Effect of the chemical composition on the structural and mechanical properties of phosphate glass fibers based on natural phosphate

New phosphate glass fibers based on natural phosphate and different minerals can be used as formulations of slow-release fertilizers. These fibers were successfully developed by melting the phosphate glass and stretch it into thin fibers by monofilament extruded machine. The chemical analysis carried out by XRF shows that these fibers belong to a complex system. The structural change with the addition of increased percentages of each mineral was studied by XRD, density measurement, FTIR and Raman. The results indicate the depolymerization of the ultraphosphate groups (Q3) and the formation of the entities Q2 and Q1 of polyphosphate groups confirming the crosslinking of phosphate chains with the substitution of part of the P–O–P bonds by more covalent P–O-M bonds. Mechanical results show an increase of tensile strength and Young's modulus with increasing mineral concentrations. The evaluation of the global effect of fibers composition on the evolution of mechanical properties was performed by the PCA statistical analysis. The results suggest the choice of oxides that have a significant effect on improving mechanical performance, which differ according to the composition of the fibers investigated.