Polystyrene Glass Research Articles

Solubility of supercritical CO2 in polystyrene

Expanded polystyrene (ePS) plays an important role in the food packaging industry. However, the foaming process is environmentally unfriendly. A sustainable alternative is dissolving supercritical CO2 (scCO2) in the polystyrene (PS) matrix. Most studies so far were performed at temperatures above the PS glass transition temperature; however, a more general temperature window is desirable. In this work, the solubility of scCO2 in polystyrene was measured at 323 K, 343 K, 363 K and 383 K and pressure up to 130 bar using a magnetic suspension balance (MSB). It was concluded that the solubility of CO2 in PS decreases with temperature and increases with pressure. The Sanchez-Lacombe Equation of State was utilized to estimate the degree of swelling. The model developed was able to derive the experimentally determined solubilities after correction for the swelling. The interaction parameter, k12, turned out to be only a function of temperature. With these results the solubility and swelling of PS in scCO2 can be more accurately assessed for different temperatures and pressures.

Trans-Stilbene aggregates and crystallites in polystyrene films: microscopy and spectroscopy studies.

Solid and liquid stilbene forms were characterized using a range of techniques, including atomic force microscopy, coherent anti-Stokes Raman scattering microspectroscopy and optical spectroscopy. The obtained experimental results were analyzed by means of quantum chemical calculations and using a non-negative matrix factorization algorithm. It was confirmed that pure cis-stilbene formed a homogeneous fluid film on a glass substrate, whereas pure trans-stilbene formed crystals. Mixtures of trans-stilbene and polystyrene were shown to form stable solid films, which were non-homogeneous on the microscopic scale: stilbene molecules self-organized into microcrystals, which floated on the surface of polystyrene glass.

Determination of optimum insulation thickness in submarines

One of the most effective ways to save energy for cooling and heating applications is thermal insulation. Because of this, determining the ideal insulation thickness is a popular topic for publications. The purpose of this study is to determine the appropriate insulation thickness needed for a submarine’s external construction while it is cruising in various locations. Since seawater makes up a submarine’s external environment, situations involving five distinct sea-water temperatures from around the globe have been studied. There are five of them: the Med-iterranean, Marmara, Aegean, Black Sea, and Sakhalin, which is in the North Pacific Ocean and has the coldest seawater on earth. By using the idea of degree-days, the annual cooling and heating needs of submarines in various regions have been computed. Based on life cycle cost analysis, optimization has been accomplished. In the beginning, the results of a study published in the literature supported the calculation methods utilized. The use of insulation materials such as rock wool, glass wool, polyurethane, expanded polystyrene, fiberglass, and foam glass, as well as fuel oil to run the generator, has been taken into account in a number of calculations, including the best insulation thickness, annual savings value, annual energy cost, and payback period. The findings indicate that depending on seawater temperatures and in-sulation materials, the ideal insulation thicknesses range between 2 and 12 cm, energy savings between 8.5% and 90%, and payback periods between 1.1 and 10 years.

Permittivity-Based Microparticle Classification by the Integration of Impedance Cytometry and Microwave Resonators.

Permittivity of microscopic particles can be used as a classification parameter for applications in materials and environmental sciences. However, directly measuring the permittivity of individual microparticles has proven to be challenging due to the convoluting effect of particle size on capacitive signals. To overcome this challenge, we built a sensing platform to independently obtain both the geometric and electric size of a particle, by combining impedance cytometry and microwave resonant sensing in a microfluidic chip. This way the microwave signal, which contains both permittivity and size effects, can be normalized by the size information provided by impedance cytometry to yield an intensive parameter that depends only on permittivity. The technique allowed us to differentiate between polystyrene and soda lime glass microparticles -below 22 microns in diameter- with more than 94% accuracy, despite their similar sizes and electrical characteristics. Furthermore, we show that the same technique can be used to differentiate between normal healthy cells and fixed cells of the same geometric size. The technique offers a potential route for targeted applications such as environmental monitoring of microplastic pollution or quality control in pharmaceutical industry. This article is protected by copyright. All rights reserved.

