Pure Styrene Research Articles

Catalytic fast pyrolysis over heavy metals-containing livestock manure biochar catalyst for polystyrene upcycling

The perpetual market demand for polystyrene results in the gradual accumulation of polystyrene waste, placing a serious burden on the environment. This study proposed a promising method to upcycle polystyrene for styrene-derived monomers through catalytic fast pyrolysis. The metals-incorporated biochar catalysts were synthesized from heavy metals-contaminated manure waste for catalytic fast pyrolysis of polystyrene. The experimental results showed that the bimetallic biochar-derived catalyst containing Zn and Cr (Zn-Cr/C) was more conducive to the liquid production, with an extremely high yield of 88.22 wt%. Monometallic Pb-incorporated biochar catalyst (Pb/C) and bimetallic Zn-Cu co-doped on biochar (Zn-Cu/C) were more favorable for the production of pure styrene, with the mass yield of 61.26 wt% and 60.39 wt%, respectively. Additionally, the study elucidated a deep understanding of the reaction mechanisms involved in the catalytic fast pyrolysis of polystyrene. Simply put, this study introduced a new concept to convert heavy metal-contaminated animal manure into metal-incorporated biochar catalysts for catalytic conversion of polystyrene waste in pure styrene-based monomers.

Vacuum pyrolysis depolymerization of waste polystyrene foam into high-purity styrene using a spirit lamp flame for convenient chemical recycling

Vacuum pyrolysis of waste polystyrene foam over a spirit lamp flame for 20 minutes produced 98% pure styrene without needing fractionation or purification, which promises a convenient closed-loop chemical recycling system.

Optimizing Host–Guest Selectivity for Ethylbenzene Capture Toward Superior Styrene Purification

The separation of ethylbenzene (EB) and styrene (ST) mixtures to obtain pure ST has been an enduring challenge for the petrochemical industry. So far, adsorptive separation using porous materials has mainly focused on capturing ST rather than EB, where high temperatures are needed to reactivate the sieving materials and collect the product. Here, we tuned the host–guest interactions in thienothiophene-based trianglimine (ThT-TI) macrocycles to selectively adsorb the unreacted EB over ST, after a dehydrogenation reaction, to readily provide pure ST without the need for further thermal treatments. This is the first report on the selective adsorptive separation of EB over ST using macrocycles as molecular hosts. Both crystalline and amorphous ThT-TI can be used to separate EB with 96% uptake capacity. Single-crystal and powder X-ray diffraction patterns suggest that this selective adsorption arises from a guest-induced structural reordering and involvement of the sulfur atoms in host/guest C–H···π interactions. We believe that this work paves the way for a new generation of molecular sieves that are designed to afford high-purity products by in situ capturing of the unreacted starting materials.

Fabrication of urea formaldehyde–epoxy resin microcapsules for the preparation of high self‐healing ability containing SBS modified asphalt

AbstractAsphalt exhibits self‐healing ability, though at a lower rate. In this study, urea formaldehyde–epoxy resin (UFE) microcapsules were prepared using polyurea formaldehyde as the wall and epoxy resin as the core material, which were in turn applied to fabricate UFE–styrene butadiene styrene modified asphalt (abbreviated as UBS asphalt). Scanning electron microscopy and transmission electron microscopy analyses revealed well‐coated microcapsules have globular geometry with obvious folds in the wall. Ductility test showed 90% higher healing rate of UBS asphalt than pure styrene butadiene styrene (SBS) modified asphalt. Dynamic shear rheometer and multi‐stress creep recovery tests indicated that UFE microcapsule incorporation can improve the viscoelasticity, high temperature stability, and permanent deformation resistance of pure SBS modified asphalt attributed to the even distribution of UFE microcapsules in asphalt and their better mutual compatibility, which was confirmed by fluorescence microscopy. At 100 and 3200 Pa, the recovery rate of 0.4% UBS asphalt was 32.1% and 71.7% higher than that of the original SBS modified asphalt, respectively. UFE microcapsule and asphalt only physically interacted as confirmed by Fourier infrared spectroscopy analysis. This study provides a feasible alternative approach for the preparation of UBS asphalt with enhanced mechanical properties and thermal stability for applications in construction and highway industries.

