Determination of Activation Energy Using Various Kinetic Models and Their Influence on Life Prediction of Neoprene Rubber

Determination of kinetic parameter (activation energy, E<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">a</inf>) is crucial in the field of fabrication, material synthesis, bio-medicals, catalysis, and many other industrial production to understand the processes like curing, thermal decomposition, crystallization and solid state transformation etc. To obtain kinetic parameters, a number of kinetic methods employing non-isothermal techniques have been devised. The main objective of this study is to investigate the consequences of various non-isothermal methods on activation energy of neoprene rubber and their impact on life prediction using ASTM E 1877. All polymers possess inherent vulnerability to oxidation, a basic process that is responsible for material deterioration overtime. Kinetic models are intended to delineate the reaction mechanisms and reaction rates, while swift qualification testing aim to establish confidence in prolonged performance during service operation. It is indispensable to assess the aging effects of extended duration at room temperature on elastomeric parts like shock isolators, O-rings etc. To comprehend this impact, accelerated thermal aging at elevated temperature (100°C for 72 hours, 144 hours and 216 hours) was investigated. This research study also delves the effect of accelerated thermal aging on the activation energy values of neoprene rubber. Determining this kinetic parameter for elastomeric material like neoprene using elongation, tensile strength, tensile modulus is both expensive and time consuming. A substitute method implicates analyzing the weight loss kinetics by Thermo Gravimetric Analysis (TGA) utilizing model free kinetics such as Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS) and Kissinger methods. This tactic is appealing because of the readily accessibility to require instrumentation and software. To ascertain the variations in the activation energy for thermo-oxidative degradation under temperature variable conditions, thermal analysis using (TGA) was carried out at different heating rates (5, 7, 10 K/min) within temperature range of 25°C to 700°C. It was revealed that activation energy obtained changes with the extent of thermal degradation. Additionally, using Fourier Transform Infrared (FTIR) spectroscopy structural changes were investigated, this study revealed that aging is associated with significant oxidation.