Mixtures Of Polystyrene Research Articles

De‐Brominating Flame‐Retardant Polystyrene by Utilizing Basic Oxides in Chemical Recycling

AbstractChemical recycling is a method to close the recycling loop for polymers. This is particularly applicable for polystyrene (PS), where the monomer styrene is directly formed by depolymerization and subsequently utilized for the production of new PS. However, some waste sources contain critical additives as legacies, such as brominated flame retardants. There is a profound need to remove these substances from the material, as current thresholds do not allow such additives above certain limits in new products. In this work we present the beneficial use of basic oxides during the thermal depolymerization of a mixture of PS and 1,2,5,6,9,10‐hexabromocyclododecane. It was demonstrated that especially barium oxide and calcium oxide allowed the reduction of bromine up to 96 % in the crude styrene oil.

Microwave-assisted In-situ catalytic co-pyrolysis of polypropylene and polystyrene mixtures: Response surface methodology analysis using machine learning

Polypropylene (PP) and Polystyrene (PS) are the major plastic fractions found in mixed plastic waste. Hence, the current study was focused to convert PP and PS into useful products via microwave-assisted pyrolysis (MAP). In addition, the understanding of feedstock conversion, product yields, and energy requirements in pyrolysis, co-pyrolysis, and catalytic co-pyrolysis was investigated. Experiments were conducted at a constant microwave power of 450 W till the reaction temperature reached up to 600 °C. When PS pyrolyzed, a heating rate of 56 °C/min resulted in 80 wt% of oil yield. Whereas PP pyrolysis produced 42 wt% of oil at a heating rate of 76 °C/min. In the PP: PS co-pyrolysis, the heating rate was decreased to 52 °C/min by yielding 51 wt% of oil. In catalytic co-pyrolysis of PP: PS with KOH resulted in variation in product yields and heating rate. An increase in PS quantity at a constant mass of PP resulted in the enhancement of oil yields from 58 to 84 wt% and a decrease in gas yields. The specific microwave power in the catalytic co-pyrolysis (7–18 W/g) is lower compared to the non-catalytic case (22–30 W/g). Whereas, the pyrolysis time in non-catalytic pyrolysis (7–11 min) is lower compared to catalytic co-pyrolysis (14–37 min). The addition of a catalyst resulted in a decrease (23–50%) in microwave conversion efficiency than that of the non-catalytic case (60–85%). The difference in predicted and actual result analysis proved co-pyrolysis synergy in product formation and energy consumption.

Kinetic Analysis of Thermal Degradation of Recycled Polypropylene and Polystyrene Mixtures Using Regenerated Catalyst from Fluidized Catalytic Cracking Process (FCC).

The pyrolysis process is a thermochemical recycling process that in recent years has gained importance due to its application in plastic waste, which is one of the biggest environmental problems today. Thus, it is essential to carry out kinetic and thermodynamic analyses to understand the thermocatalytic degradation processes involved in plastic waste mixtures. In this sense, the main objective of this study is to analyze the degradation kinetics of the specific mixture of polypropylene (25%) and polystyrene (75%) with 10% mass of regenerated FCC catalyst which was recovered from conventional refining processes using 3 heating rates at 5, 10 and 15 K min-1 by thermogravimetric analysis (TGA). The obtained TGA data were compared with the isoconversional models used in this work that include Friedman (FR), Kissinger Akahira Sunose (KAS), Flynn-Wall-Ozawa (FWO), Starink (ST) and Miura-Maki (MM) in order to determine the one that best fits the experimental data and to analyze the activation energy and the pre-exponential factor; the model is optimized by means of the difference of minimum squares. Activation energy values between 148 and 308 kJ/mol were obtained where the catalytic action has been notorious, decreasing the activation energy values with respect to thermal processes.

Innovative reference materials for method validation in microplastic analysis including interlaboratory comparison exercises

