Short answers, pulled from the story.
Polyethylene was first synthesized in 1898 by Hans von Pechmann, a German chemist, as an accidental byproduct while investigating diazomethane. His colleagues Eugen Bamberger and Friedrich Tschirner characterized the white, waxy substance and named it polymethylene. The first industrially practical synthesis was discovered accidentally in 1933 by Eric Fawcett and Reginald Gibson at ICI in Northwich, England.
During World War II, polyethylene was used to insulate UHF and SHF coaxial cables for radar sets. Its very low energy loss at high-frequency radio waves made it ideal for this purpose. Commercial distribution in Britain was suspended at the outbreak of the war and secrecy was imposed over the new production process.
The main types are high-density (HDPE), low-density (LDPE), linear low-density (LLDPE), ultra-high-molecular-weight (UHMWPE), cross-linked (PEX), medium-density (MDPE), and very-low-density (VLDPE) polyethylene. They differ primarily in density, degree of chain branching, and molecular weight, which determine properties such as tensile strength, flexibility, and crystallinity. HDPE has densities at or above 0.941 g/cm3 and is used in water pipes and rigid containers; LDPE has densities of 0.910 to 0.940 g/cm3 and is used in plastic bags and films.
Polyethylene's backbone consists entirely of carbon-carbon bonds, unlike polymers such as polyesters or polyamides that break down through hydrolysis or oxidation. This makes it degrade only very slowly under normal environmental conditions. Over 100 million tonnes are produced annually, creating substantial waste management challenges.
Robert Banks and J. Paul Hogan at Phillips Petroleum discovered a chromium trioxide-based catalyst in 1951 that enabled polymerization at mild temperatures and pressures, replacing costly high-pressure methods. Karl Ziegler developed a complementary system based on titanium halides and organoaluminium compounds in 1953. Both catalyst families became the industrial standard for high-density polyethylene production by the end of the 1950s.
Ultra-high-molecular-weight polyethylene has a molecular weight typically between 3.5 and 7.5 million atomic mass units, giving it exceptional toughness and resistance to cutting and wear. It is used for artificial hip and knee replacement implants, bearings, gears, edge protection on ice rinks, steel cable replacements on ships, and as fiber in bulletproof vests. It is produced using Ziegler-Natta and soluble catalysts.