Sharmin, Nusrat, Hasan, Muhammad S., Rudd, Chris D., Boyd, Daniel, Werner-Zwanziger, Ulrike, Ahmed, Ifty, and Parsons, Andrew J. (2017) Effect of boron oxide addition on the viscosity-temperature behaviour and structure of phosphate-based glasses. Journal of Biomedical Materials Research Part B: Applied Biomaterials, 105B (4). pp. 764-777.

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Abstract

In this study, nine phosphate-based glass formulations from the system P2O5-CaO-Na2O-MgO-B2O3 were prepared with P2O5 content fixed as 40, 45 and 50 mol%, where Na2O was replaced by 5 and 10 mol% B2O3 and MgO and CaO were fixed to 24 and 16 mol%, respectively. The effect of B2O3 addition on the viscosity-temperature behaviour, fragility index and structure of the glasses was investigated. The composition of the glasses was confirmed by ICP-AES. The viscosity-temperature behaviour of the glasses were measured using beam-bending and parallel -plate viscometers. The viscosity of the glasses investigated was found to shift to higher temperature with increasing B2O3 content. The kinetic fragility parameter, m and F-1/2, estimated from the viscosity curve were found to decease with increasing B2O3 content. The structural analysis was achieved by a combination of Fourier transform infrared spectroscopy and solid state nuclear magnetic resonance. P-31 solid-state magic-angle-spinning nuclear magnetic resonance (MAS-NMR) showed that the local structure of the glasses changes with increasing B2O3 content. As B2O3 was added to the glass systems, the phosphate connectivity increases as the as the Q(1) units transforms into Q(2) units. The B-11 NMR results confirmed the presence of tetrahedral boron (BO4) units for all the compositions investigated. Structural analysis indicates an increasing level of cross-linking with increasing B2O3 content. Evidence of the presence of P-O-B bonds was also observed from the FTIR and P-31 NMR analysis. (c) 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 764-777, 2017.

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