Sugar cane as an alternative green activator to conventional vulcanization additives in natural rubber compounds: Thermal degradation study

It is essential to deeply understand the chemical changes caused in the rubber compositions when using green additives, especially in the thermal degradation and stability. So, the objective of this research is the evaluation of the thermal degradation behavior of a typical natural rubber (NR) compound modified by silanized activator derived from sugar cane (green additive). The activator was used in order to replace the conventional zinc oxide and stearic acid additives commonly used as vulcanization activators. Different contents (1, 3, 5, 7 and 10 phr) were used in the NR compounds and the thermal stability was evaluated. It was observed that, according to the degradation proceeds, the weight loss tended to be similar at low temperatures for all the studied compounds, i.e., the reinforcement effect of the green additive was more pronounced at higher temperatures. However, the activation energy values significantly increased by using up to 3 phr of the sugar cane activator. Compared to the Control sample, this result suggested that the solid-state degradation mechanism appeared to change when the activator from sugar cane was added in the samples. In addition, the morphology showed that silanization treatment acted positively on the additive dispersion within NR matrix. In this scenario, the favorable results obtained, as well as the considerable reduction of zinc content (81%) used in the compositions, highlighted the possibility of changing the conventional activators such as zinc oxide and stearic acid by a green option from sugar cane. (C) 2018 Elsevier Ltd. All rights reserved.