Papers by Keyword: Electron Beam Irradiation

Abstract: It is a serious problem that short carbon fiber reinforced polyamide 66 (SCFRPA66) cannot be easily shaped by 3D-printing for practical usages. In order to improve on the brittleness, homogeneous low potential electron beam irradiation (HLEBI) to both sides of 3D-SCFRPA66 samples was found to increase strain at tensile strength (εts), corresponding to homogeneous deformation and fracture strain (εf), as well as resistant energy of homogeneous deformation (Ehd), whereas the HLEBI decreased the tensile strength (σts). This improvement in ductility can be explained by lone pair electrons, dangling bond generation, shortening and relaxation of the polymeric chains by the HLEBI.

Abstract: Silica/graphene (Si/GE) blends produced by conventional mixing method was added into natural rubber (NR) and subsequently vulcanized by latex mixing - electron beam (EB) irradiation to crosslink into NR composites. Characteristics investigation showed that Si and GE were held together with physical interaction. Tensile properties of NR composites were investigated. The results showed that EB irradiation could be used as a tool for crosslinking NR composites to improve their tensile properties. NR filled with 2.5 phr of the Si/0.056% wt GE blend vulcanized by EB irradiation dose at 150 KGy (NR/Si/0.0565GE_-EB) showed the highest tensile strength, acceptable moduli at 100, 300 and 500% modulus. The tear strength of the composite was higher than that of NR filled with only Si (NR/Si_-EB). It was found that too much GE content in Si/GE blends degraded the composites and lower the tensile strength.

Abstract: The objective of this study was to characterize the performance of lignocellulosic biomass (LCB) to assess its use as a potential bioethanol or biofuels through pretreatment process. The pretreatment process was performed to remove crystalline structural of biomasses in order to improve enzymatic hydrolysis process. In this work, combined electron beam irradiation and ionic liquid method was used as the pretreatment process for various LCBs such as Gigantochloa albociliata (GA), Leucaena leucocephala (LL), oil palm frond (OPF), acacia and microcrystalline cellulose (MCC) as reference. Irradiation dose was measured through electron beam accelerator over a range of 100-1000 kGy. Ionic liquid (IL) is known as green solvent that can dissolve cellulose. 50% v/v 1-ethyl-3-methylimidazolium acetate (EMIMAc) IL was employed to enhance the effect of irradiation in pretreatment process. The LCBs was analyzed by using two method; Fourier transform infrared (FTIR) and X-ray diffraction (XRD). FTIR result shows different pattern of spectra and peak for each condition. Lateral order index (LOI) based on Beer’s Law was also calculated to determine the changes in structure order after pretretament. For XRD results, the crystallinity index (CrI) of pretreated LCBs was calculated by using Segal’s Equation in order to determine the pattern based on different conditions. The highest percentage of effectiveness showed by pretreated Acacia as the values of LOI and CrI is the lowest compared to other LCBs which is 41.77% and 25.21%, respectively.

Abstract: The expansion behavior of basal plane dislocations (BPDs) in a 4H-SiC epitaxial layer on the (110) A-plane under electron beam (EB) (//[110]) irradiation was observed. BPD expanded and formed a single Shockley stacking fault (SSSF) between a partial dislocation (PD) pair. The width of the SSSF was proportional to the EB current. The dependence of the expansion velocity on the irradiation position was observed with a fixed EB spot. It was found that the electron-hole pair migration to the PD and/or SSSF can expand the SSSF. The velocity of SSSF expansion by direct SSSF excitation with an EB was much smaller than that by the preferential excitation of a PD with migrated electron-hole pairs.

