Abstract: The present invention concerns glass fiber composition comprising the following oxides: SiO2: 57.5-59.5 wt. % Al2O3: 17.0-20.0 wt. % CaO: 11.0-13.5 wt. % MgO: 8.5-12.5 wt. % wherein the sum of Na2O, K2O, and TiO2 is at least 0.1 wt. % and Li2O?2.0 wt. %, all amounts being expressed in weight % with respect to the total weight of the composition. It also concerns composite materials reinforced with such fibers, used in applications such as wind mill blades, pressure vessels, components in the automotive, machinery, aerospace applications and such products produced therewith, and wherein the temperature difference, ?T, defined as the difference between the temperature, T3, at which the composition has a viscosity of 103 Poise and the liquidus temperature, Tliq, is at least 50° C.

Abstract: The present invention concerns glass fibre composition comprising the following oxides: Si02: 57.5-59.5 wt. % AI2O3: 17.0-20.0 wt. % CaO: 11.0-13.5 wt. % MgO: 8.5-12.5 wt. % wherein the sum of Na2O, K2O, and TiO2 is at least 0.1 wt. % and Li2O?2.0 wt. %, all amounts being expressed in weight % with respect to the total weight of the composition. It also concerns composite materials reinforced with such fibres, used in applications such as wind(a) mill blades, pressure vessels, components in the automotive, machinery, aerospace applications and such products produced therewith, and wherein the temperature difference, ?T, defined as the difference between the temperature, T3, at which the composition has a viscosity of 103 Poise and the liquidus temperature, Tliq, is at least 50° C.