Structure-property relationship of established MWCNT network enhancing thermo-mechanical stability and electrical conductivity in TPU nanocomposites

• MWCNT network in TPU elastomer was constructed from MWCNT bundles behaving as Brownian entities. • MWCNT bundles geometrically entangled at Φ V , c G = 0.46 % (start of network formation). • Network was entirely formed at Φ V , c C P ≈ 1 % , (fully established network). • Fully established network impacts thermo-mechanical performance of nanocomposites. • Fully established network profoundly improves conductive performance of nanocomposites. Enhanced thermo-mechanical stability and conductive response are essential when developing carbon nanotube/elastomer-based nanocomposites for flexible sensing applications. To improve performance of such materials, it is crucial to understand structure–property relations. By using advanced experimental approaches on multi-walled carbon nanotubes/thermoplastic polyurethane system, we were able to reveal main building blocks and network’s morphology (plasma etching and SEM); identify mechanisms of network formation, and the nature of building blocks (rheological analysis); as well as determine the impacts on the thermo-mechanical (thermal and viscoelastic analysis) and conductive (electrical analysis) performance of such nanocomposites. Results showed that the network is in majority constructed from MWCNT bundles. The inherent nature of elastomeric system forces bundles and network to retain random distribution. Bundles may be considered as stiff rod-like Brownian entities, which geometrically entangle at volume fraction of Φ V , c G ≈ 0.46 % , indicating network formation. The network was considered as fully established at concentration of Φ V , c C P ≈ 1 % , as cross-over point of dynamic moduli. Finally, it was found that thermo-mechanical and conductive performance of the nanocomposite corresponds to the fully established network (and not network formation), allowing force (∼10× increase of moduli), and electron (∼10 8 × increase of conductivity) transfer, while improving thermo-mechanical stability within operating temperatures (increase of glass transition for 25 °C).