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Size-dependent reinforcement of soft-hard composites.

  • Supervisor: Prof. dr. Daniel Bonn
  • Research Team: Henri de Cagni, Kevin Haver
  • Goal: To investigate how the mechical properties of soft-hard composites depend on filler size.
  • Info: D.Bonn, K. Haver

Composites consisting of hard particles in a soft matrix are ubiquitous. Our bones, nacre but also many foodstuffs are all composed of more or less hard particles in a softer matrix material. Adding solid filler particles to an elastic material dramatically changes its mechanical behavior. The physical properties of synthetic rubber that are important for tire performance, for example, depend on the addition of nanosized fillers, typically silica or carbon black. It is well known that nanosized filler particles enhance the mechanical properties of composites in a size-dependent fashion. This is puzzling, because classical elasticity is inherently scale-free, and models for the elasticity of composite systems never predict a filler-size dependence. We will study model systems that have an elastic matrix, and add different filler sizes, types and volume fractions to see how the reinforcement depends on these parameters. We will investigate both linear and nonlinear mechanical properties of filled microgel, that serves as a good model material because the moduli of both the matrix and the filler particles can be varied.