Reference materials (RMs) are vital tools in the validation of methods used to detect environmental pollutants. Microplastics, a relatively new environmental pollutant, require a variety of complex approaches to address their presence in environmental samples. Both interlaboratory comparison (ILC) studies and RMs are essential to support the validation of methods used in microplastic analysis. Presented here are results of quality assurance and quality control (QA/QC) performed on two types of candidate microplastic RMs: dissolvable gelatin capsules and soda tablets. These RMs have been used to support numerous international ILC studies in recent years (2019–2022). Dissolvable capsules containing polyethylene terephthalate (PET), polyvinyl chloride (PVC), polyethylene (PE), and polystyrene (PS), in different size fractions from 50 to 1000 µm, were produced for one ILC study, obtaining relative standard deviation (RSD) from 0 to 24%. The larger size fraction allowed for manual addition of particles to the capsules, yielding 0% error and 100% recovery during QA/QC. Dissolvable capsules were replaced by soda tablets in subsequent ILC studies and recovery test exercises because they were found to be a more reliable carrier for microplastic RMs. Batches of soda tablets were produced containing different single and multiple polymer mixtures, i.e., PE, PET, PS, PVC, polypropylene (PP), and polycarbonate (PC), with RSD ranging from 8 to 21%. Lastly, soda tablets consisting of a mixture of PE, PVC, and PS (125–355 µm) were produced and used for recovery testing during pretreatment of environmental samples. These had an RSD of 9%. Results showed that soda tablets and capsules containing microplastics >50 µm could be produced with sufficient precision for internal recovery tests and external ILC studies. Further work is required to optimize this method for smaller microplastics (< 50 µm) because variation was found to be too large during QA/QC. Nevertheless, this approach represents a valuable solution addressing many of the challenges associated with validating microplastic analytical methods.

Plastic-made diesel (PMD) from pyrolysis via vacuum distillation process- A waste recycling fuel to diesel engine performance and emissions improvement

Plastic applications are remarkably increasing nowadays; thus disposal of waste plastic and its negative environmental impact is a great challenge. Turning waste plastic into useful diesel as an alternative to petroleum fuel in the diesel engine is very attractive for communities in terms of waste plastic recovery and reduction in dependency on fossil fuel. This study conducted experiments to evaluate the engine performance and emissions using plastic-made diesel (PMD) which was produced from pyrolytic crude oil of a mixture of high-density polyethylene (HDPE), polypropylene (PP) and polystyrene (PS) with equal proportion using a vacuum distillation process. The pyrochemical properties of PMD were first evaluated after distillation and tabulated. Then, three different ratios (5%, 10% and 20%) of PMD with ultra-low sulfur diesel (ULSD) were used as a diesel engine fuel to investigate engine performance and emission characteristics at variable speeds and loading operations. Results showed that the brake power (BP), torque and brake thermal efficiency of the engine with PMD20 were 2.9%–3.84%, 3.01%–3.21% and 3.9%–4.74% higher than those with ULSD at all tested conditions. The brake-specific fuel consumption (BSFC) of the engine using PMD20 decreased by about 3.77% compared to the engine using ULSD, thereby indicating less fuel usage at various load circumstances than the ULSD. Furthermore, CO emissions from PMD20 were 14.51% lesser than ULSD, and about 7.8% and 4.22% lesser than from PMD5 and PMD10 at all loading operations, respectively. The HC emissions of PMD20 were 15.1%–18.7% lower than that of the ULSD. The NOx emissions decreased by 2.06%, 3.01% and 3.95% on PMD blends PMD5, PMD10 and PMD20 compared to ULSD. These analyses demonstrate that PMD is a potential alternative fuel for engines and provides a useful means to recover the waste plastics.

Simple Detection of Pigment Red 53 as a Hazardous Substance in Cosmetic Preparation Using a Polymer Combination of Polystyrene (PS) and Polymethylmethacrylate (PMMA).

Pigment red 53 is a synthetic dye that has been banned in cosmetic products due to the possibility of causing blood disorders and spleen sarcoma. The indicator strip employs qualitative analysis methods that are simpler, easier, and quicker than an instrumental analysis. The indicator strip is made of a polymethylmethacrylate (PMMA) and polystyrene (PS) mixture using a reagent blending method with specific reagents of concentrated sulfuric acid (H2SO4), concentrated hydrochloric acid (HCl), or 10% sodium hydroxide (NaOH). Pigment red 53 detections with an indicator strip are based on the occurrence of a specific color change reaction between the reagent and pigment red 53 through sulfonation with concentrated H2SO4, neutralization with 10% NaOH, and reaction of pigment red 53's azo group with concentrated HCl. PMMA was made with a concentration of 5% (w/t), and mixtures of PS:PMMA 1:2, 1:3, and 1:4 had solvent-to-specific reagent ratios of 60:40, 80:20, and 90:10. The best results were obtained for PMMA-H2SO4 (90:10), PMMA-HCl (80:20), and PMMA-NaOH (60:40), with the lowest detection limits equaling 20 ppm, 50 ppm, and 20 ppm, respectively. Meanwhile, the best PS:PMMA (1:4)-based indicator strips obtained were PS:PMMA-H2SO4 (90:10), PS:PMMA-HCl (80:20), and PS:PMMA-NaOH (60:40), with the lowest detection limits being 20 ppm, 10 ppm, and 20 ppm, respectively. All indicator strips are stable for at least 80 days. Indicator strips can be used as a simple and applicable method for detecting pigment red 53 in cosmetic products with a good performance.

