Analysis Of Polystyrene Research Articles

Determination of Polystyrene Microplastic in Soil by Pyrolysis – Gas Chromatography – Mass Spectrometry (pyr-GC-MS)

Pyrolysis-gas chromatography-mass spectrometry (pyr-GC-MS) is emerging as a promising alternative for the detection and quantification of microplastic pollution. For a robust quantification it is essential to improve our understanding of interferences in the pyrolysis of microplastics. Here we investigate the effects of different soil matrices, mainly differing by their organic carbon content (Corg, 1.0–13.6%), and of the polymer molecular weight (Mw) on the pyr-GC-MS analysis of polystyrene (PS) microplastics. In addition, we evaluated the effectiveness of adding poly(4-fluorostyrene) (PSF) as internal standard to circumvent the matrix effects. The three main markers of PS pyrolysis, i.e., styrene, styrene-dimer and styrene-trimer, were monitored. The ratio between the dimer and the trimer significantly varied between the matrices and tended to decrease with the increasing of the Corg in the soil, mainly due to an increased trimer formation. A strong matrix effect affected the slope of the calibration curves by 2 to 8-fold and was correlated with the Corg in the soils. This effect was mitigated when the areas of the markers were normalized by the area of the corresponding marker of PSF. PS of low Mw (Mw 35,000) presented a reduced formation of the three markers compared to PS of high Mw (Mw 400,000), and styrene-dimer was proportionally less formed than the other two markers. Differences in the slopes of calibration curves depended on the marker chosen, highlighting the relevance of selecting the pyrolysis marker in the quantification of microplastics using pyr-GC-MS.

Analysis of polystyrene and polycarbonate used in manufacturing of water and food containers using laser induced breakdown spectroscopy

Laser-induced breakdown spectroscopy (LIBS) is one of the analytical techniques which has vast applications in the material analysis. We have applied LIBS technique for the elemental analysis to determine trace elements as impurities in polystyrene and polycarbonate polymer materials. These polymer samples were collected from one of the Saudi industries which are being used as containers for food and water. The study was carried out under high vacuum (1 × 10−5 mbar) using a 10 Hz Q-switched pulsed Nd:YAG laser at wavelength 1064 nm, 20 mJ energy and 8 ns pulse width to generate the plasma of the polymer samples. By analyzing the plasma plume emission, LIBS spectra revealed the existence of Al, Si, P, Ca, Mg, N in Polystyrene and Br, Mg, Ca, N in polycarbonate as trace elements. Molecular lines of CN, CO, C2 and CH in these samples have been observed as well. The presence of Al, Si, and P traces in these polymer samples might be harmful to the human body. LIBS is found to be a simple, non-contact, online and cost-effective method to identify the hazardous elements in polymers. The industries can adopt this method to provide harmless containers for water or food products.

Expanded Polystyrene Foam Formed from Polystyrene Beads Coated with a Nanocrystalline SiO2 Film and the Analysis of Its Moisture Adsorption and Resistance to Mechanical Stress

ABSTRACTConventional expanded polystyrene can absorb moisture, which significantly degrades its properties. In the present study, it was demonstrated that SiO2 can be deposited on polystyrene beads before pre-expansion and molding steps. Under the applied test conditions, expanded polystyrene with nanocrystalline SiO2 additives had approximately 10% lower moisture adsorption and an 8.4% better resistance to deformation. Expanded polystyrene analysis suggested that the observed improvements were caused by the hydrophobic nature of nanocrystalline SiO2 and, even more importantly, because SiO2 acted as an amalgamation catalyst and significantly increased adhesion between the expanded polystyrene beads during the expanded polystyrene molding process.

Novel co-matrix systems for the MALDI-MS analysis of polystyrene using a UV absorber and stabilizer

Co-matrix systems composed of a UV absorber and a UV stabilizer applied to the analysis of polystyrene (PS) using a matrix-assisted laser desorption/ionization-mass spectrometer (MALDI-MS) equipped with a N(2) laser (337 nm) as the light source were investigated. Various UV absorbers such as Tinuvin 234, Tinuvin 326, Tinuvin 327, Tinuvin 328, Tinuvin 329, and Tinuvin 1577 and a UV stabilizer of Tinuvin 770 were used. Analytical results using the co-matrix systems were compared with those using anthracene-1,8,9-triol (DIT) as the most common matrix for PS analysis. The MALDI mass spectrum of PS obtained using single DIT showed higher ionization efficiency than that using a mixture of DIT and Tinuvin 770 as the matrix. In contrast to this, for the UV absorbers, the ionization efficiencies were notably enhanced by using the co-matrix systems of the UV absorber and Tinuvin 770. The analytical results were explained with the enhanced compatibility with PS by the formation of a complex between the UV absorber and Tinuvin 770 and with the capability of transferring silver cations. Prices of Tinuvin 770 and the UV absorbers are much cheaper than those of the common matrices. The co-matrix systems are recommendable for the MALDI-MS analysis of PS, especially the co-matrix system composed of Tinuvin 234 and Tinuvin 770.

