Showcase Science 2007 - The Exhibits Hall

The Exhibits Hall 2007
Oundle School, Northants - Thursday 15th March 2007
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Puzzling Plastics - stringy substances and giant vortices
IRC in Polymer Science and Technology, Dept of Physics and Astronomy, University of Leeds, LEEDS LS2 9JT Dr John Embery
For fifty years, plastics have successfully concealed their secret life from us. The processing and use of plastics has leapfrogged ahead of our understanding of what is happening when the plastic is moulded into a object; whether that object is Wayne Rooney's shin guard, a Pussycat Dolls DVD or the casing of the latest mobile phone.				A polymer liquid getting really stressed. Predicted stress patterns for a liquid polymer made of branched molecules flowing through a constriction - the flow determines the final properties of the plastic
In the last fifty years, whilst the world's oil has been transformed into more and more plastic, we have been wrestling to catch up with the science of plastic molecules. This is a necessity if we are to develop such things as super-tough plastic pipes, ultra-thin and massively strong plastic bags or lighter replacements for metal in vehicles and thus, ultimately use the world's resources more effectively. In order to decipher the behaviour of plastics we need to analyse and understand, using mathematical and experimental tools, how polymer liquids flow when they are in the melt state just prior to being squeezed and cooled into a new useful shape.				Stressed polymer grows fangs! The flow of molecules in liquid polymers can now be predicted with accuracy - predicted flow (left) and observed flow (right) through a channel; the "fangs" are a fingerprint signature of branched molecules.
The ultimate step of this project is the development and hard-testing of molecular theory and process modelling before it is then applied to more typical industrial materials. A recent example of this has been to independently predict and experimentally measure the stress field that a polymer liquid experiences as it is squeezed in two directions at once. The close correlation of the two analyses shows that the theory is becoming more sophisticated in predicting real processing situations. Enormous strides have meet made in the last fifty years in attempting to describe polymer flow with mathematical modelling. Polymeric materials are greatly affected by the motion of molecules and the heat that derives from that. Statistical mechanics is concerned with what happens when things get hot. From the statistical mechanics of gases, physicists can do statistical mechanics on connected chains - the giant chains of polymers. General relativity enables physicists to measure curvature of molecular paths in space and in membranes, the two-dimensional polymers that underpin so much of biology (cells and cell walls). And quantum field theory, with its notion of summing over all fluctuating states, enables physicists to calculate the way polymers move under thermal fluctuation.

The Poster
Presentations are judged and prizes totalling
£1500
are to be awarded at Showase Science 2007.