Polystyrene Samples Research Articles

First Experiment of Spin Contrast Variation Small-Angle Neutron Scattering on the iMATERIA Instrument at J-PARC

Recently, we have developed a novel dynamic nuclear polarization (DNP) apparatus with a magnetic field of 7 T and a sample temperature of 1 K. High proton spin polarizations from −84% to 76%, for TEMPO doped polystyrene samples, have been demonstrated. This DNP apparatus satisfies the simultaneous requirement for quick and easy sample exchange and high DNP performance. On the iMATERIA (BL20) instrument at J-PARC, the first beam experiment using this DNP apparatus has been performed. For this experiment, the beamline was equipped with a supermirror polarizer. The stray magnetic field due to the superconducting magnet for DNP was also evaluated. The stray magnetic field plays an important role for in maintaining the neutron polarization during the transportation from the polarizer to the sample. The small-angle neutron scattering (SANS) profiles of silica-filled rubber under dynamically polarized conditions are presented. By applying our new analytical approach for SANS coherent scattering intensity, neutron polarization (PN) as a function of neutron wavelength was determined. Consequently, for the neutron wavelength, range from 4 Å to 10 Å, |PN| was sufficient for DNP-SANS studies.

Quantitative determination of short-range order in magnetostrictive Fe-12.5 at. % Ga alloy single crystals

FeGa alloys are an important class of magnetostrictive materials for use in actuators and sensors. Quantitative determination of short-range order is critical for a fundamental understanding of the correlation of thermal history with magnetostriction in these and other α-Fe based alloys. This paper presents quantitative assessments of short-range order (SRO) from the diffuse peaks in the high-resolution x-ray diffraction scan data of as-grown and high-temperature annealed Fe-12.5 at. % Ga alloy single crystals. The peak analyzed was the diffuse peak in the forbidden (100) peak region of the diffraction pattern of bcc Fe-12.5 at. % Ga alloy single crystals. The [001]-oriented Fe-12.5 at. % Ga alloy single crystals were obtained using the vertical Bridgman technique. To quantitatively assess SRO in these alloy single crystals, the x-ray scattering intensities obtained were converted to absolute intensity in electron scattering units. To do this, reference scans were performed on a fully dense polystyrene sample. A Python language based code was used for the analysis of short-range order, and the values for the SRO coefficients up to the seventh shell were determined. These values agree with the type of ordering indicated by (111) scans of these crystals.

Transfer of Additive Chemicals From Marine Plastic Debris to the Stomach Oil of Northern Fulmars

For this study, the transfer of plastic additives to stomach oil of northern fulmars (Fulmarus glacialis) has been investigated. Procellariiform seabirds retain oily components of their prey in theirs stomach as a means to store energy. A marine litter-derived microplastic reference mixture and separately a marine litter-derived polystyrene sample were added to stomach oils in an experiment. A total of 15 additives, including plasticizers, antioxidants, UV stabilizers, flame retardants, and preservatives were identified in the original plastic mixtures, and monitored in the leachates. These substances include those known for endocrine disruptive, carcinogenic and/or other negative effects on organisms. Stomach oil was exposed to these plastic materials and was sampled during a long-term experiment (0, 14 and 90 days exposure of plastic particles in stomach oil) and a subsequent short-term detailed study (8 hours, 1, 2, 4, 8 and 21 days). Five of the monitored substances were shown to strongly leach from the microplastic reference mixture into the stomach oil during the experiment. Four substances were identified in a marine litter-derived polystyrene foam, of which two leached into stomach oil. Leaching of harmful plastic additives to the stomach oil of fulmars may be of concern, as fulmars regularly ingest plastics which are retained and gradually ground in the gizzard before passage to the intestines and excretion.

Effect of morphology on shear viscosity for binary blends of polycarbonate and polystyrene

AbstractThe structure and rheological properties of binary blends of polycarbonate (PC) and polystyrene (PS) were investigated using various PS samples with different molecular weights, namely PS1k (Mw = 1,000), PS53k (Mw = 53,000), and PS240k (Mw = 240,000). The blends with PS53k and PS240k show phase‐separated structures, whereas the blend with PS1k is miscible. The shear viscosity decreases greatly on addition of PS53k and PS240k, especially at high shear rates, which would be a great advantage at processing operations. Because the nonlinear response occurs in the small strain region for multilayered films of PC and PS240k, the origin of the significant viscosity drop for the phase‐separated system is interfacial slippage at the phase boundary.

