A review of multiscale composite manufacturing and challenges

As the utilization of advanced composites in structural applications grows, the need for improving their through-thickness properties becomes imperative. Although the behavior of composite laminates under structural and thermal loads has received much attention with their growth in safety critical structures, more effort needs to go into selectively improving their electrical and thermal conductivities. Additionally, the ability to manufacture composite structures that can inherently monitor their own health will be exceedingly beneficial. This paper provides an overview of advances made towards multiscale composite manufacturing. Multiscale composites, especially with the use of carbon nanotubes, have been sought to provide enhanced structural (through-thickness) properties and increased electrical and thermal conductivities. This report will review the state of art in the manufacturing of multiscale composites, their scalability, and their inherent potential for multifunctionality. Current techniques mostly result in the application of carbon nanotubes throughout the entire laminates, rather than in selected areas. Subsequently, one of the main barriers, to the widespread use of carbon nanotube-applied composites, is an efficient mass-producible manufacturing process. This paper attempts to highlight the current knowledge gaps in this critical area of composites manufacturing. © The Author(s) 2012 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav

Manufacturability of advanced composites with selective and localized electrical conductivity

The displaced foam dispersion (DFD) technique is a neoteric method for incorporating nanoscale particles within the matrix of various geometric multi-scale composites. Nanoparticles have a wide range of uses and influence pre-formed materials in various ways depending upon their structure. One of the most commonly used nano constituents are carbon nanotubes (CNTs). The DFD technique utilizes a polystyrene substrate as a carrier system for the CNTs allowing desired placement. This paper discusses the implementation of the DFD technique and its influence on the localized electrical properties of manufactured multi-scale composite laminates. Single, double and multi-walled CNTs of varying lengths were tested in a design of experiments to demonstrate the contrast of the nanoparticle types and discover the maximum output. The expected results should illustrate electrical conductivity over a localized region of the composite laminate validating the DFD technique\u27s effectiveness potential multifunctional and scalable applications

Synthesis and characterization of polystyrene carbon nanotube nanocomposite for utilization in the displaced foam dispersion methodology

Incorporating nanostructured functional constituents within polymers has become extensive in processes and products for manufacturing composites. The conception of carbon nanotubes (CNTs) and their heralded attributes that yield property enhancements to the carrier system is leading many industries and research endeavors. Reported Displaced Foam Dispersion (DFD) methodology is a novel and effective approach to facilitating the incorporation of CNTs within fiber reinforced polymer composites (FRPC). The methodology consists of six separate solubility phases that lead to the manufacture of CNT-FRPCs. This study was primarily initiated to characterize the interaction parameters of nanomaterials (multiwalled carbon nanotubes), polymers (polystyrene), and solvents (dimethyl formamide (DMF) and acetone) in the current paradigm of the DFD materials manufacture. Secondly we sought to illustrate the theoretical potential for the methodology to be used in conjunction with other nanomaterial-polymer-solvent systems. Herein, the theory of Hansen\u27s solubility parameters (HSP) is employed to explain the effectiveness of the DFD materials manufacture ratios and aid in the explanation of the experimental results. The results illustrate quantitative values for the relative energy differences between each polymer-solvent system. Transmission electron microscopy (TEM) was used to characterize the multiwalled carbon nanotubes (MWCNTs) in each of the solubility stages and culminates with an indication of good dispersion. Additionally, the rate of acetone evaporation over 25 min is reported for the sorbed CNTaffy nanocomposites from 0 to approximately 60 wt percent loadings

A study on the fabrication of plasticized polystyrene-carbon nanotube nanocomposites for foaming

The impregnation of carbon nanotubes within fiber-reinforced polymers (FRPs) is a sought after capability for the advancement of composite systems. This study evaluates the novel processing of a carbon nanotube nanocomposite that has been developed to incorporate varying carbon nanotube loadings within final composite foams. This material is manufactured through a melt mix process of carbon nanotubes and polystyrene at ∼2.0–13.0 wt.% that further underwent a plasticization process in an acetone solvent. The chemical foaming agent 2.2′-Azobi(isobutyronitrile) is used to facilitate foaming at a constant 3.0 wt.% concentration. The foamed nanocomposite results in a carbon nanotube-loaded micro-porous structure showing capabilities of delivering localized carbon nanotube placement within fiber composite laminate systems. This report’s aim is to illustrate the effects of plasticizing polystyrene-carbon nanotube nanocomposite and calendaring the softened material to form foams imbedded with carbon nanotubes (carbon nanotubes). Scanning electron microscopy, differential scanning calorimetry, thermogravimetric analysis, and Fourier transform infrared spectroscopy were the tools that are used to characterize the materials at the various morphologies with their findings inclusive