Abstract: In the present work, lignin extracted from black liquor, which is industrial waste of pulp manufacturing. The extracted lignin was irradiated at various electron beam intensities from 100 to 1000 kGy. Also, the extracted lignin was thermally stabilized by heat treatment process. The characteristics of the stabilized and irradiated lignin materials were examined by means of TGA, ATR-FTIR, EA, and SEM. The ATR-FTIR result shows that both stabilized and irradiated lignin samples exhibit the decrease of characteristic absorption peaks, indicating the presence of guaiacyl and syringyl groups in the lignin structure. It reveals that the irradiation done to the ‘as-extracted’ lignin with appropriate electron beam intensity provides an efficiency as thermal stabilization of the lignin, suggesting that electron beam irradiation may apply directly to the extracted lignin, prior to carbonization the lignin without thermal stabilization process.

Abstract: Effects of irradiated rPP compatibilizer, on the mechanical and thermal properties of recycled polypropylene/microcrystalline cellulose composites (rPP/MCC), are investigated. rPP is irradiated with an electron beam at dosages ranging from 10, 20, 30 to 50kGy. A matrix, containing of unirradiated and irradiated rPP (50:50 by ratio), is then added to 5, 20 and 40wt% MCC fibres. The composites are prepared using a twin screw extruder, followed by injection moulding. The properties are then characterized using tensile and thermal degradation tests. The improvement of Young’s modulus by up to about 45% suggests a compatibilising effect of the irradiated rPP. Fracture surface observations reveal an adhesion between rPP matrix and MCC fibres. However, the thermal stability deteriorated with the addition of MCC and irradiated rPP.

Abstract: The effects of sepiolite nanofiller addition and irradiation modification on the tensile properties of epoxidized natural rubber (ENR-50)/ehylene vinyl acetate (EVA)/Sepiolite nanocomposites were investigated. The ENR-50/EVA/Sepiolite was blended by mixing in a Brabender Plastigraph at 120 °C. The samples were irradiated by using electron beam at a dose range of 50 to 200 kGy. The effect on the tensile properties and morphology were investigated as a function of sepiolite content and irradiation dose. Electron beam radiation produced an irradiation-induced crosslinking and further enhanced mechanical properties of the nanocomposites. The tensile properties of irradiated ENR-50/EVA blend were improved by the addition of sepiolite at 4 phr.

Abstract: To explore the relationship between the properties of the PTFE micropowders and the irradiation conditions, several PTFE micropowders were prepared by electron beam irradiation from 5 to 4000 kGy in air at room temperature. The properties of the irradiated PTFEs were characterized by particle size and its distribution (PSD) determination, differential scanning calorimetric (DSC) and thermogravimetric (TG) analysis, melt flow rate (MFR) and contact angle (CA) measurements. The results indicate that the particle size, the melting and crystallization temperature (T_m and T_c) and the melt viscosity of the irradiated PTFE are lower (smaller) than those of the pristine PTFE. By linear regression, the correlation between T_m (or T_c) of the PTFE micropowder and irradiation dose is established. The variation of surface properties of the irradiated PTFE micropowder is also reported.

Abstract: Effect of hydrogen on the structural and phase state of the fine-grained and submicrocrystalline structure of two-phase (alpha + beta) titanium Ti-6Al-4V alloy was investigated by the methods of electron microscopy and X-ray diffraction analysis. Hydrogenation is found to result in minor structural and phase changes both in fine-grained and submicrocrystalline samples. The use of electron beam exposure combined with heating for hydrogen release in the Ti-6Al-4V alloy is shown to reduce degassing time and decrease the hydrogen concentration to the values closed to the engineering standards for the Ti-6Al-4V alloys.

Abstract: Influence of electron beam irradiation on the morphology and contact angle of polypropylene was investigated. Electron beam processing was carried out at 8 – 10 kV accelerating voltage and a pressure of 5 – 10 Pa. Beam current density was up to 4.5 A/cm², and the pulse duration - from 150 to 300 μs. The morphology of irradiated polymer material was studied by scanning-electron and atomic-force microscopy methods. It was established formation of extended equally oriented “hills” divided by “valleys”. The height of hills increases with the growth of energy flux density per pulse.