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Rice hulls, a harmful biowaste, were used to produce nanosized activated carbon (RHAC) by combustion and phosphoric acid treatment. The developed RHAC was characterised using various structural and morphological techniques (scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy and nitrogen (N2) adsorption). The prepared RHAC was used to remove heavy metal ions (iron (III) (Fe3+) and chromium (VI) (Cr6+)) by using the adsorption mechanism. Adsorption parameters, such as contact time, dose and initial concentration of the heavy metal ions, were investigated. Five adsorption models (two and three parameters) were studied. Also, the adsorption kinetics through the intraparticle diffusion model was applied. RHAC showed adsorption capacities of 47.00 and 45.00 mg/g for iron (III) and chromium (VI), respectively. The findings recommend using RHAC as a low-cost and eco-friendly adsorbent for metal ion removal and water-treatment applications.

Ancient archaeological sites contain numerous pottery objects that suffered from different deterioration factors. This study aims to use different analytical methods to study the chemical and mineralogical composition and identification of deterioration aspects of some ancient Egyptian pottery jars from Saqqara excavation. Thus, to explain the deterioration factors' mechanisms and apply the proper conservation methods to the deteriorated pottery jars. AutoCAD, digital microscope, scanning electron microscope (SEM-EDX), and x-ray diffraction (XRD) were used to clarify the preservation states of pottery jars. The results of the investigation revealed that the selected jars suffered from different cracks, salts crystallization, some surface black spots, separation of the slip layer, and heterogeneity in the grains size. XRD analysis revealed that quartz, diopside, illite, muscovite, orthoclase, anorthite, and hematite are the main components of the jars. SEM-EDX analysis showed high concentrations of chlorides and sulfate salts, besides the presence of manganese oxide. Different treatments were performed for the pottery jars include mechanical and chemical cleaning. Additionally, the completion process was done by using a mixture of dental gypsum with grog. Moreover, the consolidation process was achieved by using paraloid B-72.

The preparation of adsorbents plays a vital part in the adsorption method. In particular, many adsorbents with high specific surface areas and unique shapes are essential for the adsorption strategy. In this study, a Zn-Mg-Al/layer double hydroxide (LDH) had been designed via a facile co-precipitation process. Adsorbent based on Zn-Mg-Al/LDH was utilized to remove crystal violet (CV) from the wastewater. The impacts of the initial dye concentration, pH, and temperature on CV adsorption performance were systematically examined. The adsorbents were analyzed both before and after adsorption using FTIR, XRD, and SEM. The roughness parameters and surface morphologies of the produced LDH were estimated using 3D SEM images. Under the best conditions (dose of adsorbent = 0.07 g and pH = 9), the maximum adsorption capacity has been achieved. Adsorption kinetics studies revealed that the reaction that led to the adsorption of CV dye onto Zn-Mg-Al/LDH was a pseudo-second-order model. Additionally, intraparticle diffusion suggests that Zn-Mg-Al/LDH has fast diffusion constant for CV molecules (0.251 mg/(g.min1/2)). Furthermore, as predicted by the Langmuir model, the maximal Zn-Mg-Al/LDH adsorption capacity of CV was 64.80 mg/g. The CV adsorption equilibrium parameter (RL) onto Zn-Mg-Al/LDH was 0.769, indicating that adsorption was favorable. The effect of temperature was performed at 25, 35, and 45 oC in order to establish the thermodynamic parameters ∆Ho, ∆So, and ∆Go. The computed values indicated exothermic and spontaneous adsorption processes. The study presented here might be used to develop new adsorbents with enhanced adsorption capabilities for the purpose of protecting the environment of water. ‎

Polymer electrolyte membrane (PEM) fuel cells have the potential to reduce our energy consumption, pollutant emissions, and dependence on fossil fuels. To achieve a wide range of commercial PEMs, many efforts have been made to create novel polymer-based materials that can transport protons under anhydrous conditions. In this study, cross-linked poly(vinyl) alcohol (PVA)/poly(ethylene) glycol (PEG) membranes with varying alumina (Al