Analysis of polystyrene‐b‐polyisoprene copolymers by coupling of liquid chromatography at critical conditions to NMR at critical conditions of polystyrene and polyisoprene

For the investigation of the molecular heterogeneity of polystyrene-b-polyisoprene block copolymers, a chromatographic separation method, namely liquid chromatography at critical conditions was developed. This method was coupled on-line with (1)H-NMR(where NMR stands for nuclear magnetic resonance) for the comprehensive analysis of the polystyrene-b-polyisoprene copolymers. The copolymers were synthesized by two different methods: sequential living anionic polymerization and coupling of living precursor blocks. While (1)H-NMR allows just for the analysis of the bulk chemical composition of the block copolymers, the coupling with liquid chromatography at critical conditions provides selective molar mass information on the polystyrene and polyisoprene blocks within the copolymers. The polyisoprene block molar mass is determined by operating at chromatographic conditions corresponding to the critical point of adsorption of polystyrene and size exclusion chromatography mode for polyisoprene. The molar mass of the polystyrene block is determined by operating at the critical conditions of polyisoprene. In addition to the molar mass of each block of the copolymers, the chemical composition distribution of the block copolymers was determined. By using the coupling of liquid chromatography at critical conditions to (1)H-NMR, one can also detect the homopolymers formed during synthesis. Finally the microstructure of the polyisoprene block in the copolymers was evaluated as a function of molar mass.

The Analysis of Polystyrene and Polystyrene Aggregates into the Mega Dalton Mass Range by Cryodetection MALDI TOF MS

Mass spectra of atactic polystyrene were collected into the mega-dalton mass range with a matrix-assisted laser desorption ionization time of flight (MALDI TOF) mass spectrometer, which incorporates a cryodetector comprised of an array of 16 superconducting tunnel junctions (STJ). The STJ cryodetector, theoretically, has no loss in signal response at any mass compared with the reduced signal found at high mass when using a conventional secondary-ionization detector. Since ion detection at high m/z is one of the fundamental limitations of mass spectrometry (MS), the cryodetector was used to explore the high m/z limit of the MALDI TOF technique for the analysis of two polymer types. Mass spectra were collected for polystyrene at Mn 170, 400, 900, and 2000 kDa and polymethyl methacrylate (PMMA) at Mn 62.6 kDa and 153.7 kDa. For polystyrene, the data showed a trend toward increased aggregation and charge state with mass. The Mn 2 MDa polystyrene data revealed a peak at m/z 2.2 MegaTh and a charge state analysis revealed that these ions were primarily polystyrene aggregates with a mass of approximately 4 MDa. This aggregate assignment was possible because the cryodetector response allows for the determination of a charge state up to about four. The contribution of each charge state for a selected peak can be determined in this fashion. This analysis revealed the preferential formation of doubly charged even-numbered aggregates over odd-numbered aggregates for high molecular mass polystyrene. A potential mechanism for the aggregation process for doubly charged species is discussed.

Relationship between Chain Length and the Concentration Dependence of Polymer and Oligomer Self-Diffusion in Solution

A complex relationship between chain length and the concentration dependence of polymer self-diffusion, Dp(c)/Dp(0), is revealed from analysis of polystyrene (PS) and oligostyrene self-diffusion in solution. Pulsed-field-gradient NMR measurements of PS self-diffusion in styrene and toluene were compared with literature results for PS self-diffusion in benzene, tetrahydrafuran, toluene, and carbon tetrachloride. An empirical relationship was used to correlate Dp(c)/Dp(0) to the concentration dependence of solvent self-diffusion, Ds(c)/Ds(0): Dp(c)/Dp(0) = [Ds(c)/Ds(0)]β where β quantifies the relationship between chain length and the concentration dependence of Dp. (This power law, with a chain-length-independent β, may be justified from Vrentas−Duda free volume theory.) Accounting for differences in the free volume contribution of the solvent species, β values obtained in the five solvents can be normalized to a single solvent, styrene, revealing universality in the relationship between chain length and ...

Post-source decay in the analysis of polystyrene by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

Various secondary series are observed in matrix-assisted laser desorption/ionization (MALDI) time-of-flight mass spectra of polystyrene. The number and positions of the series depend on the choice of matrix and added cation. For a given treatment, series observed in linear mode are not necessarily observed in reflectron mode, and vice versa. Post-source decay analysis was used to determine that the secondary series arise at least in part from formation and decay of adducts of polystyrene with matrix species. There is some treatment-to-treatment variation, but adduct formation and decay were observed for all tested treatments. The multiplicity of secondary series makes it unclear whether post-source decay occurs for the main series (polystyrene + cation) + ions under the conditions normally used for polystyrene analysis. Such ions do undergo post-source decay at laser fluences greater than normally used. Although only polystyrene was investigated in this work, other polymers may also produce adduct and decay series in MALDI analysis. Their presence can mask the presence of minor components in a sample, but at least as observed here, do not have a strong influence on molecular mass determinations.

