Effect of waterborne polyurethane on mechanical properties of impregnated fabrics

In this work, impregnation with polyurethane waterborne dispersion (WPUD) was used for improving the mechanical resistance of commercial woven fabrics. Three different textiles, constituted by natural (100% linen and 100% cotton) or synthetic fibers (100% polypropylene) have been taken into account. The addition of nanosilica particles as well as of crosslinking agent in WPUD, has been also considered in order to obtain further mechanical reinforcing effects in investigated coatings. Different conditions, for optimizing the drying process in function of desired properties, have been compared. The mechanical performance of treated fabrics were evaluated in terms of perforation tests, performed on dynamometer, equipped with a blade or spike. Preliminary results confirmed an influence of polyurethane impregnation on puncture resistance of treated fabrics: in details, if an increase of spike-puncture strength was always displayed, contemporary a worsening of blade-puncture strength was shown, especially in the case of natural fabrics. Yet, the addition of nano-sized silica as well as of crosslinker gave beneficial effect on mechanical features of WPUD coated materials. In fact, these additives provided a further increase in spike punching resistance in the case of polypropylene, and certainly, a recovery in mechanical behavior of coated materials against blades.