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Abstract. In the present work, the development and characterization of an intrinsically self-healable material based on butyl imidazole modified bromobutyl rubber (BIIR)/natural rubber (NR) blends, which are filled with carbon nanotubes (CNTs) are reported. It was found that the addition of CNTs and the blending with NR significantly enhance the tensile strength of the BIIR composites. The use of butyl imidazole as physical cross-linker for the BIIR phase provides the blend composites the non-covalent bondings, which are responsible for their self-healing properties. Owing to the increase of the viscosity of the BIIR phase upon its physical crosslinking the island-matrix morphology of the blend changes over to a co-continuous structure. The preferential wetting of the CNT surface by the low-loading NR phase in the NR/BIIR blends can be explained by the good rubber-filler interaction between the linked phospholipids of the NR molecules and the π-electrons of the CNT surface. As a result, the favored localization of the CNTs in the NR phase strongly improves the electrical properties of the blends according to the double percolation theory. On the other hand it does not deteriorate the self-healing of the BIIR phase. The high electrical conductivity provides us a possibility to heat the blend by application of an electrical voltage in order to accelerate the self-healing process.
Keywords: rubber, self-healing, carbon nanotubes, selective filler wetting
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1. Introduction
Self-healing polymers and especially elastomers have gained more and more attention in material science because of their interesting scientific aspects and variety of applications [1-8]. Such materials can be used as sealing joints, impact protection, insulation and shock-absorbing layers, anticorrosion coatings for metals, as well as adhesives or paints [9, 10]. They are, however, susceptible to damage induced by mechanical, chemical, thermal, UV radiation, or a combination of these factors. This could lead to the formation of micro-cracks or grooves deep within the structure, where detection and external intervention by conventional methods are difficult or impossible [11]. In this context, the concept of self-healing polymeric materials proposed by Jud et al. [5] in 1980s and later inspired by Dry and Sottos [6] and White et al. [7] has been expected to fill this technological gap. The successful development of self-healing polymeric materials offers great opportunities...