Scientists using neutron scattering facilities at the Australian Nuclear Science and Technology Organisation (ANSTO) are learning more about paper with an eye to developing a better understanding of fibre and overcoming frustrating jams in photocopiers, faxes and printers.
While office workers tend to blame gremlins in the machines, Dr Robert Knott of ANSTO, who is working on the project with Monash University scientist Dr Chris Garvey, says that problems with paper can often be attributed to fluctuating humidity. Dr Garvey’s study is being supported by a grant from the Australian Institute of Nuclear Science and Engineering.
"Sticking problems are caused by weight gain in paper due to atmospheric water bonding with giant cellulose molecules in paper," Dr Garvey said.
"Paper is made of up to 15 per cent water, causing major problems for paper manufacturers. In the past, the difficulty in understanding or controlling the structure of paper has hampered the study of interactions between fibres and moisture. In this study, we have probed the structure and dynamics of paper, using ANSTO’s facilities in small-angle neutron scattering."
"The process of making paper from fibres is quite different from that used to make most man-made polymers. In scientific terms, paper is a web of hydrogen-bonded semicrystalline composite fibres.
The final structure consists of a selectively degraded or reverse engineered biological material. This contrasts with the engineering approach to man-made polymers, and explains why it is difficult to modify plant fibres in a systematic manner," he said.
The response of paper to changing relative humidity is to gain or lose water. It gains mass and expands when the humidity increases, and loses mass and contracts when the relative humidity decreases. This behaviour has important implications for understanding the performance of paper and other fibres.
Paper is one of many materials now being investigated in the growing field of Small Angle Neutron Scattering. Research reactors like the one operated by ANSTO at Lucas Heights are a source of neutrons, which are increasingly being used by scientists to learn more about the molecular structure of materials we use every day.
The neutron is an ideal tool for probing the structure of solids and liquids. Thermal neutrons generated by research reactors are scattered by atoms in the material being probed. The scattering pattern reveals the sample’s structure and the dynamics of the molecules in detail.
People who use paper are already the beneficiaries of nuclear technology - nuclear gauges help paper manufacturers measure paper thickness, while radiation is applied to some types of paper to apply special types of gloss.