Properties of hardened concrete containing treated expanded polystyrene beads

This paper reports the results of an experimental investigation into the properties of hardened concrete containing chemically treated expanded polystyrene beads. The results showed that the strength, stiffness and chemical resistance of polystyrene aggregate concrete of a constant density were affected by the water to cement ratio. Drying shrinkage after 84 days of drying for polystyrene concretes, having 10 mm coarse aggregate and a nominal density of 1300 kg/m³, were 730 and 655 microstrains. Empirical equations were developed to relate the strength and pulse velocity and to predict the modulus of elasticity from its strength.     

Porous alumina ceramics prepared by slurry infiltration of expanded polystyrene beads

To produce highly porous MgO-doped alumina (Al₂O₃) ceramics, expanded polystyrene (EPS) beads were packed as a pore former and well-dispersed alumina slurry was used to infiltrate the pore space in the EPS bead compacts. The alumina particle-EPS bead green compacts were then heated to 1550°C in air to burn out the pore former and subsequently densify the MgO-doped alumina struts. The porous Al₂O₃ ceramics were featured with uniformly distributed open pore structures with porosities ranging from 72 to 78% and a pore interconnectivity of about 96%. The macropore size and the pore window size could be controlled by adjusting the size of the EPS beads and the contacting area between the EPS beads. The compressive strengths of the porous Al₂O₃ ceramics were in the range of 5.5–7.5 MPa, similar to those of cancellous bones (2–12 MPa). The porous alumina ceramics were further made bioactive after the dip coating of a sol-gel derived 58 S bioglass powder, followed by sintering at 1200°C.     

Synthesis, characterization and catalytic application of silver nanoshell coated functionalized polystyrene beads

Silver nanoshell coated cationic polystyrene beads have been synthesized at room temperature through immobilization of specific silver precursor ions followed by wet chemical reduction technique. Electrostatic field force has been taken into consideration for the immobilization of precursor ions onto the resin beads. The as-synthesized particles were characterized by XRD, XPS, SEM, EDX, and FTIR studies. The silver coated resin beads have been exploited as a solid phase catalyst to reduce 4-nitrophenol in presence of sodium borohydride. The detailed kinetics of the reduction process was monitored under varied experimental conditions. At the end of the reaction, the catalyst particles remain active, get separated from the product, 4-aminophenol and can be recycled for a number of times after the quantitative reduction of 4-nitrophenol. The activity of the solid-catalyst particles has been examined towards the reduction of other nitrophenols e.g., o-, m-nitrophenol and also for 2,4,6-trinitrophenol. The synthesis of anthranilic acid from o-nitrobenzoic acid has also been achieved using the composite materials as catalyst. The synthesis of the solid phase catalyst particles, their application and detailed kinetic aspects of the reduction of 4-nitrophenol have been reported.     

In-situ thermoset polyurethane coating of glass beads dispersed in polystyrene by reactive extrusion

The condensation reaction between hydroxyl terminated polybutadiene and an uritonimine modified 4, 4 diphenylmethane diisocyanate (liquid MDI) was carried out by reactive extrusion in the presence of propyl trietoxy amino silane treated glass-beads and polystyrene. Reactants were selected having a surface tension favoring the glass bead coating using the spreading coefficient concept. FTIR, SEC (size exclusion chromatography) and rheological analysis of the resultant material showed that condensation reaction had occurred leading to crosslinked Polyurethane located principally around the glass beads.     

A method to measure the fusion strength between expanded polystyrene (EPS) beads

Cellular polystyrene (EPS) is the most commonly used cellular thermoplast whose main applications are insulation and packages. One of its new applications is core material in building elements, and this poses higher requirements for strength. This is particularly evident in self-supporting roof elements. This study presents a method for determining the fusion strength between beads in cellular polystyrene and the dependence of this strength on processing. This method has also enabled us to determine the adhesion of cellular polystyrene beads to other materials, such as glass fibre, and it allows measurement of the fusion strength between EPS beads without the influence of porosity. Fusion strength was found to have a characteristic behaviour. It has an absolute upper limit, and fusion forces approximate this limit asymptotically as heating time is prolonged (this increase is dependent on the energy content of the steam).     

