isolant

Isolant refers to a material or component that impedes the passage of heat, electricity, sound, or vibration between two environments. In physics and engineering, an isolant is characterized by low thermal conductivity, high electrical resistance, or effective acoustic attenuation, depending on the intended application. The term is commonly used in French‑language technical literature, while in English the equivalents are “insulator” for thermal or electrical contexts and “sound‑absorbing material” for acoustic contexts.

Thermal isolants, such as mineral wool, expanded polystyrene, polyurethane foam, and aerogels, reduce heat transfer by conduction, convection, or radiation. They are employed in building envelopes, refrigeration, and industrial equipment to improve energy efficiency and maintain desired temperatures. Electrical isolants, including ceramics, glass, dry polymers, and certain composites, possess high dielectric strength and are used for wire coatings, circuit boards, and high‑voltage equipment to prevent current leakage and short circuits. Acoustic isolants, like acoustic foam, mass‑loaded vinyl, and resilient channels, attenuate sound transmission and are applied in studios, residential construction, and automotive interiors.

The performance of an isolant is quantified through parameters such as thermal conductivity (W·m⁻¹·K⁻¹), dielectric constant and breakdown voltage (V·m⁻¹), and sound transmission class (STC). Selection criteria consider operating temperature range, mechanical strength, moisture resistance, fire safety, and environmental impact. Many modern isolants are engineered to meet stringent standards (e.g., ISO 6946 for thermal resistance, IEC 60243 for electrical breakdown).

Manufacturing processes vary: fibrous materials are produced by spinning or blowing, foams are generated through polymerization and expansion, and composites are formed by layering or lamination. Recent research focuses on sustainable isolants derived from bio‑based feedstocks, recyclable polymers, and nanostructured aerogels, aiming to reduce carbon footprints while maintaining high performance.