Variability in Donor Lung Culture and Relative Humidity Impact the Stability of 2009 Pandemic H1N1 Influenza Virus on Nonporous Surfaces.

Respiratory viruses can be transmitted by multiple modes, including contaminated surfaces, commonly referred to as fomites. Efficient fomite transmission requires that a virus remain infectious on a given surface material over a wide range of environmental conditions, including different relative humidities. Prior work examining the stability of influenza viruses on surfaces has relied upon virus grown in media or eggs, which does not mimic the composition of virus-containing droplets expelled from the human respiratory tract. In this study, we examined the stability of the 2009 pandemic H1N1 (H1N1pdm09) virus on a variety of nonporous surface materials at four different humidities. Importantly, we used virus grown in primary human bronchial epithelial cell (HBE) cultures from different donors to recapitulate the physiological microenvironment of expelled viruses. We observed rapid inactivation of H1N1pdm09 on copper under all experimental conditions. In contrast to copper, viruses were stable on polystyrene plastic, stainless steel, aluminum, and glass, at multiple relative humidities, but greater decay on acrylonitrile butadiene styrene (ABS) plastic was observed at short time points. However, the half-lives of viruses at 23% relative humidity were similar among noncopper surfaces and ranged from 4.5 to 5.9 h. Assessment of H1N1pdm09 longevity on nonporous surfaces revealed that virus persistence was governed more by differences among HBE culture donors than by surface material. Our findings highlight the potential role of an individual's respiratory fluid on viral persistence and could help explain heterogeneity in transmission dynamics. IMPORTANCE Seasonal epidemics and sporadic pandemics of influenza cause a large public health burden. Although influenza viruses disseminate through the environment in respiratory secretions expelled from infected individuals, they can also be transmitted by contaminated surfaces where virus-laden expulsions can be deposited. Understanding virus stability on surfaces within the indoor environment is critical to assessing influenza transmission risk. We found that influenza virus stability is affected by the host respiratory secretion in which the virus is expelled, the surface material on which the droplet lands, and the ambient relative humidity of the environment. Influenza viruses can remain infectious on many common surfaces for prolonged periods, with half-lives of 4.5 to 5.9 h. These data imply that influenza viruses are persistent in indoor environments in biologically relevant matrices. Decontamination and engineering controls should be used to mitigate influenza virus transmission.

Membrane backtracking at the maximum capacity of nondigestible antigen phagocytosis in macrophages

The zipper model has been dominantly used to describe the driving mechanism of the engulfment process and its specific identification of antigens during phagocytosis in macrophages. However, the abilities and limitations of the zipper model, capturing the process as an irreversible reaction, have not been examined yet under the critical conditions of engulfment capacity. Here, we demonstrated the phagocytic behavior of macrophages after reaching the maximum engulfment capacity by tracking the progression of their membrane extension during engulfment using IgG-coated nondigestible polystyrene beads and glass microneedles. The results showed that, after macrophages reached their maximum engulfment capacity, they induced membrane backtracking (the reverse phenomenon of engulfment) in both polystyrene beads and glass microneedles, regardless of the difference in the shape of these antigens. We evaluated the correlation of engulfment in simultaneous stimulations of two IgG-coated microneedles and found that each microneedle was regurgitated by the macrophage independently of the advancement or backtracking of membranes on the other microneedle. Moreover, assessing the total engulfment capacity determined by the maximum amount the macrophage was capable of engulfing when imposing each antigen geometry showed that the capacity increased as the attached antigen areas increased. These results indicate that the mechanism of engulfment should imply the following: 1) macrophages have a backtracking function to recover their phagocytic activity after reaching maximal engulfment limit, 2) both phagocytosis and backtracking are local phenomena of the macrophage membrane that operates independently, and 3) the maximum engulfment capacity is determined not only by mere local cell membrane capacity but also by the whole-cell volume increase during simultaneous phagocytosis of multiple antigens by the single macrophages. Thus, the phagocytic activity may entail a hidden backtracking function, adding to the conventionally known irreversible zipper-like ligand-receptor binding mechanism during membrane progression to recover the macrophages that are saturated from engulfing targets beyond their capacity.

