Kapton
Encyclopedia
Polyimide
Polyimide is a polymer of imide monomers. The structure of imide is as shown. Polyimides have been in mass production since 1955...
film developed by DuPont
DuPont
E. I. du Pont de Nemours and Company , commonly referred to as DuPont, is an American chemical company that was founded in July 1802 as a gunpowder mill by Eleuthère Irénée du Pont. DuPont was the world's third largest chemical company based on market capitalization and ninth based on revenue in 2009...
which can remain stable in a wide range of temperatures, from -273 to +400 °C (-459 - 752 °F / 0 – 673 K). Kapton is used in, among other things, flexible printed circuits (flexible electronics
Flexible electronics
Flexible electronics, also known as flex circuits, is a technology for assembling electronic circuits by mounting electronic devices on flexible plastic substrates, such as polyimide, PEEK or transparent conductive polyester film. Additionally, flex circuits can be screen printed silver circuits on...
) and thermal micrometeoroid garment
Thermal Micrometeoroid Garment
An Thermal Micrometeoroid Garment is the outer layer of a space suit. The TMG has three functions: to insulate the suit occupant and prevent heat loss, to shield the occupant from harmful solar radiation, and to protect the astronaut from micrometeoroids and other orbital debris, which could...
s, the outside layer of space suit
Space suit
A space suit is a garment worn to keep an astronaut alive in the harsh environment of outer space. Space suits are often worn inside spacecraft as a safety precaution in case of loss of cabin pressure, and are necessary for extra-vehicular activity , work done outside spacecraft...
s.
The chemical name for Kapton K and HN is poly(4,4'-oxydiphenylene-pyromellitimide). It is produced from the condensation of pyromellitic dianhydride and 4,4'-oxydiphenylamine
4,4'-Oxydianiline
4,4’-Oxydianiline is an organic compound with the formula O2. It is an ether derivative of aniline. This colourless solid is a useful monomer and cross-linking agent for polymers, especially the polyimides, such as Kapton.- Uses :...
. Kapton 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 bond
Hydrogen bond
A hydrogen bond is the attractive interaction of a hydrogen atom with an electronegative atom, such as nitrogen, oxygen or fluorine, that comes from another molecule or chemical group. The hydrogen must be covalently bonded to another electronegative atom to create the bond...
s to the polar solvents usually employed in the reaction. The ring closure is carried out at high temperatures (200–300 °C, 473-573 K).
Usage
The thermal conductivity of Kapton in temperatures from 0.5 to 5 kelvin is rather high κ = 4.638×10−3 T0.5678 W·m−1·K−1.This, together with its good dielectric qualities and its availability as thin sheets have made it a favorite material in cryogenics
Cryogenics
In physics, cryogenics is the study of the production of very low temperature and the behavior of materials at those temperatures. A person who studies elements under extremely cold temperature is called a cryogenicist. Rather than the relative temperature scales of Celsius and Fahrenheit,...
. Kapton is regularly used as an insulator in ultra-high vacuum environments due to its low outgassing
Outgassing
Outgassing is the release of a gas that was dissolved, trapped, frozen or absorbed in some material. As an example, research has shown how the concentration of carbon dioxide in the Earth's atmosphere has sometimes been linked to ocean outgassing...
rate.
Aircraft
Kapton-insulated electrical wiring has been widely used in civil and military aircraft because it is lighter than other insulators, and has good insulating and temperature characteristics. For these reasons, it is the material of which the sunshield of the James Webb Space TelescopeJames Webb Space Telescope
The James Webb Space Telescope , previously known as Next Generation Space Telescope , is a planned next-generation space telescope, optimized for observations in the infrared. The main technical features are a large and very cold 6.5 meter diameter mirror, an observing position far from Earth,...
will be made. It was found to have very poor resistance to mechanical wear, mainly abrasion within cable harnesses due to aircraft movement. Many aircraft models have had to undergo extensive rewiring modifications, sometimes completely replacing all the Kapton-insulated wiring, because of short circuits caused by the faulty insulation.
Spacecraft
Kapton was used extensively in the Apollo program. It was used as thermal insulation on the Lunar Module. During the return journey from the Moon, Apollo 11Apollo 11
In early 1969, Bill Anders accepted a job with the National Space Council effective in August 1969 and announced his retirement as an astronaut. At that point Ken Mattingly was moved from the support crew into parallel training with Anders as backup Command Module Pilot in case Apollo 11 was...
astronaut Neil Armstrong
Neil Armstrong
Neil Alden Armstrong is an American former astronaut, test pilot, aerospace engineer, university professor, United States Naval Aviator, and the first person to set foot upon the Moon....
commented that during the launch of the Lunar Module Ascent Stage, he could see "Kapton and other parts on the LM staging scattering all around the area for great distances."
According to a NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
internal report, space shuttle
Space Shuttle program
NASA's Space Shuttle program, officially called Space Transportation System , was the United States government's manned launch vehicle program from 1981 to 2011...
"wires were coated with an insulator known as Kapton that tended to break down over time, causing short circuits and, potentially, fires." The NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
Jet Propulsion Laboratory
Jet Propulsion Laboratory
Jet Propulsion Laboratory is a federally funded research and development center and NASA field center located in the San Gabriel Valley area of Los Angeles County, California, United States. The facility is headquartered in the city of Pasadena on the border of La Cañada Flintridge and Pasadena...
has considered Kapton as a good plastic support for solar sail
Solar sail
Solar sails are a form of spacecraft propulsion using the radiation pressure of light from a star or laser to push enormous ultra-thin mirrors to high speeds....
s because of its long duration in the space environment.
X-ray
Kapton is also commonly used as a material for windows of all kinds at X-rayX-ray
X-radiation is a form of electromagnetic radiation. X-rays have a wavelength in the range of 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays and longer than gamma...
sources (synchrotron
Synchrotron
A synchrotron is a particular type of cyclic particle accelerator in which the magnetic field and the electric field are carefully synchronised with the travelling particle beam. The proton synchrotron was originally conceived by Sir Marcus Oliphant...
beam-lines and X-ray tube
X-ray tube
An X-ray tube is a vacuum tube that produces X-rays. They are used in X-ray machines. X-rays are part of the electromagnetic spectrum, an ionizing radiation with wavelengths shorter than ultraviolet light...
s) and X-ray detectors. Its high mechanical and thermal stability as well as its high transmittance to X-rays make it the preferred material. It is also relatively insensitive to radiation
Radiation
In physics, radiation is a process in which energetic particles or energetic waves travel through a medium or space. There are two distinct types of radiation; ionizing and non-ionizing...
damage. Another prominent material for these purposes is beryllium
Beryllium
Beryllium is the chemical element with the symbol Be and atomic number 4. It is a divalent element which occurs naturally only in combination with other elements in minerals. Notable gemstones which contain beryllium include beryl and chrysoberyl...
.