Influence Of Electron Beam Irradiation Research Articles

1345 ナイロンシートと異種高分子間の接着に及ぼす電子線照射の影響(J14-9 知的材料・構造システム(9) 炭素・ポリマー関連材料,ジョイントセッション,21世紀地球環境革命の機械工学:人・マイクロナノ・エネルギー・環境)

1345 ナイロンシートと異種高分子間の接着に及ぼす電子線照射の影響(J14-9 知的材料・構造システム(9) 炭素・ポリマー関連材料,ジョイントセッション,21世紀地球環境革命の機械工学:人・マイクロナノ・エネルギー・環境)

アクリル樹脂の吸水量に及ぼす電子線照射の影響

アクリル樹脂の吸水量に及ぼす電子線照射の影響

均質電子線照射による高分子材料間の高速接着

Joining between Nylon-film and Silicone-rubber was successfully developed by using homogeneous EB irradiation. Effects of electron beam (EB) irradiation on joining strength of different polymers without adhesive materials were investigated. Although excess EB-irradiation more than 300 kJ kg-1(kGy) apparently decreased the joining strength, the EB irradiation increased the joining strength of the joining sample between Nylon-film and Silicone-rubber. To discuss the influences of EB irradiation on the joining strength, electron spin resonance (ESR) signals related to dangling bonds were observed. Since EB irradiation generated dangling bonds on Nylon-film, dangling bonds probably supported the each other polymer at interface.

Influence of Electron Beam Irradiation on PP/Clay Nanocomposites Prepared by Melt Blending

AbstractIn this research, the melt blending technique was used to prepare various polypropylene (PP) based nanocomposites. A commercial organoclay (denoted 15A) served as the filler for PP matrix, and the maleic anhydride modified PP was used as compatibilizer. The specimens were subjected to electron beam (EB) irradiation. The purpose of the study focuses on the influences of EB irradiation on the thermal stability and mechanical properties of the nanocomposites. The morphology of the nanocomposites was studied using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The XRD and SEM results showed that these nanocomposites are best described as intercalated systems. PP/Clay nanocomposites showed good thermal stability in the TGA analysis. TGA data at 500KGy showed that the EB irradiation has negative effect on thermal stability of the nanocomposites. Mechanical testing showed that the EB irradiation strongly influences the mechanical properties (tensile strength, Young’s modulus and hardness) of PP/Clay nanocomposites. The value of tensile strength decreases remarkably for all specimens with increasing irradiation dose up to about 550 KGy, but this reduction for nanocomposites with 3% clay is less than that of the pure PP/PP-g-MA blend. In higher irradiation doses, reduction in tensile strength of PP nanocomposites is less than that of the pure PP/PP-g-MA blend. Optimum irradiation dose of Young’s modulus for PP/Clay nanocomposites with 5% clay is 450 KGy. The hardness of the nanocomposites with 5% clay was found to decrease with increase in irradiation dose.

The influence of electron beam irradiation of antimicrobial-coated LDPE/polyamide films on antimicrobial activity and film properties

We evaluated the effects of ionizing radiation (1–3 kGy) and incorporation of antimicrobials on the functional properties of low-density polyethylene (LDPE)/polyamide films. We established the antimicrobial effectiveness of several coatings of FDA-approved antimicrobial compounds including sorbic acid, carvacrol, trans-cinnamaldehyde, thymol and rosemary oleoresin using selected food pathogen surrogates. The antimicrobial coatings were applied to one side of the LDPE films and dried. Films were irradiated using a 10 MeV linear electron beam accelerator at room temperature. All films showed inhibition zones in an agar diffusion test against Listeria innocua ATCC 33090 and Escherichia coli ATCC 884. In the liquid culture test, the antimicrobials significantly ( p ⩽ 0.05 ) reduced the specific growth rate of L. innocua by 3.8–8.5%, and decreased final cell concentration of both strains by 5.7–14.6% and 7.2–16.8%, respectively. All active compounds retained the antimicrobial activity when exposed to 1–3 kGy. Neither the presence of active compound nor dose affected the film's tensile strength and toughness. Additionally, films became more ductile and had improved moisture barrier functionality. Film's oxygen permeability was not affected by either treatment. Results are an initial step toward the development of self-sterile active packaging materials for use in combination with irradiation treatment of foods.

