Surface Modification of Polypropylene Yarns with SiO2 Sol-Gel: A Novel Approach to Enhance Thermal and Hydrophilic Properties for Depth Filter Applications

Today, the use of polypropylene surface modification to increase thermal and mechanical properties has attracted much attention. Many methods have been proposed to improve surface filters, but these techniques are not typically suitable for depth filters. In this study, polypropylene yarns were improved by the SiO2 sol-gel process before being wrapped around the filter core, offering a novel approach for improving depth filter performance. First, the composition of the coated layer was assessed through FTIR-ATR analysis, revealing the presence of Si-O bonds formed on the yarns. Then the surface structure of the coated yarns was scanned using a scanning electron microscope. The thermal properties of coated yarns were examined in different ways, including differential scanning calorimetry. Mechanical properties, water adsorption, and porosity were also studied. The results showed that the yarns were properly modified by the method, especially in terms of temperature resistance. Water adsorption tests showed an approximately 195% increase in hydrophilicity over the untreated sample. Additionally, the coating had not affected yarn porosity and spacing, maintaining the overall structural integrity. Furthermore, the unchanged permeability indicates a lack of adhesion of the yarns by the coating. Generally, the novel and straightforward modification method significantly improved polypropylene yarns thermally and hydrophilicity, presenting a promising strategy for depth filter media applications.