Next Generation of Guanidine Quinoline Copper Complexes for Highly Controlled ATRP: Influence of Backbone Substitution on Redox Chemistry and Solubility

Ligands DMEG6etqu, TMG6etqu, DMEG6buqu, and TMG6buqu were developed on the basis of guanidine quinoline (GUAqu) ligands 1,3‐dimethyl‐N‐(quinolin‐8‐yl)imidazolidin‐2‐imine (DMEGqu) and 1,1,3,3‐tetramethyl‐2‐(quinolin‐8‐yl)guanidine (TMGqu). These ligands feature an alkyl substituent at the C6 of the quinoline backbone. The synthetic strategy developed here enables inexpensive syntheses of any kind of C6‐substituted GUAqu ligands. On one hand, the alkylation increases the solubility of corresponding copper complexes in apolar atom transfer radical polymerization (ATRP) monomers like styrene. On the other hand, it has a significant electronic influence and thus an effect on the donor properties of the new ligands. Seven CuI and CuII complexes of DMEG6etqu and TMG6etqu have been crystallized and were studied with regard to their structural and electrochemical properties. CuI and CuII complexes of DMEG6buqu and TMG6buqu turned out to be perfectly soluble in pure styrene even at room temperature, which makes them excellent catalysts in the ATRP of apolar monomers. The key characteristics of the ATRP equilibrium, KATRP and kact, were determined for the new complexes. In addition, we used our recently developed DFT methodology, NBO analysis, and isodesmic reactions to predict the influence of the introduced alkyl substituents. It turned out that high conformational freedom in the complex structures leads to a significant uncertainty in prediction of the thermodynamic properties.

A molecular dynamics study on Young's modulus and tribology of carbon nanotube reinforced styrene-butadiene rubber.

Styrene-butadiene rubber is a copolymer widely used in making car tires and has excellent abrasion resistance. The Young's modulus and tribology of pure styrene butadiene rubber (SBR) polymer and carbon nanotube reinforced polymer composites have been investigated using molecular dynamics simulations. The mechanism of enhanced tribology properties using carbon nanotube has been studied and discussed. The obtained Young's modulus shows the enhancement in mechanical properties of SBR polymer when carbon nanotubes are used as reinforcement. The concentration, temperature and velocity profiles, radial distribution function, frictional stresses, and cohesive energy density are calculated and analyzed in detail. The Young's modulus of SBR matrix increases about 29.16% in the presence of the 5% CNT. The atom movement velocity and average cohesive energy density in the friction area of pure SBR matrix was found to be more than that of the CNT/SBR composite. Graphical abstract Initial and final conditions of (a) pure SBR matrix and (b) CNT/SBR matrix subjected toshear loading and frictional stresses of top Fe layers of both pure SBR and CNT/SBR composite.

Spray process to styrene grafting onto polyethylene film surface for paintability enhancement

Abstract A direct and fast post-processing method to modify polyethylene (PE) film surface is proposed in order to improve its paintability performance without changing its bulk properties. This goal is achieved by grafting styrene onto the PE film surface using a macrocarbocationic copolymerization reaction where both catalysts and reagents are sprayed directly on softened film respectively. Pure styrene as grafting molecule and aluminium chloride suspended in n-heptane as catalyst are used. Grafting reaction occurrence was assessed by analyzing the reacted film surface before and after extraction of non-grafted reaction products. The results confirmed by three independent analytical techniques evidence reaction occurrence. A graft-copolymer layer remains onto the PE film surface even when physically adhered reaction products were extracted. This layer enhances PE film water-affinity and paintability either with water or acrylics paints because of the grafted aromatic group and roughness increase. Besides, this modification increments PE thermal degradation temperature giving another beneficial effect for future film applications. The proposed modification film methodology has potential application in continuous film production as reagents spraying onto softened films could be applicable in a cast film extrusion line.

MOF‐5‐Polystyrene: Direct Production from Monomer, Improved Hydrolytic Stability, and Unique Guest Adsorption

AbstractAn unprecedented mode of reactivity of Zn4O‐based metal–organic frameworks (MOFs) offers a straightforward and powerful approach to polymer‐hybridized porous solids. The concept is illustrated with the production of MOF‐5‐polystyrene wherein polystyrene is grafted and uniformly distributed throughout MOF‐5 crystals after heating in pure styrene for 4–24 h. The surface area and polystyrene content of the material can be fine‐tuned by controlling the duration of heating styrene in the presence of MOF‐5. Polystyrene grafting significantly alters the physical and chemical properties of pristine MOF‐5, which is evident from the unique guest adsorption properties (solvatochromic dye uptake and improved CO2 capacity) as well as the dramatically improved hydrolytic stability of composite. Based on the fact that MOF‐5 is the best studied member of the structure class, and has been produced at scale by industry, these findings can be directly leveraged for a range of current applications.

