The something useful can be as whimsical as the chair in my first post on recycling (repeated here, or as useful as a carport for your Porsche (if you have one – I certainly don’t). I did tell you that I was going to talk a little bit about the business of recycling of composites, so I thought I would start off with where it comes from and what people are making out of recycled composites.
The actual recycling of composites is still in its infancy for a couple of reasons. First is that these materials have such a long lifespan that not nearly the tonnage that is being produced today is being put into the waste stream. Composites and the technology to make them into consumer products is relatively new, so the bulk of the composites that have been made are still in service.
That being said, I mentioned last week that recycling composites is inherently difficult because of the nature of these materials – the string and the glue are difficult to separate once the material has been made. But there is enough material that is entering the waste stream now that the composites recycling business has begun to transform from the research lab into commercial production.
Fiberglass is far and away the highest tonnage waste material that is available for recycling/reuse. The companies that have begun recycling fiberglass use a number of methods to reclaim the glass fibers themselves from fiberglass. Mostly – at least initially – this has been through pyrolysis – burning out the resin. But some companies are grinding fiberglass as well. The recycled fibers find their way into concrete to reduce shrinkage and enhance durability – especially in freeze and thaw cycles which usually plays havoc on concrete sidewalk and streets.
Recycled glass fibers have also found their way back into the composites business as a filler in resins. Some other uses are for rubber fillers in tires to make them last longer, plastic wood products to reduce shrinkage, asphalt to increase durability, roofing tar to enhance life and resist cracking, and also into cast countertops to enhance stiffness and as a filler.
Carbon fiber is somewhat more difficult to recycle, but the net result is a product that retains most of the strength and stiffness of the original carbon fiber at half the weight of aluminum. Most of the recycled carbon fiber that is used today is in discontinuous fiber composites like bulk molding compound and sheet molding compound. These materials are used in the consumer product industry for a number of products, including phone cases, laptop shells, other load bearing shell structures, car door interior panels, and even water bottle cages for bicycles.
Finally, as far as the business is concerned, most of the major players in the composites business have jumped on the bandwagon and some have even taken equity positions in carbon fiber recycling startups. Hexcel has taken an equity position in Carbon Conversions, Inc., and even Mitsubishi has taken out a stake in ELG Carbon Fiber Ltd. in the U.K. Both of these companies are in the business of high temperature pyrolysis of the incoming carbon fiber composites from the waste stream, so this is a good example of the research making it into industry in a fairly large way.
The Holy Grail of course is to take end of life parts and recycle them so that they retain most of their original properties and can be made back into high performance composite parts. While that is a few years off in the future, at least the industry has come to attention and is actively developing means of complete recycling of most if not all composites.
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