'Super Paper' is more durable than cast iron

Moving your fingers through a sheet of paper will be much harder, thanks to the development of a new kind of paper that is much stronger than cast iron.

The new paper will be used to reinforce traditional paper, create super-durable adhesive tapes or durable synthetic materials in place of biological tissue, said Lars Berglund of the Royal Swedish Academy of Sciences.

Despite its tremendous durability, Berglund's "nanofibers" are made from a very common biomaterial for cellulose. This is a long-haul molecule, which is the basic component of plant cell walls and is the most common organic substance on Earth.

In the cell wall, individual cellulose molecules bind together to form fibers, about 20 nanometers in diameter, 500 times thinner than human hair. These fibers form a solid network, which helps to support the structure of the cell wall.

Cellulose is extracted from wood for making paper, and recently as new plastic material. But they are only used as a cheap filter material, which ignores their mechanical properties.

Meanwhile, pulp and paper processing destroys the fibrous structure of cellulose, and drastically reduces their strength.

Structure of nano paper. (Photo: Francesco Stellacci)

As a result, Berglund and his colleagues have developed a softer processing that preserves the strength of the wood fibers.

Accordingly, they break down the pulp by enzyme and separate it with a mechanical stick. This process leaves the cellulose gently split into component fibers. As a result, intact cellulose fibers are suspended in water. When all the water was separated, Berglund found the fibers were stuck together into a grid, creating flat plates called "nano paper".

The mechanical test shows that it has a tensile strength of 214 times MPa, stronger than cast iron (130 MPa) and almost equal to steel structure (250 MPa).

Meanwhile, ordinary paper has a tensile strength less than 1 MPa.