Showing papers on "Polystyrene published in 2021"

Pyrolysis of Polystyrene Waste: A Review.

Abstract: The manufacturing of polystyrene around the globe has escalated in the past years due to its huge applications in various areas. The perpetual market needs of polystyrene led the polystyrene wastes accretion in the landfill causing environmental deterioration. The soaring need for polystyrene also led to the exhaustion of petroleum, a non-renewable energy source, as polystyrene is a petroleum-derived product. Researchers from around the world have discovered a few techniques to take care of the polystyrene scraps, namely recycling and energy recovery techniques. Nevertheless, there are demerits involved with recycling techniques, such as they call for huge labor expenses in the separation process and cause water pollution, thereby decreasing the process sustainability. Owing to these demerits, the researchers have focused their attention on the energy recovery technique. Since petroleum is the main ingredient of polystyrene synthesis, the restoration of liquid oil from polystyrene via the pyrolysis method is a promising technique as the recovered oil has greater calorific value as compared to commercially available fuel. The present paper surveys the pyrolysis technique for polystyrene and the important process parameters that control the end product, like oil, gas, and char. The chief process parameters that are discussed in this review paper include the type of reactors, temperature, residence time, pressure, catalyst types, type of fluidizing gases, and their flow rate. A more recent technique of utilizing a solvent to perform pyrolysis and the effect of various process conditions on the product yield have been discussed. Apart from this, various outlooks to optimize the liquid oil recovery from polystyrene are also reviewed.

Efficient photocatalytic mineralization of polymethylmethacrylate and polystyrene nanoplastics by TiO2/β-SiC alveolar foams

Abstract: Household wastewaters contain microplastics and nanoplastics that end up in ecosystems because these pollutants are not filtered by current wastewater treatment plants. Therefore, there is a need for advanced removal technologies. Here, we tested the degradation of polymethylmethacrylate (PMMA) and polystyrene (PS) nanoparticles by photocatalysis with TiO2–P25/β-SiC foams under UV-A radiation. We studied the effect of flow rate, initial pH and light intensity. Results show that about 50% of the carbon of polymethylmethacrylate nanobeads are degraded in 7 h at an irradiance of 112 W/m2, a flow rate of 10 mL/min and an initial pH of 6.3. Degradation is faster at low pH (4–6) and low flow rate. 140-nm polystyrene degrades faster than 508-nm polystyrene.

Effect of addition of TiO2 nanoparticles on structural and dielectric properties of polystyrene/polyvinyl chloride polymer blend

Abstract: The present study deals with the effect of the addition of pure titanium oxide nanoparticles (TiO2 NPs) prepared by the sol–gel technique on a polystyrene (PS)/polyvinylchloride (PVC) polymer blend of a composition of 50/50 wt. % using the casting method. X-ray diffraction (XRD), high-resolution transmission electron microscopy, field emission scanning electron microscopy, and energy dispersive x-ray analysis confirmed the preparation of TiO2 NPs in semi-spherical shapes, with the average particle size ranging from 7 to 22 nm. The structural, optical, and dielectric properties of the prepared polymer nanocomposite films are restudied using different tools. In addition, the dielectric properties are studied. XRD and Attenuated Total Reflection-Fourier Transform Infrared (ATR-FTIR) spectroscopy confirmed the complexation and interaction between the PS/PVC polymer blend and TiO2 NPs. HRSEM images reveal that TiO2 NPs appeared as white spots inside the spherical domain of PS/PVC matrices. Optical properties such as absorbance, reflection, bandgap energy, refractive index, and optical dielectric (constant and loss) are studied. These results revealed that TiO2 NPs create inter-bands between valence and conduction bands. The addition of TiO2 NPs to the PS/PVC blend improves the electrical conductivity of the PS/PVC blend due to charge carrier buildup and increased polymeric chain segmental mobility inside the polymeric matrices.

