Effect of boron oxide addition on fibre drawing, mechanical properties and dissolution behaviour of phosphate-based glass fibres with fixed 40, 45 and 50 mol% P(2)O(5)

Previous studies investigating manufacture of phosphate-based glass fibres from glasses fixed with P(2)O(5) content less than 50 mol% showed that continuous manufacture without breakage was very difficult. In this study, nine phosphate-based glass formulations from the system P(2)O(5)-CaO-Na(2)O-MgO-B(2)O(3) were prepared with P(2)O(5) contents fixed at 40, 45 and 50 mol%, where Na(2)O was replaced by 5 and 10 mol% B(2)O(3) and MgO and CaO were fixed to 24 and 16 mol%, respectively. The effect of B(2)O(3) addition on the fibre drawing, fibre mechanical properties and dissolution behaviour was investigated. It was found that addition of 5 and 10 mol% B(2)O(3) enabled successful drawing of continuous fibres from glasses with phosphate (P(2)O(5)) contents fixed at 40, 45 and 50 mol%. The mechanical properties of the fibres were found to significantly increase with increasing B(2)O(3) content. The highest tensile strength (1200 ± 130 MPa) was recorded for 45P(2)O(5)-16CaO-5Na(2)O-24MgO-10B(2)O(3) glass fibres. The fibres were annealed, and a comparison of the mechanical properties and mode of degradation of annealed and non-annealed fibres were investigated. A decrease in tensile strength and an increase in tensile modulus were observed for the annealed fibres. An assessment of the change in mechanical properties of both the annealed and non-annealed fibres was performed in phosphate-buffered saline (PBS) at 37℃ for 28 and 60 days, respectively. Initial loss of mechanical properties due to annealing was found to be recovered with degradation. The B(2)O(3)-containing glass fibres were found to degrade at a much slower rate as compared to the non-B(2)O(3)-containing fibres. Both annealed and non-annealed fibres exhibited a peeling effect of the fibre's outer layer during degradation.