The idea of mixing single available materials into compounds to fulfill a set of desired properties is likely as old as mankind. Highly sophisticated polymer applications would simply be impossible without the enhancement of some of their properties through addition of fine mineral particles or synthetic or natural short fibers. Many filled polymers, either thermoplastics or vulcanizable rubbers, have different chemical natures but exhibit common singular properties. An understanding of why they do so is likely to be the source of promising scientific and engineering developments and...