Dynamic mechanical properties of styrene‐butadiene rubber vulcanizate filled with electron beam modified surface‐treated dual‐phase filler

The influence of the electron beam modification of a dual‐phase filler on the dynamic mechanical properties of styrene‐butadiene rubber (SBR) is investigated in the presence and absence of trimethylol propane triacrylate or triethoxysilylpropyltetrasulfide. Electron beam modification of the filler results in reduction of the tan δ at 70°C, a parameter for rolling resistance, and an increase in the tan δ at 0°C, a parameter for wet skid resistance of SBR vulcanizates. These modified fillers give significantly better overall performance in comparison with the control dual‐phase filler. This variation in properties is explained in terms of filler parameters such as the filler structure that leads to rubber occlusion and filler networking. These results are further corroborated using the master curves obtained by the time–temperature superposition principle. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2992–3004, 2003     

Simulation study of the thermal insulation performance of a vacuum-insulated tube inside an electrically heated device

To realize stable heating of a heated cigarette while effectively controlling the outer-wall temperature of an electric heating-type appliance, a vacuum-insulated tube (VIT) is currently widely used for thermal insulation against the heating element. The effects of the critical parameters of the VIT, gases at different pressures, wall thickness, and material on its thermal insulation performance, were simulated using Fluent to provide guidance on the structure and performance optimization of the EHD. When the absolute pressure of gas in the VIT was <0.5 Pa, increasing the degree of vacuum did not improve the thermal insulation performance. The thermal insulation performance of VITs made from different materials (stainless steel, copper, aluminium, brass, and titanium alloy) was closely related to the emissivity and thermal conductivity of the material. Stainless steel yielded better overall thermal insulation owing to its low thermal conductivity and emissivity. Highly emissive materials, such as brass and titanium alloy, contributed to higher heat transfers through the radiation inside the vacuum chamber and external radiation from the VIT, decreasing the thermal insulation performance of the VIT. Stainless steel VITs yielded an improved thermal insulation performance as the wall thickness decreased, but at the cost of decreased mechanical stability. For a wall thickness of 0.05–0.30 mm, stainless steel yielded the best structural stability. VITs with different wall thicknesses were made from stainless steel, copper, and aluminium, and the thermal insulation performance and structural stability of the EHD were optimized.     

Effect of partial delignification of kenaf bast fibers for radiation graft copolymerization

Malaysian kenaf bast fiber was treated by acidic chlorite to be applied for a trunk polymer radiation‐induced graft copolymerization. The delignification conditions such as temperature, reaction time, and sodium chlorite (NaClO₂) loading were optimized from the viewpoints of density, tensile strength, and reactivity of grafting. It was found that delignification condition at 80°C for 6 h with 0.5% NaClO₂ gave 91% of lignin removal from the kenaf bast fibers. In this case, the density, fineness, and tensile strength of the kenaf fiber decreased about 46, 44, and 87%, respectively. Reactivity of grafting was evaluated using 4‐chloromethyl styrene to obtain widely available precursor materials. The partial delignified kenaf with residual lignin less than 2% resulted in degree of grafting of 134%, which is enough for precursor materials. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Radiolysis of Tributyl Phosphate by Particles of High Linear Energy Transfer

Tributyl Phosphate (TBP), used in chemical separation processes for used nuclear fuel, is susceptible to radiolysis causing losses in process performance. We have studied its degradation by exposing dry 1M TBP/n-dodecane solutions to gamma radiation from a cesium-137 source and in a mix of low and high linear energy transfer (LET) radiation by irradiating samples in the UC Irvine TRIGA^® reactor and utilizing the ¹⁰B(n,α)⁷Li reaction. In a 1 M solution of TBP in n-dodecane the degradation of TBP (G^?_TBP) was found to be 0.36 and 0.14 μmol/J for low and high LET radiation, respectively. The formation of dibutyl phosphoric acid, DBP, (G⁺_DBP) in this solution was found to be 0.18 and 0.047 μmol/J for low and high LET radiation, respectively. In samples exposed to low LET as well as a mix of low and high LET a variety of TBP degradation products containing phosphorus were observed indicating that other degradation products than DBP and the monobutyl diacid (MBP) were formed. Our results for both low and high LET radiation compare well with previous studies on these systems indicating that high LET degrades TBP to a lesser extent than gamma radiation. Available data for high LET is not as abundant as for low LET making such comparisons challenging. Nevertheless, our method yields a value for G⁺_DBP that agrees well with previous alpha radiolysis studies indicating that our method shows promise for studying high LET radiolysis in liquid-liquid extraction systems.     

