Capillary effect of layers of rubber-fabric composite

Abstract

Rubber-fabric composites are a representative of a class of anisotropic reinforced composite laminates designed for operation in contact with a liquid medium. Each layer of the composite performs a specific function in the operation of printing machines. The rubber layer is located on the surface of the material and is impervious to hydrophilic liquids, but can swell to a limited extent in organic solvents. Layers of fabrics provide structural integrity and tension of the layered composite material and are protected from the penetration of the liquid medium by layers of rubber in a plane perpendicular to the arrangement of the layers. In a plane parallel to the arrangement of layers, the fabric is permeable to aqueous solutions and organic solvents. Permeability is based on the capillary effect of absorption. To eliminate the anisotropy of the permeability of reinforced composite layered materials, it is proposed to apply additional layers on the end surface that block the access of liquid to the capillary space through the pores, gaps between the threads and fibers of the fabric layers. An additional layer is applied by brushing or dipping into solutions of suspensions and emulsions of film-forming polymers: polyvinyl alcohol, polytetrafluoroethylene and acrylic polyester. The article describes an experimental technique for estimating porosity and calculating the average radius of capillaries using a physical model of the porous structure of the composite. The capillary pressure leading to absorption is described by Laplace's law. The laboratory stand is a modernized Klemm-Winkler device. The penetration of liquids into the porous structure of a composite rubber-fabric material through the end surface was measured. The sizes of pores in the structure of the composite, their number, volume, and the rate of filling of pores with water through the end surface in samples of anisotropic reinforced composite layered materials used in printing were calculated. A decrease in water permeability through protective layers on the end surface is shown depending on the chemical and phase composition of film-forming polymers. Diagrams of permeability, absorption kinetics and tables of porosity parameters of the rubber-fabric composite are compared. The proportions of capillaries of different diameters and their distribution over the cross-sectional area were determined.