Nonwoven needle-punched fabrics with nano-sized polyurethane reinforcing sheaths for construction application

Introduction. The purpose of the study is to investigate the influence of the impregnation degree of a non-woven needle-punched fabric with aqueous polyurethane dispersions of varying compositions on the formation of the porous structure of composite materials for construction applications. Materials and methods. The object of the study is a non-woven needle-punched fabric made of polyethylene terephthalate fibers (Technical Specifications TU 6-13-0204077-95-91) with a linear density of 0.33 tex (diameter 20-25 μm), impregnated with aqueous polyurethane dispersions of different compositions. The fibrous web was formed by mechanical means and strengthened with a primary needle-punching density of 180 cm–². The impregnation process employed aqueous dispersions of anionically stabilized polyurethane: the brand IMPRANIL DL 1380 (China), based on an aliphatic diisocyanate with a polymer concentration of 38±5%; and the brands Aquapol-11 and Aquapol-21, based on aromatic diisocyanates, produced by LLC “NPP ‘Makromer’ named after V.S. Lebedev”, Vladimir, with a polyurethane concentration of 40±2%. Results and discussion. The influence of the aqueous polyurethane dispersions on their distribution pattern on the fibers during impregnation was determined. Materials with an optimal porous structure were obtained, which governs the heat and mass transfer processes while maintaining the required physic-mechanical properties. Conclusion. At an impregnation degree of less than 0.1 or a porosity coefficient of 0.8, fragmentary structures of the IMPRANIL DL 1380 polyurethane form on the fiber surfaces. This results in strong composite materials whose air permeability is practically the same as that of the original non-woven fabric. The development of such materials is of interest for thermal and sound insulation in building structures. When using Aquapol-11 and Aquapol-21 dispersions for impregnation, the polyurethane binder almost completely fills the space between the fibers. This leads to a decrease in the overall porosity of the composite, making it promising for use as a waterproofing material in road construction.