The effect of ultraviolet (UV) radiation, with wide range of wavelengths, on Nafion 112 membrane was studied at different UV exposure times up to 24 h. The energy deposited by UV photons on each sample varies with the radiation dose expressed by the exposure time. The influence of UV on the samples examined was investigated using various techniques. The chemical and crystal structures were detected via Fourier-transform infrared (FTIR) and wide-angle X-ray diffraction (WAXD), respectively. The electrical conductivity measurement was used to give an insight into the proton conductivity of the samples. The nanostructure was examined using positron annihilation lifetime (PAL) spectroscopy. Moreover, the mechanical properties of the irradiated samples were examined via the tensile test experiment. Water uptake was also measured for the investigated samples. Finally, the various membranes were evaluated as proton exchange membranes for fuel cell performance using a single cell test. All of the above measurements and tests were carried out for comparison for with those obtained for the sample without UV radiation. The maximum power density obtained for the sample exposed to UV radiation for 12 h was ~ 47 mW/cm2, which is higher than that of ~ 37 mW/cm2 for the sample as received. An improvement in cell performance was achieved by UV radiation with certain doses.

Many of the excavated pottery artifacts are suffering from different deterioration aspects. The pressure of burial environment is considered the most deteriorative agent for pottery in soil, which leads to damage of the artifact. Therefore, it is necessary to join these damaged parts to be suitable for museum display. The adhesive materials play a significant role in the joining processes of these artifacts. In this study, Paraloid B-72 in its traditional and nano form was prepared (50% in acetone) as adhesive for pottery artifacts. Twelve pottery tiles (14 ×4×1 cm) were prepared and then were adhered together with the adhesive in traditional and nano forms. The pottery samples were exposed to artificial aging as follows; accelerated heat-humid aging (temperature 100°C and 60% relative humidity) and light aging by U.V lamp for 100 hours. Visual assessment and several analytical techniques were used for the evaluation of the selected adhesive. The analytical techniques are transmission electron microscope (TEM), scanning electron microscope (SEM), color change and tensile strength. The results obtained from transmission electron microscope showed that grain size of nano paraloid was ranging from 33 to 51 nm where the particle size of the traditional paraloid was in the range between 103 to 150 nm. Visual assessment proved that nano paraloid had some simple changes in appearance. Scanning electron microscope revealed that the nano paraloid was more resistance for aging than traditional form. Color change revealed that nano paraloid gave the lowest level of total color differences (ΔE) after light, heat-humid and light-heat aging with 2.31, 3.26 and 4.60 respectively. The tensile strength revealed that nano paraloid gave highest tensile strength (81.3 N/mm2). According to these results, we recommend the use of nano paraloid in joining of archaeological pottery artifacts.

In the present study, the effect of electric field on thermally treated Nafion 112 was investigated successfully. The electrically modified Nafion membranes were examined using various techniques such as Fourier transform infrared (FTIR), water uptake, wide-angle x-ray diffraction (WAXD), proton conductivity, thermogravimetric analysis (TGA), tensile test, and positron annihilation lifetime (PAL) spectroscopy. The FTIR patterns show that the chemical structure of the Nafion 112 is unchanged with the electric field. The electric field decreases the degree of crystallinity as deduced from WAXD. Furthermore, the hole volume size deduced from PAL measurement increases with increasing the electric field strengths. As a result of the electric field effect on the thermally treated Nafion 112 membrane, the electrochemical properties were enhanced. The proton conductivity increases from 1.0 × 10–3 to 2.1 × 10–3 S/m. The water uptake increases from 7.4 to 15.5% with increasing the electric field strength up to 80 MV/m and then it reaches a plateau. It was also found that the mechanical and thermal properties of thermally treated Nafion 112 were enhanced because of the electric field effect. The hole volume size was increased from 0.136 to 0.160 nm3 as a function of the electric field. The results from different techniques were correlated successfully. The results were presented and discussed accordingly on a theoretical basis and compared to literature review data.

