Wednesday, April 28, 2010

Carbon Nanotube and Nanoclay Polymer Nanocomposite Foams To Compete in $13 Billion Global Insulation Market

 The figure shows a single SEM micrograph of Nanomaterial Innovation LTD nanocomposite extrusion foam.

Nanomaterial Innovation LTD (Columbus, OH) and The Ohio State University Research Foundation (Columbus, OH) have developed a patent pending process to produce polymer-nanocomposite foams that have low density, high-R value, bimodal structures, good mechanical properties, and high fire retardance. 

Nanomaterials used in the nanocomposite polystyrene (PS) and other polymer foams include 1-dimensional nano/micro-material selected from the group consisting of smectite clays, organoclays, carbon nanotubes, nanographites, graphite, graphene, and graphene oxide, according to inventors Ly James Lee  (Columbus, OH)   Jintao Yang (Hangzhou, CN) Nan-Rong Chiou  (Columbus, OH) and Shu-Kai  Yeh  (Banqiao-Taipei, TW) in U.S. Patent Application  20100099782

FIGS. 4(a) through 4(d) show examples of SEM micrographs of nanofoam morphologies of water expandable  PS/3.0% AC foams with different water contents in oil bath at 135 degree C. for 15 seconds: FIG. 4(a) dried beads; FIG. 4(b) 5.2 wt % water; FIG. 4(c) 10.1 wt % water; and FIG. 4(d) 12.3 wt % water. The scale bar is 500 microns.


Synthesis of polystyrene and/or other thermoplastic polymers or polymer blends which, for example, contain activated carbon and/or bamboo carbon carrying a co-blowing agent such as water and/or at least one of 1-dimensional, 2-dimensional, and 3-dimensional nano/micro-materials in suspension polymerization without using the inverse emulsion process. CO2 or other blowing agent based foaming processes such as extrusion, batch foaming, and injection molding may then be carried out to produce polymer nanocomposite foams. 

With the soaring cost of energy, it is essential to develop new light-weight materials that can provide better thermal insulation performance in housing and construction industries and high structural strength for automotive, aerospace, and electronic applications.

For example, in the housing industry, doubling the `R` value of current thermal insulation materials can save $200 million annually in heating/cooling costs for families in the U.S. In today's average vehicles, as much as 5-10% in fuel savings can be achieved through a 10% weight reduction. Polymeric foams have been used in many applications because of their excellent strength-to-weight ratio, good thermal insulation and acoustic properties, materials savings, and other factors. By replacing solid plastic with cells, polymeric foams use fewer raw materials and thus reduce the cost and weight for a given volume.

 The North American market for foamed plastic insulations exceeds $3 billion annually, while global demand is above $13 billion. However, polymer foams, except sandwich composite foams, are rarely used as structural components in the automotive, aerospace, and construction industries because of poor mechanical strength and low dimensional and thermal stability, when compared to bulk polymers.

In recent years, several researchers have reported that foams can possess excellent mechanical strength if the cell size is smaller than the typical flaw size in bulk polymers, i.e., <10 .mu.m. Microcellular foams can reduce material usage and improve mechanical properties simultaneously. They have been commercialized for some applications (i.e., MuCell by Trexel). However, they require specially designed processing equipment, have a narrow process window, and are still not strong enough for structural applications.

Closed-cell plastic foams have better thermal insulation efficiency than glass fiber or plywood insulation materials, but the application of plastic foams in the housing industry is limited due to their poor fire resistance. A drastic reduction of thermal conductivity has been observed when the cell size is reduced to the nanoscale, e.g., aerogel. These nanofoams are currently made of ceramics in thin films and are very expensive. Foams with ultra-low density also provide better thermal insulation. To increase the expansion ratio during foaming in order to achieve ultra-low density, an expensive vacuum system is often needed in the industrial foam extrusion line. 

Last year, Nanomaterial Innovation Ltd received $100,000 in stimulus funding to further develop its nanofoam processes. The outcome is expected to significantly grow the overall share of composites in the materials industry and position Nanomaterial Innovation Ltd. (NIL) to be the industry innovation leader. While steel, wood and aluminum are prevalent today, the proposed new composite materials will enable the replacement of traditional materials with lighter, stronger, more durable, and cost effective nano-tailored composites. Successful commercialization of these higher value-added nano-tailored composite products will have a significant impact on energy generation, material use, energy consumption and environmental stewardship.

This award is expected to enhance the United States global leadership position in multifunctional nano-tailored composite materials and products. Societal benefits include reduced petroleum dependency, improved energy efficiency, and reduced use of conventional fossil fuels that contribute to global warming. Educational and scientific benefits relate to the pioneering nature of nanocomposite technology and the opportunity this project will provide to advance frontiers of knowledge and the training of future scientists.

This Small Business Innovation Research Phase I project is to design, synthesize, manufacture, and test high-performance polymeric composite structures based on commercially proven resins, long fibers and nano-sized functional particles. Long fibers can provide good mechanical properties for the composites, while affordable nanoparticles such as nanoclays, graphene, carbon nanofibers and carbon nanotubes may improve barrier properties and strengthen the matrix between long fibers. To succeed in producing these new composites, two issues need to be addressed: how to disperse nanoparticles in the presence of long fibers, and whether or not resin processability can be maintained and enhanced in the presence of nanoparticles.

Nanomaterial Innovation’s approach is to develop novel surface coatings of those nanoparticles utilizing polyaniline nanograss, which can assist the dispersion and enhance the surface oleophilicity of the particles; consequently minimizing the flow resistance resulting from the nanoparticles. Furthermore, polyaniline can also increase the reaction rate and final conversion for both epoxy and vinylester resins cured at low temperature. This is highly valuable for manufacturing large composite structures using vacuum assisted resin transfer molding process. It is anticipated that successfully incorporating this modified nanoparticles in structural composites will address multiple demanding applications in energy, transportation, construction and security industries.

Polymeric foams are widely used in certain applications such as insulation, cushions, absorbents, and scaffolds for cell attachment and growth. Polystyrene (PS) foams are the second largest volume use among different foam materials. The extrusion and batch foaming processes are the two major techniques to produce PS foams. For extrusion foaming, hydrogen-containing chlorofluorocarbons (HCFC) and fluorocarbons (HFC) are currently used as blowing agents in the foam industry. Recently, supercritical CO2 is an alternative choice because of its low cost, non-toxic, and non-flammable properties, and relatively high solubility in many polymers.

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