Increase in Properties and Self-Healing Ability of Conductive Butyl Rubber/Epoxidized Natural Rubber Composites by Using Bis(triethoxysilylpropyl)tetrasulfide Coupling Agent

Piyawadee Luangchuang; Kunakorn Chumnum; Ekwipoo Kalkornsurapranee; Yeampon Nakaramontri

doi:10.3390/polym15030547

Increase in Properties and Self-Healing Ability of Conductive Butyl Rubber/Epoxidized Natural Rubber Composites by Using Bis(triethoxysilylpropyl)tetrasulfide Coupling Agent

Polymers (Basel). 2023 Jan 20;15(3):547. doi: 10.3390/polym15030547.

Authors

Piyawadee Luangchuang¹, Kunakorn Chumnum¹, Ekwipoo Kalkornsurapranee², Yeampon Nakaramontri¹

Affiliations

¹ Sustainable Polymer & Innovative Composite Materials Research Group, Department of Chemistry, Faculty of Science, King Mongkut's University of Technology Thonburi, Bangkok 10140, Thailand.
² Department of Physical Science, Faculty of Science, Prince of Songkla University, Songkhla 10400, Thailand.

Abstract

Flexible self-healing composite was fabricated based on blending the bromobutyl rubber (BIIR) and epoxide natural rubber (ENR) filled with hybrid fillers of carbon nanotubes (CNT) and carbon black (CB). To achieve self-recoverability, modification of BIIR was carried out through butyl imidazole (IM), and the healing capability was then activated by the addition of bis(triethoxysilylpropyl)tetrasulfide (TESPT), which resulted in good dispersion of CNT/CB in BIIR/ENR blends. The silanization of TESPT and CNT/CB hybrid filler surfaces was confirmed by attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy. Adding CNT/CB and incorporating TESPT into the composites effectively improved the curing and mechanical properties of the blends in terms of estimated crosslink density and tensile modulus. Further, the self-healing propagation rate was enhanced by the thermal conductivity of fillers and the ion-dipole intermolecular forces between the rubber chains, leading to the highest abrasion resistance and electrical conductivity. Using an environmentally friendly process, the recyclability of the self-healing composites was improved by the re-compression of the samples. With this, the constant conductivity relating to the rearrangement of the CNT/CB network is examined related to the usability of the composites at 0 and 60 °C. The conductive composites filled with a TESPT silane coupling agent present an opportunity for vehicle tires and other self-repairing applications.

Keywords: butyl rubber; natural rubber; self-healing; silane coupling agent; tire application.

Grants and funding

This research was funded by Office of the Permanent Secretary, Ministry of Higher Education, Science, Research and Innovation (OPS MHESI), Thailand Science Research and Innovation (TSRI) and the National Science, Research and Innovation Fund (NSRF) via the Program Management Unit for Human Resources & Institutional Development, Research and Innovation [grant number B01F640031].