Project Number: KD04JNG, KD01JNG and KD02RGC
Auxetics are materials and systems which exhibit the very unusual properties of becoming wider when stretched and narrower when squashed, that is, they have Negative Poisson's Ratio.
A team of University researchers have extensive expertise on materials possessing auxetic properties and how they can be used to develop and manufacture new or improved commercial structures and products.
They have also developed a novel way of converting conventional foam to auxetic foam through the use of solvent instead of heat. The process which was developed can be divided into three steps:
Why opt for an auxetic material?
Apart from possessing a Negative Poisson's Ratio, auxetic materials display additional unique qualities such as increased shear stiffness, an increased plane strain fracture toughness and an increased indentation resistance. When an object hits an auxetic material and compresses it in one direction, the material contracts laterally. That is, material flows into the location of impact creating a denser material which is less resistant to impact.
Auxetic materials are also known to have better shock and vibration absorption properties. They also have a natural tendency to form dome-shaped double-curved surfaces, unlike conventional materials which tend to form saddle-shaped surfaces. Such materials are particularly desirable in applications that require highly curved hard surfaces, such as those found in the body parts of aircrafts and cars.
How can this be applied to foams?
Current methods of converting conventional foams to auxetic foams focus around compressing, heating and cooling the foam. This method can be time consuming and costly when considering the heating equipment required. The proposed production process is more energy efficient than current methods since it does not require heating. This, coupled with the fact that solvents may be reused several times lowers the production costs and also allows for a more environmentally friendly process. The use of solvents also removes the risk of the foam being degraded as part of the heating process. As solvents flow homogenously, the process for converting large samples of auxetic foam blocks would be more efficient than current processes.
Auxetic materials and structures can also be used to replace conventional components in various products used in specialised applications to produce higher quality products.
This technology surrounding auxetic foams may be used to produce a number of products, for which enhanced capabilities will emerge as a result of the superior properties that auxetic foams have over conventional foam. This can be applied to:
The foam has been prototyped.
Patent granted. A patent application number GB1107220.4 was submitted by the University of Malta in the United Kingdom in May 2011. This was granted under number in July 2013. Patent application number MT4236 submitted in Malta was also granted to the University of Malta.
The team have extensive know how in the field of auxetics and how it can be applied to the development and manufacture new or improved commercial structures and products. We are interested in collaborating with entities to design smart materials around their technologies.
Prof. Joseph N Grima
Prof. Ruben Gatt
Dr Daphne Attard
K Boba K., Bianchi M., McCombe G., Gatt R., Griffin AC., Richardson RM., Scarpa F., Hamerton I., Grima JN. (2016). '.' ACS Applied Materials & Interfaces 8 (31), 20319-20328,
Attard D., Degabriele EP., Grima JN. (2016). '.' Physica Status Solidi (b) Vol 253, Issue 7 (1419-1427)
Attard D., Caruana-Gauci R., Gatt R., Grima JN. (2016). '.' Physica Status Solidi (b) Vol. 253, Issue 7 (1410 - 1418)
Grima JN., Mizzi L., Po藕niak AA., Wojciechowski KW. (2016). '.' Elsevier: Composites Part B- Engineering.
Evans E.E., Grima JN.(2006) ''. Journal of Materials Science 41; 3193鈥�3196
Dudek KK., Attard D., Caruana-Gauci R., Grima JN,. Wojciechowski KW. (2016) '.' IOP Publishing: Smart Materials and Structures Vol 25, Issue 2 (0205009)
Azzopardi KM., Gatt R., Grima JN, Mizzi L.(2016). '.' Advanced Materials Vol 28, Issue 2 (385-389)
Attard D., Gatt R., Grima JN., Mizzi L, Pozniak AA., Wojciechowski KW (2015). '.' Elsevier: Composites Part B: Engineering Vol 80 (84-91)
Agius TP., Attard L., Azzopardi KM., Casha A., Chockalingam N., Formosa C., Gatt A., Gatt R., Grima JN., Schembri-Wismayer P., Vella Wood M, Zarb F. (2015). '.' Elsevier: Acta biomaterialia Vol 24 (201-208)
Caruana-Gauci R., Dudek KK., Dudek MR., Grima JN., Wojciechowski KW. (2015) ''. IOP Publishing: Smart Materials and Structures Vol 24, Issue 8 (085027)
Attard D., Bajada M., Dudek KK., Gatt R., Grima JN., Scerri S. (2015). ''. The Royal Society: Proc. R. Soc. A Vol 471 Issue 2179 (20150188).
Alderson A., Grima JN., Scarpa F., Wojciechowski KW. (2015). ''. Physica Status Solidi (b) Vol 252, Issue 7 (1421-1425)
Gatt R., Grima JN., Mizzi L. (2015). ''. Physica Status Solidi (b) Volume 252, Issue 7 (1559-1564)
Cauchi R., Formosa JP., Grima JN. (2015). ''. Physica Status Solidi (b) Vol 252 Issue 7 (1656-1663)
Attard D., Azzopardi KM, Gatt R., Grima JN., Mizzi L. (2015). ''. Physica Status Solidi (RRL)-Rapid Research Letters Vol 9 Issue 7 (425-430)
Attard D., Azzopardi JI., Azzopardi KM., Briffa J., Casha A., Gatt R., Mizzi L., Grima JN. (2015). ''. Nature Publishing Group: Scientific reports Vol 5 (8395)
Attard D., Cauchi R., Grech MC., Gatt R., Grima JN., Mizzi L., Rybicki J., Winczewski SN., Wojciechowski KW. (2015). ''. Advanced Materials Vol 27 Issue 8 (1455-1459)
Azzopardi KM., Brincat JP., Gatt R., Grima JN., Mizzi L. (2015). ''. Advanced Engineering Materials Vol 17 Issue 2 (189-198)
Gatt R., Grima R., Mizzi L., Trapani L. (2015). ''. TASK Quarterly: scientific bulletin of Academic Computer Centre in Gdansk Vol 19 Issue 3 (237-296)
Azzopardi KM., Brincat JP., Gatt R., Grima JN. (2015). ''. RSC Advances Vol 5 Issue 12 (8974-8980)
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