Probing polystyrene cationization in matrix-assisted laser/desorption ionization

It has been observed that the use of the salts of transition metals other than silver, copper or palladium as the cationizing agent, often fails to cationize polystyrenes in matrix-assisted laser/desorption ionization (MALDI). This work shows that the ability of MALDI to reduce metals to the oxidation state +1 is critically important to polystyrene cationization. Without this reduction, MALDI tends to fail to form polystyrene–metal cations. In addition, this work demonstrates the importance of the use of a good combination of metal salts and matrix in polystyrene cationization. Finally, the implications of this work in the MALDI time-of-flight analysis of polystyrenes are discussed.

Analysis of Polystyrene (PS) by XPS

We report x-ray photoemission spectra of polystyrene (PS). XPS spectra were measured with the SSI, SSX-100 model, using monochromated Al Kα x-rays. We present the survey spectrum (binding energy range of 0–1100 eV) and a narrow spectrum of C 1s. The polymer is used as a reference to study the influence of PS surface modification by rf plasma for biochemical applications.

Characterization of Polymers Using Supercritical Fluid Chromatography: Application of adsorption chromatography, size exclusion chromatography and adsorption chromatography at critical conditions

Abstract Supercritical fluid chromatography (SFC) utilizes fluids or mixtures of fluids above their critical temperature and critical pressure which exhibit greater solvating properties with simultaneously reduced viscosities and higher diffusion coefficients compared with their liquid state; supercritical fluids, thus, offer new possibilities for characterizing polymers. The three modes of liquid chromatography are applied in the analysis of polystyrenes, using supercritical fluids (mixtures of dichloromethane with carbon dioxide) in each mode: adsorption chromatography for the separation of oligomers, size exclusion chromatography for the determination of molar mass distribution, and adsorption chromatography at critical conditions for the characterization of functionality type distribution. Advantages and disadvantages of size exclusion chromatography with fluids in their supercritical, subcritical and liquid phase are discussed with the system polystyrene in dichloromethane.

Liquid chromatography of polymer mixtures applying combination of exclusion and full adsorption mechanisms. I. Analysis of polystyrene in its mixture with polymethylmethacrylate single column/single eluent approach

AbstractComponents of polymer mixtures with different chemical composition can be separated by liquid chromatography by applying appropriate conditions (column packing, eluent, temperature, and pressure) in which just one type of macromolecule is eluted in the size exclusion mode while the other component is fully retained within on column packing. The feasibility of this idea has been demonstrated using the mixtures of polystyrene (PS) plus polymethylmethacrylate (PMMA) with silica gel as the column packing and toluene as an eluent. The PMMA was retained by the silica get at ambient temperature and moderate pressures of several MPa while the PS was eluted by a typical SEC mecahanism. Furthermore, the molar mass distribution of the PS could be determined in one step with the same precision as if injected alone. Surprisingly large amounts of PMMA were trapped within the column prior to its SEc characteristics being influenced. After a series of analyses the column has to be regenerated with a brief flushing with a desorbing liquid, tetrahydrofuran in the system studied. The re‐equilibrization of the column with the initial eluent, toluene, was fast and a new series of analyses could be started soon after the characterization step had seen finished. © 1995 John Wiley & Sons, Inc.

Cation attachment in the analysis of polystyrene and polyethylene glycol by laser‐desorption time‐of‐flight mass spectrometry

AbstractAl+, Cr+ and Cu+ gas‐phase ions have found to attach effciently to two polymers, polystyrene and polyethylene glycol (PEG) in laser‐desorption time‐of‐flight experiment, and are shown to be viable alternatives to be commonly used Na+, K+ and Ag+ ions. At high laser powers, in the range 8.0 × 107 to 2.0 × 108 W/cm2, ions can be attached by desorption from a support made of the apporoptite meal. An alternative method is to add the metal ion in the form of a salt containing the metal in the +1 oxidation state, when such salt are available. This method requires lowe laser powers, in the range 2.0 × 107 to 8.0 × 107 W/cm2. The two desorption/attachment methods are characterized by different optiomal time‐delay values for recording of spectra. Polystyrence has been found to have a hight affinity for attachemnt to Al+, Cr+, and Cu+ than to K+, while PEG has ben found to have a hight affinity for K+ than for Al+, Cr+. These preferential attachments are discussed in terms of the hard and soft acids and bases principle.

Synthesis and Application of Tailored Graft Copolymers from Polystyrene Macromonomer

Abstract Comb graft copolymers prepared by macromonomer technique has become applicable for permanent modification of polymer surfaces. In this paper the association and adsorption behavior in solution of the well designed graft copolymer prepared from polystyrene macromonomer and various hydrophilic comonomer was studied and the mechanism of surface accumulation of hydrophilic segment was clarified by surface analysis of polystyrene containing the graft copolymers. Wetting of modified polymer surfaces and the permeability of gases through the film was also discussed.

Analysis of polystyrene and related resins by pyrolysis gas chromatography

Pyrolysis gas chromatography was used for the determination of the monomeric composition of some hydrocarbon resins resulting from the liquid product of naphtha pyrolysis. The effect of working conditions on the peak composition of the pyrogram was investigated. From the monomer peak areas corrected by experimental factors the monomeric composition of a copolymer can be calculated.