Carbon-based, nano-composites
Composites (composed of different materials with clear boundaries between them) are fundamental building blocks of lightweight yet very strong structural components for the transport sector. Such composites typically consist of a resin matrix embedded with reinforcing materials. Among several, fibreglass is best known and carbon fibres of various morphologies act as important reinforcements as well. With the advent of nanotechnology, nanofillers such as carbon nanotubes (CNTs) have played an increasingly important role in the development of novel, multi-functional composites. Scientists working on the EU-funded BME CLEAN SKY 032 project are employing CNTs in both the epoxy (polymer) resin matrix and carbon fibre reinforcement. The goal is production of aeronautical components with improved mechanical, electrical and thermal performance. Processing of such complex materials is not a simple task. Researchers focused on a three-step masterbatch technique for dispersing the CNTs in the epoxy resin matrix. Masterbatch refers to polymer granules rather than liquid, powder or paste. These granules provide even dispersion and increased process stability. Investigators used electro-spinning to form CNT-reinforced carbon nanofibre yarns for the quasi-unidirectional reinforcement of an epoxy–CNT hybrid matrix. Prepared laminate samples were then tested and characterised. Multi-wall CNTs (MWCNTs) were very effective reinforcements of epoxy matrix, both in isolation and in combination with conventional carbon fibres. The masterbatch mixing method achieved excellent dispersion of MWCNTs in epoxy matrices. This should facilitate easier production of ready-to-use MWCNT-containing epoxy resin tapes (prepegs or pre-impregnated with fibre reinforcement). Further, the carbonisation method developed to produce the carbon nanofibres was much faster and more cost effective than traditional production methods. The CNT-loaded carbon nanofibres demonstrated excellent conductivity, enhanced stability and improved mechanical properties as well. BME CLEAN SKY 032 has contributed a number of important materials and processing techniques expected to be of great interest to composites manufacturers. The parameters required for industrial-scale production have been determined and commercialisation should foster development of novel improved components in the near future.
