Incorporation of different dimensional carbon allotropes within elastomeric matrices has been established as an effective strategy to fabricate functional conductive polymer nanocomposites (PNC). In this work, a higher dimensional 3D hybrid carbon nanofillers - comprising the synergistically integrated multi-walled carbon nanotubes immobilized into few-layers graphene – were incorporated into thermoplastic polyurethane (TPU) matrix, to demonstrate its effectiveness as a strain sensor. The conductive films fabricated through a simple solution casting technique, in which the mechanical, electrical and strain sensing characteristics are studied in view of filler’s distribution, structural confinement, and interfacial interactions. Analyses using wide-angle X-ray scattering, Raman spectroscopy, and tensile testing, revealed a higher degree of filler reinforcement within TPU moieties, indicating the pronounced interfacial interactions. Further, the tensile modulus heightened significantly with filler loading above their percolation threshold (363% for 20wt% loading). The structural features of dispersed filler aggregates were explored through an iterative model fitting of the ultra-small angle X-ray scattering (USAXS) data, along with scanning electron microscopy (SEM). As a strain sensor, the films displayed a superior working-strain Gauge Factor (GF=123), with an exceptional stability under both unidirectional and cyclic strain. Further, a large strain GF of 601.5 was evidenced for the composites with higher 3D filler loading. The findings provide a fundamental understanding, alongside validating the potential of hybrid carbonaceous fillers for the fabrication of PNCs with futuristic applications.
Babu et al. (Thu,) studied this question.