No abstract

The unique geometry and extraordinary mechanical, electrical, and thermal conductivity properties of carbon nanotubes (CNTs) make them ideal candidates as functional fillers for polymeric materials. In this paper we review the advances in both thermoset and thermoplastic CNT composites. The various processing methods used in polymer/CNT composite preparation; solution mixing, in-situ polymerization, electrospinning, and melt blending, are discussed. The role of surface functionalization, including ‘grafting to’ and ‘grafting from’ using atom transfer radical polymerization (ATRP), radical addition–fragmentation chain transfer polymerization (RAFT), and ring-opening metathesis polymerization (ROMP) in aiding dispersion of CNTs in polymers and interfacial stress transfer is highlighted. In addition the effect of CNT type, loading, functionality and alignment on electrical and rheological percolation is summarized. We also demonstrate the effectiveness of both Raman spectroscopy and oscillatory plate rheology as tools to characterize the extent of dispersion of CNTs in polymer matrices. We conclude by briefly discussing the potential applications of polymer/CNT composites and highlight the challenges that remain so that the unique properties of CNTs can be optimally translated to polymer matrices.

Composites of poly(ε‐caprolactone) (PCL) and molybdenum sulfur iodine (MoSI) nanowires were prepared using twin‐screw extrusion. Extensive microscopic examination of the composites revealed the nanowires were well dispersed in the PCL matrix, although bundles of Mo6S3I6 ropes were evident at higher loadings. Secondary electron imaging (SEI) showed the nanowires had formed an extensive network throughout the PCL matrix, resulting in increased electrical conductivity of PCL, by eight orders of magnitude, and an electrical percolation threshold of 6.5 × 10−3 vol%. Thermal analysis (DSC), WAXD, and hot stage polarized optical microscopy (HSPOM) experiments revealed Mo6S3I6 addition altered PCL crystallization kinetics, nucleation density, and crystalline content. A greater number of smaller spherulites were formed via heterogeneous nucleation. The onset of thermal decomposition (TGA) of PCL decreased by 70°C, a consequence of the thermal degradation of Mo6S3I6 to MoO3, which in turn accelerates the formation of volatile gases during the first stage of PCL decomposition. Copyright © 2010 John Wiley & Sons, Ltd.

The temperature dependencies of ultrasonic velocity and attenuation were measured in composites of inorganic nanoparticles with two types of polymers, poly(urea) elastomer with inorganic Mo 6 S 4 I 6 nanowires and poly(e-caprolactone) (PCL) with Mo 6 S 3 I 6 nanowires. Below room temperature large ultrasonic relaxation attenuation maxima and velocity dispersion were observed. It was found that the attenuation peak in the elastomer shifted to higher temperature after doping with nanoparticles and this behavior was related to the shift of glass transition temperature. The ultrasonic attenuation data was fitted to a relaxation equation with a single temperature dependent relaxation time. The thermal activation energy of the relaxation process, which was calculated from ultrasonic data, was found to increase in the poly(urea) elastomer doped with MoSI nanowires. The low temperature ultrasonic velocity increased in the poly(urea) with nanowires added and is determined by the increase in elastic modulus. Similar ultrasonic behavior was obtained for PCL composites with inorganic MoSI nanowires. In this case, the increase in elastic modulus was smaller in comparison to the composites of poly (urea) and nanowires. Therefore, reinforcement of PCL was less pronounced.

Graphene oxide (GO) was prepared by a solvothermal synthesis method using sodium and ethanol.