Isolation and Characterisation of Electrogenic Bacteria from Mud Samples.

To develop efficient microbial fuel cell systems for green energy production using different waste products, establishing characterised bacterial consortia is necessary. In this study, bacteria with electrogenic potentials were isolated from mud samples and examined to determine biofilm-formation capacities and macromolecule degradation. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry identifications have revealed that isolates represented 18 known and 4 unknown genuses. They all had the capacities to reduce the Reactive Black 5 stain in the agar medium, and 48 of them were positive in the wolfram nanorod reduction assay. The isolates formed biofilm to different extents on the surfaces of both adhesive and non-adhesive 96-well polystyrene plates and glass. Scanning electron microscopy images revealed the different adhesion potentials of isolates to the surface of carbon tissue fibres. Eight of them (15%) were able to form massive amounts of biofilm in three days at 23 °C. A total of 70% of the isolates produced proteases, while lipase and amylase production was lower, at 38% and 27% respectively. All of the macromolecule-degrading enzymes were produced by 11 isolates, and two isolates of them had the capacity to form a strong biofilm on the carbon tissue one of the most used anodic materials in MFC systems. This study discusses the potential of the isolates for future MFC development applications.

Integration of Energy Simulations and Life Cycle Assessment in Building Refurbishment: An Affordability Comparison of Thermal Insulation Materials through a New Sustainability Index

Energy efficiency and greenhouse gas reduction have become two of the most important issues to address in fighting climate change. Focused strategies have been implemented aiming at reducing the energy consumption of buildings since it is one of the most energy-intensive sectors, but they are mainly concerned with energy reduction without considering their environmental impact. The present work therefore aims at assessing the energy and environmental impacts of the use of insulation materials for building envelope refurbishment as the thermal coating. Reference buildings were used to perform energy simulations in representative cities of Italy and energy and environmental impacts of the most common and sustainable insulation materials were thus evaluated. Relevant outcomes have been focused on defining a new Economic and Environmental Sustainability Index (EESI) capable of considering both economic and environmental aspects; particularly, sustainable materials (such as cellulose fiber) can have the same affordability as traditional ones (such as polystyrene foam slab, glass wool, or stone wool) if environmental impact is also taken into account, despite their higher cost. However, according to EESI, the affordability of traditional insulation materials remains evident in the warmest climatic zones because of the lower energy needs of buildings.

Two phases of trans-stilbene in a polystyrene matrix.

Variability in the spectral properties of solid conformations of stilbene under various external conditions still remains obscure. The photophysical properties of trans-stilbene solution in solid polystyrene glass have been studied by absorption and time-resolved fluorescence. Concentration-induced quenching has been observed for small concentrations of stilbene. At large concentrations, the spectroscopic characteristics become split between the two phases of the sample: single-molecule properties are responsible for absorption, while the micro-crystalline phase dominates in fluorescence. Ab initio and molecular dynamics analyses suggest permanent twisting of the stilbene molecular structure upon crystallization, which supports spectroscopic phase separation.

Regulating polystyrene glass transition temperature by varying the hydration levels of aromatic ring/Li+ interaction.

Polymer properties can be altered via lithium ion doping, whereby adsorbed Li+ binds with H2O within the polymer chain. However, direct spectroscopic evidence of the tightness of Li+/H2O binding in the solid state is limited, and the impact of Li+ on polymer sidechain packing is rarely reported. Here, we investigate a polystyrene/H2O/LiCl system using solid-state NMR, from which we determined a dipolar coupling of 11.4 kHz between adsorbed Li+ and H2O protons. This coupling corroborates a model whereby Li+ interacts with the oxygen atom in H2O via charge affinity, which we believe is the main driving force of Li+ binding. We demonstrated the impact of hydrated Li+ on sidechain packing and dynamics in polystyrene using proton-detected solid-state NMR. Experimental data and density functional theory (DFT) simulations revealed that the addition of Li+ and the increase in the hydration levels of Li+, coupled with aromatic ring binding, change the energy barrier of sidechain packing and dynamics and, consequently, changes the glass transition temperature of polystyrene.