Tuning the index of refraction of a polyvinyl toluene and polystyrene copolymer toward a heterogenous, index‐matched neutron detector

AbstractOne class of neutron detectors for illicit nuclear materials are capture‐gated detectors, which use organic scintillators to slow neutrons while emitting fluorescent light and elements that have high neutron capture cross‐sections to provide a second signal. Homogeneous detectors composed of neutron capturing metallo‐organics within plastic darken due to their chemical instability, while heterogeneous detectors frequently result in non‐transparent material due to a mismatch of the refractive index. These detectors are often polymerized through bulk polymerization, but there is little data available on this process applied to mixtures of polystyrene (PS) and polyvinyl toluene (PVT), two commonly used polymers in plastic scintillators. This work presents bulk polymerization processing toward an index‐matched, heterogeneous capture‐gated neutron detector based on PS and PVT copolymers with a range of refractive indices. Specifically 1:3, 1:1, and 3:1 PS:PVT ratios were manufactured and their refractive indices, measured by refractometry, were compared to a theoretical model based on a mixture of the refractive indices of pure PS and PVT. Finally, a composite of PS/PVT and an Ohara S‐BAL42 glass was developed to confirm the index‐matching capability of the process as a step toward developing a heterogenous, capture‐gated neutron detector with high light transmission efficiencies allowed by index‐matched materials.

Utilization of Used Polystyrene As Adhesive In Polymer Emulsion Asphalt

The utilization of used polystyrene as adhesive material for emulsion polymer asphalt has been carried out. Polystyrene foam was dissolved in toluene at the ratio of 30:70 mL, then the solution was mixed with aquadest at ratios of 90: 10 mL, 70: 30 mL, 50: 50 mL, 30:70 mL, and 10: 90 mL. Then added with 10 mL of Sodium Dodecyl Sulfate solution at concentrations of 10%, 20%, and 30%. The most stable latex polystyrene was mixed with 200 g of sand aggregate at volume ratios of 10 mL, 20 mL, 30 mL, 40 mL, and 50 mL. Then the mixture was pressed into a hotpress at 150ºC for 20 minutes. The mixture obtained was characterized using tensile strength testing, water absorption, and SEM spectroscopy. The results showed that the mixture of sand aggregate with 50 mL latex polystyrene has the best compressive strength and water absorption, at a load of 1606 Kg.f, a stroke of 14.93 mm/minutes, and a water absorption percentage of 18%. The morphology result showed that the surface of sand aggregate with 50 mL of latex polystyrene mixture contains smaller and least holes than the surface of sand aggregate with 10 mL of latex polystyrene mixture.

Kinetic modeling of the hydrocracking of polystyrene blended with vacuum gasoil

The kinetic modeling of the hydrocracking of a mixture of polystyrene (PS) and vacuum gasoil (VGO) over a PtPd/HY catalyst has been carried out. The reactions have been performed in a batch reactor under the following conditions: 380–420 °C; 80 bar; content of PS in the feed, 10 wt%; catalyst/feed ratio, 0.1 in mass; and time, 30–300 min. Different reaction networks and kinetic models have been studied, in which the evolution of product distribution (unconverted PS, dry gas, liquefied petroleum gases, naphtha, light cycle oil, heavy cycle oil and coke) with the extent of time has been quantified by considering three different simultaneous deactivation mechanisms (plastic fouling, coke deposition and metal poisoning). The kinetic model selected (based on a 7-lump reaction network) has been used for performing a parametric study, determining that 400 °C and 180 min are the optimal conditions for maximizing the yield of naphtha (35 wt%) at the same time that PS is totally converted. This original kinetic model may act as a basis for scaling-up studies focused on the large-scale valorization of waste plastics by co-feeding them into a hydrocracking unit of a Waste-Refinery.

Pyrolysis Study of Mixed Polymers for Non-Isothermal TGA: Artificial Neural Networks Application.

Pure polymers of polystyrene (PS), low-density polyethylene (LDPE) and polypropylene (PP), are the main representative of plastic wastes. Thermal cracking of mixed polymers, consisting of PS, LDPE, and PP, was implemented by thermal analysis technique “thermogravimetric analyzer (TGA)” with heating rate range (5–40 K/min), with two groups of sets: (ratio 1:1) mixture of PS and PP, and (ratio 1:1:1) mixture of PS, LDPE, and PP. TGA data were utilized to implement one of the machine learning methods, “artificial neural network (ANN)”. A feed-forward ANN with Levenberg-Marquardt (LM) as learning algorithm in the backpropagation model was performed in both sets in order to predict the weight fraction of the mixed polymers. Temperature and the heating rate are the two input variables applied in the current ANN model. For both sets, 10-10 neurons in logsig-tansig transfer functions two hidden layers was concluded as the best architecture, with almost (R > 0.99999). Results approved a good coincidence between the actual with the predicted values. The model foresees very efficiently when it is simulated with new data.