Catalytic Pseudomonas taiwanensis VLB120ΔC Biofilms Thrive in a Continuous Pure Styrene Generated by Multiphasic Segmented Flow in a Capillary Microreactor

This study investigated the survival and catalytic potential of a single species Pseudomonas taiwanensis VLB120ΔC biofilm for the conversion of styrene to (S)-styrene oxide in a multiphasic capillary microreactor containing the highly toxic substrate styrene as a pure phase. The catalytic biofilm was cultivated under high fluidic stress in a continuous three-phase segmented flow system comprising aqueous medium, air, and styrene. This concept required an adaptation period of 7 days, during which P. taiwanensis VLB120ΔC developed a biofilm exhibiting a remarkable cellular integrity with nearly 70% intact cells. In a three-phase segmented flow biofilm microreactor, an average specific styrene epoxidation rate of 10 g/Ltube/day was achieved continuously for a period of 20 days without any clogging problems. Overall, this note highlights the robustness of biofilms as a promising biocatalyst format for the conversion/synthesis of toxic organic chemicals and the applicability of multiphasic capillary microreactors for biofilm based catalysis.

Replacing styrene with bioderived alternatives in polyesters

Composites offer high strength and stiffness at a lower density compared to other structural materials, therefore are of growing use to a variety of lightweight structures in order to reduce emissions and improve performance. However, traditional composites have the highest embodied carbon content of all engineering materials with limited methods of recycling. Therefore moving composites to a biobased sourcing can have a large impact in the eco-footprint of these materials. 2-Methoxy-4-vinylphenol has previously been shown to be sustainably biosourced from microbial degradation of lignin and has been termed ‘biostyrene’. In this work, the authors investigate the use of 2-methoxy-4-vinylphenol analogues as a replacement for styrene as a reactive thinner for thermoset polyester, which is commonly used in fibreglass composite. 2-Methoxy-4-vinylphenyl acetate and 2-methoxy-4-vinylphenyl oleate were synthesised and along with unmodified 2-methoxy-4-vinylphenol and 1,2-dimethoxy-4-vinylbenzene (3,4-dimethoxystyrene) were compared to styrene in typical polyester formulations. The mechanical properties by way of tensile tests and water-uptake tests and thermal properties by way of dynamic scanning calorimetry were used for comparison. Overall, the solubility issues were apparent using the biostyrenes, however, blends of biostyrenes with styrene of up to 50% showed no statistical difference with pure styrene in properties and so may be a viable styrene replacement in polyester used for fibreglass.

Study of nitrile-containing proton exchange membranes prepared by radiation grafting: Performance and degradation in the polymer electrolyte fuel cell

The fuel cell performance and durability of three kinds of styrene based radiation grafted membranes are investigated and compared in the single cell. The styrene/methacrylonitrile (MAN) co-grafted membrane exhibits the best performance among the tested radiation grafted membranes. The accelerated tests under open circuit voltage (OCV) conditions and post-mortem analysis demonstrate that the nitrile-containing membranes exhibit significantly enhanced durability compared to the pure styrene grafted membrane, which is associated with the reduced gas crossover rates and attributed to the improved gases barrier properties due to the polarity of the nitrile group. To understand the influence of each functional group in the co-monomer units, both styrene/MAN and styrene/acrylonitrile (AN) co-grafted membranes are evaluated in a set of tests at OCV. The degrees of loss of the graft components are subsequently quantitatively analyzed based on FTIR spectra, showing a comparable decomposition rate of grafted styrene units, but more loss of nitrile in case of the styrene/AN co-grafted membrane. The styrene/AN co-grafted membrane, with AN lacking protection at the α-position in contrast to MAN, is found to be susceptible to significant hydrolysis, directly leading to an accelerated degradation in the late stages of the 130 h OCV test and inhomogeneous in-plane degradation.

Volumetric and Viscometric Studies of Molecular Interactions of Binary Liquid Mixtures of Styrene with Acetone and Dimethylsulphoxide at Different Temperatures

The present work reports the results of densities, ρ, viscosities, η, ultrasonic speeds, u, and refractive indices, n, of pure styrene (STY), acetone (ACT) and dimethylsulphoxide (DMSO) and of their binary liquid mixtures over the entire composition range at 298.15, 303.15, 308.15, and 313.15 K. The excess molar volumes, V E , excess intermolecular free lengths, , deviations in isentropic compressibilities, Δk s , viscosities, Δη, and in refractive indices, Δn were calculated from the experimental data. Partial molar volumes, , and partial molar compressibilities, , of ACT and DMSO in styrene at infinite dilution and at different temperatures have been evaluated. Apart from using density data for the calculation of V E , excess molar volumes have also been estimated by using the Flory's statistical theory and refractive index measurements.