Densification of a polymer glass under high-pressure shear flow

The properties of glasses can change significantly as they evolve toward equilibrium. Mechanical deformation appears to influence this physical aging process in conflicting ways, with experiments and simulations showing both effects associated with rejuvenation away from and overaging toward the equilibrium state. Here we report a significant densification effect in a polymer undergoing shear flow under high pressure. We used the high-aspect ratio geometry of the layer compression test to measure the uniform and homogeneous accumulation of plastic strain during isothermal confined compression of a deeply quenched film of polystyrene glass. Combined scanning transmission x-ray microscopy (STXM) and atomic force microscopy confirmed defect-free deformation leaving up to 1.2% residual densification under conditions of confined uniaxial strain. At higher peak strain, plastic shear flow extruded glass from below the compressing punch under conditions of a high background pressure. A further density increase of 2% was observed by STXM for a highly thinned residual thickness of polymer that nevertheless showed no signs of crystallization or internal strain localization. While the confined uniaxial densification can be accounted for by a simple elastic--plastic constitutive model, the high-pressure extrusion densification cannot.

Acoustic properties of commercially available thermal insulators − An experimental study

Thermal insulators are used structural applications, such as walls, floors, doors, roofs, duct wrappings, machine and wall linings, and vehicle envelopes. There is very little scientific comparative research about the acoustic performance of thermal insulator materials. The purpose of our study was to compare various acoustic properties of insulator materials to improve comprehensive understanding. Thirteen commercially available insulator types produced by several manufacturers were studied for thicknesses 50, 100, and 200 mm. The materials were stone wool, glass wool, cellulose, wood fiber, expanded polystyrene, polyisocyanurate, phenol foam, and cellular glass. Six acoustic quantities were measured: sound reduction index of bare insulator, sound reduction index of encapsulated insulator (insulator between two boards), sound absorption coefficient, airflow resistivity, dynamic stiffness, and reduction of impact sound pressure level in a floating floor. The acoustic performance differed significantly between insulator types for each quantity. The value range for the abovementioned six quantities for 100-mm thick insulator was extremely large: 10–27 dB, 33–52 dB, 0.20–0.78, 3.0–2700 kPa s/m2, 1.5–730 MN/m3, and 15–36 dB, respectively. Closed-pore materials usually carried worse acoustic properties than open-pore materials. Unexpectedly, lower thermal conductivity was associated with worse acoustic performance of two acoustic quantities. The study is the broadest acoustic investigation of thermal insulators because of the large number of studied acoustic quantities and insulator types. The study provides strong evidence that the choice of thermal insulator material plays an important role in the acoustic properties of the structural application. Manufacturers should consider declaring all six acoustic quantities to facilitate design.

Thermophoretic force on a sphere of arbitrary thermal conductivity in a rarefied gas

The thermophoretic force on a sphere with arbitrary thermal conductivity immersed in a rarefied gas subject to a uniform temperature gradient is calculated in the framework of kinetic theory of gases in a range of the Knudsen number which covers the free molecular, transition and continuum regimes of the gas flow around the sphere. The condition of continuity of the radial heat flux at the gas–solid interface is used to calculate the thermophoretic force as a superposition of the thermophoretic force on a sphere with an uniform temperature and the radiometric force on a sphere due to its thermal polarization. Both solutions were previously obtained from the Shakhov model to the linearized Boltzmann equation and the Cercignani–Lampis model of gas–surface interaction. To analyze the influence of the gas and particle thermal conductivities on the thermophoretic force, spheres of PolyStyrene Latex (PSL), glass and nickel in helium and argon gases are considered. The force is calculated for several values of tangential momentum accommodation coefficient and normal energy accommodation coefficient as introduced in the Cercignani–Lampis scattering kernel. A comparison with experimental data available in the literature allowed to extract the values of the accommodation coefficients for helium interaction with the particle surface.