Thermocatalytic Conversion of Plastics into Liquid Fuels over Clays.

Recycling polymer waste is a great challenge in the context of the growing use of plastics. Given the non-renewability of fossil fuels, the task of processing plastic waste into liquid fuels seems to be a promising one. Thermocatalytic conversion is one of the methods that allows obtaining liquid products of the required hydrocarbon range. Clays and clay minerals can be distinguished among possible environmentally friendly, cheap, and common catalysts. The moderate acidity and the presence of both Lewis and Brønsted acid sites on the surface of clays favor heavier hydrocarbons in liquid products of reactions occurring in their pores. Liquids produced with the use of clays are often reported as being in the gasoline and diesel range. In this review, the comprehensive information on the thermocatalytic conversion of plastics over clays obtained during the last two decades was summarized. The main experimental parameters for catalytic conversion of plastics according to the articles’ analysis, were the reaction temperature, the acidity of modified catalysts, and the catalyst-to-plastic ratio. The best clay catalysts observed were the following: bentonite/spent fluid cracking catalyst for high-density polyethylene (HDPE); acid-restructured montmorillonite for medium-density polyethylene (MDPE); neat kaolin powder for low-density polyethylene (LDPE); Ni/acid-washed bentonite clay for polypropylene (PP); neat kaolin for polystyrene (PS); Fe-restructured natural clay for a mixture of polyethylene, PP, PS, polyvinyl chloride (PVC), and polyethylene terephthalate (PET). The main problem in using natural clays and clay minerals as catalysts is their heterogeneous composition, which can vary even within the same deposit. The serpentine group is of interest in studying its catalytic properties as fairly common clay minerals.

Visualization of Macrophase Separation and Transformation in Immiscible Polymer Blends

Visualization of Macrophase Separation and Transformation in Immiscible Polymer Blends

Modification of mechanical properties of Shanghai clayey soil with expanded polystyrene

Abstract In the present study, the resistance characteristics of Shanghai clayey soil-expanded polystyrene (EPS) mixture have been explored, using unconfined compressive and consolidation and rebound tests. EPS beads were mixed homogenously with clay soil in accordance with different mass ratios of beads to soil, that is, 0, 0.02, and 0.03%. Four particle sizes of EPS were used in the mixtures, that is, 0.5, 1, 3, and 7 mm, to reconstruct the samples. The experimental results indicated that (1) under the condition of unconfined compressive test, with the increase of EPS particle size, the compressive strength of reinforced soil increases significantly, but the compressive strength of reinforced soil decreases compared with the control sample, and it also decreases with high content compared to low EPS content; (2) under the consolidation and rebound test, compression index and rebound index of reinforced soil increased obviously compared with the control sample, but the compression modulus of reinforced soil decreases significantly; (3) in addition, the ductility of reinforced soil decreases with the increase of EPS particle size but increases compared with the control sample. At the same time, the stiffness of reinforced soil is much decreased compared with the control sample. Finally, the cause of deformation characteristics of reinforced soil was explained based on the feature of EPS material and the interaction between soil particles and particles of EPS beads.

Development of carbon foams with hierarchical porosity

Mesoporous carbon materials (pore size ranging 2-50 nm) have been used in applications as membranes, filters, catalyst supports or electrodes in electrochemical devices. Their problems related with diffusion of reactants/products and heat leading off from or supplied to the reactors have motivated the efforts directed to obtain new materials capable of combining pores in different scales. In this work a double templating method is used to generate carbon foams with hierarchical pore structure. The mixture of mesophase pitch (MP) and polystyrene (PS) allows infiltrating preforms of packed NaCl particles which afterwards can be removed away by dissolution in water, forming the large pores in the material. Posterior heat treatments allow removing an interconnected fine microstructure created by the PS, which is able to create the fine porosity in the material. The success of the process depends on the solidification conditions of the infiltrating mixture and the careful removal of the templates. By this method a new class of materials with hierarchical porosity (pores in the range 500 mm-20 nm) has been obtained.