EBI Joining Between Different Polymers Without Adhesive Materials

ABSTRACTJoining between Nylon-film and Silicone-rubber was successfully developed. Effects of EB-irradiation on joining strength of different polymers without adhesive materials were investigated by using homogeneous EB irradiation. The EB irradiation increased the joining strength of the joining sample between Nylon-film and Silicone-rubber. Excess EB-irradiation more than 0.3 MGy apparently decreased the joining strength. To discuss the influences of electron beam irradiation on the joining strength, ESR signals related to dangling bonds were observed. Since the EB irradiation produced detectable dangling bonds on Nylon-film, using dangling bonds probably joined the different polymers.

Influence of electron beam irradiation and polyfunctional monomer loading on the physico‐chemical properties of polyethylene/polypropylene blends

AbstractDifferent polyethylene–polypropylene blends have been prepared in the presence of trimethylol propane trimethacrylate (TMPTMA) monomer. The prepared polymeric samples were cured using an electron beam accelerator at different irradiation doses ranging from 5 to 50 kGy. The influence of loaded TMPTMA wt% and irradiation doses on the physico‐mechanical properties reveal that the gel content is higher for polyethylene‐rich blend and reaches its maximum values at 30 kGy. Moreover, incorporation of TMPTMA monomer was found to positively influence the gel content of all samples under investigation. On the other hand, the mechanical strength increases on increasing the irradiation dose and attains its highest value at 20 kGy; a more pronounced effect was observed due to incorporation of TMPTMA into isotactic polypropylene (iPP) than LDPE samples at low irradiation doses. However, higher irradiation doses have a deleterious influence on iPP or iPP‐rich blends. In addition to the physico‐mechanical properties, the influence of TMPTMA loading as well as irradiation doses on heat shrinkage parameters of the neat polymers and their blends have also been studied. © 2006 Wiley Periodicals, Inc. Adv Polym Techn 25:208–217, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20072

The influence of electron beam irradiation on the shear bond strength of glass-reinforced frameworks and veneer composites

The bond between glass fibre framework and veneer composite can be achieved by silane coupling agents or by monomers that penetrate into a polymer network. However, it has been clinically demonstrated that his bond can fail. This study investigated whether electron beam irradiation improved the bond strength of fibre-frameworks and veneer composite with and without additional coupling agents.

The Influence of Electron Beam Irradiation on the Effectiveness of Trans‐cinnamaldehyde‐coated LDPE/Polyamide Films

ABSTRACT: We have evaluated the effect of electron beam irradiation (up to 20 kGy) on the functional and barrier properties of trans‐cinnamaldehyde‐coated low‐density polyethylene (LDPE)/polyamide films. Irradiation did not affect the tensile strength and toughness of the films, but the 20 kGy treatment increased the percent elongation‐at‐break significantly. The barrier properties were also enhanced (approximately 18.8%) when the films were exposed to 20 kGy. Addition of trans‐cinnamaldehyde with 3% of polyamide coating solution (w/w) did not affect the tensile strength and barrier properties of the films, but significantly decreased the percent elongation‐at‐break and toughness. Films with 3% and 10% coating were used to wrap fresh‐cut romaine lettuce samples to determine their antimicrobial activity. Total aerobic plate count (APC) and yeast and mold growth were determined as a function of dose (0, 0.5, and 1.0 kGy) for 14 d of storage at 4 °C. Irradiation reduced the total APC and yeast and mold counts (YMC) as dose increased. The 0.5‐ and 1.0‐kGy treatments decreased initial APCs by 1.2‐ and 1.5‐logs, and no YMCs were observed in the 1.0‐kGy treated samples at day 0. Irradiation exposure significantly lowered APCs of lettuce samples by almost 1‐log colony‐forming unit (CFU)/g compared to the nonirradiated controls, though it only slightly reduced YMCs. The effectiveness of using irradiation with antimicrobial films was enhanced with increased radiation dose and trans‐cinnamaldehyde concentration (3% to 10%).

