# Structural and Electromechanical Insights into Thermoplastic Polyurethane/3D Hybrid Carbon Nanocomposites for Strain Sensor Applications

## TL;DR

This paper explores how adding 3D hybrid carbon nanofillers to a polymer improves its performance as a strain sensor.

## Contribution

The study introduces 3D hybrid carbon nanofillers (graphene and carbon nanotubes) for enhanced strain sensing in polymer composites.

## Key findings

- Films showed a Gauge Factor of 123 with stability up to 8% strain.
- Tensile modulus increased by 363% at 20 wt% filler loading.
- Filler reinforcement and interfacial interactions were confirmed via X-ray and Raman analyses.

## Abstract

Incorporation of carbon allotropes of different dimensions
within
elastomeric matrices has been established as an effective strategy
to fabricate functional conductive polymer nanocomposites (PNCs).
In this work, higher-dimensional 3D hybrid carbon nanofillers, comprising
synergistically integrated multiwalled carbon nanotubes immobilized
onto few-layer graphene, were incorporated into the thermoplastic
polyurethane (TPU) matrix to demonstrate their effectiveness as strain
sensors. The conductive films were fabricated through a simple solution
casting technique, in which the mechanical, electrical, and strain-sensing
characteristics were studied in view of filler 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 the TPU moieties, indicating
pronounced interfacial interactions. Further, the tensile modulus
increased significantly with filler loading above its percolation
threshold (363% for 20 wt % 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, up to
8%), with exceptional stability under both unidirectional and cyclic
strain. The findings provide a fundamental understanding while validating
the potential of hybrid carbonaceous fillers for the fabrication of
PNCs with futuristic applications.