Polyimide film developed by DuPont in the late 1960s that remains stable across a wide range of temperatures, from −269 to +400 °C (−452 to 752 °F; 4–673 K).[ Polyimide Tape Is used in, among other things, flexible printed circuits (flexible electronics) and thermal blankets used on spacecraft, satellites, and various space instruments. The chemical name for polyimide tape is poly (4,4′-oxydiphenylene-pyromellitimide). It is produced from the condensation of pyromellitic dianhydride and 4,4′-oxydiphenylamine. Polyimide tape synthesis is an example of the use of a dianhydride in step polymerization. The intermediate polymer, known as a “poly(amic acid)”, is soluble because of strong hydrogen bonds to the polar solvents usually employed in the reaction. The ring closure is carried out at high temperatures (200–300 °C, 473–573 K). polyimide film is a tough, aromatic polyimide film, exhibiting an excellent balance of physical, chemical, and electrical properties over a wide temperature range, particularly at unusually high temperatures. The thermal durability of polyimide film depends on the environmental conditions under which it is aged and tested. Polyimide is also commonly used as a material for windows of all kinds at X-ray sources (synchrotron beam-lines and X-ray tubes) and X-ray detectors. Its high mechanical and thermal stability and high transmittance to X-rays make it the preferred material. It is also relatively insensitive to radiation damage.