4 4 Falipou, M., Donnet, C., Maréchal, F., and Charenton, J.‐C. (1997). Sticking temperature investigations of glass/metal contacts – determination of influencing parameters. Glass Sci. Technol. 70: 137–140.
5 5 Rieser, D., Spieß, G., and Manns, P. (2008). Investigations on glass‐to‐mold sticking in the hot forming process. J. Non Cryst. Solids 354: 1393–1397.
6 6 Manns, P., Döll, W., and Kleer, G. (1995). Glass in contact with mould materials for container production. Glass Sci. Technol. 68: 389–399.
7 7 Falipou, M., Zahouani, H., and Donnet, C. (1999). Effect of surface morphology upon friction of a metal substrate sliding against hot viscous melt under extreme conditions. In: Lubrication at the Frontier: The Role of the Interface and Surface Layers in the Thin Film and Boundary Regime (eds. D. Dowson, M. Priest, C.M. Taylor, et al.), 91–99. Amsterdam: Elsevier.
8 8 Coenen, M. (1978). Festigkeit von Glasschmelzen. Glastech. Ber. 51: 17–20.
9 9 Schaeffer, H.A. (2010). Hohlglas, Glass Hollowware. Munich: Deutsches Museum.
10 10 Muncke, J. (2009). Exposure to endocrine disrupting compounds via the food chain: is packaging a relevant source? Sci. Total Environ. 407: 4549–4559.
11 11 Sax, L. (2010). Polyethylene terephthalate may yield endocrine disruptors. Environ. Health Perspect. 118: 445–448.
12 12 Moore, C.J. (2008). Synthetic polymers in the marine environment: a rapidly increasing, long‐term threat. Environ. Res. 108: 131–139.
Note
1 Reviewers: A.J. Faber, Celsian Glass & Solar, Eindhoven, The NetherlandsC. van Reijmersdal, Bucher Emhart Glass S.A., Niderwenigen, Switzerland
1.6 Continuous Glass Fibers for Reinforcement
Hong Li and James C. Watson
Fiber Glass Science and Technology, PPG Industries, Inc., Shelby, NC, USA
1 Introduction
Numerous examples of the use of glass drawn as fibers can be found throughout history. The early Egyptians wrapped glass fibers over clay vessels and then fused them to form glass vessels. Venetian glass blowers in the sixteenth and seventeenth centuries used glass fibers to decorate elaborate glass articles. Glass fibers were even used as fabric elements in fashion garments in the late nineteenth century. It was in the mid‐1930s, however, that two key developments created the means for glass fibers to become the base for a new industry based on composites–organic polymers reinforced with glass fibers, more commonly known as glass reinforced plastics, or GRP. The first was improvements in the process of manufacturing glass fibers at the Owens‐Illinois Glass Company so that commercial fibers could be made in a multifilament strand form that met basic material handling requirements for downstream processing into composite structures [1]. The second was the development of polymeric resin systems by DuPont and others that could be combined readily with glass fibers. These glass‐fiber reinforced polymer–matrix composites offered key material advantages over conventional metallic materials, including light weight, stiffness, and strength, and resistance to corrosion and fatigue.
Today, glass fibers have become the most widely used and cost‐effective reinforcing fibers in the arena of commercial polymer–matrix composites. Early melt spun processes producing discontinuous fibers have evolved to today's large‐scale direct melt continuous fiber‐forming operations. One of the first needs for continuous fibers was for insulation of electrical wires for high‐temperature applications, leading to the development of a new glass composition based on a CaO–Al2O3–SiO2–B2O3 system that met the electrical requirements and subsequently became known as E‐glass. Because these fibers also exhibited excellent mechanical properties and could be made in relatively high‐volume manufacturing operations, the original E‐glass compositions rapidly spread into many composite applications. Today, the glass fiber reinforcement spectrum has grown to include an increasing array of specialty glass compositions that are targeted for key expanding markets in electronics, transportation, corrosion, construction, and in energy management.
Prior to 2000, most major glass fibers manufacturers were concentrated in North America and Western Europe. Today, fiberglass production facilities are flourishing in China and beginning to spread to other regions of the world to satisfy a constantly growing demand of GRP. It is the intent of this overview to provide insight into the technology that is associated with the continuing success of glass as a reinforcing fiber. Fiberglass technology associated with both material characteristics and manufacturing processes are described at a high level.
2 Commercial Glass Fibers
2.1 History of Fiberglass Development and Glass Chemistry
2.1.1 Fiber Types
Reinforcement glass fibers can be broadly divided into two categories – general‐purpose and premium special‐purpose fibers. The former are known as E‐glass and subject to specific compositional ranges as defined by recognized standards such as ASTM D578 [2]. Historically, E‐glass fibers have been predominant in the commercial production of fiberglass products for use as reinforcements in various industrial polymer–matrix composites applications. Other types of fibers that have been used in special purpose and low‐volume applications include S‐glass, R‐glass, D‐glass, ultrapure silica fibers, and hollow fibers [3].
Continuous glass fibers for composite reinforcement have been categorized by the specific properties required for end‐use applications (Figure 1). An overview of the historical timeline of the development and commercial use of these major glass types is represented on the horizontal axis. Further detail on the typical oxides and oxide ranges, physical and mechanical properties, and processing‐related properties that are characteristic of the major glass types used in glass fibers are listed in Tables 1 and 2, respectively. More specific examples of recent developments in the areas of D‐, S‐, and R‐glasses are also included.
2.1.2 E‐Glass
First commercialized in the late 1930s [1], E‐glass fiber remains the most widely used class of fiberglass for GRP materials [3, 4]. Its composition primarily lies within the ternary CaO–Al2O3–SiO2 system with B2O3 and F2 contents that vary from 0 to 10 wt % and 0 to 2 wt %, respectively. For much of its history, E‐glass fiber production incorporated B2O3 in commercial compositions at levels of 7–8 wt %, which provided an optimal balance of melting and fiber‐forming characteristics, mechanical properties, and electrical properties. Over time, however, increasingly restrictive environmental emissions requirements for particulates have been driving costs up for emission control systems. Countries such as Canada and Norway were leaders in the push to improve environmental conditions, leading to the introduction of the first boron‐free commercial glass fibers. These glasses had in addition excellent corrosion resistance under strongly acidic conditions [7]. They have been designated as E‐corrosion resistant (E‐CR) glass fibers in the late 1970s. Over time, optimizations of minor oxide components such as TiO2, ZnO, and MgO served to improve their cost and manufacturing efficiencies while also providing proprietary regions in the compositional space as their use was growing rapidly.
In key areas outside of the corrosion markets, however, there was resistance to move to low‐boron compositions. The electronics industry, dominated by E‐glass fabrics used in printed wiring boards (PWB), relied on the unique value set of electrical consistency, dimensional stability, processing