Any material can break during its lifetime. As a result of fatigue, the ageing of a material due to repeated mechanical loading cycles, this failure may happen suddenly, with sometimes catastrophic results. This is a major concern in polymer composites, which are these days used in constructions, car and trains, airplanes,... . When designing items or constructions, the effects of fatigue or higher loadings than usual are compensated for by overdimensioning. To prevent or at least postpone failure, the size of the structure is taken larger than needed for expected loads, an aspect known as "the factor of safety". In this project, the use of reversible bonds to improve the fatigue and impact properties of network polymers will be studied. Stiff polymer networks will be made that consist of two materials at the molecular level. One of the materials is stiff and contains reversible bonds, while the other one is rubbery and has permanent bonds only. When a certain deformation is exceeded, the stiff material breaks, while the rubbery material keeps the broken parts together. This behavior can be compared to safety glass as used in banks, where the glass that breaks upon impact is kept together by the rubber in between the glass layers. A crucial difference in our material is, however, that the reversible bonds – the weakest links in the stiff material - will be able to relink spontaneously after breaking, thus permitting the recovery of the initial properties.
Effective start/end date1/01/1731/12/18

ID: 28716901