Thermochemical changes involve decomposition of the explosives and binders, loss of strength of binder as it softens or melts, or stiffening of the binder if the increased temperature causes crosslinking of the polymer chains. The changes can also significantly alter the porosity of the material, whether by increasing it (fracturing of crystals, vaporization of components) or decreasing it (melting of components). The size distribution of the crystals can be also altered, e.g. by Ostwald ripening. Thermochemical decomposition starts to occur at the crystal nonhomogeneities, e.g. intragranular interfaces between crystal growth zones, on damaged parts of the crystals, or on interfaces of different materials (e.g. crystal/binder). Presence of defects in crystals (cracks, voids, solvent inclusions...) may increase the explosive's sensitivity to mechanical shocks.