B1 (ended): Development of aligned (CNT based) and 3-dimensional interconnected (Aerographite based) carbon nanocomposites
The project B1 focuses on the investigation of the electrical, thermal and mechanical properties of polymer based nanocomposites with reinforcing carbon nanoparticles in form of (i) aligned carbon nanotubes (CNTs) and (ii) novel 3-dimensional interconnected graphitic networks of Aerographite. Physical properties, mechanisms and interactions have to be studied over different hierarchical levels in order to estimate their potential also in conventional fiber reinforced composites.
Situation and background
Based on previous work within the framework “Landesexzellenzinitiative: Integrated Materials Systems (LEXI)” there was developed:
(i) a novel shear/pressing manufacturing route for film-like aligned CNT/epoxy composites (APNCs) with electrical conductivities of 36000 S/m and a highly increased Young’s modulus (compared to neat resins). These properties were achievable by embedding approx. 68 wt% of mm-long, quasi-unidirectional oriented MWCNTs in an epoxy matrix .
(ii) the synthesis of novel 3-dimensional interconnected and covalently bonded graphitic networks. This material is called Aerographite and exhibits an extremely low density but is electrically conductive and mechanically robust .
Within project B1 the electrical, thermal and mechanical properties together with the piezoelectric behavior of epoxy based nanocomposites will be investigated for both types of nanofillers. In comparison to disordered CNT/epoxy composites, which are often produced by just dispersing nanofillers, the inner structure of aligned CNT/polymer composites is less complex. Nevertheless, manufacturing is challenging. The simple morphology intents to deliver an ideal model-material to investigate basic scientific questions of reinforcement and conductivity, but also towards technical applications.
By producing APNCs with identical CNT orientations and loadings, studies on the influence of different types of CNTs (e.g. number of walls, structural quality, functionalization, geometry,...), different inter-CNT-spacing’s and different epoxy resins on the overall composite properties are possible. Systematic studies of electrical conduction and mechanical reinforcement using the mechanically enforced CNT orientations and distances are planned in order to gain a much deeper understanding of the underlying mechanisms.
The investigation of Aerographite/epoxy nanocomposites is of high interest, because they deliver a non-oriented but directly interconnected graphitic framework inside the nanocomposite volume. Investigations of similarities and differences of Aerographite- towards CNT-based nanocomposites can deliver new findings on the influence of the morphology on reinforcing and conducting with carbon nanofillers.
Aerographite is the result of collaboration between the “Institute of Polymers and Composites” (Prof. K. Schulte) at TUHH and the “Institute of Materials Science – Functional Nanomaterials” (Prof. R. Adelung) at the University of Kiel. Initial characterization of the potential of these interconnected graphite structures on the electrical, thermal and mechanical properties of epoxy nanocomposites are of high interest: Aerographite networks do not exhibit preferred orientations and therefore isotropic composite behavior is expected. Due to the ability to adjust network morphology towards density of interconnections and designing manifold shapes, tailored structures promote the understanding of the development of the electrical conductivity mechanisms of different classes of carbon based polymer nanocomposites.
 M. Mecklenburg, K. Schulte: „Verfahren zur Herstellung von elektrisch leitfähige Nanopartikel enthaltenden Polymer-Kompositen sowie mit dem Verfahren hergestellte Polymer-Komposite; Patentanmeldung Nr. 10 2011 051 871.1, Aktenzeichen: 10 2011 051 871.1.; Eingereicht am 15.07.2011.
 M. Mecklenburg, A. Schuchardt, Y.K. Mishra, S. Kaps, R. Adelung, A. Lotnyk, L. Kienle, K. Schulte; Aerographite: Ultra Lightweight, Flexible Nanowall, Carbon Microtube Material with Outstanding Mechanical Performance; Adv. Mater. 2012, Vol. 24 No. 26 pp 3486-3490.