Adsorption of Th4+ from aqueous solution onto Poly(N,N-diethylacrylamide-co-acrylic acid) microgels

Preparing glass to be used as a radioactive waste immobilizer from municipal waste is the aim of this paper. Up to 90 wt% of municipal waste was obtained by burning the raw waste at 700 °C for 5 h; this were successfully vitrified into borosilicate and sodium borate glasses at ~1,200 °C. The long term behavior of such glass is one of the most important factors, which is determined by their durability in aqueous solution. Experimental durability data of the prepared glass immersed in ground water together with γ-irradiation was found to be affected according to the different irradiation doses. In addition, thermal analysis and glass surface morphology were investigated. The evolution of the damage on the studied properties was correlated to the changes in the glass network depending on their composition and irradiation dose. The results showed that glass matrix containing higher amount of municipal waste possess high durability and low thermal expansion after being gamma irradiated. The results showed that glass containing higher amount of municipal waste possess high durability and low thermal expansion after irradiation.     

Structural and thermal characterization of Zn2−xCoxTiO4

In this work, spinels with the general formula Zn_2?xCo_xTiO₄ were synthesized by the polymeric precursor method and thermally treated at 1,000 °C. The powder precursors were characterized by TG/DTA. A decrease in the DTA peak temperature with the amount of zinc was observed. After the thermal treatment, the characterizations were performed by XRD, IR, colorimetry and UV/VIS spectroscopy. The XRD patterns of all the samples showed the presence of the spinel phase. Infrared spectroscopy showed the presence of ester complexes for Zn₂TiO₄ after thermal treatment at 500 °C, which disappeared after cobalt addition, indicating that organic material elimination was favored.     

Study of crystallization process of soda lead silicate glasses by thermal and spectroscopic methods

The crystallization process of some glasses in the ternary Na₂O–SiO₂–PbO system with good chemical stability that can be used for waste inertization was studied using X-ray diffraction (XRD), infrared spectroscopy (FT-IR), differential thermal analysis (DTA) and scanning electron microscopy. The parent glasses were characterized by XRD and FT-IR, and their vitreous state was determined. DTA measurements evidenced glass transition (T _g) and crystallization temperatures (T _c). The thermal treatments were conducted at vitreous transition temperature (400 °C) and at highest effect of crystallization (650 °C). XRD evidenced the lead and sodium silicate crystalline phases in samples treated at 650 °C for 12 h. Micrometer crystallites dispersed in the glass matrices have affected the transparence of glasses and made them opaque after treatment at 650 °C. The influence of oxide quantities in compositions on the crystallization tendency was revealed. A PbO higher content than that of SiO₂ as well as lower Na₂O content decreased the tendency of crystallization.     

Preparation and thermal analysis kinetics of the core–nanoshell composite materials doped with Sm

The core–nanoshell composite materials with magnetic fly-ash hollow cenosphere as core and nano SmFeO₃ as shell were synthesized by high-energy ball milling method. The magnetic fly-ash hollow cenosphere, samarium nitrate, and iron nitrate were used as raw materials. The synthesis and growth kinetics of the composite materials were investigated using the thermogravimetry and differential thermal analysis (TG–DTA) at different heating rates. The results show that the precursor of the composite materials decomposes in three steps. The apparent activation energy of each stage was calculated using the Doyle–Ozawa and Kissinger methods. The reaction order, frequency factor, and rate equations were also determined. The activation energy of the nano crystallite growth is calculated to be 16.12 kJ mol^?1 according to kinetics theory of nano crystallite growth. It can be inferred that the crystallite grows primarily by means of an interfacial reaction during the thermal treatment. The magnetic properties and microwave absorbing properties of samples were analyzed by the vibrating sample magnetometer analysis and vector network analyzer. The results indicated that the exchange coupling interaction happens between ferrite of magnetic fly-ash hollow cenosphere and nanosized ferrite coating, which cause outstanding magnetic properties. In the frequency between 1 MHz and 1 GHz, the absorbing effectiveness of the composite absorbers can achieve ?32 dB. The magnetic properties of the composite material are better than those of single phase. So it is consistent with requirements of the microwave absorbing material at the low-frequency absorption.     

