Recycling Composite Materials

For many reasons, composite material products need to have a better solution for their end of life. Thermoset composites have difficulties in reprocessing, however thermoplastic composites are showing some promise. Technology Review discusses some breakthroughs in recycling PET, which may provide some foundation for recycling fiber reinforced PET in the future. Essentially, researchers at IBM have figured out how to chemically break down PET to their original parts, which then can be used again. Traditional recycling of PET uses heat and pressure to melt down the plastic.

Although recycling composite materials is necessary, composites still provide valuable environmental savings during their life. In composite transportation products such as marine, rail, aerospace, and automotive, the fuel saving and carbon reduction benefits can outweigh the downside of not being able to recycle. Here is a Swedish study of a Life Cycle Analysis (LCA for short, and likely an acronym we hear often) of fiber reinforced composites.

In the study, the researched compared the LCA of a steel ship with composite sandwich structures. Even though steel is recycled in the end, the emission reductions and corrosion benefits of using composite materials outweigh the recycling benefit.

Now, imagine the LCA comparison when fully recyclable composites are used...

Photo Credit: jsbarrie via flicker

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New Composite Building System for Haiti

Below is a guest post by James Bancroft discussing a new building technology:

Rexwall/Aqua Homes (Germany) has developed and is producing a lightweight composite honeycomb-core panels used in both houseboats and land based homes. These are large insulated wall panels, glued into place.

I am not a fan of prefabricated panelized housing systems. Each house needs to be individually engineered, offering limited styles and require special assembly skills. Panelization might offer certain benefits for large housing tracts where the houses are all identical but have limited value for custom construction.

The concept for the lightweight composite building blocks allows for a variety, different sizes and architectural styles of structures without detailed architectural plans. Using only three or four standard, off-the-shelf blocks almost any type of structure can be built--local unskilled labor can easily visualize how they "fit together" and can adapt structures to the local topography.

Key to the success of any high tech building material is its adaptability to incorporate local building finishes--creating structures which fit into the historical context, customs and local design traditions--the use of materials which people have grown accustomed to--houses people want and feel comfortable living in.

Below and above are several illustrations demonstrating how this can be achieved using the composite blocks, rough exterior finishes allowing them to be stuccoed with local cementitious materials (Haiti-colorful Caribbean colors), roof panels reflecting local materials and natural flooring coverings.

For building green issues, the central insulating core could use recycled EPS, the buildings can be easily adapted to changing needs (unstacking and rebuilding) or be completely "disassembled" and recycled into new structures.

The next step in exploring and testing potential of the blocks would be to have a composite manufacture produce a number of prototype blocks, assemble them into a model small garden type house--take it apart and reassemble it several times to work out the details.

For more information contact Jim Bancroft at agatha43@comcast.net.

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Composite Shipping Container

Since the advent of composite materials, and in particular, strong lightweight composite sandwich panels, engineers have been trying to replace the commonly used steel sea-land ISO shipping containers with composite materials.

It seems logical, steel shipping containers are extremely heavy, they spend a good deal of their life in a highly corrosive environment, and they don't last very long. However, the main barrier to entry is the fact that steel cargo containers are dirt cheap, especially as the majority of these containers are manufactured in low labor Asian markets.

As the raw material costs of steel rise, composite materials will have more of a realistic chance. In particular, niche composite containers such as refrigerated containers will likely be the first to be introduced.

Here is an article discussing a development program through the Department of Homeland Security for the design of composite tamper-proof containers. Besides the need for containers to be tamper proof for homeland security reasons, containers that are x-ray transparent will be easier to inspect at ports. Composite material is the viable long-term solution.

It is likely the use of composite shipping containers is inevitable. One aspect that must be kept in the forefront during the design process, is the containers' end of life. Current steel containers are easily recyclable, and the same will need to be true of composite replacements. Perhaps reinforced thermoplastic composites will be the design winner...

Photo Credit: Marc oh! via flicker

Composite Road Mats - For Oil Fields

The US consumes a ton of oil, far more then we produce, and according to a DOE EIA Report, the US imports about 2/3'rds of the oil consumed, with Canada providing the largest portion of oil to the US. As of June 2009, the US was consuming 2 million barrels of Canadian Oil, or Alberta Tea as I like to call it...

To get these 2 million barrels a day to pipelines, massive temporary roads are constructed, going over the difficult terrain of the tundra and swampy bogs. Giant 8' x 15' mats are placed together to create a road. These roads have massive trucks with heavy loads going back and forth over uneven ground. Needless to say, these mats take a serious beating.

Traditionally, mats are made with thick planks of wood and steel frames. These however are extremely heavy, and do not last as long as desired. More recently, composite materials are being introduced using light weight sandwich panels. The requirements are not easy as the panels need to be stiff, withstand wear and impact, and be able to connect to other panels.

Here is a recent article from the Oil & gas inquirer, describing a composite road mat system using a polypropylene honeycomb core and FRP skins. The article also discusses alternative methods to constructing these roads using wood chips over geotextile mats...

Photo Credit: jakesmome via flicker