Lateral earth pressure of granular backfills on retaining walls with expanded polystyrene geofoam inclusions under limited surcharge loading

Existing studies have focused on the behavior of the retaining wall equipped with expanded polystyrene(EPS)geofoam inclusions under semi-infinite surcharge loading rather than limited surcharge loading.In this paper,the failure mode and the earth pressure acting on the rigid retaining wall with EPS geofoam inclusions and granular backfills(henceforth referred to as EPS-wall),under limited surcharge loading are investigated through two-and three-dimensional model tests.The testing results show that different from the sliding of almost all the backfill in the EPS-wall under semi-infinite surcharge loading,only an approximately triangular backfill slides in the wall under limited surcharge loading.The distribution of the lateral earth pressure on the EPS-wall under limited surcharge loading is non-linear,and the distribution changes from the increase of the wall depth to the decrease with the increase of the limited surcharge loading.An approach based on the force equilibrium of a differential element is developed to predict the lateral earth pressure behind the EPS-wall subjected to limited surcharge loading,and its performance was fully validated by the three-dimensional model tests.

Performance Evaluation of Novel Eco-Materials Composed of Millet Husks, Rice Husks, and Polystyrene

Managing agricultural waste and expanded polystyrene (EPS) poses significant environmental and economic challenges. This study aims to create composites from millet husks, rice husks, and recycled EPS, using a manufacturing method that involves dissolving the polystyrene in a solvent followed by cold pressing. Various particle sizes and two binder dosages were investigated to assess their influence on the physico-mechanical properties of the composites. The mechanical properties obtained range from 2.54 to 4.47 MPa for the Modulus of Rupture (MOR) and from 686 to 1400 MPa for the Modulus of Elasticity in Bending (MOE). The results indicate that these composites have potential for applications in the construction sector, particularly for wood structures and interior decoration. Moreover, surface treatments could enhance their durability and mechanical properties. This research contributes to the valorization of agricultural and plastic waste as eco-friendly and economical construction materials.

Study of Rice Husks and Expanded Polystyrene Composites for Construction Applications

In the current context of environmental challenges, this study focuses on developing innovative and eco-friendly composites using rice husk and recycled expanded polystyrene. This dual-responsibility approach valorizes a by-product like rice husk, often considered waste, and reuses polystyrene, a plastic waste, thereby contributing to CO2 emission reduction and effective waste management. The manufacturing process involves dissolving recycled polystyrene into a solvent to create a binder, which is then mixed with rice husk and cold-compacted into composite materials. The study examines the impact of two particle sizes (fine and coarse) and different proportions of recycled polystyrene binder. The results show significant variations in the mechanical characteristics of the composites, with Modulus of Rupture (MOR) values varying from 2.41 to 3.47 MPa, Modulus of Elasticity (MOE) ranging from 223.41 to 1497.2 MPa, and Stiffness Coefficient (K) from 5.04 to 33.96 N/mm. These characteristics demonstrate that these composites are appropriate for various construction applications, including interior decoration, panel claddings, and potentially for furniture and door manufacturing when combined with appropriate coatings. This study not only highlights the recycling of agricultural and plastic waste but also provides a localized approach to addressing global climate change challenges through the adoption of sustainable building materials.

Study of the Conversion of Postconsumer Polystyrene on CeO2/HZSM-5 Type Materials

The catalytic conversion of polystyrene (PS) was studied in the presence of the materials type HZSM-5, CeO2, 10% CeO2/HZSM-5 and 20% CeO2/HZSM-5, which were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and nitrogen adsorption at 77K. The catalytic tests were performed via thermogravimetric analysis (TG) at heating rates of 5, 10 and 20˚C min−1 in a temperature range from 30˚C to 900˚C. For the tests, a ratio of 30% by mass of each catalytic material mixed with PS was used and the activation energy of the degradation process was determined by the Vyazovkin method. The obtained results showed that the addition of the catalyst to the PS in general reduced its degradation temperature. The 10% CeO2/HZSM-5 catalyst showed greater efficiency, as it resulted in lower activation energy for PS degradation. Thus, the combination of CeO2 with HZSM-5 resulted in materials with potential for application in the catalytic degradation of polystyrene and the results indicate that the production of a composite material can be a good strategy to generate an increase in catalytic activity and a decrease in energy process activation.