Synthesis and characterization of Na2O–CaO–SiO2 glass–ceramic

The Na₂O–CaO–SiO₂ ternary glass–ceramic with the composition of 49 mass% Na₂O, 20 mass% CaO, and 31 mass% SiO₂ was prepared by the conventional method. The ternary glass–ceramic was characterized using X-ray diffraction (XRD), differential thermal analysis (DTA), thermogravimetric analysis, Fourier transform infrared spectroscopy, and scanning electron microscopy techniques. The Na₂CaSiO₄ phase, having the cubic crystal system, with the crystallite size of 25.14 nm and lattice parameter of 0.7506 nm was determined from the XRD pattern. The activation energy of the glass–ceramic calculated from the DTA curves was found to be 162.02 kJ mol^?1. The Avrami exponent was found to be ~2 indicating a one-dimensional growth process. The mass loss percent from ambient temperature to 1,173 K is less than 1 %. The density was calculated to be 2,723 kg m^?3. The fine-grained microstructure with the particle sizes less than 1 μm was confirmed by the scanning electron microscope micrograph.     

Preparation and properties of 3-aminopropyltriethoxysilane functionalized graphene/polyurethane nanocomposite coatings

Silicone-modified graphene was successfully synthesized by treating graphene oxide with 3-aminopropyltriethoxysilane (AMEO) and then reduced by hydrazine hydrate. Subsequently, the AMEO-functionalized graphene was incorporated into polyurethane (PU) matrix to prepare AMEO-functionalized graphene/PU nanocomposite coatings. The functionalized graphene could disperse homogenously by means of a covalent connection with PU. AMEO-functionalized graphene (AFG)-reinforced PU nanocomposite coatings showed more excellent mechanical and thermal properties than those of pure PU. A 227 % increase in tensile strength and a 71.7 % improvement of elongation at break were obtained by addition 0.2 wt% of AFG. Meanwhile, thermogravimetric analysis reveals that thermal degradation temperature was enhanced almost 50 °C higher than that of neat PU, and differential scanning calorimetry analysis demonstrates that glass transition temperature decreased by around 9 °C. The thermal conductivity of AFG/PU nanocomposite coatings also increased by 40 % at low AFG loadings of 0.2 wt%.     

Characterization of Pentaclethra macroloba oil

The Pracaxi oil—(Pentaclethra macroloba) contains high concentrations of fatty acids with emollient action that contribute to skin hydration. The use of this oil is supported by the utilization of natural resources thus enabling regional development and social contribution. The objective of this study was to characterize the P. macroloba oil by thermogravimetry (TG, DTG, and DTA), gas chromatography, Fourier transform infrared spectroscopy (FT-IR), and oxidation stability—Rancimat, aiming at the quality control of plant raw material. Three samples of crude oil sold by Amazon Oil Industry (Ananindeua, Pará, Brazil) were studied. The analysis of these oil samples showed different fatty acids, especially the behenic, oleic, linoleic, and lignoceric acids totalizing approximately 96 % of the grease composition and in smaller percentage arachidic, lauric, myristic, palmitic, and linolenic acids were found. The major acids have wide medicinal use. According to the TG/DTG curve, thermal stability was observed up to 220 °C, indicating a greater mass loss related to the dehydration and elimination of volatile substances. The thermal decomposition process occurred in the range of 430–450° C according to the DTG curve. The absorption spectrum in the infrared region (FT-IR) showed well-defined bands confirming the presence of functional groups present in the oil. Tests in a Rancimat have shown an induction period between 8 and 10 h demonstrating that the samples are in agreement with the standards required by ANP No. 14/2012 which requires at least 6 h of testing.     

Mechanical and thermal properties of Acacia leucophloea fiber/epoxy composites: Influence of fiber loading and alkali treatment

In this work, the influence of fiber content and alkali treatment on the mechanical and thermal properties of Acacia leucophloea fiber-reinforced epoxy composites was studied. Ten composite samples were fabricated by varying fiber content (5, 10, 15, 20, and 25 wt%); both untreated and treated fiber were soaked in a 5% NaOH solution for 45 min by using hand-layup method. The composite reinforced with 20 wt% treated fiber content exhibited better mechanical properties and thermal properties. Fourier transform infrared analysis, morphological analysis by atomic force microscope, and scanning electron microscope of composites were also performed.     

P2O5对Li2O-SiO2-Al2O3-K2O-ZnO体系微晶玻璃析晶性能的影响

采用差热分析、X射线衍射及扫描电镜分析手段研究了P₂O₅对Li₂O-SiO₂-Al₂O₃-K₂O-ZnO体系牙科微晶玻璃析晶性能的影响, 并确定了P₂O₅的最适含量. 结果发现P₂O₅是该玻璃体系的有效成核剂, 未添加P₂O₅的玻璃体系成核密度低, 热处理后不能形成微晶体, 且主晶相为硅酸锂; 添加P₂O₅使玻璃在热处理后形成以二硅酸锂为主晶相的微晶玻璃. 该玻璃体系中添加4.5 wt%的P₂O₅可以得到较高体积含量和理想显微结构的牙科二硅酸锂微晶玻璃. P₂O₅含量为6 wt%的基质玻璃发生乳浊, 呈不透明的乳白色.     

