5. Functional properties

5.1 Mechanical properties

• Resistance to mechanical impact: a detailed description of the mechanical properties of glass is given in the article on glass [A 2 108] in the Plastiques et Composites textbook.

  Glasses, especially those used in packaging, break without prior deformation under the effect of extensional stresses; elastic deformation, without a plasticity phase, until breakage characterizes brittle materials as opposed to ductile materials.

  The intrinsically high strength of –– glass is considerably lowered by the surface microcracks and accidents that inevitably occur during the forming process, as shown by the following...