Comprehensive analysis of sodium polystyrene sulfonate-induced colitis:A systematic review

BACKGROUND Sodium polystyrene sulfonate(SPS)is commonly prescribed for the management of hyperkalemia,a critical electrolyte imbalance contributing to over 800000 annual visits to emergency departments.AIM To conduct a systematic review of documented cases of SPS-induced colitis and assess its associated prognosis.METHODS Following the PRISMA-P guidelines,our study employed Medical Subject Headings and Health Sciences Descriptors,skillfully combined using Boolean operators,to conduct comprehensive searches across various electronic databases,including Scopus,Web of Science,MEDLINE(PubMed),BIREME(Biblioteca Regional de Medicina),LILACS(Latin American and Caribbean Health Sciences Literature),SciELO(Scientific Electronic Library Online),Embase,and Opengray.eu.Language criteria were confined to English,Spanish,and Portuguese,with no limitations on the publication date.Additionally,we manually scrutinized the reference lists of retrieved studies.To present our findings,we utilized simple descriptive analysis.RESULTS Our search strategy yielded a total of 442 references.After rigorous evaluation,we included 51 references,encompassing 59 documented cases of colitis.Predominant clinical presentations included abdominal pain,observed in 35(60.3%)cases,and bloating,reported in 18(31%)cases.The most frequently affected sites of inflammation were the cecum,rectum,and small intestine,accounting for 31%,25.8%,and 22.4%of cases,respectively.Colonoscopy findings were described in 28(48.2%)cases,and 29(50%)of patients required surgical intervention.Among the subset of patients for whom outcome data was available,39(67.2%)experienced favorable outcomes,while 12(20.6%)unfortunately succumbed to the condition.The mean time required for resolution was 36.7 d,with a range spanning from 1 to 120 d.CONCLUSION SPS demonstrates the capacity to effectively lower serum potassium levels within 24 h.However,this benefit is not without the risk of bowel injury.Our study highlights the absence of high-quality data pertaining to the incidence of adverse events associated with SPS usage,making it challenging to determine whether the potential risks outweigh the benefits.However,a significant mortality rate related to SPS-induced colitis was noted.Future investigations should prioritize randomized controlled trials with a sufficiently large patient cohort to ascertain the true utility and safety profile of this medication.

An energetic nano-fiber composite based on polystyrene and 1,3,5-trinitro-1,3,5-triazinane fabricated via electrospinning technique

Electrospinning is a simple technique used to fabricate polymeric nano-fibrous membranes.These nano-fibers have found a wide range of valuable applications in the biomedical field.However,it has not been utilized with solid high explosives yet.Herein,the electrospinning technique has been used to fabricate polystyrene(PS)/1,3,5-trinitro-1,3,5-triazinane(RDX)composite nanofibers.The governed electrospinning parameters,voltage,distance from the collector,flow rate,mandrel rotating speed,time,and solution concentration,that greatly affect the morphology of the obtained nanofibers were optimized.The fabricated PS/RDX nano-fibers were characterized using scanning electron microscopy(SEM),X-ray diffractometer(XRD),and Fourier Transform Infrared(FTIR)spectroscopy.The impact and friction sensitivities of PS/RDX were also measured.The thermal behavior of the prepared composite and the pure materials were studied by the thermal gravimetric analysis technique(TGA).SEM results proved the fabrication of PS/RDX fibers in the nano-size via electrospinning.FTIR spectroscopy confirmed the existence of the characteristic functional groups of both PS and RDX in the composite nano-fibers.XRD sharp peaks showed the conversion of amorphous PS into crystalline shape via electrospinning and also confirmed the formation of PS/RDX composite.The PS fibers absorbed the heat and increased the onset decomposition of the pure RDX from 181.5 to 200.7℃in the case of PS/RDX fibers.Interestingly,PS/RDX nano-fibers showed the relatively low impact and friction sensitivities of 100 J and 360 N respectively.These results could introduce PS/RDX nanofibrous composite in the field of explosives detection with high levels of safety.

HALOMETHYLATION OF POLYSTYRENE AND SUBSEQUENT PYRIDINATION VIA A HOMOLYTIC PATHWAY

Chloromethylation of polystyrene （PS） with two different chloromethylating systems methylal/thionyl chloride and paraformaldehyde/trimethylchlorosilane was studied. Soluble chloromethylated polystyrene with a degree of substitution of 89% was obtained. The Conant-Finkelstein reaction on the chloromethylated PS afforded soluble iodomethylated polystyrene with a degree of substitution as high as 96%. The reaction conditions of Minisci were employed to radically pyridinate PS via its iodomethylated derivative. Polyelectrolytes were formed which could be converted to normal polymers by treatment with a 20% aqueous solution of NaOH.

