**5. Polylactide‐based composites**

Composites combine two (or more) different components: a continuous phase, called matrix, acts as binder and distributs homogeneously the forces through whole composite; and a discontinuous phase, called reinforcement, fundamentally is used to carry the applied load. Depending on the form of the reinforcements, they are arranged in different groups, of which two most important are fibers and particles. Normally, the aim of the reinforcements is to enhance the stiffness and tensile strength of the matrix, although sometimes fillers are used to reduce the price of the final product or modify the physical, rheological, optical or other properties. However, more important is the interface between both components to assure good transmission among constituents of the composite.

Efforts made for advancing in technology lead to the scientific community to introduce nanoscale in material science and consequently in polymer science. It must pay special attention in nanocomposites, because it is foreseen remarkable improvement in properties with less quantity of reinforcement than micro or macroscale composites.

Different families of reinforcements can be classified into function of their chemical nature and it is analyzed the effect that induces in polylactides.