The influence of electron beam irradiation on fibre‐reinforced composite specimens

This study investigated whether glass fibre-reinforced composite (FRC) specimens can benefit from post-curing using electron beam irradiation. Twenty-four frameworks of the Vectris and 24 of the Stick glass fibre-reinforced system were veneered with their correspondent veneer materials. Eight specimens of both systems were post-cured using electron beam irradiation (3 x 33 kGy, 10 MeV). The specimens were fixed in a restrained-end apparatus and inserted in an artificial mouth. With the exception of controls (n = 8 each) all other groups were thermally cycled and mechanically loaded (TCML). Finally, all samples were loaded to fracture using a universal testing machine. In two of eight non-irradiated Vectris/Targis specimens facing fracture occurred during TCML. Irradiation avoided these failures. No Stick/Sinfony facing fractured. However, Stick frameworks showed considerable torsions. Post-curing with electron beam irradiation made Stick frameworks stiffer. The fracture load of irradiated Stick/Sinfony specimens reached 520 +/- 31 N; control (without TCML and irradiation) 396 +/- 14 N, TCML-group without irradiation 362 +/- 41 N. Irradiated Vectris/Targis had a fracture resistance of 575 +/- 57 N; the control 556 +/- 36 N and the TCML group without irradiation 383 +/- 51 N. This investigation demonstrated that different types of FRC systems could considerably benefit from electron beam irradiation. The reconstructions became stiffer and resisted higher load.

TEM in situ study of degradation mechanisms induced by temperature annealing and electron beam irradiation in a ZnSe/GaAs heterostructure

Transmission electron microscopy is used to investigate the microstructure evolution of a ZnSe/GaAs layer under the simultaneous influence of electron beam irradiation (in the range 1000–5000 A/m 2) and specimen heating (in the range ambient—250 °C). Degradation of the layer is connected to the nucleation and growth of dislocation loops. At 150 °C, loops nucleate on pre-existing misfit dislocations lying in 〈3 1 0〉 directions by point defect accumulation consistent with a climb mechanism. At 250 °C, large zones of very tangled dislocations propagate rapidly mainly by climb under electron beam excitation leading to a complete degradation of the ZnSe layer. The elementary mechanisms involved in dislocation multiplication are enhanced by non-radiative recombination of electron hole pairs.

Influence of Electron Beam Irradiation on the Impact Value of Alkali Free Glass

Influences of electron beam irradiation on impact fracture energy indicated by impact value are studied for alkali free glass. The irradiation, which is able to be one of short-time treatments, reduced the brittleness and increased the impact value of alkali free glass. The impact value enhancement can be explained by stress relaxation induced by increase in density of dangling bonds.

炭素繊維強化型ポリマーの電子線照射によるシャルピー衝撃値の向上

Influences of electron beam irradiation on Charpy impact value of carbon fiber reinforced polymer (CFRP) have been investigated. The irradiation, which is one of short-time treatments, enhanced the Charpy impact value of CFRP. Furthermore, strengthening of carbon fiber, ductility enhancement of polymer and interface effects on impact test explains the impact value enhancement of CFRP.

Catalytic conversion of CO 2–CH 4 mixture into synthetic gas—Effect of electron-beam radiation

The radiolysis of methane (0.7 MeV electron beam) was studied as a function of its concentration at two doses: 5 and 20 kGy. In both cases the G (–CH 4) value raised with the increase of the substrate concentration. Thereby the yields observed at 20 kGy are much lower, because of recombination processes. Results are also reported on the conversion of the gas mixture CH 4:CO 2:He=1:1:1 into synthetic gas (H 2/CO) at 500 °C, using two catalysts : (N5) and (N20), containing 5 wt% Ni and 20 wt% Ni, respectively, supported on γ-Al 2O 3. In an experimental series the catalysts (N5) and (N20) were treated by irradiation (4 MGy dose) before use. The highest conversion yields (above 35%) were observed by implementation of N5 and N20 catalyst at 500 °C under the influence of electron beam radiation.

Influence of electron beam irradiation on the alloy‐to‐resin bond strength

The aim of this study was to investigate whether postcuring using electron beam irradiation had an effect on the bond strength of resin-to-base-metal after priming their surfaces using silicoating methods or functional monomers. Composite cylinders were bonded on a restricted area of 5 mm2 to flat rectangular titanium and cobalt-chromium specimens. Under investigation were the silicoating system Rocatec, the thiol-phosphate system Metal Primer II and the phosphate ester SR Link. Tensile strength and shear bond strength were determined for the three test groups in each case: (i) after 24 h, (ii) after electron beam irradiation (100 kGy), and (iii) after irradiation (100 kGy) + 12,000 cycles of thermal cycling (5 degrees /55 degrees C). The bond strength was highly affected by irradiation and the metal priming method used. However, the tribochemical silicoating method and phosphate-ester group showed no significant statistical change in bond strength. Only the thiol-phosphate system showed considerably higher tensile and shear bond strengths after irradiation. Thermal cycling did not deteriorate this bond and there was a tendency for higher bond strength on titanium. As a result it was determined that thiol-phosphate primers in combination with postcuring using electron beam irradiation can considerably improve the bond strength between resins and titanium or cobalt-chromium alloys.

