Self-healing based
on noncovalent bonds and mechanical strengthening
based on fillers are contradictions for commercial rubbers. To solve
this problem, in this paper, we constructed a hydrogen bonding supramolecular
hybrid network by incorporating carboxymethyl chitosan (CMCS) into
epoxidized natural rubber (ENR) through a solution-mixing method.
The regenerated CMCS with multiple hydrophilic groups formed hydrogen
bonding interactions with ENR chains, which served as multifunctional
linkages to construct the supramolecular hybrid network. In this way,
the regenerated CMCS belonged to the hydrogen bonding healing system
and simultaneously improved the mechanical properties of the ENR/CMCS
composites. The dispersion, structure of regenerated CMCS, and formation
of the hydrogen bonding supramolecular hybrid network in the ENR/CMCS
composites were studied and confirmed by Fourier-transform infrared
spectroscopy, scanning electron microscopy, transmission electron
microscopy, differential scanning calorimetry, X-ray diffraction,
dynamic mechanical analysis, and equilibrium swelling experiment.
It was found that the ENR with 5 and 10 wt % CMCS possessed improved
tensile strengths of 1.40 and 1.92 MPa, respectively, and simultaneously
exhibited considerable self-healing efficiency of about 90% (room
temperature, healing 12 h). When the CMCS content exceeded 10 wt %,
although the mechanical property increased continuously, the self-healing
effect decreased significantly because of the unavoidable negative
effect of filler restriction. The dynamic nature of hydrogen bonding
interactions facilitated the rearrangement of the supramolecular hybrid
network, which endowed ENR/CMCS composites with derived recycling
capacity. However, the mechanical properties are reduced after multi-recycling.
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