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 MIL-HDBK-1013/12
annealed glass. There are some security polycarbonate laminates
which incorporate a ply of acrylic material in their interior.
2.2.2
Laminated Cross-Sections. Combining interlayer bonding
materials with plies of glass, polycarbonate, or both produces
cross-sections that perform well against ballistic, blast, and
forced entry attack. This paragraph describes the following
types of lamination materials and laminated cross-sections:
a)
Interlayer Materials
b)
Fragment Retention Film
c)
Thermally Tempered Glass
d)
Laminated and Fused Polycarbonate
e)
Glass-Clad Polycarbonate
f)
Glass-Clad Ionomer
The resultant fracture pattern from failed annealed,
heat, and chemically strengthened glass are larger shards than
those produced from TTG. Larger shards provide benefits to
security laminates in areas of ballistic and forced entry attack
resistance because there is more unbroken material to resist
subsequent impacts. The larger shards strengthen a laminate,
enabling a fractured glazing to remain in a frame and increase
the probability that subsequent ballistic rounds will not find a
break in the material. Larger shards also provide a defender
with greater visibility.
The ballistic resistance of glass is directly related
to the amount of kinetic energy absorbed in breaking up the
glass. During a ballistic attack, interlayer material in a
laminate holds glass material in place ahead of a bullet and
absorbs energy from a bullet impacting the glass plate preceding
it. Containment of fractured glass material forces a bullet to
pulverize the material into a fine powder before it can make its
way though the glass material.
2.2.2.1
Interlayer Materials. Selection of interlayer material
is driven by compatibility issues and cost. Consideration must
be given to incompatibilities when bonding nonhomogeneous
materials. As a consequence, there are only two basic types of
material which are available and used by laminators for the
lamination of security laminates. They are Plasticized Polyvinyl
Butyral (PVB) and Aliphatic Urethane.
There is a third interlayer material, Copal, which is
composed of silicone and polycarbonate materials. This
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