Incumbent E-glass compositions, which are used for the manufacture of reinforcing fibres for structural composites (eg in automotive applications) and for electronic laminates, contain 6-8% B2O3 and 0.1-1.0% fluorine. B2O3 and fluorine can cause hazardous particulate and toxic vapour emissions during manufacture. New, environmentally friendly E-glass compositions, which are beginning to replace these compositions in structural applications are fluorine-free and contain either no B2O3, or only small amounts of B2O3. This paper deals with the design of ternary, boron-and fluorine-free fiberglass compositions which have the lowest possible log3 fibre forming temperature in the ternary SiO2-Al2O3-CaO system, would be suitable for use in a continuous commercial melt and fibre forming process and would require the lowest possible process energy.