Modification of chloromethylated polystyrene with 2-mercabtobenzothiazole for application as a new sorbent for preconcentration and determination of Ag+ from different matrices

Chloromethylated polystyrene polymer (CMSP) modified with 2-mercabtobenzothiazole (MBT) has been developed for the selective separation and/or preconcentration of silver. The modified polymer (CMS-MBT) was characterized by elemental analysis and IR spectra. Batch and column modes were applied. The newly designed polymer quantitatively sorbed Ag⁺ at pH 2 when the flow rate is 5 ml min^?1. The maximum sorption capacity was 0.493 mmol g^?1 while the preconcentration factor was 250 for Ag⁺. The detection limit was 8 ng ml^?1. The desorption was effective with 5 ml of 2 mol l^?1 HNO₃ prior to detection using AAS. The modified polymer was highly ion-selective in nature even in the presence of large concentrations of electrolytes or organic media, with a preconcentrating ability for Ag⁺. The utility of the modified polymer to synthetic and drugs samples showed RSD values of <3% reflecting its accuracy and reproducibility.     

Deconvolution method for two-dimensional spatial-response mapping of lithographic infrared antennas

The spatial impulse response of antenna-coupled infrared detectors with dimensions comparable with the wavelength is obtained from a two-dimensional scan of a tightly focused CO(2)-laser beam. The method uses an experimental setup with submicrometer resolution and an iterative deconvolution algorithm. The measured spatial response is compared with numerically computed near-field distributions of a dipole antenna, with good agreement.     

Investigation and assessment of epoxy resin adhesives using Fourier-transform infrared spectrometry

Epoxy resin adhesives are very attractive for many industries, especially in the aerospace and automotive industries because they eliminate heavy connection elements, such as bolts and screws, and reduce the total weight. This study assesses developed epoxy resin adhesives using Fourier-transform infrared spectrometry. The curing reaction between Epikote 828 epoxy resin and Epikure polyamidoamine curing agent 3090, and the chemical structure of the additives (CAB-O-SIL TS-720) used for rheology control and six different types of fillers (calcite with particle diameters of 700 nm, 5 μm, and 10 μm, coated calcite with a particle diameter of 900 nm, and barite and calcite with a particle diameter of 5 μm) employed in the adhesives are investigated. The Fourier-transform infrared spectrometry results of the epoxy resin and curing agent demonstrate that 83.5 % epoxy conversion is achieved at a temperature of 25 °C. The chemical composition of the additives with six different types of fillers and 1 %, 3 %, and 5 % additions of CAB-O-SIL TS-720 prepared in both nujol mull and potassium bromide discs is characterized using Fourier-transform infrared spectrometry. The potassium bromide discs yield higher intensities owing to good packing of cubic particles of potassium bromide with nano particle size CAB-O-SIL TS-720 and all filler types.     

有机硅交联剂对硅树脂/聚苯乙烯多孔复合材料性能的影响

以苯乙烯(St)为单体,含甲基丙烯酰氧基丙基的有机硅树脂(MTQ)为交联剂,采用高内相比乳液模板(HIPE)法制备了蜂窝状、低密度及高孔隙率的MTQ/聚苯乙烯(PS)多孔复合材料,研究了MTQ对聚合物多孔复合材料微观结构、压缩性能及热稳定性的影响。结果表明:MTQ/PS多孔复合材料的泡孔呈立体球形且泡孔壁上有丰富的互连孔,相互贯通性良好,泡孔直径为2~9μm,互连孔的孔径大小介于0.35~1.85μm;所得多孔材料孔隙率可控,总孔隙率最高可达92%;该多孔复合材料的压缩强度为0.28~0.74 MPa,压缩模量为4.86~13.54MPa。当MTQ与St的质量比为30:100时,可获得泡孔直径较小、互连孔道较窄、压缩性能和热稳定性较好的MTQ/PS多孔复合材料。      

Computer simulation and infrared investigation on a novolac formaldehyde phenolic resin

Atomistic molecular dynamics computer simulations and infrared experiments have been performed to characterize the solid state of a formaldehyde phenolic resin. The infrared measurement of Novolak 1940 H qualitatively proves the existence of hydrogen bonding. Upon heating, the band of the free O-H vibrations increased at the cost of the associated band. The simulation of a system of purely ortho-substituted chains in comparison to the ensemble of randomly ortho-para substituted chains, showed that the amount of hydrogen bonding, which in both cases mainly acts intramolecularly, is much smaller in the latter system due to the larger separation of the polar OH groups.     