Influence of expanded polystyrene size on deformation characteristics of light weight soil

Deformation characteristics of light weight soil with different EPS (expanded polystyrene) sizes were investigated by consolidation tests.The results show that the confined stress-strain relation curve is in S shape,which has a good homologous relation with e-p curve and e-lgp curve,and three types of curves reflect obvious structural characteristics of light weight soil.When cement mixed ratio and EPS volume ratio are the same for different specimens,structural strength decreases with the increase of EPS size,but compressibility indexes basically keep unchanged within the structural strength.The settlement of light weight soil can be divided into instantaneous settlement and primary consolidation settlement.It has no obvious rheology property,and 90% of total consolidation deformation can be finished in 1 min.Settlement-time relation of light weight soil can be predicted by the hyperbolic model.S-lgt curve of light weight soil is not in anti-S shape.It is proved that there is no secondary consolidation section,so consolidation coefficient cannot be obtained by time logarithm method.Structural strength and unit price decrease with the increase of EPS size,but the reducing rate of the structural strength is lower than that of the unit price,so the cost of mixed soil can be reduced by increasing the EPS size.The EPS beads with 3-5 mm in diameter are suggested to be used in the construction process,and the prescription of mixed soil can be optimized.

Weatherability Studies on External Insulation Thermal System of Expanded Polystyrene Board,Polystyrene Granule and Polyurethane Foam

Atmospheric exposure tests including two experimental stages of high temperature-spraying water cycle and heating-refrigeration cycle were carried out on three currently used ETIS of expanded polystyrene（EPS） board,polystyrene granule mortar and polyurethane foam in order to study the weatherablility of external thermal insulation system（ETIS）.The change rules of adhesive strength were hereby studied at different time period of atmospheric exposure tests.The experimental results show that the adhesive strength of three kinds of ETIS changes a little during high temperature-spraying water cycle,but the adhesive strength of ETIS with EPS board decreases significantly after heating-refrigeration cycle.The lowering rate of adhesive strength with painting finishes is obviously faster than that of tile finishes for ETIS of EPS board during heating-refrigeration cycle.The weatherability of ETIS with EPS board is worse than the other two,and ETIS of polystyrene granule mortar and polyurethane foam are more suitable than ETIS of EPS board in cold area.

Study on Synthesis, Characterization and Catalytic Activity of Polystyrene-supported Mo (VI) Complex in Epoxidation of Cyclohexene

Molybdenum (VI) complex, namely molybdenum dioxobis(2,4-pentanedione) [MoO2(acac)2] used as epoxidation catalyst species, was synthesized and characterized by elemental analysis and infrared spectrum. Polystyrene-supported molybdenum dioxobis(2,4-pentanedione) [MoO2(acac)2] for synthesis of epoxycyclohexane was prepared by phase transfer catalysis method. Effects of various factors in synthesis of epoxycyclohexane by reaction of cyclohexene and t-BuOOH in the atmosphere of nitrogen catalyzed by polystyrene-supported MoO2(acac)2 were also investigated. Under the following conditions, n(cyclohexene):n(t-BuOOH)=3.5:l (based on 0.1 mol of t-BuOOH), volume of solvent -10ml, reaction temperature -80℃, reaction time -60min, and mass of molybdenum in the catalyst -2.30×0^(-3)g, the yield of epoxycyclohexane on the basis of t-BuOOH is over 99.5%, and the purity of epoxycyclohexane is about 99.9% by gas chromatogram(GC) analysis.

Hydrogenation of Commercial Polystyrene over Pd/BaSO_4 Catalysts: Effect of Carrier Structure

A variety of barium sulfate(BaSO4) carriers with or without mesopore structure were synthesized via precipitation reaction in aqueous solution of barium hydroxide and sulfuric acid with ethylene glycol as a modifying agent, and then calcined at various temperatures. The obtained BaSO4 was used as catalyst carriers for polystyrene(PS) hydrogenation, and BaSO4 supported palladium(Pd) catalysts with Pd content of 5wt% were prepared by using impregnation method. N2 physisorption, transmission electron microscopy, X-ray diffraction and kinetics studies were used to investigate the effect of carrier structure on the dispersion and geometric location of active metal and their catalytic activities in PS hydrogenation. It was found that the pore structure of carrier played an important role in the dispersion and location of Pd grains. The activation energy values for all the Pd/BaSO4 catalysts were around 49.1kJ/mol, while the pre-exponential factor for Pd/BSC-6H was much higher than others. The Pd/BSC-6H without mesopores had Pd grains deposited on the external surface of the carrier, and exhibited better activity than the mesoporous catalysts. It is indicated that the utilization of Pd/BSC-6H can reduce the pore diffusion of PS coils and enabled more active sites to participate in the PS hydrogenation.

