Strengthened Glasses

Fig. 7. Cross section of Sierracin windshield used on Boeing 747 (32) A, 2.2-mm chemically strengthened glass B, Sierracote 3 conductive coating C, 1.9-mm PVB D, 23-mm stretched acryflc E, 1.3-mm PVB F, laminated cloth spacer ring G, 23-mm stretched acryflc H, 0.6-mm PVB and I, 3.0-mm...

A third type of security glass is installed in modem penal institutions. This product is utilized for prisoner detention and obviates iron bars and their demeaning aspect. Typical construction utilizes three or more layers with at least one ply of thick PVB. Other constructions utilize polycarbonates, polyurethanes, and modified acrylics. Strengthened glass and electrically conductive circuits for alarms may be included. Large, heavy sections of similar construction have been used for underwater windows for boats, submarines, and aquariums. Four plies of fully tempered, 10-mm glass plus three plies of PVB totaling 44.5 mm in thickness has a modulus of rupture of 172 MPa (25,000 psi) (39). 

Although both heat and ion tempering both successfully strengthen glass, heatstrengthening and ion tempering do not satisfy either ANSI or federal specifications for safety glazing. 

Other methods of chemically strengthening glass include Li ions diffused into a sodium-containing glass to create a composition profile in which the resulting surface has a lower expansion than the core region, and thus develops a compressive layer on... 

Most scientists involved in high-pressure kinetics believe that activation volumes can be determined more accurately, and that they are easier to interpret, than activation entropies. Our group has studied, with the strengthened glass cell, a fairly large series of amides and A, 7V-disubstituted amides by this technique. The results are described in more detail in a recent review. Only one example will be given here, an example in which two independent conformational equilibria are observed in the spectra. 

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