The effect of flow on the physical properties of polyurethane/carbon nanotubes nanocomposites: Repercussions on their use as electrically conductive Hot-Melt adhesives

Abstract

The properties of multiwall carbon nanotubes (MWCNT)/polyurethane (PUR) nanocomposites after being submitted to flow, i.e., in conditions similar to their application as electrically conductive adhesives (ECA), are investigated. A decrease of the elastic modulus is observed after flow is stopped, compatible with a rearrangement of the MWCNT/PUR network during flow. The implications of the viscoelastic results on probe‐tack data are elucidated and a slightly higher energy of adhesion is observed for sheared samples. Dynamic viscoelastic measurements reveal that crystallization of PUR is fastened with MWCNTs, shortening the solidification process for samples submitted to flow or not. Electrical conductivity results show that the 4 wt% MWCNT/PUR nanocomposite can be submitted to flow and give, on cooling to room temperature, values of the electrical conductivity between 10−2 and 10−1 Siemens /m. 2 wt% MWCNT/PUR sample presents a shear induced semiconductor to insulator transition and a temperature‐induced isolator to semiconductor transition. We conclude that MWCNT/PUR nanocomposites are good candidates to develop Hot Melt ECAs, since they display satisfactory viscosity, tack, crystallization (linked to permanent adhesion), and electrical conductivity. POLYM. COMPOS., 36:704–712, 2015. © 2014 Society of Plastics Engineers

Effect of pH and nanoclay content on the morphology and physicochemical properties of soy protein/montmorillonite nanocomposite obtained by extrusion

“…Interestingly, the best fit was obtained for an exponent, t, fairly close to 1, with a percolation threshold concentration ϕc = 1.6 wt.%. Although the percolation threshold is similar to values obtained by other authors for segregated networks of micro or nanoparticles into molten polymers [27,29], the values for parameter t are lower than those found in the literature that typically range between 1.6 and 2…”

“…Several models have been postulated to explain network formation of a solid in a liquid, one of the most widely used being the percolation model. This model has been useful to explain the percolation threshold in molten polymers with nanocarbon tubes [26][27][28][29], exhibiting remarkable changes in both electrical conductivity and rheological properties. However, this parameter has 8 been used not only in molten polymers, but also in polymers in a solid state at room temperature [30].…”

Polymeric Additive Manufacturing: The Necessity and Utility of Rheology

“…cohesive failure, adhesive failure, or both) can be obtained. Furthermore, a tack test can be preceded by a shearing test, where the effects of shearing on tack properties can be measured [50].…”

Rheology of Polymer Processing in Spain (1995–2020)

“…Other groups in Spain have also investigated on the rheology of adhesives, but much less extensively than the Adhesion and Adhesives Group of the University of Alicante. The research, led by Professor Antxon Santamaria at the University of the Basque Country (UPV/EHU), is centred on the viscosity and SAOS results of polyurethane and carbon nanotubes (CNT) composites, apt as hot melt adhesives [ 102 , 103 , 104 ]. The main objective of these papers is to study the effect of adding carbon nanotubes to polyurethane, on the rheology and adhesion of electrically conductive hot melt adhesives.…”