放射性料位仪表在石油化工装置中的应用

介绍放射性仪表的基本测量原理、Y射线对衰减系数的影响参数,列举了几种常见屏蔽介质的衰减系数与屏蔽层厚度之间的关系;阐述石油化工装置中常见放射性料位仪表的测量形式,不同形式的放射源与探测器适用的场合、测量特点及安装要求;明确了放射源活度的选择和影响计算的要素。     

Photocuring of Empty Fruit Bunches of Oil Palm (Elaeis guineensis) Fibers with Allyl Methacrylate (AMA): Effect of Additives on Mechanical and Degradable Properties

Empty fruit bunches of oil palm fibers can be used as environmentally friendly alternatives to conventional reinforcing fibers, like glass, carbon, etc. In order to improve the interfacial properties, this fiber was subjected to grafting with bulk monomer allyl methacrylate (AMA) and cured under UV radiation. It was found that UV curing enhanced the physicomechanical properties to a large extent compared to the untreated virgin fiber. Among different AMA concentration, the fibers treated with 10% monomer showed the best mechanical properties after 15 passes of UV radiation. Different additives such as urea, acrylamide, and NVP were added with the 10% AMA solution, and the effect of additives was studied. It was found that fibers treated with 2% urea showed even better PL and tensile properties than those treated only with AMA. the treated and untreated fiber samples were also subjected to various weather conditions such as simulating weather, soil, and water aging to determine the degradable properties. It was observed that the minimum loss in each case was shown by the sample treated with the formulations that contain urea as additives with AMA and that fiber aged in soil showed higher loss of weight and tensile properties than that aged in water.     

Improved Ultraviolet (UV) Radiation Stability of the Polypropylene (PP) Films of Woven Jumbo Bags for Outdoor Applications

Several formulations were developed with polypropylene (PP) in combination with antioxidants, calcium stearate, hindered amine light stabilizers (HALS) and ultraviolet light absorber (UVA) for making woven jumbo bags, which will be capable of carrying a load of two tons of materials in outdoor conditions. Thin films of these formulations were extruded followed by stretching to improve mechanical properties. Both stretched and un-stretched PP films were subjected to severe accelerated weathering by ultraviolet (UV) radiation for various periods and it was observed that un-stretched films reached 50% retention of tensile strength (TS) within 500 hours of exposure, while stretched films (tapes) did not reach 50% TS retention even after 10,500 hours of the exposure indicating an improved UV stability of the stretched films of PP.     

Effect of Pretreatment with Ultraviolet Radiation on the Physicomechanical Properties of Photocured Coir (Cocos nucifera) Fiber with 1-Ethyl-2-Pyrrolidone (1-E-2-P) Monomer

Coir fiber (Cocos nucifera) was modified with 1-ethyl-2-pyrrolidone (1-E-2-P) monomer by photocuring. A series of formulations of different concentration of 1-ethyl-2-pyrrolidone (3, 5, 10, 20, 30, and 70%) in methanol was prepared along with 2% photoinitiator (Darocur-1664). Concentration of 1-E-2-P, soaking time, and radiation doses were optimized and found that 5% 1-E-2-P, 7 min soaking time, and 5th pass of UV radiation was the optimized condition that gave the maximum values as polymer loading (PL) (21%) and 71% higher tensile strength over virgin one. The coir fiber was pretreated with ultraviolet (UV) radiation of various intensities for further improvement of mechanical properties. The mechanical properties, such as TS (tensile strength), Eb (elongation at break), and modulus (σ) of the pretreated fiber, were monitored. Fiber treated with 130th pass of radiation showed the higher TS, Eb, and σ. The fiber irradiated at 130th pass of UV radiation gave the maximum values as PL (35%) and 74% and 18% higher tensile strength and elongation at break, respectively. The fiber, both treated and untreated, was subjected to water absorption. The pretreated and cured coir fiber showed the minimum water uptake behavior.     

INTERACTION OF SURFACE RADIATION WITH CONJUGATE MIXED CONVECTION FROM A VERTICAL PLATE WITH MULTIPLE NONIDENTICAL DISCRETE HEAT SOURCES

Some of the important results of a numerical investigation into interaction of surface radiation with conjugate mixed convection from a discretely heated vertical plate with three nonidentical heat sources are provided here. The heat sources with identical rate of volumetric heat generation are placed flush-mounted along the plate in the descending order of their height from the bottom to the top ends of the plate. The heat sources are positioned at the leading edge, center, and the trailing edge of the plate, while the cooling medium considered is air, which is assumed to be radiatively transparent. The governing equations for fluid flow and heat transfer are initially converted into vorticity-stream function form and are later solved using the finite volume method coupled with Gauss-Seidel iterative solver. A computer code is written for the purpose. The effects of modified Richardson number, surface emissivity, and thermal conductivity on temperature distribution, peak temperature, drag coefficient, and relative contributions of mixed convection and radiation to heat dissipation are studied.     

Comparison of mechanical and degradation properties of EG and EGDMA grafted gelatin films

Thin films of gelatin were prepared from gelatin granules in aqueous medium by casting and its mechanical properties like tensile strength (TS), tensile modulus (TM), and elongation at break (Eb %) were studied. Gelatin films were procured with two types of monomers such as 5% ethylene glycol (EG) and 5% ethylene glycol dimethacrylate (EGDMA) to increase the mechanical properties. Five percent of monomer solutions were prepared in MeOH along with 2% photoinitiator; Irgacure-651. Soaking time and UV radiation intensities were optimized with the extent of polymer loading (PL) and the mechanical properties of the cured films. Comparing the properties of EG and EGDMA treated gelatin film, EG showed the best performance. The EG-cured gelatin film with 5?min soaking time showed the highest tensile strength (58.6?MPa) and elongation at break (11.2%). The water uptake was determined for raw film (500.1%), EG grafted gelatin film (375.3%), and EGDMA grafted film (412.9%). The degradation properties in water and soil were determined for the raw and cured gelatin films. It was observed that the raw film degrades more than that of the treated films.