Improvement in Heat Transfer of a Two-Phased Closed Thermosyphon Using Silver-Decorated MWCNT/Water

Hereby, a comparative study of thermal and thermodynamic properties of nanofluids based on multiwalled carbon nanotubes (MWCNTs) and water is described. The first nanofluid includes pristine MWCNT while the second nanofluid prepared by MWCNT decorated with silver. To achieve the covalent functionalization, morphology of MWCNT-Ag was studied by transmission electron microscopy. Subsequently, the value of the entropy generation and thermal performance of nanofluids (MWCNT/water and MWCNT-Ag/water) were inspected in a two-phased closed thermosyphon (TPCT). The results suggested as the concentration and input power increased, the thermal resistance decreased. Also in different concentrations, the thermal efficiency of nanofluids obeyed the sequence: MWCNT-Ag (1 wt%) > MWCNT-Ag (0.5 wt%) > MWCNT (1 wt%) > MWCNT (0.5 wt%) > water. A variation of the vacuum pressure was also studied in the synthesized nanofluids as compared with pure water. The results were shown a lower pressure drop of MWCNT-Ag/water than MWCNT/water and the water. Also it was found that the higher thermal performance is produced using higher extent of covalent functional groups (with higher thermal conductivity). MWCNT-Ag/water can be an appropriate substitution for the water in the thermal equipment due to the intensive thermal efficiency and/or low thermal resistance compared with pure water.      

Intrinsic dosimetry of glass containers: a potential interrogation tool for nuclear forensics and waste management

Intrinsic dosimetry is the method of measuring total absorbed dose received by the walls of a container holding radioactive material. By considering the total absorbed dose received by a container in tandem with the physical characteristics of the radioactive material housed within that container, this method has the potential to provide enhanced pathway information regarding the history of the container and its radioactive contents. We report the latest in a series of experiments designed to validate and demonstrate this newly developed tool. Thermoluminescence (TL) dosimetry was used to measure dose effects on raw stock borosilicate container glass up to 70 days after gamma ray, X-ray, beta particle or ultraviolet irradiations at doses from 0.15 to 20 Gy. Two main peaks were identified in the TL glow curve when irradiated with ⁶⁰Co, a relatively unstable peak around 120 °C and a more stable peak around 225 °C. Signal strength of both peaks decayed with time. The minimum measurable dose using this technique is 0.15 Gy, which is roughly equivalent to a 24 h irradiation at 1 cm from a 50 ng ⁶⁰Co source. As a result of fading, this dose would be detectable for approximately 1 year post-irradiation. In a more detailed analysis, the TL glow curves were separated into five peaks centered near 120, 160, 225, 300, and 340 °C. Differences in TL glow curve shape and intensity were observed for the glasses from different geographical origins. These differences can be explained by changes in the intensities of the five peaks. This suggests that mechanisms controlling radiation induced defect formation from gamma, beta, X-ray, and UV sources may be similar.     

Synthesis of cellulose/silica nanocomposite through electrostatic interaction to reinforce polysulfone membranes

Cellulose/nanosilica (CNS) nanocomposite fiber has been synthesized via a novel surface modification of cellulose and nanosilica, prepared from rice husk as a low cost natural source, by anionic and cationic surfactants through electrostatic interaction. The effect of the prepared nanocomposite on the structural, mechanical, thermal and morphological properties of polysulfone nanofiltration membranes was comprehensively studied. The scanning electron microscope image was used to investigate the relationship between solidity aspect and morphological properties qualitatively and quantitatively. From the results, the membrane with 0.25 wt% of CNS fiber shows the highest mechanical strength and thermal stability with a glass transition temperature of about 201 °C. It was found that an increase in the filler content increases the surface roughness of the membranes. The same behavior was observed for hydrophilicity based on contact angle measurements (from 78.7° to 61.5°). The adsorption of dye molecules during the filtration process was studied by batch adsorption experiments obeying Langmuir isotherm (R² > 0.91). For all samples of fabricated membranes, the rejection of Crystal Violet dye from aqueous solution was higher than 80%.     