Integration of an immunosorbent assay system: analysis of secretory human immunoglobulin A on polystyrene beads in a microchip

An immunosorbent assay system was integrated into a glass microchip. Polystyrene beads were introduced into a microchannel, and then human secretory immunoglobulin A (s-IgA) adsorbed on the bead surface was reacted with colloidal gold conjugated anti-s-IgA antibody and detected by a thermal lens microscope. The scale merits of liquid microspace on the molecular behavior remarkably contributed to reduced assay time. The integration cut the time necessary for the antigen-antibody reaction by 1/90, thus shortening the overall analysis time from 24 h to less than 1 h. Moreover, troublesome operations required for conventional immunosorbent assays could be replaced by simple operations.     

Two-step curing reaction of epoxy resin studied by thermal analysis and infrared spectroscopy

A curing reaction of bisphenol A diglycidyl ether epoxy resin with 4,4'-diaminodicyclohexyl methane hardener was investigated by means of modulated differential scanning calorimetry (MDSC) and infrared (IR) spectroscopy. MDSC observation revealed that the curing process of the resin occurred in two steps. Mid-infrared and near-infrared spectra of the resin were measured as a function of temperature. The obtained spectra were analyzed by perturbation-correlation moving-window two-dimensional correlation spectroscopy (PCMW2D-COS). The first step was revealed as a polymerization reaction among the oxirane group and primary and secondary amine groups, followed by etherification; the second step of the curing process occurred in the vicinity of the gelation point and was characterized by the growth of a three-dimensional cross-linking structure with tertiary amine and etherification of the hydroxyl group.     

A convenient approach to synthesize silver nanoshell covered functionalized polystyrene beads: A substrate for surface enhanced Raman scattering

The synthesis of ultra-thin silver nanoshell on anionic polystyrene bead has been reported from specific silver precursor [Ag(NH₃)₂]⁺ primarily through ion exchange mechanism. The particles were characterized by SEM, EDX, XPS and XRD analysis. Finally, the particles were exploited as a solid substrate for surface enhanced Raman scattering study using crystal violet as a Raman probe.     

环氧树脂/微胶囊红磷体系对高抗冲聚苯乙烯阻燃性能的研究

用锥形量热仪、TGA、LOI及UL94垂直燃烧研究了Novolac对MRP阻燃高抗冲聚苯乙烯(HIPS)性能的影响.结果表明,在MRP阻燃HIPS中添加适量的Novolac,可以使材料的阻燃性能满足使用要求,且随着Novolac用量的增加,材料的阻燃性能和热稳定性上升.     

Near-field infrared imaging and spectroscopy of a thin film polystyrene/poly(ethyl acrylate) blend

The application of broadband, near-field infrared microscopy to the characterization of the mesoscale structure of a thin film polymer blend is described. Key features of this instrument, which couples the nanoscale spatial resolution of scanning probe microscopy with the chemical specificity of vibrational spectroscopy, include broad tunability and bandwidth, parallel spectral detection for high image acquisition rates, and infrared-transparent aperture probes. Nearfield spectral transmission images of a thin film of polystyrene/poly(ethyl acrylate) acquired in the C-H stretching region are reported. An assessment of the relative importance of transmission image contrast mechanisms is a significant aim of this work. Analysis of the near-field infrared spectra indicates that the image contrast in the C-H stretching region is largely due to near-field coupling and/or scattering effects. Identification and differentiation of the operative contrast mechanisms on the basis of their relative dependence on wavelength is discussed. Analysis of the contrast attributed to absorption is consistent with the chemical morphology of this sample derived from previous chemical modification/atomic force microscopy studies.     

Discrimination between virgin and recycled polystyrene containers by Fourier transform infrared spectroscopy and principal component analysis

A rapid and reliable method for discriminating virgin and recycled expanded polystyrene (EPS) containers was developed using Fourier transform infrared spectroscopy combined with principal component analysis. Standard normal variate, first and second‐order derivative spectra were compared for the discrimination results. The results show that carbonyl region (1780‐1620 cm^?1) spectra using first derivative transformation give the optimum classification results. In addition, the carbonyl compounds in EPS containers were detected to clarify the chemical difference between virgin and recycled containers, with a higher concentration of carbonyl compounds observed in recycled EPS containers. The combination of carbonyl region of Fourier transform infrared spectroscopy with chemometrics proved to be a promising method to discriminate virgin and recycled EPS containers, which could function as an additional tool for quality control of plastics.     

Improved stability of CdSeS/ZnS quantum dots against temperature,humidity, and UV-O3 by encapsulation in crosslinked polystyrene beads

Journal of Materials Science - Cadmium-based quantum dot nanocrystals are promising optoelectronic materials due to their core/shell structure, excellent properties, and fascinating potential...