Investigation of Surface Modification of Polystyrene by a Direct and Remote Atmospheric-Pressure Plasma Jet Treatment.

Localized functionalization of polymer surface with an atmospheric-pressure plasma jet was investigated at various treatment conditions. Polystyrene samples were treated with the plasma jet sustained in argon under direct or remote conditions. The two-dimensional evolution of surface wettability and the spot size of the treated area was determined systematically by measuring apparent water contact angles. Modification of surface chemistry and the formation of functional groups were investigated by X-ray photoelectron spectroscopy (XPS). The saturation of surface wettability and functional groups was observed even after a second of treatment providing the sample was placed close to the exhaust of the discharge tube. The spot diameter of the modified area increased logarithmically with increasing treatment time. However, it decreased linearly when increasing the distance. At the edge of the glowing plasma, however, the modification of surface properties was more gradual, so even 30 s of treatment caused marginal effects. With a further increase in the distance from the edge of the glowing plasma, however, there were no further treatment effects. The results are explained by significant axial as well as radial gradients of reactive species, in particular hydroxyl radicals.

Controlled Arrangement of Gold Nanoparticles on Planar Surfaces via Constrained Dewetting of Surface-Grafted RAFT Polymer.

Linear and four-arm star polystyrene samples prepared by RAFT polymerization were grafted to gold surfaces directly via their thiocarbonylthio-end groups. Nanoscale polymer patterns were subsequently formed via constrained dewetting. The patterned polymer films then served as a template for the precise arrangement of gold nanoparticles in a monolayer with a well-defined and regular structure. Using star polymers as a linker between the planar gold surface and the particles, the structural stability of the arranged particles can be further enhanced. The surface-bound nanocomposite films made of polymer and nanoparticles can also reversibly switch their nanostructures by simple wetting or dewetting treatment.

Effect of VUV Radiation on Surface Modification of Polystyrene Exposed to Atmospheric Pressure Plasma Jet.

Precise tailoring of surface properties by gaseous plasma treatments remains a key scientific challenge, especially when adequate surface wettability should be laterally distributed, and sharp interfaces between hydrophobic and hydrophilic areas are desirable. The evolution of surface wettability and functional groups on polystyrene (PS) upon treatment with argon plasma jet was monitored by water contact angles and X-ray photoelectron spectroscopy (XPS). An array of water droplets was deposited on PS samples treated either directly by the plasma jet or only VUV radiation arising from the plasma. Rather sharp interfaces between the activated and not-affected regions were observed in both cases. The functionalization with highly-oxidized carbon functional groups, as determined by high-resolution C1s XPS spectra, was by far more efficient using the VUV radiation only. In contrast, the optimal wettability was achieved using direct plasma treatment. The results were explained by different mechanisms involved in the interaction of radiation and reactive plasma species with the polymer surface.

Model Calculation for Enthalpy Relaxation of Polystyrene to Estimate the Size of Cooperative Rearranging Region for Glass Transition

The structural relaxation process has been studied for polystyrene samples by conducting physical ageing experiments. The energy barrier of the conformational transition in the isolated chain was d...

Biodiversity of Microorganisms Colonizing the Surface of Polystyrene Samples Exposed to Different Aqueous Environments

The contamination of marine and freshwater ecosystems with the items from thermoplastics, including polystyrene (PS), necessitates the search for efficient microbial degraders of these polymers. In the present study, the composition of prokaryotes in biofilms formed on PS samples incubated in seawater and the industrial water of a petrochemical plant were investigated. Using a high-throughput sequencing of the V3–V4 region of the 16S rRNA gene, the predominance of Alphaproteobacteria (Blastomonas), Bacteroidetes (Chryseolinea), and Gammaproteobacteria (Arenimonas and Pseudomonas) in the biofilms on PS samples exposed to industrial water was revealed. Alphaproteobacteria (Erythrobacter) predominated on seawater-incubated PS samples. The local degradation of the PS samples was confirmed by scanning microscopy. The PS-colonizing microbial communities in industrial water differed significantly from the PS communities in seawater. Both communities have a high potential ability to carry out the carbohydrates and amino acids metabolism, but the potential for xenobiotic degradation, including styrene degradation, was relatively higher in the biofilms in industrial water. Bacteria of the genera Erythrobacter, Maribacter, and Mycobacterium were potential styrene-degraders in seawater, and Pseudomonas and Arenimonas in industrial water. Our results suggest that marine and industrial waters contain microbial populations potentially capable of degrading PS, and these populations may be used for the isolation of efficient PS degraders.

