[en] The interaction of ionizing radiation with organic substrates to produce useful physical and chemical changes is the basis of the radiation processing industry for plastics. Electron beam (EB) accelerators dominate the industry; however, there are a few small applications that use gamma radiation. The five general product categories that account for over 95% of the worldwide EB capacity used for plastics production are the following: wire and cable insulation; heat-shrinkable film, tubes and pipes; radiation-curable coatings; rubber products; and polyolefin foam. A total of 6.1% of the yearly production of these products in the United States is EB treated. The United States accounts for 59% of the total worldwide EB capacity of 20.5 MW (1984), followed by Europe (16%) and Japan (15%). There are 469 to 479 individual EB units worldwide used for the production of plastics and rubber. The average annual rate of growth (AARG) for the EB processing of plastics in Japan, from 1977 to 1987, was 13.3%. The AARG for Japan has decreased from 20% for 1977 to 198, to 6.4% for 1984 to 1987. Radiation cross-linking, of power cable insulation (cable rating ≥75 kV), thick polyolefin and rubber sheet (≥15 mm), and thick-walled tubing is one fo the potential applications for a 5- to 10-MeV EB system. Other products such as coatings, films and wire insulation may be economically EB-treated using a 5 to 10 MeV accelerator, if several layers of the product could be irradiated simultaneously. Two general product categories that require more study to determine the potential of high-energy EB processing are moulded plastics and composite materials. 32 refs

[en] Radiation polymerization has helped us understand polymer chemistry, and is also playing an increasing role in the field of practical applications. Radiation curing has a present market share of about 5% of the total market for curing of polymers and composites and the annual growth rate of the radiation curing market is ≥20% per year. Advantages of radiation curing over thermal or chemical curing methods include: improved control of the curing rate, reduced curing times, curing at ambient temperatures, curing without the need for chemical initiators, and complete (100%) curing with minimal toxic chemical emissions. Radiation treatment may also be used to effect crosslinking and grafting of polymer and composite materials. The major advantage in these cases is the ability to process products in their final shape. Cable insulation, automotive and aircraft components, and improved construction materials are some of the current and near-future industrial applications of radiation curing and crosslinking. 19 refs

[en] A potential application of electron-beam processing in composite manufacturing is curing carbon-fibre prepregs. These thermally curable prepregs, carbon fibres or fabrics preimpregnated with liquid polymer resin, are commonly used in the aircraft industry. A radiation-property specifications of a leading aircraft manufacturing company. Characterization studies showed that the maximum gel fraction in the cured polymer occurred at a dose of about 50 kGy and varied from 91 to 97%, depending on the type of atmosphere (air or nitrogen) and the pressure (100 to 1000 kPa) during irradiation. Only the acrylate groups of the resin took a significant part in the curing reactions. Some carbon dioxide was produced during radiation curing. The polymer was amorphous with a softening point of about 235 degrees Celsius and a linear thermal expansion coefficient of 1.3 x 10^-4 m/(m·degrees Celsius) between 25 and 150 degrees Celsius (30 to 50 kGy). Preliminary mechanical and physical testing of the prepreg composites has also been started

[en] Since its incorporation in 1998, Acsion Industries Inc. has been working with clients to develop industrial uses of electron processing for improving products and manufacturing processes. Acsion has promoted this technology for sterilizing medical devices and pharmaceuticals, for treating wood pulp in the viscose/rayon process, for reducing pathogens in food and animal feed, and for curing advanced composites for the aerospace industry. As a result of significant developments in its composite curing programs, Acsion has recently made major modifications to its facility to increase its production and R and D capabilities. These modifications are described in this paper

[en] Advanced composites, specifically carbon fiber reinforced epoxies, are being used for a variety of demanding structural applications, primarily because of their high strength-to-weight and stiffness-to-weight ratios, corrosion resistance, and damage tolerance characteristics. For these composites the key advantages of using electron beam (EB), rather than thermal curing, are curing at ambient temperature, reduced curing times for individual components, improved resin stability, fewer volatiles, and better control of the profile of energy absorption. Epoxy compounds do, however, have to be modified to make them EB curable. The electron beam penetration limit, a function of beam energy, product density, and the thickness of any container required, must also be examined when considering EB processing. Research is being conducted to develop EB-curable carbon fiber-acrylated epoxy composites. The tensile properties of these laminates are comparable to those of thermally cured epoxy laminates. Research is continuing to develop suitable resin formulations and coupling agents to optimize the mechanical properties of EB-cured carbon fiber laminates. In this chapter the EB curing of epoxies, processing considerations, and typical properties of EB-cured carbon fiber-acrylated epoxy laminates are discussed. (orig.)

[en] Electron curing of fiber-reinforced composites to produce materials with good mechanical properties has been demonstrated by the authors' work, and by Aerospatiale. The attractions of this technology are the technical and processing advantages offered over thermal curing, and the projected cost benefits. Though the work so far has focused on the higher value composites for the aircraft and aerospace industries, the technology can also be used to produce composites for the higher volume industries, such as transportation and automotive

No abstract available

[en] The use of advanced composites made with carbon-, glass-, aramid-, or polyethylene fibres and epoxy- or acrylated resins is becoming increasingly prevalent within the aerospace sector. The advantages these materials offer compared to metal are making them suitable alternatives not only for secondary components but also for primary structural components on aircraft. Composites are presently cured in autoclaves using heat and pressure. Electron processing offers several advantages over thermal curing and has been investigated by Acsion personnel for over a decade. This paper discusses the latest developments at Acsion on using electron curing to manufacture components for the next generation of aerospace vehicles and to repair damaged structures on aircraft. (author)

[en] Electron beam (EB) processing involves using electrons to initiate polymerization or cross-linking reactions in suitable substrates, thereby enhancing specific physical and chemical properties. A relatively new use of EB processing is now emerging: the production of fibre-reinforced composites. EB curing at ambient temperature has the potential to reduce the residual stresses in an advanced composite, a result of expansion during thermal curing, and to significantly increase the overall cure speed and process throughput. Wood fibres are used as a filler material for various thermoplastics such as polypropylene. EB treatment, combined with selected EB-curable coupling agents, significantly increases the adhesion between the wood fibres and the thermoplastic polymer, resulting in improved material properties. Work to develop both products and processes for the EB curing of fibre-reinforced composites is currently underway at AECL Research. This paper briefly updates these developments

[en] Radiation processing is the utilization of ionizing radiation, usually photons or electron beams, to produce useful physical and chemical changes in a material. A potential application for electron beam processing for composite manufacturing is for curing carbon fibre prepregs. These prepregs, carbon fibres or fabrics preimpregnated with liquid polymer resin, are commonly used in many industries, including aircraft and aerospace, automotive, electronics, construction and various commercial products. The objective of this experimental program is to design and manufacture a radiation-curable polymer-carbon fibre prepreg that meets the typical mechanical and physical property specifications set by the aircraft industry. This paper describes our current work in the design, manufacture and characterization of radiation-curable prepregs