Copolene is a dielectric copolymer made from polystyrene and polyisobutylene, once widely used in coaxial cable insulation as a more flexible alternative to pure polystyrene.
Copolene was developed to overcome the brittleness and rigidity of early polystyrene insulation used in electrical and communication cables. By combining polystyrene with polyisobutylene, manufacturers created a material with greater flexibility, improved handling characteristics, and moderate resistance to mechanical stress and moisture absorption. This blend made copolene a practical dielectric for coaxial cable designs during the mid-20th century, where maintaining stable impedance and low signal loss was essential.
As a dielectric material, copolene served as the insulating layer between the central conductor and the shield in coaxial cables, directly influencing signal clarity and attenuation. However, its performance was eventually outclassed by newer materials such as polyethylene (PE), which offered superior electrical insulation, thermal stability, and long-term durability. PE’s low dielectric constant and high moisture resistance made it the preferred choice for both analog and digital communication systems, leading to copolene’s gradual obsolescence.
Today, references to copolene primarily appear in legacy documentation or maintenance contexts involving older coaxial installations. Understanding its role in historical cable construction helps engineers identify and evaluate older systems still in operation in industrial or AV environments.
Dielectric and insulation materials like copolene are subject to testing and certification under UL (Underwriters Laboratories), ASTM (American Society for Testing and Materials), and IEEE (Institute of Electrical and Electronics Engineers) standards. These organizations define criteria for dielectric strength, flammability, and material performance in electrical and communication cables.
Developed in the mid-20th century, copolene emerged as part of the industry’s effort to replace rigid insulations such as polystyrene with more flexible compounds. It represented an important step toward modern polymer innovation but was soon replaced by polyethylene (PE) and fluoropolymers, which delivered superior dielectric and environmental performance. While no longer used in modern cable manufacturing, copolene played a transitional role in advancing cable insulation technology.