Application of Atmospheric Pressure Argon Plasma Jet (APAPJ) in Biomedical Science and Engineering

In this paper, we demonstrated the application of atmospheric pressure argon plasma jet (APAPJ) in biomedical science such as cancer therapy and biomedical engineering such as surface modification of polystyrene Petri dishes for animal cell culture. We observed that APAPJ, when exposed to breast cancer cell line (MDA-MB-231) for 60 seconds at a distance of ~ 2.5 cm, reduced the cancer cells by 57%. This reduction in cancer cell concentration demonstrated the cancer-killing property of APAPJ. Further optimization of APAPJ's various operational parameters and in-depth biochemical study is required to figure out the mechanism responsible for killing cancer cells. Also, we investigated cell adhesion and proliferation due to APAPJ treatment by Crystal Violet (CV) staining and MTT Assay. We observed that APAPJ treatment of polystyrene Petri dishes for 60 - 240 s at a distance of ~ 3.5 cm exhibited enhancement in adhesion of breast cancer cell line (MDA-MB-231). We also demonstrated the increase in hydrophilicity by a reduction in contact angle to 30.3°±3 after 240 seconds of APAPJ treatment of polystyrene samples. The hydrophilicity of the substrate has proven to enhance cell adhesion. Consequently, APAPJ could be employed as a simple, inexpensive and environmentally friendly method for surface modification of polystyrene plates for animal cell culture.

First experimental observation of a photoabsorption-edge induced shock by its coalescence onto a regular ablation-shock

Implosion experiments of an inertial confinement fusion (ICF) target on the laser megajoule (LMJ) and the National Ignition Facility require, for certain designs, a precise timing coalescence of four shocks at a specific point of the capsule, which strongly depends on the ablator equation of state. In experiments at the Ligne d'Intégration laser facility, a prototype for the LMJ, coalescence of two shocks was studied in a planar polystyrene (CH) sample in an indirect drive configuration. Shocks were driven by x-ray emission generated in a spherical hohlraum radiatively heated using a 12 ns duration laser pulse temporally shaped to produce two steps in the radiation temperature history that launches these two successive ablation-shock waves. Shock velocity was inferred from a Velocity Interferometer System for Any Reflector (VISAR). Shot performed with 10 ns long truncated laser pulses reduces VISAR blanking, which allows us, for the first time to our knowledge, to observe a photoabsorption-edge induced shock, edge-shock for short, which is a third shock out of the two-step radiation temperature history, coalescing with the second ablation shock. The accurate measurement of this shock with well-controlled x-ray drive should potentially help to constrain the equation of state and opacity of carbon in coronal plasma conditions since the behavior of this shock is very sensitive to both. Moreover, since they can drastically alter the speed of coalesced shocks (in keyhole experiments or ignition designs for ICF), measurements of these edge-shocks may also contribute to improving our ICF design capabilities.

THERMOGRAVIMETRIC STUDIES OF POLYSTYRENE OF MODIFIED COBALT 5-METHYL-5-HEXEN-2,4-DIONATE

Thermogravimetry was used to study polystyrene samples modified with cobalt 5-methyl-5-hexene-2,4-dionate (MHD-Co) in two ways. The first method consists in copolymerizing styrene with the metal monomer MHD-Co, which simultaneously acts as an initiator and an inhibitor in this process, namely it exhibits a multifunctional effect in radical copolymerization with vinyl monomers. The polystyrene obtained in this way contains ≤ 0,5% cobalt in the form of β-diketonate groups covalently linked to the macromolecule, which are located both at the ends and in the middle of the polymer chain. Such polymers can be macroinitiators and graft side chains already at the stage of their synthesis; therefore, they have a branched structure of macrochains. The second modification method consists in the preliminary preparation of a styrene copolymer with unsaturated β-diketone followed by the complexation reaction of the obtained macroligand with a metal salt. In this case, when using the Co (III) salt, polymer chelates are formed as a result of the interaction of several polymer chains, and in the case of the Co (II) salt, two β-diketone groups inside the same macromolecule form a chelate structure. Moreover, for coordination saturation, metal complexes include solvent molecules. Thus, depending on the production method, polystyrene samples containing cobalt β-diketonate have a different structure, which affects the destruction mechanism, which will be different in each method. However, regardless of the modification method, all the studied samples have increased resistance to thermal oxidative degradation compared to the sample obtained using the traditional initiator benzoyl peroxide. The paper discusses the reasons for increasing the thermal stability of polystyrene containing an organometallic modifier.

