Material modification

Radiation technology can be used to modify various materials. This brings about certain changes in their properties, many of which can be used in a wide variety of commercial applications.

Various radiation sources are used to modify materials, such as high-intensity radioisotope sources, electron accelerators of various energies, and X-rays derived from them. Radiation is also used for the grafting and partial modification of materials.

The main commercial application of the technology is the crosslinking of polymer chains, used for instance in producing wire and cable insulations, car tires or natural rubber latex for medical items, such as gloves. This room temperature method is able to crosslink finished products, achieves superior material properties and helps eliminate toxic chemical residues. 

Other worldwide commercial applications are heat shrinkable tubing, food wraps and self-regulating heaters. Crosslinked water-soluble polymers, also known as hydrogels, are commercialized for wound dressing, specifically for burn wounds and diabetic ulcers. Emerging applications of hydrogels include superabsorbents for health care and agricultural applications, wastewater purification and enzyme immobilization. 

The controlled degradation of polymers through radiation, also called chain scission, is used to improve the properties as well as the compatibility and processing parameters of both natural and synthetic polymers. The largest commercial application of this technology is the degradation of polytetrafluoro-ethylene (PTFE) by irradiation in the air, which results in a lower molecular-weight micropowder with improved compatibility with other materials that thencan be used as an additive to inks and coatings. 

Radiation grafting is used when different bulk and surface properties of a material are needed.  Commercial products include battery separators; grafted fibres with  enhanced dyeability; adsorption and concentration of valuable ions; removal of toxic ions and purification and filtration; products with biocompatible and non-fouling surfaces; and cell-culture surfaces for cell sheet engineering.

Another use of the radiation technique is “surface patterning,” by which only certain parts of the surface or a material are modified, either by induced crosslinking, chain scission or grafting. Commercial applications of such processes are the X-ray, electron beam and ion-beam lithography applied to the microelectronic circuits of computer chips.

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