The effect of silica/polyurethane waterborne dispersion on the perforating features of impregnated polypropylene-based fabric

In an attempt to improve the puncturing behavior of a commercial technical textile, this study investigated the effects of fabric impregnation with waterborne polyurethane dispersions (WPUDs). The infusing solutions were prepared by mixing a commercially available WPUD with other components, such as water, hydrophilic and hydrophobic silica (SiO2) nanoparticles, and a crosslinker. Quasi-static perforation tests were performed on a dynamometer machine equipped with a spherical spike and pointed blade as piercing probes. The results showed that the polyurethane impregnation augmented the puncture performances of the treated textiles. Then, further improvements in the spike and blade strength of the impregnated fabrics were obtained by adding hydrophilic silica nanoparticles and crosslinker into WPUDs, respectively. No effect of silica functionalization (hydrophilic or hydrophobic) has been verified on the mechanical features of the respective treated samples for the tested filler contents of 3% and 5% in wt. The best fabric features (blade strength increase of +63% and puncture strength increase of +71% compared to the neat material) were obtained by combining the two additives, nano SiO2 and crosslinker, into the polyurethane. The performances of these last systems were also superior to those obtained by doubling the amount of polymeric dispersion applied to the neat materials. The discussion of the results was supported by electron scanning microscopy, infrared spectroscopy, and further measurements of the cutting resistance. Finally, the mass per unit area of the substrate for the impregnated samples was measured in order to assess weight gain due to treatment.