Vulcanization kinetics and reinforcement behaviour of natural rubber-carbon black composites: Addition of Shea-butter versus aromatic oil as plasticizers

Bismark Mensah; Boateng Onwona-Agyeman; Frank Nsaful; Isaac Adjaye Aboagye; Nii Longdon Sowah; Prosper Naah Angnunavuri; Vitus Atanga Apalangya

doi:10.1016/j.heliyon.2024.e25592

Vulcanization kinetics and reinforcement behaviour of natural rubber-carbon black composites: Addition of Shea-butter versus aromatic oil as plasticizers

Heliyon. 2024 Feb 13;10(4):e25592. doi: 10.1016/j.heliyon.2024.e25592. eCollection 2024 Feb 29.

Authors

Bismark Mensah¹, Boateng Onwona-Agyeman¹, Frank Nsaful², Isaac Adjaye Aboagye³, Nii Longdon Sowah³, Prosper Naah Angnunavuri⁴, Vitus Atanga Apalangya²

Affiliations

¹ Department of Materials Science and Engineering, School of Engineering Sciences, College of Basic and Applied Sciences, University of Ghana, Legon, Ghana.
² Department of Food Process Engineering, School of Engineering Sciences, College of Basic and Applied Sciences, University of Ghana, Legon, Ghana.
³ Department of Computer Engineering, School of Engineering Sciences, College of Basic and Applied Sciences, University of Ghana, Legon, Ghana.
⁴ Department of Civil and Environmental Engineering, School of Engineering, University of Energy and Natural Resources, Sunyani, Ghana.

Abstract

This work is a comparative study between Shea butter (SB) and treated distillate aromatic extract oil (TDAE) as plasticizers in the vulcanization of natural rubber (NR)- carbon black (CB) vulcanizates (-CB-S-NR-). The plasticized -CB-S-NR- composites extended scorch (Ts2) and optimum (T90) curing times. The delays in crosslinking reaction were suspected to be due to the increased viscosity (ML) and insulation of the reacting species (NR, CB, Sulfur and other curing aids) by the films of plasticizers. This effect increased the activation energy (Ea (KJ/mol)) for vulcanization. The -CB-S-NR- without plasticizer SB (SBO), showed higher ML, crosslinking density index (ΔM), rheological strength (MH) and low cure reversion properties than others. In comparison, the SB loaded -CB-S-NR- composites showed improvement in ML, ΔM, T90, with lowers Ea (KJ/mol) than TDAE samples. Also, the SB compounds exhibited higher Young's modulus Eo(MPa) than SBO and TDAE compounds. For instance, the Eo(MPa) of SB5 was over 7 and 1200 % higher than SBO and STD5 respectively. However, -CB-S-NR- filled with TDAE generally showed higher strength(MPa), attributed to stronger CB-NR interactions. Therefore, environmentally friendly SB could replace petroleum based oils for compounding rubbers.

Keywords: Aromatic oil; Composites; Natural rubber; Plasticizer; Reversion and reinforcement; Shea butter oil.