Superhydrophobic and superoleophilic polystyrene/carbon nanotubes foam for oil/water separation

Abstract: In this study, a novel superhydrophobic and superoleophilic polystyrene/carbon nanotubes foam (PCF) for oil/water separation was fabricated via a facile two-step strategy. The combination of phase inversion and porogen leaching generated hierarchical porous structure with high porosity. Carbon nanotubes (CNTs) were firmly immobilized on the polystyrene (PS) skeleton, constructing a nanoscale-rough surface with superhydrophobicity and superoleophilicity. The PCF displayed large absorption capacity, fast absorption rate, and strong preference for organic liquids, capable of removing oil efficiently from water surface and surfactant stabilized oil-in-water emulsion. The PCF shows great potentials in oil spill treatment and chemical accident remediation. In addition, the raw PS used in PCF fabrication was from recycled packages, providing a feasible path for reducing the environmental pollution and changing waste into valuable resources.

Depolymerization of polystyrene under ambient conditions

Abstract: Depolymerization of the addition polymer polystyrene to monomeric styrene is facilitated by mechanochemical processing at room temperature under ambient atmosphere. The reaction occurs in metal-based milling media in concert with scission of macromolecular chains that generates carbon-centered free-radicals detectable by EPR spectroscopy, even though the processing is performed in air.

Polydopamine Nanobottles with Photothermal Capability for Controlled Release and Related Applications

Abstract: Nanobottles refer to colloidal particles featuring a hollow body connected to a single opening on the surface. This unique feature makes them ideal carriers for the encapsulation and controlled release of various types of cargos. Here a facile route to the fabrication of uniform nanobottles made of polydopamine by leveraging swelling-induced pressure is reported. When polystyrene spheres are coated with polydopamine and then incubated with a toluene/water emulsion, the polystyrene will be swollen to automatically poke a single hole in the shell because of the pressure inside the shell. After quenching the swelling with ethanol and then removing all the polystyrene with tetrahydrofuran, polydopamine nanobottles are obtained. The dimensions of the hollow body are determined by the polystyrene template, while the size of the opening can be tuned by varying the shell thickness. Through the opening, different types of cargos, including small molecules and biomacromolecules, can be easily loaded with a thermoresponsive material into the cavity. The cargos can be released in a controllable manner through direct heating or polydopamine-enabled photothermal heating. In a proof-of-concept experiment, the polydopamine nanobottles are used for temperature-controlled release of thrombin to trigger the formation of fibrin gels in situ.

The effect of dispersion condition on the structure and properties of polystyrene/graphene oxide nanocomposites

Abstract: The realization of an optimum strategy for dispersing graphene nano‐sheets in a thermoplastic matrix is important for obtaining a successful preparation and, consequently, a better enhancement of different properties for the resultant polymer/graphene nanocomposites. In this study, nanocomposites of polystyrene (PS) and graphene oxide (GO) were prepared using solution blending method with tetrahydrofuran as the solvent. Magnetic stirring, water bath sonication, and shear mixing were utilized to disperse GO nano‐sheets in PS. Different periods of mixing for the last two techniques were examined to study their effect on the structure and properties on the PS/GO nanocomposites. For the first sample, water bath sonication and shear mixing were used for 30 and 60 minutes, respectively. For the second sample, both mixing periods were doubled. The results obtained by employing different characterization techniques showed a good dispersion of nano‐sheets in the matrix and enhanced thermal and thermomechanical properties for both samples, with a superiority for the first sample in terms of storage modulus to prevent the nano‐sheets from damage due to the application of sonication and mixing for a shorter period of time.

Diffusion Coefficients and Activation Energies of Diffusion of Organic Molecules in Polystyrene below and above Glass Transition Temperature.

