ИСТИНА

In order to develop methods of controlling copolymer adhesion properties the effect of chemical bonds grid on the physicomechanical and energy characteristics of acrylic copolymers was investigated. The object of the study was a statistical copolymer of butyl acrylate (70%), vinyl acetate (25%) and acrylic acid (5%). The adhesive macromolecules were cross-linked by carboxyl groups of acrylic acid at room temperature. A polyisocyanate (Desmodur 3300) was used as a crosslinking agent. The concentration of polyisocyanate varied from 0.26 to 5 parts by mass. The density of spatial bonds grid was studied using ATR IR spectroscopy (Nicolet iN10) and DSC (Netzsch DSC 204 F1 Phoenix). The chemical grid density was monitored by the intensity of characteristic bands of 2274 (N=C=O) and 1689 cm–1 (C=O) of isocyanate IR spectra corresponding to asymmetric vibrations of named bonds. The energy characteristics of adhesive surface were determined by the static sessile drop method (EasyDrop). An elastic modulus and adhesion characteristics were investigated on a Zwick/Roell Z010 tensile testing machine. Adhesive properties were determined by peeling at an angle of 180º of adhesive applied to test surfaces made of polished steel and PET. It is shown that with increasing of isocyanate concentration, an increase in the density of the chemical bonds grid occurs, as evidenced by an increase in the tensile modulus and a character change of the stress-strain curve. It is established that the increase in the density of the grid leads to a decrease in the copolymer adhesive characteristics. The isocyanate concentration ranges that provide cohesive and adhesive peeling mechanisms were determined. Based on the glass transition temperatures of systems with various crosslinker contents, the macromolecular mass between the nodes of the spatial grid of chemical bonds was estimated and the concentration of polyisocyanate (0.19 parts by mass) was determined at which a chemical grid with a high conversion degree was formed.