Renewable energy and alternative fuel from different conventional resources such as biomass, plastic waste, and recyclable polymers are impertinent environmental issues worldwide. Furthermore, to replace fossil fuel and reduce greenhouse gas emissions that have a negative impact on climate change. This article exhibits the effect of metal oxide composite/clay in the thermal decomposition of Polypropylene. That hetrocatalyst composed nano-clay thin layer loaded with MnO2 –NPs works on cracking of polypropylene under different reaction conditions like heating temperature, rate of reaction, reaction time, and composite loading ratio. Various techniques such as GC and TEM were used to characterize pyrolysis gases and char, in addition to scanning electron microscopy (SEM), Fourier transform infrared (FTIR), Thermo-gravimetric analyzer (TGA), and X-ray diffraction (XRD) were used for composite characterize. High gas yield and char rate conversion were obtained using synthesize composite.

The adsorption of H2 in dehydrated and hydrated Materials of Institute Lavoisier (MIL-101) was investigated theoretically. The effect of terminal water molecules on adsorption as one of the more vital MIL-n trivalent chromium-based porous carboxylates in metal-organic frameworks application in the renewable energy field was also theoretically studied. The MIL-101 structures were optimized for geometry and energy minimization was performed. The calculations were carried out using density functional theory approach with B3LYP functional and mixed basis set of Lanl2DZ and 6-31G(d, p) for Cr and light atoms (C, H, O, F), respectively, as implemented in the Gaussian 09 program package. The spin and atomic charges distribution on the Cr metal atoms, adsorbate, and water molecules are calculated using natural bond orbital (NBO). The density of states (DOS) for the clusters was obtained using Gaussian smearing of Kohn–Sham orbital energies. The natural bond orbital (NBO) for molecular orbital analysis and atomic charge calculations were utilized. For the dehydrated MIL-101, more adsorbate molecules were found near the exposed Cr2 sites than the fluorine saturated Cr1 sites. Furthermore, terminal water molecules in the hydrated MIL-101 made more interaction sites and enhanced adsorption.

Positron annihilation lifetime (PAL) as a function of temperatures were measured to determine the thermal expansion coefficient () of the ortho-positronium (o-Ps) hole volume for poly(vinyl alcohol), PVA. On the other hand, the thermal expansion coefficient ( of the bulk volume of PVA has been calculated from measuring the bulk volume as a function of temperature. The group contribution method is used for the calculation of the fractional of the free volume in the glassy and the rubbery states. For the glassy and rubbery states, the ratio of the thermal expansion coefficient of the bulk volume to that of the total free volume is calculated. There is an agreement between these ratios in glassy and rubbery states and those outcomes acquired from the PAL and the substance volume information. This indicated that the o-Ps lifetime is a sign to the free volume in the sample which is also proportional to the total free volume.

Two processes for crosslinking polyvinyl alcohol (PVA) with sulfosuccinic acid (SSA) and thermal crosslinking were used to fabricate a proton exchange membrane (PEM). Such PEMs are used in different fields involving fuel cell applications. The crosslinking reaction between PVA and SSA was confirmed using Fourier-transform infrared (FTIR) spectroscopy. The characterization of the prepared membranes, namely, ion exchange capacity (IEC), thermal analyses, water uptake, and ionic conductivity, was carried out. The IEC of the prepared membranes was found to be between 0.084 and 2.086 mmol g-1, resulting in an essential increase in the ionic conductivity. It was observed that the ionic conductivity was in the range of 0.003-0.023 S cm-1, depending on both temperature and SSA content. From the thermogravimetric analysis (TGA) results, it was revealed that the thermal stability of the crosslinked membranes improved. Moreover, water uptake decreased with increasing SSA content. Positron annihilation lifetime spectroscopy (PALS) was used to study the microstructure of the PVA/SSA membranes and their distribution at different ambient temperatures and relative humidity (RH) values. At room temperature, no significant change was observed in the free-volume holes up to 15 wt% SSA; thereafter, the size of the free-volume holes increased with the SSA content. The PALS results show that at different humidity values, the size of the free-volume holes for crosslinked PVA/SSA membranes is lower than those for Nafion membranes, i.e., the gas permeability for the prepared PVA/SSA membranes is less than that for the Nafion membrane. In addition, a strong correlation between the water uptake, ionic conductivity, tensile strength, and free-volume holes was observed.

