Degradation properties and microstructural analysis of 40P _2O_5-24MgO-16CaO-16Na_2O-_4Fe2O _3 phosphate glass fibres

摘要

The paper describes the physical, chemical, mechanical and thermal properties of 40P_2O_5-24MgO-16CaO-16Na_2O- 4Fe_2O_3 phosphate glass fibres. The initial mechanical properties of the fibres were determined to examine changes of these properties over time and also due to the variation of fibre diameter. A theoretical chain length of the fibres is calculated and that was validated using high resolution X-ray photoelectron spectroscopy (XPS) analysis. These fibres were degraded for 12 weeks in deionised water with pH adjusted to ~ 7.4 at 37 C. Mass loss percentage, change of pH, degradation rate and the mechanical properties of the degraded fibres were determined. An XPS analysis of the 12 week degraded fibre was conducted without etching and after 40 min etching from the degraded surface. The elemental percentages of fibres degraded for different time periods were determined using energy dispersive X-ray (EDX) analysis. Scanning electron microscopy (SEM) analysis of the non-degraded and degraded fibres was also presented in order to assess changes in the fibre surface during degradation. The evolving surface of these water-soluble fibres was further characterised by Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The works completely elucidated the chemical nature and degradation pattern of the bulk fibre surface of this glass composition.