Electron beam irradiation of molten polysulfone

Polysulfone (PSU) is an amorphous thermoplastic polymer which is frequently used in automotive, electrical, electronic and medical parts because of the excellent mechanical properties and radiation resistance. Heat stability of polysulfone is also quite high compared to other polymeric materials. Nevertheless, it is desirable to improve heat stability and shrinkage behaviour for some special high performance applications. Therefore, influence of electron beam irradiation at different temperatures on structure of polysulfone was investigated with the goal of generating a molecular network by crosslinking. Crosslinking should enhance the thermo-mechanical properties. From such an electron beam irradiation treatment an increase of molar masses up to the formation of a gel results. Furthermore, electron beam irradiation in the molten state is more effective than irradiation below the glass transition temperature.

Modeling the influence of electron beam irradiation on the heat resistance of Bacillus cereus spores

The effect of electron beam irradiation (EBI) on Bacillus cereus spore heat resistance was investigated. Irradiation with accelerated electrons had an important heat-sensitizing effect on distilled-water spore suspensions. After irradiation doses of 1.3, 3.1, or 5.7 kGy followed by heating at 90 °C, calculated D 90-values for strains Escuela Politécnica Superior de Orihuela (EPSO)-41WR and EPSO-50UR were reduced more than 1.3, 2.4, and 4.6 times, respectively. Plots of calculated log D T -values versus irradiation doses (1.3, 3.1, and 5.7 kGy) yielded straight parallel lines for the 85–100 °C heating temperature range, which made it possible to develop an equation to predict the changes in heat sensitivity of B. cereus spores that occurred with changing irradiation dose. Radiation-induced heat-sensitivity was characterized by a z EBI-value which was determined as the irradiation dose that should be required to reduce the decimal reduction time ( D T ) by one log 10 cycle when log 10 D T was plotted against irradiation treatment. A model is proposed to describe the influence of a pre-irradiation treatment with electron beams followed by heating on the heat resistance of B. cereus spores. This study also suggests the potential use of EBI followed by heating for food preservation.

The influence of electron-beam irradiation on the volume resistivity of polyethylene and kapton

Electron-beam irradiation is used for the measurement of the volume resistivity of some types of polyethylene (PE) and kapton (PI) with a maximum thickness of 75 μm. The energy of the electrons is 3.5–5.5 keV and the maximum time of irradiation is 46 min. The results obtained by this method are compared with those of classic and standardized methods, and the influence of electron-beam irradiation on volume resistivity is studied as well.

Electron beam induced crosslinking of nylon 6 with and without the presence of TAC

The influence of electron beam irradiation on neat nylon 6 was manifested by formation of molecular branches deduced from increase in melt flow index and intrinsic viscosity. Crosslinking of nylon 6 was carried out using electron beam irradiation in presence of triallyl cyanurate (TAC). The crosslinked samples showed a high level of gel content. At a given dose, increasing the TAC level from 1% to 3% increased the gel content of the samples slightly and correspondingly decreased the percent of water absorption. The melting temperature decreased with increasing the dose and the TAC level. All samples containing TAC showed some decrease in crystallinity under exposure to electron beam. The crosslinked nylon 6 samples showed higher thermal stability as it was verified by its heat deflection temperature. Elongation at break decreased while the tensile strength and yield stress increased as a function of TAC level and absorbed dose.

無アルカリガラスの衝撃破壊エネルギーに及ぼす電子線照射の影響

Influences of electron beam irradiation on impact fracture energy indicated by impact value were studied for alkali free glass. The irradiation, which was able to be one of short-time treatments reduced the brittleness and increased the impact value of alkali free glass. The impact value enhancement can be explained by stress relaxation induced by increase in density of dangling bonds.