Old circuit boards can be recycled through a process that separates toxic heavy metals from polychlorinated biphenyl, leaving behind a fine, metal-free powder that can be added to virgin polymer to make asphalt modifier.
What's more, the recycled polymers are just as effective as virgin polymers.
"The nonmetals consist of thermosetting polymers, fiberglass, brominated flame retardants, and other additives," says the report from two universities in Shanghai. "Thermosetting polymers cannot be re-melted or reformed because of their network structure," which makes them strong additives.
The report goes on to note that "the use of waste polymers as asphalt modifiers is considered a rather new and interesting way of modification because it involves two important aspects: waste material utilization and asphalt property enhancement. In our previous research, the nonmetals were reused as reinforcing fillers...proving that the nonmetals can be a good filler for different polymer matrixes."
In 2007 Americans threw out 2.2 million tons of electronics. Nearly threequarters of heavy metals found in landfills are from such waste, and more than 70% of a circuit board is plastic.