Active research
Click on the headings for more details. If you are interested in working in any of these areas, check Joining the Group for information. You can find details about past and present research group members here.
Characterisation and modelling of filled elastomers
I am working on both mechanical and electrical testing, and modelling, of large deformations in filled elastomers. These materials are typically filled with carbon black, or with nanoparticles such as carbon nanotubes. They exhibit an unusual form of behaviour upon reloading known as the Mullins effect, and a similarly unusual behaviour in their electrical response. The ability to understand and predict such behaviour and the changes in structure that accompany it is crucial in the design of these materials, and can lead to interesting applications in the area of sensors and smart materials. Read more...
Predicting properties of processed glassy polymers
As part of the large interdisciplinary collaboration Microscale Polymer Processing (mPP2) between universities and industry, I am working on the development of physically based predictive models for processed glassy polymers. The mechanical properties after processing depend crucially on the residual orientation in the melt, and the project involves a coupling of rheological models and solid-state models. In addition, I have looked in detail at the effects of molecular length, architecture and orientation on environmental stress craze initiation, a failure mode that often limits the usefulness of glassy polymers. On-going work includes investigations on the effects of polydispersity and branching on solid-state properties. Read more...
Multifunctional nanocomposites
The addition of small quantities of nanofillers to polymer matrices to produce nanocomposites offers interesting opportunities to produce multifunctional materials. In particular, adding conductive nanoparticles such as carbon nanotubes can produce nanocomposites that are not only strong but also electrically and thermally much more conductive than traditional polymers. In collaboration with Nanocyl, we are now investigating CNT-filled thermoplastic elastomers and CNT-filled polycarbonate nanocomposites.
Degradable polymers and nanocomposites for medical implants
Degradable polymers such as poly(lactic acid) are used in both degradable packaging applications and medical implants. As part of collaborative work with the Polymer Composites group here in Nottingham, we have studied the processes by which polymer degrades, and the influence this has on the mechanical properties during degradation. Through the use of subtle interplay between crystallisation and degradation, it is possible to maintain relatively steady properties for extended periods of time, prior to a sudden collapse and degradation at a specified time - ideal for medical implant applications. A large project is now under way investigating bioresorbable nanocomposites, more information here.
Adhesion and tack of prepregs for automated composite manufacture
In collaboration with the University of Nottingham's Polymer Composites group, we are studying the adhesion and tack of prepregs, employing techniques from polymer rheology.
Past projects
Click on the headings for more details
Medical Devices
I have worked on the mechanics of a needle-less injection device in collaboration with PowderJect Pharmaceuticals. The device uses a gas shock wave to accelerate a thin elastomeric membrane holding the drug powder to velocities sufficient to penetrate the skin. Read more...
Deployable Structures
Together with Simon Guest of Cambridge University I developed a class of folding patters based on the deployment mechanism found in beech and hornbeam leaves. The biomimetic patters have applications as deployable structures. Such structures are used predominantly in space applications where large structures such as solar arrays and antennas need to be packaged compactly during transportation. Read more...