Catalytic thermochemical cracking of polyethylene has been investigated in presence of a series of bentonite clay based nanocomposite with a view toward assessing their suitability in a process for converting plastic waste to fuel. Metal oxides such as manganese oxide (MnO), titanium oxide (TiO2) and zinc oxide (ZnO) were impregnated with sodium montomorillonite bentonite. The clay catalysts were characterized by x-ray diffraction (XRD), scan electron microscope (SEM), transmission electron microscope (TEM) and energy dispersive x-ray (EDX) spectrometers. The effect of different catalysts on the composition and the yield of gaseous was evaluated. ZnO nanocomposite bentonite clay achieved the highest methane gas formation around 93%. The superior catalytic performance of nanocomposites is probably attributed to their uniform dispersed of oxides particles on montmorillonite support.

Geothermal energy is probably the biggest wellspring of sustainable power sources. Compared with sunlight and wind power the geothermal power has numerous focal points, including being impenetrable to climate changes, having a steady base burden, and high heat productivity (for the high-temperature geothermal assets). In any case, the total capacity of installed geothermal energy plants falls behind sun based and wind. In this work, the geothermal power has been converged with solar energy. A test model concentrator thermoelectric generator utilizing an explanatory dish concentrator was created and tried. A sunlight-based gatherer has been utilized as the hotspot for the hot side of the thermoelectric module and the geothermal power has been applied as the cold wellspring for the cold side for the thermoelectric module. An electric flow as per the Seebeck hypothesis has been produced, as another wellspring of the sustainable power source. The capability of utilizing concentrated sunlight-based power age framework dependent on the thermoelectric module and geothermal power has been examined. The maximum voltage 11.7 V was obtained in the present work, when the maximum temperature for the hot side 93 °C and cold side 21°C.

Fourier transform infrared (FTIR), γ-ray attenuation and positron annihilation lifetime (PAL) spectroscopies were performed to study the physical and nanostructure properties of prepared Na2O-B2O3–PbO–SiO2–Bi2O3 (NBSi) glasses with different concentration of TiO2. The FTIR spectra of alkali lead titanate borosilicate glasses had different ratios of Bi2O3 are analyzed. The detailed examination revealed a creation of BO4 on the expense of BO3 and BiO3 structural units. This process with the increment of Bi2O3 polymerized the network of the studied glasses. The decrease in the fraction N4 indicates this process. It was found that the γ-ray attenuation parameters [the half value layer HVL, the tenth value layer TVL, the mean free path MFP, the linear attenuation coefficient μ and the mass attenuation coefficient μm] at the energy of 661.7 keV and the density ρ decreases with increasing the TiO2 contents on the prepared glasses. The size of the ortho-positronium hole volume (o-Ps) (obtained from PAL) with its contents decrease with increasing the TiO2 concentration as a result of filling the hole with TiO2. There is a fair agreement between density, relative fractional of the o-Ps open hole size and mass attenuation coefficient μm of the glass samples. The acquired results indicated a formation of non-bridging oxygens associated with the borosilicate network, which decreases its rigidity and thus, decreases its preceding physical parameters.

The original version of this article unfortunately contains mistakes introduced during the production process. The article’s title was erroneously changed to “Tracking free volume changes in bisphenol-a based in polycarbonate a positron sheets after treatment with liquid acetone”.