Cyclic Carbonate Synthesis Catalysed by Bimetallic Aluminium–Salen Complexes

The development of bimetallic aluminium-salen complexes [{Al(salen)}(2)O] as catalysts for the synthesis of cyclic carbonates (including the commercially important ethylene and propylene carbonates) from a wide range of terminal epoxides in the presence of tetrabutylammonium bromide as a cocatalyst is reported. The bimetallic structure of one complex was confirmed by X-ray crystallography. The bimetallic complexes displayed exceptionally high catalytic activity and in the presence of tetrabutylammonium bromide could catalyse cyclic carbonate synthesis at atmospheric pressure and room temperature. Catalyst-reuse experiments demonstrated that one bimetallic complex was stable for over 60 reactions, though the tetrabutylammonium bromide decomposed in situ by a retro-Menschutkin reaction to form tributylamine and had to be regularly replaced. The mild reaction conditions allowed a full analysis of the reaction kinetics to be carried out and this showed that the reaction was first order in aluminium complex concentration, first order in epoxide concentration, first order in carbon dioxide concentration (except when used in excess) and unexpectedly second order in tetrabutylammonium bromide concentration. Further kinetic experiments demonstrated that the tributylamine formed in situ was involved in the catalysis and that addition of butyl bromide to reconvert the tributylamine into tetrabutylammonium bromide resulted in inhibition of the reaction. The reaction kinetics also indicated that no kinetic resolution of racemic epoxides was possible with this class of catalysts, even when the catalyst was derived from a chiral salen ligand. However, it was shown that if enantiomerically pure styrene oxide was used as substrate, then enantiomerically pure styrene carbonate was formed. On the basis of the kinetic and other experimental data, a catalytic cycle that explains why the bimetallic complexes display such high catalytic activity has been developed.

Volumetric and ultrasonic studies of molecular interactions in binary liquid mixtures of styrene with toluene at different temperatures

This paper presents experimental data for densities (p) and ultrasonic speeds (u) of pure styrene and toluene and of their binary liquid mixtures over the entire composition range at 298.15, 303.15, 308.15 and 313.15 K. From the experimental data the excess molar volumes (V E ), deviations in isentropic compressibilities (Δk s ), and in acoustic impedances (ΔZ), were calculated for the binary mixtures over the entire composition range at all the temperatures. Moreover, partial molar volumes, V 0 φ,1 and V 0 φ , 2 and partial molar isentropic compressibilities, K 0 φ,1 and K 0 φ,1 at infinite dilution of styrene in toluene and toluene in styrene were examined. The variations of these parameters with composition of mixture suggest the strength of interactions between the component molecules under study.

Volumetric, ultrasonic, viscometric and refractive index behaviour of binary mixtures of styrene with ethylalcohol and chlorobenzene at different temperatures ( T = 298.15 K to 313.15 K)

This paper presents experimental data for densities, ρ, viscosities, η, ultrasonic speeds, u, and refractive indices, n, of pure styrene (STY), chlorobenzene (CB), ethylalcohol (EA) and of their binary liquid mixtures over the entire composition range at 298.15, 303.15, 308.15, 313.15 K. The uncertainties in density, ultrasonic speed, viscosity, and refractive index measurements are ± 0.0001 g cm − 3 , ± 0.15 m s − 1 , ± 0.003 mPa s, and ± 0.0002 units, respectively. From these experimental data, excess molar volume, deviations in isentropic compressibility, viscosity and in refractive index and internal pressure are calculated for all the binary mixtures, over the entire composition range. The apparent molar volume, V ϕ ,2, and apparent molar compressibility, K ϕ ,2, of CB and EA in styrene were also calculated. Partial molar volume, V− ϕ ,2 0, and partial molar compressibility, K− ϕ ,2 0, were estimated by using the values of V ϕ ,2 and K ϕ ,2 of CB and EA in styrene at infinite dilution. The excess and deviation functions were fitted to Redlich and Kister type polynomial equation. Moreover, theoretical predictions of refractive index of the two binary mixtures are made on the basis of empirical and semiemperical relations by using the experimental values of the pure components. The results provide information on the molecules in the pure liquids as well as in the binary mixtures.