“Cutting effect” of organoclay platelets in compatibilizing immiscible polypropylene/polystyrene blends

In this work, polypropylene (PP)/polystyrene (PS) blends with different organoclay concentrations were prepared via melt compounding. Differing from the results of previous reports, the organoclay platelets are mostly located in the dispersed PS phase instead of the interface. The dimensions of the dispersed PS droplets are greatly reduced and apparent compatibilization effect still exists, which cannot be explained by the traditional compatibilization mechanism. A novel compatibilization mecha- nism, "cutting" to apparently compatibilize the immiscible PP/PS blends was proposed. The organoclay platelets tend to form a special "knife-like structure" in the PS domain under the shear stress of the continuous PP phase during compounding. The "clay knife" can split the dispersed PS domain apart and lead to the dramatic reduction of the dispersed domain size.

Fabrication of Large-area 3-D Ordered Silvercoated Colloidal Crystals and Macroporous Silver Films Using Polystyrene Templates

The highly ordered silver-coated colloidal crystals arrays and macroporous silver films were derived through an electrostatics-induced adsorption effect using polystyrene(PS) as templates. Carboxyl-modified PS microspheres were prepared by emulsifier-free emulsion polymerization using methacrylic acid(MAA) as the functional monomer. PS microspheres were self-assembled into close packing colloidal crystals of facecentered cubic arrays to the substrate with vertical deposition method. These colloidal crystals were modified using dopamine(DA) to form poly-dopamine(PDA) during its oxidative polymerization. Through electrostatic interaction, the silver nanoparticles were deposited and adsorbed onto the surfaces of colloidal crystals templates by exposing [Ag(NH_3)_2]^+solution to infrared irradiation. Removal of the polymeric template by etching with methylbenzene solvent resulted in 3D ordered macroporous silver films. The structural and properties of the ordered silver-coated arrays and macroporous silver films were characterized by field emission scanning electron microscopy(FE-SEM), X-ray diffraction(XRD), UV-vis spectroscopy and surface-enhanced Raman spectroscopy(SERS). The results indicate that the prepared silver-coated arrays and macroporous silver films possess the features of ordered multilayer arrangement, uniformity and repeatability as well as an ideal SERS effect.

VAPOR-LIQUID EQUILIBRIA FOR MIXTURES OF TOLUENE AND POLYSTYRENE WITH DIFFERENT MOLECULAR WEIGHTS

An experimental system for measuring the VLE of polymer solutions based on the staticvapor-pressure method has been established,VLE data for mixtures of toluene and polystyrene withdifferent molecular weight covering a wide range from 2.98×10~3 to 3.84×10~6 were obtained at 35℃.The reduced pressure p/p°versus weight fraction W plot is found to be independent on the molecularweight of the polymer within the experimental error.Calculated activity coefficients are also independenton the molecular weight.However,for the Flory-Huggins interaction parameter x,not only a strongconcentration dependence is observed,but also the molecular weight of the polymer exerts definiteinfluence.Generally,the parameter x slightly increases as the molecular weight of the polymer decreasesespecially when the molecular weight is low.The dependence of the parameter x on the molecularweight can be neglected when the molecular weight of polymer is greater than 1.00×10~4.

Prediction of Sintering Strength for Selective Laser Sintering of Polystyrene Using Artificial Neural Network

In the present work,a study is made to investigate the effects of process parameters,namely,laser power,scanning speed,hatch spacing, layer thickness and powder temperature, on the tensile strength for selective laser sintering( SLS) of polystyrene( PS). Artificial neural network( ANN) methodology is employed to develop mathematical relationships between the process parameters and the output variable of the sintering strength. Experimental data are used to train and test the network. The present neural network model is applied to predicting the experimental outcome as a function of input parameters within a specified range. Predicted sintering strength using the trained back propagation( BP) network model showed quite a good agreement with measured ones. The results showed that the networks had high processing speed,the abilities of error-correcting and self-organizing. ANN models had favorable performance and proved to be an applicable tool for predicting sintering strength SLS of PS.

