adhesiivi

Adhesive, known in Finnish as adhesiivi, is a substance used to join two surfaces by creating adhesion and cohesion. Most adhesives are viscous liquids or pastes that cure to form a solid bond. They rely on chemical or physical mechanisms to attach materials, and their performance depends on surface conditions, material composition, and environmental factors.

Common types of adhesives include natural and synthetic varieties. Natural adhesives originate from plant or animal sources, such as starch-based pastes or casein. Synthetic adhesives cover a broad range, including epoxies, polyurethanes, cyanoacrylates, acrylics, silicones, hot-melt adhesives, and UV-curable formulations. Each type has distinct properties in terms of strength, flexibility, curing speed, temperature resistance, and environmental durability.

Bonding mechanisms of adhesives typically involve wetting the surface to maximize contact, chemical bonding to the substrate, mechanical interlocking, or diffusion of adhesive components into porous materials. Curing methods vary: some rely on solvent evaporation, others on moisture or heat, and some on exposure to light or on two-part chemical reactions.

Applications of adhesives span construction, woodworking, packaging, electronics, automotive manufacturing, and medical fields. Medical and dental adhesives, for example, are formulated for biocompatibility and controlled cure. Selection considerations include open time, shear and peel strength, temperature and chemical resistance, viscosity, and substrate compatibility, as well as safety, handling, and environmental impact.

Standards and testing for adhesives cover adhesion strength, durability, and reliability, evaluated through methods such as peel, lap shear, and tack tests. Environmental and occupational safety concerns focus on volatile organic compounds, skin and eye irritation, flammability, and proper disposal.