Biocompatibility Evaluation and Enhancement of Elastomeric Coatings Made Using Table-Top Optical 3D Printer

In this experimental report, the biocompatibility of elastomeric scaffold structures made via stereolithography employing table-top 3D printer Ember (Autodesk) and commercial resin FormLabs Flexible (FormLabs) was studied. The samples were manufactured using the standard printing and development protocol, which is known to inherit cytotoxicity due to remaining non-polymerized monomers, despite the polymerized material being fully biocompatible. Additional steps were taken to remedy this problem: the fabricated structures were soaked in isopropanol and methanol under different conditions (temperature and duration) to leach out the non-polymerized monomers. In addition, disc-shaped 3D-printed structures were UV exposed to assure maximum polymerization degree of the material. Post-processed structures were seeded with myogenic stem cells and the number of live cells was evaluated as an indicator for the material biocompatibility. The straightforward post-processing protocol enhanced the biocompatibility of the surfaces by seven times after seven days soaking in isopropanol and methanol and was comparable to control (glass and polystyrene) samples. This proposes the approach as a novel and simple method to be widely applicable for dramatic cytotoxicity reduction of optically 3D printed micro/nano-scaffolds for a wide range of biomedical studies and applications.

Dynamically pre-compressed hydrocarbons studied by self-impedance mismatch

Using the SG-III prototype laser at China Academy of Engineering Physics, Mianyang, we irradiated polystyrene (CH) samples with a thermal radiation drive, reaching conditions on the principal Hugoniot up to P ≈ 1 TPa (10 Mbar), and away from the Hugoniot up to P ≈ 300 GPa (3 Mbar). The response of each sample was measured with a velocity interferometry diagnostic to determine the material and shock velocity, and hence the conditions reached, and the reflectivity of the sample, from which changes in the conductivity can be inferred. By applying the self-impedance mismatch technique with the measured velocities, the pressure and density of thermodynamic points away from the principal Hugoniot were determined. Our results show an unexpectedly large reflectivity at the highest shock pressures, while the off-Hugoniot points agree with previous work suggesting that shock-compressed CH conductivity is primarily temperature-dependent.

Leaching of flame-retardants from polystyrene debris: Bioaccumulation and potential effects on coral

Marine plastic debris can act as a reservoir of chemical additives that can pose a potential threat to sensitive ecosystems such as coral reefs. A survey of foam macrodebris collected on beaches indeed revealed high concentrations of hexabromocyclododecanes (ΣHBCDD) in polystyrene (PS) samples (up to 1940 μg g−1). Results also showed that PS fragments can still leach over 150 ng g−1 d−1 of ΣHBCDD (primarily as the α-isomer) for relatively long durations, and that these additives are readily bioaccumulated and well-retained by corals. Despite significant HBCDD bioaccumulation in coral tissue, short-term exposure to HBCDD or PS leachate had no considerable effect on coral photosynthetic activity, symbiont concentration and chlorophyll content. Exposure to the PS leachate did however cause consistent polyp retraction in nubbins over the 5-day exposure. This response was not observed in animals exposed to HBCDD alone, suggesting that another constituent of the leachate stressed corals.

Interaction of oxygen with polystyrene and polyethylene polymer films: A mechanistic study

In this work, first principles calculations combined with advanced surface diagnostics are used to unravel the mechanisms of plasma oxygen interaction with organic films of interest for advanced patterning in semiconductor device manufacturing. Results from a combination of x-ray photoelectron spectroscopy (XPS) diagnosed oxygen plasma exposed polystyrene films and first principles modeling of organic films (polystyrene, polyethylene, and derivatives) provide insights into how organic films are oxidized by oxygen atoms. XPS measurements show the rapid formation of C-O structures and their saturation after oxygen exposure on both pristine and argon bombarded polystyrene samples. Quantum mechanics calculations confirm that C-OH formation can be immediate without recourse to previously formed dangling bonds. Multiple oxygen impacts are required for scission of pristine ethylene carbon strands. Therefore, ethylene films can be converted to polyols that are stable, whereas more likely strands are broken before polyol formation through the formation of water and C=O. On the contrary, intermediate compounds with adjacent C=O bonds are not likely to form stable structures. The combination of XPS measurements and modeling implies that the oxidation of polystyrene and polyethylene is self-limiting on both hydrogen saturated and dehydrogenated (after argon ion plasma bombardment) surfaces.

