Recent developments in the application of electron accelerators for polymer processing

• The development of high current electron accelerators starting in the 1950s and their early commercial use is summarized.
• The down-sizing of mid and low-energy self-shielded electron beams facilitates process integration for proven and new uses.
• Surface decontamination of packing materials used in aseptic filling and curing of metal coil coatings are new applications.
• Powerful new accelerators (700 kW) make X-ray conversion an industrially viable alternative to isotope use for sterilization.
• Promising developments with natural polymers, nano-technology, fiber composites, nano-gels and grafting are noted.

There are now over 1700 high current, electron beam (EB) accelerators being used world-wide in industrial applications, most of which involve polymer processing. In contrast to the use of heat, which transfers only about 5–10% of input energy into energy useful for materials modification, radiation processing is very energy efficient, with 60% or more of the input energy to an accelerator being available for affecting materials. Historic markets, such as the crosslinking of wire and cable jacketing, of heat shrinkable tubings and films, of partial crosslinking of tire components and of low-energy EB to cure or dry inks and coatings remain strong. Accelerator manufacturers have made equipment more affordable by down-sizing units while maintaining high beam currents. Very powerful accelerators with 700 kW output have made X-ray conversion a practical alternative to the historic use of radioisotopes, mainly cobalt-60, for applications as medical device sterilization. New EB end-uses are emerging, such as the development of nano-composites and nano-gels and the use of EB processing to facilitate biofuel production. These present opportunities for future research and development.