Polyborodimethylsiloxane is a substance called a dilatant that in its raw state flows freely but on shock locks together to absorb and disperse energy as heat before returning to its semi-fluid state. The commercial material known as D3O is, in essence, a closed-cell polyurethane foam composite with polyborodichdmethylsiloxane (PBDMS) as the dilatant dispersed through the foam matrix which makes the product rate-sensitive thus dissipating more energy than plain polyurethane at specific energy levels. The patent cites optimal proportions for a shock-absorbing foam composite formulaee: by volume, 15–35% of PBDMS and 40–70% fluid (the gas resulting from the foaming process, generally carbon dioxide) the remainder being polyurethane. D3O's technology is found in many sports equipment such as body armour. British engineers Dr Phil Green and Richard Palmer discovered the material in 1999, first isolating it at the University of Hertfordshire. Palmer and Green went on to found the firm D3O Lab to develop and market the product.
 The company commercialized the D3O material in 2006. In 2009, the UK Ministry of Defence awarded D3O Lab £100,000 to fit helmets in order to reduce the kinetic energy of a bullet or shrapnel on impact, because of its moldable properties.
D3O has been applied in the following areas:
- Sports, including ski and snowboard, lacrosse, baseball, fencing, cricket, volleyball, tennis, squash, ballet, boxing, shooting and sailing, mountain biking and cycling, equestrian and water sports
- Motorcycle apparel
- Cases for electronic devices
- Ice skating and figure skating
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