Free volume properties, size and distribution, in the bisphenol-a based polycarbonate (PC) sheets were investigated as a function of the treatment duration by liquid acetone using the positron annihilation lifetime (PAL) spectroscopy. Along with increasing the PC treatment duration, the free volume sizes decreased and the holes-distribution broadened, which in turns led to the polymer crystallization induction. From the PAL and WAXD data, it has been confirmed that the crystallization capability of the amorphous PC tremendously enhanced, with a rapid increase of the PC crystallinity along with increasing the treatment duration by liquid acetone. These findings were further confirmed by the surface chemistry and topography characterization techniques which revealed the formation of crystalline structure after liquid acetone treatment. The solvent-induced crystallization of PC sheets promoted restrictions to the infrared induced molecular vibrations the surface functional groups which was reflected as drop in peaks intensities and shift of the carbonyl peak of the Fourier transform infrared (FTIR) spectrum.

Slow positron beam and optical absorption measurements are carried out to study structural defects and positronium formation in 40 keV B(+)-implanted polymethylmethacrylate (B:PMMA) with ion doses from 6.25 × 10(14) to 5.0 × 10(16) ions/cm(2). Detailed depth-selective information on defects in implanted samples was obtained by measuring of Doppler broadening of positron annihilation γ rays as a function of incident positron energy and these experimental results were compared with SRIM (stopping and range of ions in matter) simulation results. Two general processes, appearance of free radicals at lower ion doses (10(16) ions/cm(2)) and carbonization at higher ion doses (10(16) ions/cm(2)), are considered from the Doppler S-E and W-E dependences in the framework of the concept of defects formation during radiation damage of polymer structure. Probabilities of ortho-positronium (o-Ps) formation are analyzed using S-W plot and slow positron annihilation lifetime measurements. Dose dependence of o-Ps lifetime τ3 and intensity I3 at the incident positron energy of 2.15 keV correlates well with the dose dependence of S-parameter and seems to account for the existence of the expected two processes, i.e., scission of polymer chains and appearance of free radicals preceding the aggregation of the clusters resulting in the formation of network of conjugated bonds at lower ion doses and carbonization at higher ion doses. The increase of optical absorption observed with increasing ion implantation dose also suggests a formation of carbonaceous phase in the ion-irradiated PMMA.

Fuel cell has two essential problems, its cost and the durability, which hinder its commercialization. Platinum is the ideal catalyst that has high activity, stability and selectivity but has high cost. An attempt has been done to find a cheaper catalyst instead of platinum. Zinc oxide nanoparticles were synthesized via sol-gel method using zinc acetate and citric acid in basic media with different calcination temperatures (420, 520 and 620 °C). From X-ray diffraction (XRD) patterns, the calculated particles size is 7.7, 15.6 and 19.3 nm as the calcination temperature of 420, 520 and 620°C, respectively, indicating that the particles size increases with increasing the calcination temperature. Different concentrations (5 and 10 wt.%) of ZnO nanoparticles with 10 wt.% polyvinyl alcohol (PVA) were prepared and calcinated at 750 °C to get carbon/ZnO as a catalyst for fuel cell applications. A carbon core-shell surrounding by mono-disperse ZnO nanoparticles with large surface area that required for the new catalyst with believable morphology was shown by transmission electron microscope (TEM). Also, XRD presents high purity of the new composite with uniformly distinguishable peaks. Fourier transformation infrared (FTIR) spectroscopy shows the change in the carbon/ZnO nanoparticles spectra due to ZnO characteristic vibration band at 440-460 cm−1. Cyclic voltammetry (CV) exhibits a good promising catalytic activity and current density with oxidation behaviour is reported. Finally, ZnO used to enhance carbon electrochemically performance as a result of a novel non-precious catalyst.

To study the property of proton conduction for electrolyte thin film inside catalyst layer, model ionomer thin films were prepared on different surfaces such as carbon and platinum substrates. An atomic force microscopy coupled with electrochemical technique (e-AFM) demonstrated that proton conduction reduced with film thickness, and abruptly decreased when film thickness was less than 10 nm for both carbon and platinum substrate. This indicates that number of active proton conductive pathway and/or connectivity of proton path network change with film thickness, and is though that the morphology of thin film is essentially different from that of a bulk membrane.

