Joule effect self-heating of epoxy composites reinforced with graphitic nanofillers

Abstract

Self-heating of conductive nanofilled resins due to the Joule effect is interesting for numerous applications, including computing, self-reparation, self-post-curing treatment of resins, fabrication of adhesive joints, de-icing coatings and so on. In this work, we study the effect ofthe nature and amount of graphitic nanofiller on the self-heating of epoxy composites.The addition of graphitic nanofillers induced an increase in the thermal conductivity ofthe epoxy resins, directly proportional to the nanofiller content. Percolation was not observed because ofthe heat transport through phonons. In contrast, the electrical conductivity curves present a clear percolation threshold, due to the necessity of an electrical percolation network. The electrical threshold is much lower for composites reinforced with carbon nanotubes (CNTs, 0.1 wt.%) than for the resin filled with graphene nanoplatelets (GNPs, 5 %). This fact is due to their very different specific areas.The composites filled with CNTs reach higher temperatures than the ones reinforced with GNPs, applying low electrical voltage because of their higher electrical conductivity. In contrast, the self-heating is more homogeneous for the GNP/epoxy resins due to their higher thermal conductivity. It was also confirmed that the self-heating is repetitive in several cycles, reaching the same temperature when the same voltage is applied.M S. G. Prolongo

Effect of graphene and CNT reinforcement on mechanical and thermomechanical behavior of epoxy—A comparative study

“…Thermal stability is reduced at ≥0.3 wt % Gr content and the graph shifted toward low temperature in comparison with the epoxy. The improvement in thermal stability of the Gr composite is postulated due to a sheet barrier effect or torturous path effect, which prevents the entry of oxygen and exit of volatile products evolved at high temperature or during thermal degradation …”

“…With further increase in filler content, the modulus starts to reduce due to agglomeration. The retention of higher modulus by composites above room temperature, as compared to neat epoxy, is due to the restricted segmental mobility of polymer structure . Storage modulus and elastic modulus are different properties.…”

Synthesis and properties of fluorinated graphene oxide bisphenol a epoxy nanocomposites

“…According to the Fick's second diffusion law, the diffusivity of water in an epoxy matrix can be obtained from the linear part of W t ~ t 0.5 curve. At the initial stage of absorption, the following equation is arguable : where w i is the initial weight and w t is the weight at a specific time t , w m is the equilibrium weight, D is the diffusivity, and h is the thickness of the specimen.…”

“…From Table , the epoxy composite filled with 0.3 wt% GOSiF has a low diffusivity coefficient of 1.29 × 10 −06 mm 2 /s. The water absorption through epoxy composite is influenced by many aspects, including free volume, cross‐linking degree of the matrix, morphology, hydrophobicity, and so forth . The decreases in the water equilibrium and diffusion coefficient of epoxy composites can be explained by two reasons.…”

Accelerated Curing and Enhanced Material Properties of Conductive Polymer Nanocomposites by Joule Heating

“…In previous engineering applications, conventional oven heating was mostly used to cure polymer-based composites, but it was often observed that the heat distribution was not uniform, and that a relatively long period of heating was required during manufacturing. Therefore, internal heating methods, such as Joule, microwave, and induction heating, have been of great interest due to their non-contact heating process, which creates uniform thermal distribution and requires only short heating times [ 14 , 15 , 16 , 17 , 18 ]. In particular, Joule heating is one of the most effective ways to provide uniform heating of conductive composites.…”