Preparation of high‐performance carbon nanotube/polyamide composite materials by elastic high‐shear kneading and improvement of properties by induction heating treatment.

Polyamide 66 (PA66) nanocomposites were prepared by compounding carbon nanotubes (CNTs) using an elastic high‐shear kneading method, and the mechanism to understand their excellent properties was verified. In addition, we developed a microwave heat treatment that increases toughness quickly and at low cost. By combining 6.6 vol% or more of CNTs, PA66 with improved mechanical properties, such as higher elastic modulus and yield strength, was achieved, making it possible to obtain a composite having excellent high‐temperature characteristics that does not melt even at a temperature above the melting point. These effects appeared to be due to defibration of CNT aggregates and isolation and dispersion in PA66. A lamellar crystal of PA66 grows around the CNT, forming an interphase. The higher performance appeared to be attributable to a continuous three‐dimensional structure in which CNTs are bound via the interphase, and the improvement of the elastic modulus of the composite material was tentatively ascribed to a Halpin‐Tsai model in which the size of the unit cell of the three‐dimensional structure is introduced. The resulting CNT/PA66 composite materials are superior not only in performance but also in price. [ABSTRACT FROM AUTHOR]