International Journal of Applied Glass Science, 5 [1] 65–81 (2014) DOI:10.1111/ijag.12053
High-Performance Glass Fiber Development for Composite Applications Hong Li,*,† Cheryl Richards,* and James Watson Fiber Glass Science and Technology, PPG Industries, Inc., 400 Guys Run Road, Cheswick, Pennsylvania 15204
The article provides a review of historical commercial glass fiber development and recent developments of high-performance glass fibers with improved mechanical performance for glass fiber-reinforced polymer–matrix composite applications. Glass composition design is outlined in conjunction with theoretical and experimental modeling approaches. Challenges in glass melting and fiber forming are briefly discussed.
Introduction Glass fiber and glass fiber-reinforced plastic (GFRP) composite industries have been enjoying continuous growth globally, especially in the most recent decade. This article is intended to provide a general review, with examples, of the history of fiber glass development as well as recent development. The review will cover glass fiber chemistry and composition design, mechanical property characterizations, and topics relevant to glass melting and fiber forming. This article by no means provides a comprehensive review on the subject; rather, it provides researchers and professionals with an update on the state of glass fiber technology with a focus on fibers with improved mechanical properties. The article is divided into four major sections: (i) overview of glass fibers, (ii) chemical approach to glass fiber mechanical performance, (iii) glass fiber mechanical property characterizations, and (iv) glass *Members, The American Ceramic Society. †
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fiber processing. The article concludes with a summary that points to the continuous advancements in glassmelting technology that meet the growing challenges of the commercial production of high-performance glass fibers. Overview of Glass Fibers Market Growth As GFRP materials have gained broader usage, global glass fiber output has steadily increased, to meet that demand, over the past decade. Applications in automotive, consumer goods, and industrial tanks, and piping markets have seen rapid expansion. Brisk growth has also been seen in wind turbine blades and printed circuit board (PCB) applications. The growing demands of existing GFRP products and identification of new applications are further fueled by the megatrends of energy efficiency (automobile and aerospace industries requiring lighter weight), a cleaner environment (tied to energy efficiency and lower emissions),
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and renewable energy production (wind turbines). Other key factors impacting the growth and global expansion of the GFRP market have been the maturity of GFRP composites in commercial applications maturity and secure supplies of glass fiber products with known performance features at competitive cost points. Figure 1 illustrates global glass fiber annual production, whose growth in the recent decade has been strongly supported by Chinese production.1 Classification and History of Commercial Glass Fibers Glass fibers are the most common reinforcement used for polymer–matrix composites and are classified based on required key properties for specific composite applications as highlighted in Fig. 2. The time periods shown represent significant activities occurring in research and development based on our literature search and projections.
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Glass fiber production (10 MT)
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Fig. 1. Global glass fiber production history (in metric ton).1
Fig. 2. History of major commercial glass fiber development.
Vol. 5, No. 1, 2014
E-Glass is the most widely used glass fiber for GFRP and is primarily composed of CaO, Al2O3, and SiO2, conditionally with B2O3 from 0 to 10 wt.%. E-Glass offers suitable mechanical properties (tensile strength and modulus), electrical properties [dielectric constant (Dk); dielectric loss (Df); and dielectric strength], and chemical stability for most GFRP applications including those for PCB electronics and numerous general industrial applications.2,3 General-purpose E-Glass fibers are defined according to ASTM D578 specifications.4 Historically, E-Glass compositions started with relatively high concentrations of boron (B2O3) and fluorine (F or F2), which enhanced batch melting, glass fining, and fiber drawing. Over the years, E-Glass compositions with low or zero B2O3, and essentially no fluoride, were developed to address environmental and legislative regulatory requirements. These changes are reflected in the general purpose definition of E-Glass as shown in ASTM Standard D 578 Section 4.2.2.4 A more specific designation for boronfree modified E-Glass composition is called out in Section 4.2.4 of the standard. Known as E-CR Glass, it has improved resistance to corrosion by most acids. E-CR fiber development and commercialization have been further aided by advancements in furnace and bushing technology that enabled high furnace throughput. Large-scale commercialization of E-CR fiber glass surfaced in the mid-1980s, was broadly accepted and produced in the 1990s, and is widely accepted today. Representative commercial E-CR fiber products in the market today include Advantexâ from Owens Corning (OC, Columbus, OH), INNOFIBERâ CR fiber glass from PPG Industries, Inc. (PPG, Pittsburgh, PA), and E6-CR from Jushi Group Co. Ltd. (Tongxiang, Zhejiang, China), etc.
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High-Performance Glass Fiber Development
Although E-CR glass fibers are evolving to become the GFRP industry standard for most corrosion-resistant applications, improved chemical resistance was originally obtained from boron-free C-Glass fibers (Na2O, CaO, Al2O3, and SiO2), which offered good chemical resistance against acid attack. Boron-containing C-Glass fiber was invented in 1943 (U.E. Bowes, US 2,308,857, OC, 1943), which had limited use in building material insulation applications because of lower resistance to acidic environments due to boron presence in the glass. The mechanical performance of boron-free C-Glass fiber is inferior to E-CR Glass and E-Glass, and these properties limit its use as a reinforcement. Further limiting the broad commercial use of C-Glass is the fact that it has lower hydrolytic resistance under high humidity environments at elevated temperatures. Starting in the mid-1960s, boron-free C-Glass fiber and E-Glass fiber products served the general industrial market. Because of their lower cost, boron-free C-Glass fiber products are still used in combination with E-Glass fibers in nonstructural corrosion barrier applications. However, boron-free C-Glass volume is