Fabrication of Fluorescent Porphyrin/Polystyrene Composite Nanospheres by Electrospinning

Fluorescent polystyrene（PS）/porphyrin（TPPA） composite nanospheres were successfully fabricated by electrospinning. The SEM images clearly show that owing to adding TPPA in PS, the averaged diameter of the composite nanospheres became smaller, from 1500 to 580 nm. Fourier-transform infrared（FTIR） spectra determined the chemical composition of the resulting PS/TPPA composite nanospheres. The photoluminescent（PL） spectral analysis indicates that the peak position of the composite nanospheres in either solid state or water is identical to that of pure TPPA, at about 652 nm, and is still unchangeable when they are left for at least 20 d, indicating the stable photoluminescent property of the fluorescent composite nanospheres.

Effective Organochlorine Pesticides Removal from Aqueous Systems by Magnetic Nanospheres Coated with Polystyrene

In this paper, magnetic nanospheres coated with polystyrene （Fe3O4@PS） were prepared for the removal of organochlorine pesticides from aqueous solutions. The obtained Fe3O4@PS was round shape with diameter of 55±11 nm. The VSM results illustrated that its higher saturated magnetization was 36.76 emu g^-1 and it could be easily separated from aqueous solutions with a permanent magnet. The adsorption results showed that pesticides could be effectively adsorbed and the adsorption equilibrium time was less than 20 mins. The pseudo-second-order model was suitable to describe the adsorption kinetics. Compared with the Freundlich adsorption model, the adsorption data fitted well with Langmuir model. The effect of salinity and humic acid was also studied and the results illustrated that they could be neglected under optimized conditions. The asobtained sorbent showed a good performance with more than 93.3% pesticides removal in treating actual water samples.

Facile Fabrication of Large Area Polystyrene Colloidal Crystal Monolayer via Surfactant-free Langmuir-Blodgett Technique

A facile and novel method for the production of a large area of well-ordered polystyrene （PS） colloidal crystal monolayer was established using the surfactant-free Langmuir-Blodgett （LB） technique. The hydrophobic property （film-forming ability） of PS spheres was improved by a thermo-rheology treatment before LB assembly, and a large film was obtained. In contrast to the traditional LB technique, no surfactant was needed in this method, which could eliminate the additional contamination of surfactants in the preparation process and provided the products with versa- tile applications in nanosphere lithography （NSL） for biosensor, surface plasmon resonance, and surface enhanced Raman spectroscopy .

Ambiguity of Polystyrene Aerosol Beads Properties Found with Mie Spectra Analysis

Broadband Mie scattering is used to determine the parameters of polystyrene aerosol beads in air,such as size and wavelength dependence of refractive index.This method consists in the selection of such parameters of the scattering object,which reproduce observed spectrum properties.That is why it is very sensitive and hence very precise.We found that there is an ambiguity of polystyrene aerosol beads properties,determined with this method.Different combinations of polystyrene particle size and its refractive index can give the same position of Mie resonances.This ambiguity leads to an increase in the error in determining the size and refractive index of the particle.The refined errors are calculated and the way of their reduction is indicated.

Seed-mediated growth of gold nanoparticles using self-assembled monolayer of polystyrene microspheres as nanotemplate arrays

Arrays of noble metal nanoparticles show potential applications in （bio-）sensing, optical storage, surface-enhanced spectroscopy, and waveguides. For all such potential devices, controlling the size, morphology, and interparticle spacing of the nanoparticles is very important. Here, we combine seed-mediated growth with nanosphere lithography to study the controllable growth of gold nanoparticles （Au NPs）, in which the self-assembly monolayer of polystyrene （PS） on a silicon surface is used to guide the modification of allaunesilanes and the subsequent adsorption of gold seeds; seed-mediated growth is applied to controlling the morphology and size of Au NPs. The size of adsorption region （determining the number of adsorbed gold seeds） is controlled by etching PS microspheres with oxygen plasma or annealing PS microspheres at the glass transition temperature. The size and morphology of the Au NPs are controlled by changing growth conditions. In such a way, we have achieved the dual control of the obtained Au NPs. Preliminary results show that this strategy holds a great promise. This approach can also be extended to a wide range of materials and substrates.