Epoksivaigud

Epoksivaigud, or epoxy resins, are a class of reactive prepolymers and polymers containing epoxide (glycidyl) groups. They are typically produced by reacting epichlorohydrin with bisphenol A or related phenols to form glycidyl ethers, such as diglycidyl ether of bisphenol A (DGEBA). On curing, they form dense, crosslinked thermosets through reactions with curing agents.

Most epoxy systems are two-component: a resin and a hardener, though one-component systems exist that cure upon heating. Common hardeners include amines, anhydrides, and amine-adducts; catalysts or accelerators may adjust cure rate. Epoxies can be formulated with various modifiers to tailor properties, producing low- or high-functionality resins such as novolac types for higher crosslink density.

Key properties include strong adhesion to a wide range of substrates (metal, wood, concrete), good chemical and moisture resistance, excellent mechanical strength, and good electrical insulation. Thermal stability and toughness depend on formulation; epoxies can be brittle unless impact modifiers or elastomers are added. They typically cure to rigid, heat-resistant networks, with properties strongly influenced by cure conditions and resin–hardener combination.

Applications are diverse: protective coatings and floor coatings, structural and surface adhesives, laminates and fiber-reinforced polymer matrices, encapsulation and potting for electronics, and automotive or aerospace bonding and composites.

Safety and environment: epoxy resins and curing agents can be skin sensitizers; handling requires protective equipment and good ventilation. Cured epoxy is less hazardous than uncured resin, but waste disposal and recycling of crosslinked materials remain challenging. Some formulations may involve BPA-related resins, guiding regulatory and labeling considerations.