Solutions of Nafion® with an ion exchange capacity (IEC) of 0.91 meq g(-1), which are on the verge of the formation of SO(3)H nanoclusters, were spin coated on silicon (Si), glassy carbon (GC) and platinum/silicon (Pt/Si) substrates to form films of up to 256 nm thickness. Nanostructure of the films was studied using Doppler broadening of annihilation radiation (DBAR), positron annihilation lifetime (PAL), X-ray photoelectron spectroscopy (XPS), an atomic force microscope (AFM) and contact angle measurements. Contact angles as low as 10 degrees indicate that the surface of dry ultrathin Nafion® films on Si is highly hydrophilic. XPS data of 10 nm thick, ultrathin film on Si show that oxygen concentration is enhanced and the SO(3)H group concentration, in other words, IEC on the surface is much higher than other films. The S parameter measured by DBAR of an ultrathin Nafion® film on Si is much higher than that of the films on the other substrates. We consider that a large number of hydrophilic, reversed micelle like SO(3)H groups are on the surface of the ultrathin Nafion® film on Si but not on the surface of other films. Positrons implanted into the film are trapped by the SO(3)H clusters, annihilating with the electrons of oxygen and exhibit the high S parameter. The SO(3)H concentration on the surface of thin Nafion® films on GC and Pt/Si substrates may not be so high as the threshold for the formation of a large number of SO(3)H clusters. Positrons implanted into the films annihilate mostly with fluorine atoms, resulting in a low S parameter. The film-substrate interaction plays an essential role in nanostructuring of Nafion® thin films, which may also be the case for Nafion® on the catalysts of polymer electrolyte fuel cells.

Nafion® is one of the most popular proton conducting membranes for polymer electrolyte fuel cells (PEFCs). For the integration of Nafion® to the catalyst layers, very thin layers of the polymer are often formed on the catalysts of PEFC from dilute solutions. We applied energy variable positron annihilation to characterizing the structure of thin Nafion® films prepared by spin and dip coating from ethanol/water solutions of Nafion® on Si substrates. Experimental data suggest that the nano-structure of 23 nm thick spin coated Nafion® film is different from 220 nm thick film and also from 26 and 227 nm thick dip coated films, possibly due to the preservation of the unique rod-like structure of Nafion® in the dilute solution.

Variations of ortho-positronium (o-Ps) lifetime and gas permeability of the Aquivion® E8705 membrane were studied as functions of temperature under vacuum and relative humidity at room temperature. When the temperature was varied between 0 and 100 °C in vacuum, the hole volume of Aquivion® E8705, deduced from the ortho-positronium lifetime, gradually increased. However, when the relative humidity was changed at room temperature, the hole volume was essentially unchanged. Good linear correlations between the logarithm of permeabilities of O2 and H2 and reciprocal hole volume at different temperatures indicates the importance role of free volume in gas permeation in dry Aquivion® E8705. However, for hydrated Aquivion® E8705 the permeability less depends on hole volume.

Positron annihilation lifetime spectroscopy (PALS) has widely been used for probing open volume defects in various materials. PALS is in principle non-destructive, yet conventional PALS is not strictly non-destructive because cutting out of two specimens from the material is required. Recently we developed a novel method of PALS, which is potentially applicable to non-destructive, onsite material inspection. In order to explore the possibility of onsite monitoring of polymer degradation by this novel method of PALS, we studied variations of positron lifetime and mechanical properties of ultra high molecular weight polyethylene (UHMWPE) subjected to γ-irradiation. Correlations were found between the mechanical properties and ortho-positronium lifetimes, suggesting the feasibility of non-destructive, onsite monitoring of polymer degradation by PALS. The effect of γ-irradiation on positronium formation is discussed.

The behavior of positrons that do not form positronium in dry fluorinated polymer electrolyte membranes (Nafion®, Fumapem® and Aquivion®) with various ion exchange capacities (IECs) was studied by the combined use of Doppler broadening of annihilation radiation (DBAR) and the positron lifetime technique. The drastic increase of the S parameter, measured by DBAR, with increasing IEC above 0.91 meq/g indicates that increasing numbers of positrons are trapped by oxygen atoms and annihilate with the electrons bound in them. Reversed micelle like SO3H nanoclusters to trap positrons possibly appear at IEC = 0.91 meq/g and their concentration increases with increasing IEC.

