Abstract Submitted to the    NANOTUBE'04 Conference:

Due to their extraordinary mechanical properties and very low densities, carbon nanotubes are seen as the future reinforcement agents for high-tech polymers. In addition to their mechanical properties they show excellent thermal and electrical properties. Tensile tests were carried out on free-standing composite films of polyvinyl alcohol and seven different types of carbon nanotubes. Furthermore, polymer functionalised carbon nanotubes were included in a polypropylene matrix. Significant increases in Young’s modulus and strength by up to a factor of five were observed in all cases. Known theories for polymer/carbon fibre reinforcements such as Krenchel’s rule-of-mixtures or the Halpin-Tsai-theory could not explain the relative differences between composites made from different tube types. However, it is possible to show that the reinforcement scales linearly with the total nanotube surface area in the films. In addition, in all cases crystalline coatings around the nanotubes were detected by calorimetry suggesting similar polymer-nanotube interfaces. This supports the fact that the reinforcement is critically dependent on the polymer-nanotube interfacial interaction.