Scale-up and Continuous Highly Aligned Multi-Walled Carbon Nanotube Sheets for High-Performance CNT/Bismaleimide Nanocomposites

Abstract

The mechanical properties of carbon nanotube (CNT) sheets, or buckypaper (BP), can be substantially enhanced by applying simple mechanical stretching on the random CNT network to achieve super alignment degree. However, the stretching media, serving as the lubricant, is crucial to the degree that random CNT networks can be elongated. Several mechanical stretching approaches with different stretching media were investigated. These included dry BP stretching, liquid solution assisted BP stretching, and resin assisted BP prepreg stretching. Different stretch ratios of BP were achieved ranging from 20% by dry stretching, to 40% by liquid solution assisted stretching, and up to 80% by resin assisted stretching. The different mechanical stretching methods were studied by optimizing the stretching speed, stretching pressure, and temperature. A manufacturing guidance for different stretching methods with consistent stretching quality was made through this study. The CNT alignment degree was characterized by Raman microscopy. The mechanical properties and failure modes of stretched BP tapes by different stretching media and their corresponding BP composites were also evaluated.