Experimental study on the influence of temperature and humidity on the thermal conductivity of building insulation materials

At present, thermal conductivity is usually taken as a constant value in the calculation of building energy consumption and load. However, in the actual use of building materials, they are exposed to the environment with continuously changing temperature and relative humidity. The thermal conductivity of materials will inevitably change with temperature and humidity, leading to deviations in the estimation of energy consumption in the building. Therefore, in this study, variations in the thermal conductivity of eight common building insulation materials (glass wool, rock wool, silica aerogel blanket, expanded polystyrene, extruded polystyrene, phenolic foam, foam ceramic and foam glass) with temperature (in the range of 20–60 °C) and relative humidity (in the range of 0–100%) were studied by experimental methods. The results show that the thermal conductivity of these common building insulation materials increased approximately linearly with increasing temperature with maximum growth rates from 3.9 to 22.7% in the examined temperature range. Due to the structural characteristics of materials, the increasing thermal conductivity of different materials varies depending on the relative humidity. The maximum growth rates of thermal conductivity with humidity ranged from 8.2 to 186.7%. In addition, the principles of selection of building insulation materials in different humidity regions were given. The research results of this paper aim to provide basic data for the accurate value of thermal conductivity of building insulation materials and for the calculation of energy consumption.

Impact of Direct Plasma Jet and Indirect Plasma Activated Mist on Surface Properties of Different Material Samples during Bacterial Inactivation

During plasma surface decontamination of hospitals' accommodations and medical instruments, one should expect some changes to occur on the surfaces of different materials exposed to plasma. In this study we have investigated effects of cold atmospheric plasma on four common materials likely to be found in medical facilities, namely medical polyvinyl chloride, polystyrene, stainless steel, and borosilicate glass. Two plasma configurations are used, one directly using an atmospheric pressure plasma jet (APPJ) and the other indirectly using plasma activated mist through a gliding arc discharge producing plasma activated mist. After plasma treatment, surface properties of the considered materials are investigated using water drop analysis, attenuated total reflectance Fourier transform infrared spectroscopy, and atomic force microscopy. Plasma is found to reduce bacterial contamination and on the same time alters, in different proportions, surface materials' properties such as wettability, surface energy, and roughness, of the treated samples. We have found that although direct plasma using APPJ can act more rapidly than indirect plasma concerning bacterial elimination from different materials' surfaces, indirect application through plasma activated mist is able to achieve the same bacterial death rate on longer time periods. This can be advantageous due to mild and best penetrating behavior of plasma activated mist on sensitive medical installations.

Study of microplastics with semicrystalline and amorphous structure identification by TGA and DSC.

The potential of thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) to identify, distinguish among the most relevant microplastics, and quantification, has been studied, including semicrystalline polymers (polypropylene (PP), polyamide (PA), high density polyethylene (HDPE), low density polyethylene (LDPE) and polyethylene terephthalate (PET)) and amorphous polymers (polystyrene (PS) and Polyvinyl Chloride (PVC)). The identification has been carried out by analyzing the decomposition, melting and glass transition temperatures. Both amorphous polymers (PVC and PS) can be properly identified by DSC using the glass transition temperature. Semicrystalline polymers, PA, PET, PP, HDPE and LDPE can be identified by using the melting temperature without the interference of other polymers, neither semicrystalline nor amorphous. The main limitation of the evaluated techniques is to distinguish between the semicrystalline polymer LDPE and the amorphous PS, as LDPE melting temperatures overlap with PS glass transition temperature, and this parameter would be useful only if one of these two polymers is present in the sample to be analyzed, since interference with other polymers (PA, PP, PET, LDPE, PVC and PS) do not exist. If both LDPE and PS are present in the sample, the best but not ideal option would be to analyze the decomposition temperature curves, since overlapping is weak in this case.

