Electron beam curing with glycerol methacrylate

Glycerol methacrylate and hydroxyethyl methacrylate in combination with glycerol dimethacrylate as crosslinker were applied with electron beam irradiation to consolidate the color painting of the terracotta army of the first Chinese Emperor Qin Shihuangdi. The described mixture allowed reducing the necessary irradiation dose for consolidation to 40 kGy. The formation of glossy spots could be suppressed. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6660–6663, 2008     

Electron beam curing of methacrylated gelatin studied by EPR and FT-Raman spectroscopy

Gelatin was modified with glycidyl methacrylate. The methacrylated gelatins were cross-linked by electron irradiation. The cross-linking process was studied by FT-Raman and EPR spectroscopy.     

Electron beam curing — taking good ideas to the manufacturing floor

Acsion is exploiting several emerging electron beam EB applications ranging from composite curing and repair to viscose manufacturing. EB curing of composite structures offers several advantages: significantly reduced curing times; improvements in part quality and performance; reduced environmental and health concerns; improvements in material handling; and reduced overall manufacturing costs compared to thermal curing. The aerospace industry is developing EB technology in all of their market sectors, including military aviation and space products. Some specific products include cryogenic fuel tanks, improved canopy frames for jet aircraft, and the all-composite military aircraft. This paper discusses each of these opportunities.     

Electron beam stimulated chemical reaction in solids

Use of electron beams allows to obtain new effects in high temperature chemistry of solid state. A stimulated influence of irradiation at comparable temperature conditions may be a subject of technological interest taking into account that increase of reaction rate can reach significant values.     

Investigation of irradiation dose rate on curing characteristics of carbon fiber/polymer composites by low‐energy electron beam

During in situ low‐energy electron beam (E‐Beam) curing for carbon fiber‐reinforced polymer composite, prepregs undergoes 3 sequenced curing processes, namely E‐Beam‐induced curing, postray curing after irradiation, and thermally induced curing. In this study, the irradiation dose rate (IDR) is demonstrated to be influential on the redistribution of the curing portions in the 3 curing stages and directly influences the interlaminar bonding quality of the stepwise cured laminates. Differential scanning calorimetry results showed that higher IDR resulted in higher temperature of irradiated prepregs, and hence, a higher degree of curing was induced by the E‐Beam within a dose range of 0 to 500 kGy as compared to lower IDRs, which decreased the interlaminar physical adhesive quality between layers. Analysis indicates that other than pure physical adhesion between uncured layers, postray curing can further enhance the interlaminar shear strength for cured laminates by introducing cross‐layer chemical bonding in the interlaminar zone.     

The state of nuclear archaeology in North America

We address three main topics in this paper. First, we briefly review the history of neutron activation analysis (NAA) as an archaeological tool in the United States and Canada. Second, we assess the current potential for undertaking NAA in North America. Third, we comment on methodological and technical issues in archaeometric NAA that are raised by other papers included in this special section.     

E-beam curing of epoxy-based blends in order to produce high-performance composites

In this work, blends of a difunctional epoxy monomer and a thermoplastic toughening agent are E-beam irradiated at two different dose rates and two different total absorbed doses. The influence of the processing conditions on the thermal properties and on the morphology of the obtained matrices has been investigated. In particular, it is shown how the increase of the dose rate causes an increase of the temperature during irradiation, thus inducing a simultaneous thermal and radiation curing. On the contrary, at low-dose rate the system mainly undergoes to radiation curing, thus making the cured material very sensible to a post-irradiation thermal treatment with a significant improvement of the thermal properties.     

Electron beam curable coating for marble

Natural marble is, in general, characterized by graceful aspect, fine texture and hard property. However, it has a trend to produce staining and to lose its glossy face with white powdering when exposed to the outdoor environment. This study deals with a method for prevention of the deterioration of marble by application of an electron beam curable acrylic clear coating of nonsolvent type. It is proved that the method is effective for the minimization of the deterioration of marble.     

