INVESTIGATION OF THE ORIGIN AND ACCUMULATION OF INTERNAL STRESSES IN POLYMER AND PAINT COATINGS BASED ON EPOXY RESINS AND POLYESTER VARNISHES
Keywords:
Internal stresses; Epoxy resins; Polyester coatings; Molecular weight; Crosslink density; Polymer coatings; Relaxation processes; Adhesion properties.Abstract
Internal stresses in polymer and paint coatings significantly affect their mechanical, adhesion, and durability properties. This study investigates the mechanisms of stress formation and accumulation in epoxy resin–based and polyester coatings. The origin of internal stresses is attributed to delayed relaxation processes caused by uneven curing rates, temperature and moisture gradients, and interactions between polymers and substrates or fillers. Experimental results show that heating above the glass transition temperature (up to 80 °C) reduces internal stresses to 0.1–0.5 MPa. Furthermore, molecular weight plays a decisive role: with increasing molecular mass of epoxy resins, internal stresses decrease due to improved flexibility and reduced crosslink density
