Thermogravimetric Studies of the Decomposition Kinetics of Four Different Hevea Rubber Clones using Ozawa's Approach

Abstract

Thermal degradation behavior of rubber from four rubber clones (RRIM 600, PB 235, GT1 and IAN 873) of the Hevea brasiliensis species was studied by thermogravimetry (TG) using Ozawa's approach to assess the kinetic parameters of the decomposition process. These parameters indicated that the thermal behavior of natural rubber depends on the type of rubber clones studied. The order of reaction was found to be dependent on the degree of conversion indicating that both the early and the latter stages of rubber degradation follow zero or pseudo-zero order kinetics whereas the intermediate stages follow a first order kinetics and the activation energy was found to be dependent on the degree of conversion and the type of clone used ragging from 148 to 236 kJ/mol. Rubber from clones IAN 873, GT1 and RRIM 600 presented the best overall thermal stability whereas the clone PB 235 presented the lowest thermal stability, therefore in agreement with the plasticity retention index (PRI) behavior.