title: Effect of boron oxide addition on the viscosity-temperature behaviour and structure of phosphate-based glasses.
abstract: In this study, nine phosphate-based glass formulations from the system P2O5-CaO-Na2O-MgO-B2O3were prepared with P2O5content fixed as 40, 45 and 50 mol%, where Na2O was replaced by 5 and 10 mol% B2O3and MgO and CaO were fixed to 24 and 16 mol%, respectively. The effect of B2O3addition 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 B2O3content. The kinetic fragility parameter, m and F1/2, estimated from the viscosity curve were found to decease with increasing B2O3content. The structural analysis was achieved by a combination of Fourier transform infrared spectroscopy and solid state nuclear magnetic resonance.31P solid-state magic-angle-spinning nuclear magnetic resonance (MAS-NMR) showed that the local structure of the glasses changes with increasing B2O3content. As B2O3was added to the glass systems, the phosphate connectivity increases as the as the Q1units transforms into Q2units. The11B 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 B2O3content. Evidence of the presence of P-O-B bonds was also observed from the FTIR and31P NMR analysis. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 764-777, 2017.
authors.affiliation: Division of Materials, Mechanics and Structures, Faculty of Engineering, University of Nottingham, Nottingham NG7 2RD, United Kingdom.
authors.forename: Nusrat
authors.initials: N
authors.lastname: Sharmin
authors.affiliation: Purac Biomaterials, 5150 N Royal Atlanta DR., Tucker, Georgia, 30084.
authors.forename: Muhammad S
authors.initials: MS
authors.lastname: Hasan
authors.affiliation: Division of Materials, Mechanics and Structures, Faculty of Engineering, University of Nottingham, Nottingham NG7 2RD, United Kingdom.
authors.forename: Chris D
authors.initials: CD
authors.lastname: Rudd
authors.affiliation: Department of Applied Oral Sciences, Faculty of Dentistry, Dalhousie University, Halifax, Nova Scotia, B3H 4R2, Canada.
authors.forename: Daniel
authors.initials: D
authors.lastname: Boyd
authors.affiliation: Department of Chemistry, Dalhousie University, Halifax, Nova Scotia, B3H 4J3, Canada.
authors.forename: Ulrike
authors.initials: U
authors.lastname: Werner-Zwanziger
authors.affiliation: Division of Materials, Mechanics and Structures, Faculty of Engineering, University of Nottingham, Nottingham NG7 2RD, United Kingdom.
authors.forename: Ifty
authors.initials: I
authors.lastname: Ahmed
authors.affiliation: Division of Materials, Mechanics and Structures, Faculty of Engineering, University of Nottingham, Nottingham NG7 2RD, United Kingdom.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Parsons
mesh_terms: D001896:Boron Compounds / Q000737:chemistry*; D002516:Ceramics / Q000138:chemical synthesis* / Q000737:chemistry*; D006358:Hot Temperature; D010710:Phosphates / Q000737:chemistry*; D014783:Viscosity
chemical_list: C022107:Bioglass; D001896:Boron Compounds; D010710:Phosphates; C042168:boron oxide
keywords: FTIR; MAS-NMR; fragility; phosphate-based glass; viscosity