Influence of high loading of cellulose nanocrystals in polyacrylonitrile composite films

Polyacrylonitrile-co-methacrylic acid (PAN-co-MAA) and cellulose nanocrystal (CNC) composite films were produced with up to 40 wt% CNC loading through the solution casting method. The rheological properties of the solution/suspensions and the structural, optical, thermal, and mechanical properties of the resulting films were investigated. The viscosity of the composite suspensions increased with higher CNC loadings and with longer aging times. PAN-co-MAA/CNC films maintained a similar level of optical transparency even with up to 40 wt% CNC loading. The glass transition temperature (Tg) increased from 92 to 118 °C, and the composites had higher thermal stability below 350 °C compared to both neat PAN-co-MAA and neat CNC. The mechanical properties also increased with higher CNC loadings, elastic modulus increased from 2.2 to 3.7 GPa, tensile strength increased from 75 to 132 MPa, and the storage modulus increased from 3.9 to 10.5 GPa. Using the Kelly and Tyson model the interfacial shear strength between the PAN-co-MAA and CNC was calculated to be 27 MPa.     

Biopolyols obtained via crude glycerol-based liquefaction of cellulose: their structural,rheological and thermal characterization

In this work lignocellulose biomass liquefaction was used to produce biopolyols suitable for the manufacturing of rigid polyurethane foams. In order to better evaluate the mechanism of the process, pure cellulose was applied as a raw material. The effect of time and temperature on the effectiveness of liquefaction and the parameters of resulting biopolyols were characterized. The prepared materials were analyzed in terms of their chemical structure, rheology, thermal and oxidative stability, and basic physical and mechanical properties that are important from the point of view of polyurethane manufacturing. The optimal parameters for the biopolyol production with a 94 % yield were achieved at 150 °C for a 6-h reaction duration. The obtained polyols were characterized by the hydroxyl number of 643 mg KOH/g and enhanced thermal and oxidative stability compared to the polyols obtained at lower temperatures, which is associated with the altered mechanism of liquefaction. The results of rheological tests, analyzed with the use of Ostwald-de Waele and Herschel Bulkley models, revealed that the prepared biopolyols can be classified as pseudoplastic fluids with the viscosity values similar to those of commercially available products. Rigid foams obtained via partial substitution of petrochemical polyol with prepared bio-based one were characterized by slightly increased apparent density and average cell size comparing to unmodified materials. The best mechanical performance was observed for the sample containing 35 wt% of biopolyol in the polyol mixture, which indicates a synergistic effect between the applied polyols. The applied modification delayed thermal degradation of foams due to changes in thermal decomposition process. In conclusion, the presented work confirms that lignocellulose biomass liquefaction can be successfully applied as a manufacturing method of polyols later used in the production of polyurethanes.     

Synthesis of calcium sulfate hemihydrate whiskers using oyster shells

Herein, the feasibility of preparing long and homogeneous hemihydrate (HH) whiskers using waste oyster shell was investigated. The whiskers formed from the sintered raw material had higher aspect ratios and more uniform morphology than non-sintered. The effect of reaction temperature, reaction time, and concentration were investigated. It was found that the optimum reaction temperature, reaction time, and concentration for stable and well-grown whiskers were 140 °C, 5 h, and 4 wt%, respectively. Direct transition from calcium sulfate dehydrate (DH) to HH was detected by X-ray diffraction (XRD) patterns, and the result showed DH completely transformed to HH after 5 h. The preferred direction of growth along the c-axis was confirmed by XRD pattern, selected area diffraction pattern, and high-resolution transmission electron microscopy (HRTEM).     

Synthesis and thermal properties of NiSbS–As doped phase

The substitution of Sb with As in the NiSbS intermetallic compound was studied in the framework of evaluating a possible increase of the thermoelectric properties. Different NiSb_1?xAs_xS samples were synthesized with increasing amounts of As (0 < x < 0.66) employing a simple synthetic route using a muffle furnace. Scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy was used to investigate the microstructure. X-ray powder diffraction techniques were employed in order to study the possible existence of a solid solution between NiSbS and NiAsS compounds, as well as to identify the crystal structure and determine the lattice parameters. All compounds were found to crystallise with the NiSbS prototype (cP12-P2₁3), with lattice parameters varying from a = 0.59341(7) nm (x = 0) to a = 0.56849(6) nm (x = 1). Good agreement with Vegard’s law was evidenced. Thermal measurements on NiSb_1?xAs_xS samples were carried out using DTA instruments to evaluate the thermal stability and the melting temperatures.     

