Effect of curing condition on the piezoresistivity of multi-walled carbon nanotube/epoxy nanocomposites. (April 2023) - Wong, Ting Yui
Abstract: Non-monotonic electrical resistance changes have been observed in multi-walled carbon nanotube (MWNT)/epoxy nanocomposites subjected to tensile loading, but the mechanism is not fully understood. While most previous works investigated the effect of nanofiller content on the piezoresistivity of MWNT/epoxy nanocomposites, this work evaluates the impact of curing condition. The results indicate that the monotony of the piezoresistivity could be enhanced by using a higher curing temperature. It is therefore proposed that when cured under a different temperature, an epoxy matrix would exhibit a different level of spatial heterogeneity in molecular structure and hence in mechanical properties, causing the MWNT network inside the matrix to undergo a different movement trend under tensile loading. This study will facilitate future research on elucidating the underlying mechanism of the non-monotonic piezoresistivity of CNT/epoxy nanocomposites through considering the contribution of the molecular structure of the polymer matrix. Graphical abstract: Image 1 Highlights: MWNT/epoxy nanocomposites are fabricated under different curing cycles. Curing condition impacts the piezoresistivity of these materials under tension. Curing condition affects the distribution of crosslinking densities in matrices. Non-uniformity in crosslinking density causes localized viscoelasticity and plasticity. Viscoelastic and plastic deformations lead to a large number of conductive MWNT paths.