Cellular Vibropneumatic Compacted Corundum. Part 3. Selection of Pressing Force and Order of Application During Vibration Treatment of Alumina-Foam Polystyrene Mixtures

Cellular Vibropneumatic Compacted Corundum. Part 3. Selection of Pressing Force and Order of Application During Vibration Treatment of Alumina-Foam Polystyrene Mixtures

Cellular Vibropneumatically Compacted Corundum. Part 2. Features of Physical and Mechanical Vibration Treatment Processes of Alumina-Foam Polystyrene Mixtures

Cellular Vibropneumatically Compacted Corundum. Part 2. Features of Physical and Mechanical Vibration Treatment Processes of Alumina-Foam Polystyrene Mixtures

All-solid-state potassium-selective sensor based on carbon black modified thermoplastic electrode

Thermoplastic carbon composite electrodes have been introduced by our group as novel electrodes with improved electrochemical properties and previously applied for accurate detection of biomarkers using voltammetric methods. Because of their exceptional properties, we hypothesized they would work well as potentiometric ion-selective electrodes as well. In this work, potassium selective thermoplastic electrodes (TPEs) were developed for potentiometric detection for the first time and applied in biofluids. TPEs were fabricated using mixture of polystyrene and polycaprolactone and two types of graphite (MG1599 and Nano19) for comparison, and modified with carbon black via drop-casting. Carbon black modification was optimized in the presence of various numbers of carbon black layers, while ion selective membrane components were optimized at different component ratios. Under optimized conditions, TPEs exhibited Nernstian response to K+ with sensitivity of 59.3 ± 1.01 mV decade−1 and near-Nernstian response with sensitivity of 56.8 ± 1.7 mV decade−1 within a linear range of 1.0 × 10−4 M-1.0 × 10−1 M with a LOD of 1.0 × 10−4- M for Nano19- and MG1599-based TPEs, respectively. The K+-selective TPEs demonstrated rapid response (4 s) and excellent stability, repeatability and reproducibility. The applicability of electrodes were shown in human pooled urine and artificial interstitial fluid samples with potassium ion concentrations ranging from healthy and unhealthy levels. Therefore, the electrodes could be used in healthcare applications for accurate detection of K+ exists in complex matrix and can be easily adapted to simultaneously monitor other ions for diagnosis of diseases due to miniaturization of TPEs.

FEATURES OF IN SITU FORMATION OF MIXTURES OF LINEAR POLYMERS

This article is devoted to the analysis of the results of the investigation of the process of forming mixtures of linear polymers formed simultaneously in situ according to different mechanisms. The first mechanism is polyaddition, the second mechanism is radical polymerization. This is one of the possible ways to obtain multicomponent polymer systems. The kinetics of chemical reactions of the formation of components and the phase separation which accompanies these reactions were studied for mixtures of poly(methyl methacrylate) (PMMA) with two polyurethanes (PU) of different chemical nature of both flexible and rigid blocks. PU-1 was synthesized from macrodiisocyanate based on oligo(tetramethylene glycol) with molecular mass 1000 g·mol–1 and hexamethylene diisocyanate taken in the molar ratio 1 : 2 using diethylene glycol as a chain extender. PU-2 was synthesized from macrodiisocyanate based on olygo(propylene glycol) with molecular mass 1000 g·mol–1 and toluylene diisocyanate taken in the molar ratio 1 : 2 using butanediol as a chain extender. The mixture of polystyrene (PS) with PU-2 was studied too. It is established that regardless of the chemical nature of the components, the process of in situ mixture formation is subject to general laws. In particular, the change in the chemical nature of the component formed by the mechanism of polyaddition (mixtures PMMA/PU-1 and PMMA/PU-2) or of the component formed by radical polymerization (mixtures PMMA/PU-2 and PS/PU-2) does not affect the nature of the dependence of the conversion degree of components and the fraction of formed polymers at the beginning of the phase separation on the composition of the initial reaction mixtures. Only the absolute values of these parameters change due to different reactivity and different thermodynamic compatibility of the mixed components.

Cellular vibro pneumatic compacted corundum. Part 1. Features of the use of vibropressing when obtaining highly phase refractories based on a spherical burning additive

The study of a spherically burning supplement and methods of vibropressing alumina-foam polystyrene mixtures with low molding moisture ensure immediate raw flooring, the mechanization of the main technological converters, the elimination of cropping and grinding products. The peculiarities of the physico-mechanical processes of vibropressing molding masses on the easier-forming polystyrene foam, based on the features of the macro and microstructure of the burning additive are considered. Ill. 1.

Cellular vibro pneumatic compacted corundum. Part 2. Features of physical and mechanical processes of vibration treatment of alumina-foam polystyrene mixtures

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