Synthesis and surface properties of self-crosslinking core–shell acrylic copolymer emulsions containing fluorine/silicone in the shell

Stable emulsions of a core–shell acrylic copolymer (non-crosslinkable V0, and crosslinkable V2, V4, V6, and V8, where the numbers indicate the wt% of crosslinking agent based on the total acrylate monomer content) containing butyl acrylate (BA, 45 wt%), glycidyl methacrylate (GMA, 45 wt%), heptadecafluorodecyl methacrylate (PFA, 10 wt%), and various contents of crosslinking agent (vinyltriethoxysilane, VTES) were synthesized using a three-stage seeded emulsion polymerization process with a small amount of surfactant. The average particle size and viscosity of emulsions increased significantly with increasing VTES content. This study examined the effects of the VTES content on the surface/mechanical properties of self-crosslinked copolymer film samples containing a fixed acrylate monomer content to find the optimum VTES content. XPS showed that the film–air surface of the copolymer samples had a higher fluorine/silicone content than the film–dish interface. The tensile strength/modulus, thermal stability, and two Tgs (α and β Tgs) of the film samples increased significantly with increasing VTES content. The contact angle of the film samples increased with increasing VTES content up to approximately 6 wt%, and then decreased slightly. The optimum VTES content was approximately 6 wt% based on the total acrylate monomer content to obtain a high water/oil repellent coating material (V6) with the highest water/methylene iodide-contact angles (118.2°/81.8°) and lowest surface energy (18.4 mN/m).     

Influence of synthesis route on physicochemical properties of nanostructured electrolyte material La0.9Sr0.1Ga0.8Mg0.2O3−δ for IT-SOFCs

Nanosized La_0.9Sr_0.1Ga_0.8Mg_0.2O_3?δ (LSGM) has been synthesized by both gel-combustion method and solid state reaction method as an electrolyte material for IT-SOFCs. The effect of synthesis route on phase purity of the samples has been studied by X-ray diffraction technique. In the gel-combustion method, perovskite structure was formed at 1,200 °C with only trace amount of impurity and has an average crystallite size of 27 nm obtained by Scherrer’s equation. In solid state route, phase pure product was obtained only at the calcination temperature of 1,500 °C. The characteristics of the samples were also studied using FTIR, TG/DTA, Small angle X-ray scattering, BET surface area, thermal expansion measurements, and electrochemical impedance spectroscopy. The activation energy for oxide ion conduction of LSGM samples derived from Arrhenius plot is ~1.01 and 1.09 eV for gel-combustion and ceramic route, respectively. Linear increment of thermal expansion obtained by Dilatometry shows that there is no phase change at higher temperature in the sample. Sintered densities and microstructural features of the samples were also studied. The chemical compatibility of this electrolyte material has been studied with the perovskite oxide-based cathode material La_0.6Sr_0.4Co_0.2Fe_0.8O_3?δ and NiO.     

Thermal behavior of lignin and cellulose from waste composting process

The lignin and cellulose were extracted from reference material (leaves and twigs) and food of compost at different times composting: zero (raw), 30, and 120 days. According to thermogravimetric analysis and its derivative and differential scanning calorimetry curves for these samples, were verified during composting process there were considerable changes in its thermal profiles, as well as, characteristics lignin in cellulose samples and cellulose in lignin samples. These features were found by fourier transformed infrared spectroscopy.     

Coefficient of thermal expansion evolution for cryogenic preconditioned hybrid carbon fiber/glass fiber-reinforced polymeric composite materials

Polymeric matrix composites are susceptible to degradation and material properties changes if subjected to low-temperature environmental conditions. This paper attempts to present a study on effective coefficient of thermal expansion for various hybrid carbon fibers/glass fibers polymeric composite structures previously subjected to low-temperature environmental conditioning. The hybrid composite architectures were made from various layers of glass mat and/or glass woven embedded along with layers of unidirectional carbon fibers into a polymeric matrix. The samples were preconditioned to a low-temperature environment at a constant temperature of ?35 °C for 1-week long, 24 h/day. The instantaneous CTE and thermal strain fields were recorded with a DIL 402 PC/1 dilatometer from Netzsch GmbH (Germany) by setting a monotonically linear rise of temperature from 20 to 250 °C, at a rate of 1 °C min^?1. The experimentally retrieved data were compared with the values obtained by running a micromechanical-based approach simulation on a representative volume element.