The ortho-positronium (o-Ps) lifetime was measured as a function of temperature for the perfluorinated PEMs Nafion NR212 and Aquivion E8705. The o-Ps lifetime in Aquivion E8705 was found to be shorter than Nafion NR212 in the entire temperature range studied. Abrupt changes in the temperature coefficient of the o-Ps lifetime were noticed and the a-relaxation, b-relaxation,and stress relief temperatures were identified. It turned out that Aquivion E8705 has higher a-relaxation and stress relief temperatures than Nafion NR212. Dissociation of the ionic clusters and large change in the nanostructure after heating to 1608C were observed for Nafion NR212 but not for Aquivion E8705. It is demonstrated that Aquivion E8705 has a higher thermal stability than Nafion NR212.

Free volume, O2 permeability, and uniaxial compression storage modulus of biphenol-based sulfonated poly(arylene ether sulfone) (BPSH) with an ion exchange capacity (IEC) of 1.60 mequiv./g were studied as a function of relative humidity at room temperature. The free volume hole size was quantified using the positron annihilation lifetime (PAL) technique, whereas the uniaxial compression storage modulus was measured by dynamic nanoindentation. Favorable formation of positronium (Ps) due to the anti- inhibition effect of -SO2- allowed for the application of the PAL technique to the study of free volume in BPSH. It was found that as the polymer is hydrated the free volume hole size (VFV,Ps) and O2 permeability (PO2 ) first decrease and then increase. A semi-logarithmic plot of PO2 versus 1/VFV,Ps for BPSH at different relative humidities showed a good correlation similar to that for different polymers such as polystyrene and polycarbonate in the dry state. Tendency of PO2 deviating from the correlation in highly hydrated BPSH suggests an effect of polymer softening on O2 permeation in addition to the dominant effect of the free volume.

Gasification is one of the most important solutions for plastic waste management. We researched the conversion of plastic waste to fuel using sustainable material (Nano Clay) modified with Nano transition metals (TiO2, MnO, and ZnO). This was processed in a fix bed reactor design. After studying the reaction mechanism of the gasification process, we evaluated the optimize (reactor temperature, reaction time and feeding ratio of the modified catalyst) on the gasification process with its application for the modified catalyst on the degradation of polyethylene high density(PEHD), other waste plastic to fuel (CH4, H2, and other light component gasses). This method can be used as an important resource for renewable energy (like generating electricity and clean fuel), rather than waste for landfills and the incineration process which is the main source of CO2 emissions.

Positron annihilation lifetime and oxygen permeability in ion-exchanged forms (H+-, Na+-, K+-, Cu2+-, Ni2+-, and Fe3+-forms) of Nafion® membranes for polymer electrolyte fuel cells (PEFC's) have been investigated as a function of temperature. Exchange of H+ with Cu2+, Ni2+, or Fe3+ in Nafion® decreases both the o -Ps lifetime and its intensity, being interpreted as the result of inhibition and quenching of Ps. For the H+-, Na+-, and K+-forms good correlations were observed between the logarithm of the O2 permeability and o -Ps lifetime (free volume size) at different temperatures indicating the important role played by the free volume in O2 permeation. Considerable downward deviation of the correlations for the Na+- and K+-forms from the H+-form revealed the importance of polymer stiffening in O2 permeation. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Variations of the free volume, O2 permeability, and structure of the Nafion membrane upon ion exchange of H+ with Na+ and K+ were studied. The free volume was quantified using the positron annihilation lifetime (PAL) technique, whereas the polymer structure was characterized by dynamic mechanical analysis (DMA), nanoindentation, and wide-angle X-ray diffraction (WAXD). It was found that the ion exchange significantly expands the free volume and at the same time decreases the O2 permeability. This is opposed to the simple free volume model in which the structure with less open volume is more amenable to lower permeability. Comparison of experimental data collected by different techniques revealed that not only the free volume but also the polymer stiffness plays an essential role in O2 permeation.