Electron beam irradiation of fluoropolymers containing polyethers

A highly fluorinated monomer, 1,3-bis(1,1,1,3,3,3-hexafluoro-2-pentafluorophenyl methoxy-2-propyl)benzene (12F-FBE) was polymerized with some diphenols by polycondensation and then was electron beam irradiated between 100 and 1000 kGy to determine degradation radiochemistry yield (G_s) by gel permeation chromatography (GPC). The samples were characterized after irradiation by DSC, FTIR, and nuclear magnetic resonance (NMR). The fluoropolymers show apparent degradation in mechanical properties at 300 kGy, except 12F-FBE polymerized with biphenol and bisphenol A, when they did not show any apparent physical change up to 300 kGy; and continue to be flexible and transparent, with a radiochemical yield scission (G_s) of 0.75, 0.53, 0.88, and 0.38 for 12F-FBE/SDL aliphatic, 12F-FBE/biphenol, 12F-FBE/bisphenol A, and 12F-FBE/bisphenol O, respectively. The number average molecular weights for three of the polymers decrease upon 1000 kGy irradiation to 10% of their original values; however, the polymer from bisphenol A is much more stable and its M_n decreases to only 24% of original.     

Electron beam induced changes in transition metal oxides

Electron beam induced changes in maximal valence transition metal oxides V(2)O(5), M(o)O(3) and TiO(2) (anatase) were studied by means of electron energy-loss spectroscopy and electron diffraction in transmission electron microscopy. For V(2)O(5), the observed chemical shifts of the L-edge reveal the reduction of V(5+) to V(2+). The structure changes from orthorhombic V(2)O(5) to cubic VO. MoO(3) can be reduced to a phase with an oxidation state less than that in MoO(2). No notable structural or electronic change in TiO(2) (anatase) is observed. The different behaviours of the studied oxides under an electron beam are discussed with respect to bonding energy and lattice structure.     

Electron beam crosslinking of non-lead PVC formulations

PVC samples with lead-free and lead-base stabilizer, containing TMPTMA (trimethylolpropane trimethacrylate) as a crosslinker and DOP (2-ethylhexyl phthalate) as a plasticizer, were electron beam treated at different doses (2–200 kGy) and characterized to evaluate crosslinking and other several properties, as a continuation of our previously reported paper, where these PVC formulations, typical for wire and cable applications, underwent gamma irradiation. The PVC was formulated with two different stabilizing systems: Ca/Zn and dibasic lead phthalate for comparison, to use them as jackets for a 22 wire gage (AWG). Small samples of the jacketed wires were irradiated in an industrial Dynamitron electron accelerator for the corresponding doses, along with two dosimetric systems: radiochromic thin film and alanine pellets dosimeters. The maximum dose applied was decided as the crosslinking increased, until the gel content was stable. The dose of 200 kGy was the condition for the highest crosslinking, so most of the wire was irradiated at such dose. Chemical and mechanical evaluations were carried out to the irradiated wire. The results show that 200 kGy was too high dose for the materials, since an important degradation is observed for the Ca/Zn systems. Unfortunately, such dose affects basically to CaZn formulations, which showed much poorer performance than classical lead-containing compositions. The results also indicate that gel content is not the best way of deciding the optimum condition for irradiation.     

Electron beam induced degradation of clopyralid in aqueous solutions

The degradation characteristics of clopyralid irradiated by electron beam (EB) was studied in aqueous solutions. The effects of factors, such as initial clopyralid concentrations, addition of radicals scavenger, initial solution pH and addition of H₂O₂, were investigated on clopyralid degradation efficiency and mechanism. It was found that the EB-radiolysis was an effective way to degrade clopyralid and its degradation rate decreased with the increasing of substrate concentration. In the investigated initial concentrations range of 100?C400 mg L^?1, the radiolytic degradation of clopyralid followed a pseudo-first kinetic order. The results from addition of radicals scavenger indicated that both ^?OH and e _aq ^? played significant roles in the degradation of clopyralid. Furthermore, the alkaline condition and addition of H₂O₂ (<10 mM) in the solution also slightly enhanced the efficiency of clopyralid degradation. The ion chromatography analysis showed that some organic acids (formic acid, acetic acid and oxalic acid) were formed, while the completely dechlorination of the substrate was achieved and organic nitrogen was recovered in the form of ammonium and nitrate ions during the irradiation process.     

