S. Deevi et al., REACTIVITIES OF ALUMINUM AND ALUMINUM-MAGNESIUM ALLOY POWDERS IN POLYMERIC COMPOSITES, Journal of Materials Science, 31(4), 1996, pp. 1043-1051
Polymeric compositions containing Al-Mg alloys show higher reactivitie
s, in comparison with similar compositions containing aluminium. This
is observed irrespective of the amount of oxidizer, type of oxidizer u
sed, type of polymeric binder, and over a range of the particle sizes
of the metal additive. This is evident from the higher calorimetric va
lues obtained for compositions containing the alloy, in comparison to
samples containing aluminium. Analysis of the combustion residue shows
the increase in calorimetric value to be due to the greater extent of
oxidation of the alloy. The interaction between the polymeric binder
and the alloy was studied by coating the metal particles with the poly
mer by a coacervation technique. On ageing in the presence of ammonium
perchlorate, cracking of the polymer coating on the alloy was noticed
. This was deduced from differential thermal analysis experiments, and
confirmed by scanning electron microscopic observations. The increase
in stiffness of the coating, leading to cracking, has been traced to
the cross-linking of the polymer by magnesium.