Positron annihilation technique as a probe of subatomic vacancies is described for non-positron polymer scientists.Although positronium (Ps) is an unparalleled unique probe of inter-molecular vacancies in insulating materials, withboth its intensity and mean lifetime carrying information about the free volume, the processes that lead to these phys-ical quantities are not simple. The state-of-the-art understandings of how Ps is created and how its mean lifetime isdetermined in vacancies are described, and examples of the unique feature as well as the problems and precautionsare illustrated.

Doppler broadening of annihilation radiation (DBAR) and positron annihilation lifetime spectroscopy (PALS) have been successfully applied to the study of positronium (Ps)—forming amorphous solids such as polymers and silicon oxide in the bulk. Implementing depth selectivity to DBAR and PALS by combining them with variable-energy positron beams considerably broadens their applicability. Variation of incident positron energy over a wide range enables depth-profiling, whereas tuning of the beam energy enables the studies of surfaces, interfaces and thin films. In this paper, we discuss fundamentals and applications of energy variable DBAR and PALS for Ps—forming polymers and silicon oxide.

The mechanism of gas permeation in Nafion membranes for polymer electrolyte fuel cells has been investigated from the viewpoint of free volume. Three different samples, a membrane with ionic exchange capacity (IEC) = 0.92 meq/g, and recast samples with IEC = 0.92 and 1.00 meq/g were used after drying. Free volume was quantified using the positron annihilation lifetime (PAL) technique and gas permeabilities were measured for O 2 and H 2 as functions of temperature and relative humidity. Good linear correlations between the logarithm of the permeabilities at different temperatures and reciprocal free volume indicate that gas permeation in dry Nafion is governed by the free volume. Nevertheless permeabilities are much smaller than the corresponding flexible chain polymer with a similar free volume size due to stiff chains of the perfluoroethylene backbone. In highly hydrated Nafion above 60% relative humidity, where the O 2 permeability varies oppositely to the free volume, gas permeation proved to be controlled by the gradual increase in overall flexibility of the Nafion–water system.

Coincidence Doppler broadening of annihilation radiation (CDBAR) and Vickers hardness techniques were performed to study pure Al2O3, pure polyvinyl chloride (PVC), and doped PVC with different concentrations of Al2O3 (10–50%). The CDBAR ratio curves with respect to pure PVC were presented and reflect the momentum distribution of all the samples. The peak around 14.5 ×10−3 moC in the CDBAR ratio curves suggests a large contribution of positron annihilation with the Al2O3. There is a linear correlation between the height of this peak and the Al2O3 concentration. The S- and W-parameters were extracted from the CDBAR spectra and increase with increasing the Al2O3 concentration showing discontinuity at 30% of Al2O3 concentration on PVC. The present data confirmed that there is no positronium formation in pure Al2O3 as a result of smaller S-parameter. The Vickers hardness increases with increasing the Al2O3 concentration in PVC showing a linear dependence with two different slopes depend on the Al2O3 concentration range. A correlation between the Vickers hardness (macroscopic data) and the W-parameter (microscopic data) was observed. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

The effect of gamma irradiation dose on microscopic structure of polymethylmethacrylate (PMMA) has been studied using positron annihilation lifetime (PAL) and Doppler broadening of annihilation radiation (DBAR) techniques. The measurements were performed at room temperature as a function of the γ-irradiation doses from 60-1200 kGy. The observed lifetime spectra were resolved into three components. The size and the fraction of the o-Ps hole volume were estimated from the positron annihilation parameters. The effect of γ-irradiation was identified at lower doses to be cross-linking while at higher doses the chemical degradation of the polymer was observed. Moreover, the distribution of the free volume shifts from a large to small size as the irradiation increases and has very similar Gaussian-like distribution. The PAL results were confirmed with X-ray measurement. A correlation between the macroscopic mechanical properties Hv and positron annihilation parameters has been demonstrated. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)