analysis (TGA). The thermooxidative decomposition of CNR had two weight-loss step changes in the TGA curves, which occurred at the two distinct temperature ranges of about 160-390 and 390-850°C, respectively. The gaseous products of the first step change were mainly HCl with a little CO 2 , and the apparent reaction order (n) was 1.1. The reaction activation energy (E) increased linearly with the increment of heating rate (B), and the apparent activation energy (E 0 ), calculated by extrapolation back to zero B, was 101.7 kJ/mol. Bs ranging from 5 to 30°C/min were used. The initial temperature of weight loss (T 0 ) was 1.31B ϩ 252°C, where B is in degrees Celsius per minute. The final temperature of weight loss (T f ) was 0.93B ϩ 310°C, and the temperature of maximum weight-loss rate (T p ) was 1.03B ϩ 287°C. The decomposition weight-loss percentage at T p (C p ) and that at T f (C f ) were not affected by B, and the average values were 38 and 60%, respectively. The second weight-loss step change was an oxidative decomposition of the molecular main chain. The value of n was 1.1. E increased linearly with the increment of B, and E 0 was 125.0 kJ/mol. C f after the second step approached 100%, which indicated complete decomposition. The thermal decomposition of CNR in a N 2 atmosphere had only one weight-loss step change with an n of 1.1. E increased linearly with the increment of B, and E 0 was 98.6 kJ/mol. T 0 was 1.25B ϩ 251°C, T f was 0.91B ϩ 315°C, and T p was 1.09B ϩ 286°C. C p and C f were not affected by B, and the average values were 37 and 68%, respectively. The weight percentage of more stable, nonthermal decomposed residue was about 30%. The thermal decompositions of CNR in both atmospheres were similar, mainly by dehydrochlorination, at the low temperature range (160-390°C) but were different at the high temperature range (390-850°C).

Thermooxidative degradation of natural rubber/clay composite

“…From the DTG curves of the test samples, it can be seen further, that a main peak appears at 376.1-381.5°C, and a shoulder peak appears at 424.4 -431.6°C, which is different from the DTG curve of thermooxidative degradation of NR pure gum vulcanizate. On the DTG curve of NR pure gum vulcanizate, there is no shoulder peak by side of the main peak, 19 which indicates that the thermooxidative degradation of the test samples is more complicated than the thermooxidative degradation of NR. It is inferred that the appearance of the shoulder peak is possibly caused by the following fact: at higher temperature, the metal components in the test samples accelerate the degradation of rubber hydrocarbon, which conforms substantially to the result of the infrared spectrogram stated above.…”

Preparation and thermal stability of brominated natural rubber from latex

“…Up to the present, a great amount of research work has been done about the preparation, structure, properties, and reaction mechanism of CNR. [2][3][4][5][6][7][8][9] BNR can be prepared by the brominated modification of NR from solution and the solubility and structure of BNR product were investigated. 10 In the solution process, the BNR was prepared by dissolving the NR in the solvent, such as tetrachloromethane, and then brominating.…”

Thermal degradation and ageing behavior of microcomposites of natural rubber, carboxylated styrene butadiene rubber latices, and their blends

“…The stability of rubber vulcanizates depends on environment because degradation is primarily dependent on thermal or thermooxidative degradation. Li et al14 analyzed the thermal decomposition of chlorinated NR from latex at different atmospheres.…”