Novel chip-based isoelectric focusing device for fractionation of bacteria prior to their mass spectrometry identification

We have developed a planar chip utilizing divergent geometry of separation channel capable of vertical free-flow electrophoresis of particles at flows of lower hundreds of microliters per minute. The divergent flow isoelectric focusing (DF-IEF) chip consists of two sheets of clear polystyrene glass which serve as a base with working channels and a top cover sealing the separation channel. Optimization showed that the chip is capable to form pH gradient within 1 h and separation is completed in 5 or more minutes depending on the sample volume. The vertical position of the chip enabled analysis of sedimenting particles including microorganisms. Four different common bacteria species inactivated with H2O2 vapors were analyzed in a series of experiments. Isoelectric points were determined with capillary isoelectric focusing with following fractionation using DF-IEF with intact cell matrix-assisted laser desorption/ionization mass spectrometry detection. The DF-IEF chip fractionation proved promising for bacterial sample preparation from complex matrices for subsequent identification of whole cells by mass spectrometry.

Thermoplasmonic Patterning of Silver Nanocrystal/Polymer Composite Thin Films

AbstractThe lithographic patterning of polymer films is ubiquitous in manufacturing processes. In this work, the high photothermal conversion efficiency utilizes plasmonic nanoparticles to locally pattern polystyrene films. Silver nanocubes on polystyrene thin films are used as a heat source for photothermal lithographic patterning using a continuous‐wave, visible laser. Distinct states of the nanocomposite defined by their own far‐field optical properties and microscale topography are observed. At low intensities the nanocubes can be embedded into the polymer at a nanometer scale displacement precision and produce a notable shift in the distinct localized surface plasmon resonance, enabling two‐color optical patterning. Numerical modelling indicates the temperatures reached in the film surpass polystyrene's glass transition temperature (Tg, ≈90 °C). At higher laser intensities sufficient temperatures are reached to achieve pronounced polymer film displacement enabling direct‐write lithography. Temperature estimates highlight the role of collective contribution of nanoparticle heating in the process. The process can be controlled by selecting excitation wavelengths to tune the power absorbed by the nanocubes in accordance with their plasmonic absorption spectrum. The approach here outlines a general method of 2D optical patterning utilizing thermoplasmonics, which can be further expanded to other materials, applications, and potentially to subdiffraction length scales.

Experimental and theoretical study of sandwich composites with Z-pins under quasi-static compression loading

This study aims to enhance the compressive properties of sandwich composites containing extruded polystyrene (XPS) foam core and glass or carbon face materials by using carbon/vinyl ester and glass/vinyl ester composite Z-pins. The composite pins were inserted into foam cores at two different densities (15 and 30 mm). Compression test results showed that compressive strength, modulus and loads of the sandwich composites significantly increased after using composite Z-pins. Sandwich composites with 15 mm pin densities exhibited higher compressive properties than that of 30 mm pin densities. The pin type played a critical role whilst carbon pin reinforced sandwich composites had higher compressive properties compared to glass pin reinforced sandwich composites. Finite element analysis (FE) using Abaqus software has been established in this study to verify the experimental results. Experimental and numerical results based on the capabilities of the sandwich composites to capture the mechanical behaviour and the damage failure modes were conducted and showed a good agreement between them.

Virulence of clinically relevant multidrug resistant Corynebacterium striatum strains and their ability to adhere to human epithelial cells and inert surfaces

Corynebacterium striatum is a nosocomial pathogen which is increasingly associated with serious infections in both immunocompetent and immunocompromised patients. However, little is known about virulence factors and mechanisms that may enhance the establishment and long-term survival of Corynebacterium striatum. in the hospital environment. In this study, we investigated the ability of 22 multidrug-resistant C. striatum clinical isolates to adhere to human epithelial cells and to produce biofilm on polystyrene plates, glass and various tracheostomy tubes. We also tested the virulence of these strains on the nematode Caenorhabditis elegans. They showed good adhesion to epithelial human cells after 180 min of infection. The 22 C. striatum were able to produce biofilms on positively and negatively charged abiotic surfaces at 37 °C. They were also able to infect and to kill Caenorhabditis elegans after 5 days of infection. The virulence condition was associated with the presence of SpaDEF operon encoding pili in all strains. This study provides new insights on virulence mechanisms that may contribute to the persistence of C. striatum in the hospital environment, increasing the probability of causing nosocomial infections.