Electrically Conductive Adhesive Based on Thermoplastic Hot Melt Copolyamide and Multi-Walled Carbon Nanotubes

Abstract

For the bonding of the lightweight composite parts, it is desired to apply electrically conductive adhesive to maintain the ability to shield electromagnetic interference. Among various solvent-based adhesives, there is a new group of thermoplastic hot melt adhesives that are easy to use, solidify quickly, and are environment-friendly. To make them electrically conductive, a copolyamide-based hot melt adhesive was mixed with 5 and 10 wt% of carbon nanotubes using a melt-blending process. Well-dispersed nanotubes, observed by a high-resolution scanning microscope, led to the formation of a percolated network at both concentrations. It resulted in the electrical conductivity of 3.38 S/m achieved for 10 wt% with a bonding strength of 4.8 MPa examined by a lap shear test. Compared to neat copolyamide, Young’s modulus increased up to 0.6 GPa and tensile strength up to 30.4 MPa. The carbon nanotubes improved the thermal stability of 20 °C and shifted the glass transition of 10 °C to a higher value. The very low viscosity of the neat adhesive increased about 5–6 orders of magnitude at both concentrations, even at elevated temperatures. With a simultaneous growth in storage and loss modulus this indicates the strong interactions between polymer and carbon nanotubes.

Progress in polyacrylate‐based electrically conductive adhesives: Featured properties, preparation, applications, and perspectives

“…While for ECAs, as the condition of the adherents, the bonding processes, the loading conditions, and the effective bonding areas of the ECAs in practical applications are different, 6,47,48 it is better to evaluate the adhesion properties of the ECAs with bonding strengths rather than bonding forces. In recent literatures, shearing, stretching, uneven peeling, and peeling are regarded as the four main forms of external forces to cause failures of adhesive bonding.…”

“…[1][2][3] Adhesion featuring light weight, high specific strength, and fast operation, is preferred, and increasingly developed for low-carbon bonding. 4,5 As a special kind of adhesives, electrically conductive adhesives (ECAs) can offer both a strong bonding effect as well as desirable electrical conductivity, 6,7 and therefore have significantly advanced in many conductive connection areas such as industrial plant joints, microelectronic packaging, and medical device adhesions. [8][9][10][11] In particular, the advanced bonding technology provided by ECAs can replace some laggard spot-welding operations 3,12 in which high welding temperatures 13 are needed and undesired oxides 14 are formed.…”