Polycarbonate glazing

MEYERS and tancreto Design Criteria for Polycarbonate Glazing... 

The polycarbonate glazing is modeled as a simply supported plate subjected to nonlinear center deflections up to 15 times the pane thickness. Using the finite element solution of Moore (Reference 4), the resistance function is generated for each pane under consideration. Typically, the resistance is concave up, as illustrated for typical pane sizes in Figure 1. This occurs because membrane stresses induced by the stretching of the neutral axis of the pane become more pronounced as the ratio of the center pane deflection to the pane... 

In many cases, the dynamic amplification factor or the ratio of static load to dynamic load capacity will exceed two. This is because of the concave up shape of the resistance function and the mobilization of membrane resistance at large deflection to thickness ratios. Because of this phenomenon, it is unconservative to assume the blast capacity of polycarbonate glazing to be no less than one half of its static pressure load capacity. 

Focusing collectors are usually cast acrylic Fresnel lenses, or mirrors of aluminized polyester film in frames of aluminum. These reflectors are either enclosed in a bubble of poly(vinyl fluoride) film, or under polycarbonate glazing, which may be covered with a fluorocarbon film to reduce the reflectivity. The absorbers for active systems are copper or aluminum since the temperatures are too high (325—370°C) for plastics. The frames, however, can be molded ABS, high density polyethylene or polyurethane, either solid or structural foam. Polybutylene or chlorinated PVC can be used for piping hot water, and tanks can be made of either reinforced polyester or blow- or rotational-molded, high density polyethylene (12—15). 

Margard sheet [GE Plastics] Extraded polycarbonate glazing grade sheet uv stabilized, coated on both faces with mar-resistant silicone coating. 

Of the 1-7 Mt of phenol produced in the U.S.A. in 1983, 34% went into phenol-formaldehyde resins (for plywood adhesives), 15% to caprolactam and 5% to aniline. However, an increasing proportion (presently 35%) is being converted into bisphenol A , the basis for polycarbonate glazing and high-performance engineering resins " ... 

Bonenfant N. Cellular polycarbonate glazing— the glass alternative. ITie Construction Specifier 2004. 

The cost of solar collectors can be reduced by using polymeric glazing and absorber materials, but the durability of their optical and mechanical properties must be demonstrated. Polycarbonate glazings with ultraviolet screening layers have been shown to survive accelerated light intensity for an equivalent 20 years outdoor exposure in Miami, FL. The mechanical properties of two candidate absorber materials— metallocene-based multi-density polyethylene and polypropylene— have been measured as a function of wet and dry thermal exposure. 

Figure 3. Effect of UV exposure on impact strength transmittance of 2.3-mm-thick polycarbonate glazing.

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