Material World

Fake tears, E numbers, and a whole lot of skin. No, I’m not talking about the latest episode of The Only Way is Essex (thankfully).

The above is a list of just some of the things that can come out of studying complex fluids - to be specific cellulose derivatives such as  Hydroxypropyl Cellulose (HPC) which is used as: E number 463, a DNA 'sieve' in DNA screening, artificial tears and a leather manuscript preservation fluid.

The Linkam Optical Shearing System (CSS450) allows structural dynamics of complex fluids to be directly observed via standard optical microscope while they are under precisely controlled temperature and various shear modes. Dr Pedro Almeida, who is using this stage, noted that this system is both "compact and friendly” and that a great advantage is the simplicity of the stage which is easy for beginner researchers to use.

Dr Almeida, a researcher from the Polymeric and Mesomorphic Materials Group, is studying the rheological characterization of anisotropic materials which are materials whose properties depend on orientation - such as wood which has a fixed grain and is stronger in one direction than the other. Some, but not all anisotropic materials are complex fluids, as when they undergo stress and shear a molecular reorganisation takes place, and their mechanical properties change. They also possess properties similar to both liquids and solids. 

Dr Almeida says: “The rheological behaviour of the materials under study is closely linked to its orientation, and so it is very important to be able to follow the orientation by optical microscopy, while under shear. The processing of the materials is dominated by its rheology, so, knowing the rheological behaviour, which depends on the degree of orientation, is crucial for processing design.”

As the researchers understand these complex fluids better they will be able to develop new applications which, as you can see from the above list, can be incredibly varied.

By Caroline Feltham