From Plastic to Fuel - New Challenges

The increased demand for energy sources is the driving force to convert organic compounds into alternative fuels. Plastic waste disposal affects the environment, since they are not easily recycled and, during the recycling process, they can produce waste ash, heavy metals, or potentially harmful gas emissions. In the plant design for plastic converting into fuel, the chemical reactor is one of the advanced equipment in the field of chemical and process engineering. This study emphasizes the feasibility of pyrolysis process for valorisation plastics by producing energy-efficient products. In this respect, samples of polypropylene, polyethylene and polystyrene were used as models and subjected to pyrolysis processes at 450 �C, in the presence of two types of mesoporous silica materials, MCM-41 and SBA-15, using a modern developed reactor. The use of mesoporous materials increased the calorific value of the obtained oil and gas, thus improving the economic potential of the process end products. This study dealt with the extraction of oil from plastics termed as plastic pyrolysis oil (PPO) and plastics pyrolysis gas (PPG), with a composition rich in different types of hydrocarbons and they can be marketed at much cheaper rates compared to that present in the market.

Continuous-wave coherent Raman spectroscopy for improving the accuracy of Raman shifts.

Raman spectroscopy is an appealing technique that probes molecular vibrations in a wide variety of materials with virtually no sample preparation. However, accurate and reliable Raman measurements are still a challenge and require more robust and practical calibration methods. We demonstrate the implementation of a simple low-cost continuous-wave (cw) stimulated Raman spectroscopy scheme for accurate and high-resolution spectroscopy. We perform shot noise-limited cw stimulated Raman scattering as well as cw coherent anti-Stokes Raman scattering on polystyrene samples. Our method enables accurate determination of Raman shifts with an uncertainty below 0.1 cm-1. The setup is used for the characterization of reference materials required for the calibration of Raman spectrometers. Compared with existing standards, we provide an order of magnitude improvement of the uncertainty of Raman energy shifts in a polystyrene reference material.

Development of a simple setup for temperature dependent mass spectrometric measurements for the investigation of outgassing effects in polymeric materials for solar application

A simple experimental setup for temperature dependent mass spectrometric measurements has been constructed. It consists of a heated sample chamber and a mass spectrometer and allows for measurements under inert gas and ambient air. Based on initial measurements on two extruded polystyrene (XPS) samples a methodology for the data analysis has been developed. With this methodology the outgassing temperature of volatile compounds, which were used as blowing agents, has been identified. Furthermore, the composition of the blowing agents has been analyzed by temperature dependent mass spectra. The results indicate the use of ambient air in one material and a mixture of the banned blowing agents R142b and R22, both hydrochlorofluorocarbons (HCFC), in the other material. The here described methodology provides an easy to use approach to identify such compounds, for example as part of environmental or quality control.

Simultaneously enhanced thermal conductivity and fracture toughness in polystyrene/carbon nanofiber composites by adding elastomer

The common strategy to enhance the thermal conductivity of the polymer composites through increasing filler content usually results in the deterioration of the fracture toughness of the composite articles, which greatly restricts the real engineering application of the composites. In this work, carbon nanofibers (CNFs) and elastomer (styrene-ethylene/butylene-styrene, SEBS) were simultaneously incorporated into polystyrene (PS) through melt-compounding method. The dispersion state of CNFs and the processing flowability of the composites were comparatively investigated. The results show that SEBS tailors the dispersion of CNFs and promotes the formation of CNF assemblages and simultaneously, the processing flowability of the composites is improved to a certain extent. The thermal conductivity of the composites gradually increases with increasing CNF content, and it can be further enhanced by adding SEBS. The PS/20CNF and PS/20CNF/30SEBS composite samples show thermal conductivities of 1.074 and 1.358 W/m·K, respectively, which are 496.6% and 654.5% higher than that of the pure PS sample. Furthermore, incorporating SEBS greatly improves the fracture toughness of the composite samples. For example, the PS/20CNF/30SEBS composite sample shows impact strength of 45.2 kJ/m2, which is 407.9% higher than that of the PS/20CNF composite sample (8.9 kJ/m2). The simultaneously enhanced thermal conductivity and fracture toughness endow the ternary PS/CNF/SEBS composites with great potential applications in the fields relating to heat transfer and mechanical impact.