A team of scientists from the Universities of Manchester and Leeds have created a new composite material from a mixture of chalk and polystyrene cups.
Taking their inspiration from the calcification formation of seashells, the team successfully used polystyrene instead of naturally-occurring proteins to reinforce a ceramic material made from chalk.
The new material is tougher and more ductile compared to its original brittle form, and could one day be used in applications such as bone replacement and crack-resistant building materials.
Dr Steve Eichorn from the School of Materials at the University of Manchester said: “People have been trying to develop ceramic structures based on seashells since the 1970s, and a lot of work has gone into trying to extract the proteins from shells.
"We used a commodity material because it has to be commercially viable.”
The mechanical properties of shells can rival those of man made ceramics, which are manufactured at high temperatures and pressures. In shells, calcium carbonate is combined with proteins to bind the crystals together, and make the material tougher and stronger. Their construction helps to distribute stress over the structure and control the spread of cracks.
The new material is especially promising, because when it cracked, the polymer lengthened within the cracks – a well-known mechanism for absorbing energy and enhancing toughness.
However, Eichorn admitted the process to make the material is currently slow, as it is in shells, and needs further manufacturing development before it could be used in many applications.
“It’s difficult to envisage having polymers in ceramics because they are used in high temperature applications,” he said: “We are now looking at other materials that might speed the process up and lightweight structures like sea urchin spines and echinoderms.”
© PE Publishing, 10 March 2010
