[BEIJING] Chinese scientists have developed a method to turn the circuit boards from old computers into a strong material that could be used to make park benches and fences.
Waste printed circuit boards (PCBs) account for around three per cent by weight of all electronic waste. Current recycling methods primarily recover only metals, such as copper, while non-metal waste — accounting for 70 per cent of the circuit boards — go to landfills or incineration.
Xu Zhenming and colleagues from Shanghai Jiao Tong University, instead pulverised the non-metal materials of PCBs, mixing them with resin and polystyrene. They then heated the mixture and pressed it to form sheets of durable material almost as strong as reinforced concrete.
The resin, an unsaturated polyester (UP), was chosen as a bonding agent partly because of its low cost. The mechanical properties of the new material show good results with tests revealing better properties than pure UP polymers.
"The mechanical properties are similar to other polymers, but the inexpensiveness of waste PCBs mean this technology has good potential," Xu told SciDev.Net.
The authors suggest that the material could be used in place of wood, as it is stronger, whilst helping to recycle old computer hardware.
Masatoshi Iji, director of Nano Electronics Research Laboratories at the NEC Corporation, says there is potential in the technique, adding that epoxy resin, similar to the structure of PCBs, could be used as a bonding agent in the future.
But he says that investigation and improvement of processes such as pulverization and separation of PCBs from their metal components are still needed to adapt the process to a large scale.
Additional properties such as moldability, heat resistance and water resistance will be also need to be added if the material is to be used in some durable products, Iji says.
Xu's team is now focusing on evaluating the safety of the material and looking to improve its mechanical properties.
The research was published in the July issue of Environmental Science & Technology.
Environmental Science & Technology 42, 5267 (2008)