Abstract: General Purpose Polystyrene (GPPS) and High Impact Polystyrene (HIPS) is used in packaging food as well as for technical products. Knowledge of the diffusion behavior of organic molecules in polystyrene (PS) is important for the evaluation of the diffusion and migration process. Within this study, diffusion coefficients were determined in GPPS and HIPS below and above the glass transition temperature. Diffusion coefficients were determined from desorption kinetics into the gas phase using spiked GPPS and HIPS sheets as well as from permeation kinetics through a thin GPPS film. Overall, 187 diffusion coefficients were determined in GPPS and HIPS at temperatures between 0 °C and 115 °C. From the temperature dependency of the diffusion coefficients 45 activation energies of diffusion EA and the pre-exponential factor D0 were determined. As expected, the activation energies of diffusion EA show a strong dependency from the molecular volume of the investigated substances. At the glass transition temperature, only a slight change of the diffusion behavior were observed. Based on EA and D0, prediction parameters for diffusion coefficients were established.

Biobased Thermoplastic Elastomer Based on an SMS Triblock Copolymer Prepared via RAFT Polymerization in Aqueous Medium

Abstract: In recent years, there has been a great interest in preparing polymers from bioresources, as this practice has several advantages over petrobased polymers. Thermoplastic elastomers (TPEs) are an interesting class of polymers that can be easily processed, reused, and recycled. The terpene, β-Myrcene (MY), is an important vinylic monomer having a conjugated diene in the backbone, which has a resemblance to the isoprene unit, a building block for natural rubber. MY is available from several bioresources like hops, lemongrass, bay plants, and so forth. In this work, reversible addition–fragmentation chain-transfer (RAFT) polymerization was used for the very first time to prepare an ABA-type triblock copolymer, polystyrene-b-poly(β-myrcene)-b-polystyrene (SMS), where poly(β-myrcene) acted as the soft block and polystyrene (PS) as the hard block. For this, styrene was initially polymerized using S,S-dibenzyl trithiocarbonate as a bifunctional RAFT agent, and the resultant PS was then used as a macro-RAFT agent to polymerize MY to attain SMS triblock copolymers. The successful preparation of the block copolymers (BCPs) was confirmed by NMR, FTIR, and GPC analyses. The DSC and AFM analyses showed the phase-separated morphology of hard and soft domains of PS and PMY, respectively. These SMS BCPs showed good tensile properties and a low tension set of 4.12%, indicating their application as a potential TPE. The scrapes of these SMS BCPs were successfully recycled and reused, indicating the sustainability of the process for this potential TPE.

Electrospun highly corrosion-resistant polystyrene–nickel oxide superhydrophobic nanocomposite coating

Abstract: A key challenge in producing superhydrophobic coatings (SHC) is to tailor the surface morphology on the micro-nanometer scale. In this work, a feasible and straightforward route was employed to manufacture polystyrene/nickel oxide (PSN) nanocomposite superhydrophobic coatings on aluminum alloys to mitigate their corrosion in a saline environment. Different techniques were employed to explore the influence of the addition of NiO nanoparticles to the as-prepared coatings. PSN-2 composite with ~ 4.3 wt% of NiO exhibited the highest water contact angle (WCA) of 155° ± 2 and contact angle hysteresis (CAH) of 5°. EIS Nyquist plots of 3 g of electrospun polystyrene coatings (a) without and with (b) 0.1, (c) 0.15, and (d) 0.2 g of NiO.

Comparative study of effect of different coupling agent on mechanical properties and water absorption on wheat straw-reinforced polystyrene composites:

Abstract: The present work deals with the effect of various treatments on the mechanical properties and water absorption of wheat straw (WS)-reinforced polystyrene (PS) composites. Four different surface tre...

Synthesis of aminophosphonate-functionalised ZnO/polystyrene-butadiene nanocomposite and its characteristics for uranium adsorption from phosphoric acid

Abstract: A new ZnO/polystyrene-butadiene (ZnO/PSBN) and aminophosphonate (Ap) functionalised ZnO/PSBN nanocomposites synthesised via chemical processes. Scanning electron microscopy, BET isotherm studies, X...