Electron beam generated plasma decomposition of 1,1,1-trichloroethane

Dilute concentrations of 1,1,1-trichloroethane (TCA) in air were decomposed in an electron beam generated plasma reactor. The energy required for high levels of TCA decomposition (greater than 90%) was determined as a function of inlet concentration. For 99%, decomposition of TCA, ez300 eV/molecule at 250 ppm inlet concentration, and ¨~100 eV/molecule at 3000 ppm. A radical reaction mechanism is proposed which accounts for the formation of the major reaction products: 1,1-dichloroethylene, HCl, chloroacetylchloride, CO₂, and COCl₂. A model is derived based on first-order inhibited kinetics; a fit of the data to the model shows that at high decomposition fractions, radical scavenging by reaction products is a significant inhibitor of TCA decomposition.This work was supported by the Contaminant Plume Containment and Remediation Focus Area, Office of Environmental Management, U.S. Department of Energy.Also affiliated with the Department of Nuclear Engineering.     

Electron beam treatment of high NOx concentration off-gases

High concentration of NO_x removal from simulated off-gases was investigated using electron beam (EB) technology. Simulated off-gases were prepared by combusting Polish light oil or nature gas with addition of NO from a NO gas cylinder. Irradiation was carried out under a ILU-6 accelerator. It was found that removal efficiency of NO_x was influenced by inlet concentration of NO, temperature, SO₂ concentration, absorbed dose and irradiation dose rate. Methods of enhancing NO_x removal efficiency with additives using EB were also discussed.     

PDLC films prepared by electron beam and ultraviolet curing: influence of curing conditions on the electro-optical properties

Polymer dispersed liquid crystal (PDLC) films were prepared by polymerization-induced phase separation processes using ultraviolet (UV) and electron beam (EB) radiation. A mixture of the nematic LC material E7, an aromatic polyester acrylate, and additional monomeric acrylates was exposed to the EB radiation. A photoinitiator was included in the initial mixture in the case of UV exposure. The electro-optical behaviour of the PDLC films obtained has been investigated as a function of the chosen radiation. The transmission versus voltage curves strongly depend on the curing conditions, and are highly reproducible. Threshold and saturation voltages continuously increase with increasing dose values for UV-cured films, whereas plateau values were reached for EB-cured samples. A small memory effect has been observed for UV-cured systems.     

PDLC films prepared by electron beam and ultraviolet curing: influence of curing conditions on the electro-optical properties

Polymer dispersed liquid crystal (PDLC) films were prepared by polymerization-induced phase separation processes using ultraviolet (UV) and electron beam (EB) radiation. A mixture of the nematic LC material E7, an aromatic polyester acrylate, and additional monomeric acrylates was exposed to the EB radiation. A photoinitiator was included in the initial mixture in the case of UV exposure. The electro-optical behaviour of the PDLC films obtained has been investigated as a function of the chosen radiation. The transmission versus voltage curves strongly depend on the curing conditions, and are highly reproducible. Threshold and saturation voltages continuously increase with increasing dose values for UV-cured films, whereas plateau values were reached for EB-cured samples. A small memory effect has been observed for UV-cured systems.     

Development of an autoclave curing system for fibre reinforced polymer composites

An autoclave curing system has been developed and fabricated which is capable of curing both flat and contoured fibre reinforced polymer composite components. The system can operate at up to 20 bar pressure whilst achieving a 0·1-bar vacuum within the lay-up film bagging. Cure temperatures of up to 180°C were achieved using a stepwise temperature controlling system, which enabled the dwell temperature to be maintained within a ±1 °C tolerance.