Glazing material

The ASA (now ANSI) performance code for Safety Glazing Materials was revised in 1966 to incorporate these improvements in windshield constmction. The addition of test no. 26 requiring support of a 2.3-kg ball dropped from 3.7 m defined this level of improvement. It was based on a correlation estabUshed between 10-kg, instmmented, head-form impacts on windshields, on 0.6 x 0.9-m flat laminates, and the standard 0.3 x 0.3-m laminate with the 2.3-kg ball (28). Crash cases involving the two windshield interlayer types were matched for car impact speeds and were compared (29). The improved design produced fewer, less extensive, and less severe facial lacerations than those produced in the pre-1966 models. 

Polymethacrylates. Poly(methyl methacrylate) [9011-14-7] is a thermoplastic. Itis the acryUc resin most used in building products, frequendy as a blend or copolymer with other materials to improve its properties. The monomer is polymerized either by bulk or suspension processes. Eor glazing material, its greatest use, only the bulk process is used. Sheets are prepared either by casting between glass plates or by extmsion of pellets through a sHt die. This second method is less expensive and more commonly used. Peroxide or azo initiators are used for the polymerization (see Methacrylic polymers). 

When these pigments are used with lead-containing glazes, care should be exercised to use lead-safe glaze materials (see Lead compounds, industrial toxicology). 

Acryloid and Plexigum. These were soft gummy products of interest as surface coatings rather than as mouldable plastics materials. About 1930 R. Hill in England and W. Bauer in Germany independently prepared poly(methyl methacrylate) and found it to be a rigid, transparent polymer, potentially useful as an aircraft glazing material. ... 

The methacrylic polymer remains a useful glazing material. In aircraft applications it is used extensively on aircraft which fly at speeds less than Mach 1.0. They form the familar bubble body of many helicopters. On land, acrylic sheet is useful for coach roof lights, motor cycle windscreens and in do-it yourself cabins for tractors and earth-moving equipment. Injection mouldings are frequently used for plaques on the centre of steering wheels and on some fascia panelling. 

Rather more recently Rohm and Haas GmbH have introduced Plexidur plus which is a copolymer of acrylonitrile and methyl methacrylate. It is best considered as a glazing material for use in schools, sports halls and vehicles. The material also has good clarity, rigidity and surface hardness. Some typical properties compared with PMMA are given in Table 15.2. 

Frank T., Nussbaumer T., and Carl S. Optical and thermal properties of glazing materials. Final report BEW-project EF-REN(92) 081 "Glasdatenbank GLAD-PC" [in German]. Diicbcndorf EMPA, 1996. 

Lampert, C. M., and Ma, Y. (1992). Fenestration 2000 Advanced Glazings Materials Study. St. I lelens, UK Pilkmgton Glass. 

Chapter 5 of the ASCE Physical Security report addresses the various types of glazing materials and staictural components of window frames and should be referred to for a detailed discussion of the topic. 

This section cannot describe all the provisions in the code, but the code contains specific requirements for a variety of materials, both based on the type of material and its application. For example requirements exist for insulation materials (loose-fill, foamed, and others), kiosks and children s playground structures in malls, siding, combustible materials in exterior walls, roofs and decks, and glazing materials, among the others. It also specifies that all materials contained within plenums must meet the requirements of the IMC.3... 

In comparison to bulk plastics, thermoplastic polymethylmethacrylate (PMMA) is much more expensive. Its particular characteristics are clarity, hardness, low absorbance and resistance to aqueous solutions, acids, alkalis, carbon dioxide and fat. It is attacked or dissolved by polar organic solvents. The world-wide use of PMMA in 1997 was ca. 1.2 x 106 t, principaly for optical articles in cars and buildings and glazing material in aircraft. Typical food contact articles are dishes, cups and silverware. In addition it has orthopedic and denture uses. 

Safety Glazing Materials for Glazing Motor Vehicles Operating on Land Highways, May 16, 1950. 

Replace glass with break-resistant glazing materials such as polycarbonate, acrylic, or laminated glass. 

The ideal glazing would transmit all the solar energy into the collector and, at the same time, reflect the long-wave reradiation from the collector. Research with glazing materials to improve the transmittance and reduce reradiation losses could improve the economics of a solar heat collector. It is, therefore, recommended that these two avenues of investigation be considered by researchers in this field. 

---