Kinetics of Miniemulsion Polymerization of Styrene in the Presence of Organoclays

AbstractThe impacts of nanoclays on the miniemulsion polymerization kinetics of styrene were studied. It was found that both RP and the fractional conversion decreased upon increasing the organoclay content in the miniemulsion system. In the presence of nanoclay the molecular weight of polystyrene nanoclay composite is lower and the particle size polydispersity of the final composite latex is greater than that of pure styrene miniemulsion polymerization. The effect of the nanoclays is mainly caused by the destabilization of the miniemulsion by the organoclay particles. The increase in the monomer viscosity and the decrease in the diffusion rate of the monomer and the living polymer inside the monomer droplet also accounts for the reduction in the polymerization rate.magnified image

Catalytic Depolymerisation of Polystyrene

Polystyrene waste was depolymerised by using various acidic and basic catalysts. Among the metal oxides, calcium oxide was found to be the cheapest and most effective catalyst for the depolymerization of waste polystyrene into styrene. Metal carbonates provided pure styrene, but in low yields. Acids were found to be poor catalysts for depolymerisation, since they led to further reactions leading to side products.

Effects of −COOH Groups on Organic Particle Surface on Hydrous Alumina Heterogeneous Coating

The effects of the −COOH groups on polystyrene particle surface on the heterogeneous coating of hydrous alumina in an aqueous process were studied. Pure polystyrene particles and particles loaded with different densities of −COOH groups were used in the hydrous alumina coating process. The particles were synthesized by the emulsifier-free emulsion polymerization of pure styrene, and copolymerization of styrene and methacrylic acid (MAA), with potassium persulfate (K2S2O8) as initiator. The amount of the −COOH groups on the copolymerized particle surface was determined by conductometric titration. High-resolution transmission electron microscopy (HRTEM) images showed that, when the density of −COOH groups loaded on the particle surfaces was high enough, the particles could be easily heterogeneously coated with hydrous alumina; when it was too low, there was much homogeneous nucleation on the coated particles and in the bulk. In the absence of −COOH groups, i.e., pure polystyrene, the particles could hardly be coated under the same conditions. It is inferred that the precipitation and reaction occurred at the sites of −COOH groups on the particle surfaces in the coating process.

NMR Microscopy: A Tool for Measuring Monomer Diffusion in Supercritical CO2

AbstractSummary: The diffusion of styrene into linear low density polyethylene in a solution of supercritical CO2 was investigated using NMR microimaging. For both pure styrene and styrene dissolved in supercritical CO2, the diffusion was found to follow Fickian kinetics. Supercritical CO2 was found to enhance the rate and extent of diffusion of styrene into the substrate by up to three times under the conditions of this investigation, compared to pure styrene. NMR imaging was used to measure the concentration profiles of the styrene penetrants in real time, and the results were fitted to a Fickian model for diffusion. At a CO2 pressure of 150 bar and temperature of 40 °C, the diffusion coefficient of a 30 wt‐% solution of styrene into LLDPE was calculated to be 1 × 10−11 m2 · s−1. This is significantly faster than the diffusion coefficient measured for pure styrene diffusion at 40 °C (3 × 10−12 m2 · s−1). The diffusion coefficients determined by gravimetric analysis were slightly higher than those determined by the imaging method. This was probably due to residual styrene and/or polystyrene adhering to the surface of the films in the gravimetric technique.NMR image of styrene in linear low density polyethylene following supercritical fluid enhanced impregnation.imageNMR image of styrene in linear low density polyethylene following supercritical fluid enhanced impregnation.

Single-Step in Situ Preparation of Polymer-Grafted Multi-Walled Carbon Nanotube Composites under 60Co γ-Ray Irradiation

We present single-step in situ syntheses of polystyrene-grafted multi-walled carbon nanotubes (MWNTs) under 60Co γ-ray irradiation. Pristine MWNTs were first dispersed in pure styrene under sonication, and polystyrene (PS) was then covalently attached to the surface of MWNTs when the mixture was subjected to γ-ray irradiation. The polymer content in PS functionalized MWNTs can be up to ∼15 wt %, as determined by thermal gravimetric analysis (TGA). The functionalized MWNTs can be dispersed well in common organic solvents such as THF, toluene, and CHCl3, etc. The presence of PS in the functionalized carbon nanotube composites was further evidenced by Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM/HRTEM). The mechanism of the irradiation grafting process was also proposed. The reported γ-ray irradiation grafting technique is expected to be suitable for industrial scale-up preparation of functionalized carbon nanotubes (CNTs).