High Styrene Content Research Articles

Structure-Property Relationships of CO2 Absorbing Core-Shell Microparticles with Encapsulated Ionic Liquid.

The demand for new ionic liquid (IL)-based systems to selectively sequester carbon dioxide from gas mixtures has prompted the development of individual components involving the tailored design of IL themselves or solid-supported materials that provide excellent gas permeability of the overall material as well as the ability to incorporate large amounts of ionic liquid. In this work, novel IL-encapsulated microparticles comprising a cross-linked copolymer shell of β-myrcene and styrene and a hydrophilic core of the ionic liquid 1-ethyl-3-methylimidazolium dicyanamide ([EMIM][DCA]) are proposed as viable materials for CO2 capture. Water-in-oil (w/o) emulsion polymerization of different mass ratios of β-myrcene to styrene (i.e. 100/0, 70/30, 50/50, 0/100) yielded IL-encapsulated microparticles, where the encapsulation efficiency of [EMIM][DCA] was dependent on the copolymer shell composition. Thermal analysis using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) revealed that both thermal stability and glass transition temperatures depend on the mass ratio of β-myrcene to styrene. Images from scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to observe the microparticle shell morphology as well as measure the particle size perimeter. Particle sizes were found to be between 5 and 44 μm. CO2 sorption experiments were conducted gravimetrically using TGA instrumentation. Interestingly, a trade-off between CO2 absorption capacity and ionic liquid encapsulation was observed. While increasing the β-myrcene content within the microparticle shell increases the amount of encapsulated [EMIM][DCA], the observed CO2 absorption capacity did not increase as expected due to reduced porosity compared to microparticles with higher styrene content in the microparticle shell. [EMIM][DCA] microcapsules with a 50/50 weight ratio of β-myrcene/styrene showed the best synergistic effect between spherical particle diameter (32.2 μm), pore size (0.75 μm), and high CO2 sorption capacity of ∼0.5 mmol CO2/g sample within a short absorption period of 20 min. Therefore, core-shell microcapsules composed of β-myrcene and styrene are envisioned as a promising material for CO2 sequestration applications.

Chemical recycling of waste polystyrene by thermo-catalytic pyrolysis: A description for different feedstocks, catalysts and operation modes

Chemical recycling by thermo-catalytic pyrolysis/degradation offers the possibility of converting waste plastics into their original monomers or other valuable chemicals which can be used as feedstocks in chemical and petrochemical industries. Plastic wastes of polystyrene (PS) based materials can be a good source of styrene as well as mono-aromatic (BTEX: benzene, toluene, ethylbenzene, xylenes) compounds. The selectivity of pyrolysis products can be tuned by choosing the right catalyst as well as appropriate operating conditions/operation modes. In this regard, the focus of the present work was to perform thermo-catalytic pyrolysis of different waste polystyrene (WPS) feedstocks over acid and base catalysts employed in ex-situ and in-situ modes. The main goal was to compare the compositions of pyrolysis products obtained by changing feedstocks, catalysts and operation modes. A further goal was to discuss the suitability of the catalysts employed for the enhanced recovery of desired products from WPS pyrolysis. It was demonstrated that expanded polystyrene gives very similar product distribution as compared to virgin PS, both giving high styrene content. Likewise, hard PS-based random packing materials produce similar results as compared to high impact polystyrene (HIPS). Moreover, it was shown that solid base catalysts influence the composition of the pyrolysis products only slightly as compared to thermolysis. Solid acid catalyst however, showed significant impact on the composition of the pyrolysis products as compared to non-catalytic pyrolysis. These results may provide new insights for the chemical recycling of plastic wastes.

New Flory‐Huggins interaction parameter between SBR and p‐phenylenediamine antioxidants and the predictive power in molecular structure and rubber formula design

AbstractThe software package was employed to calculate the three‐dimensional solubility parameters (HSP) of SBR and antioxidants. The HSP values of antioxidants are higher than SBR, meaning that the antioxidants have higher polarity compared with SBR. The solubility measurements of antioxidants in both sulfur and peroxide cured SBR vulcanizates were performed at elevated temperatures from 80 to 130°C. The maximum solubilities (∆S) of antioxidants were correlated with the temperature and also with the new Flory‐Huggins interaction parameters (χN) calculated by the HSP values. The results turn out to be that ∆S increases with increasing temperature as expected and 4020 shows higher ∆S value. Furthermore, ∆S increases with decreasing χN, and by quantitatively mathematical fitting, one functional relationship between ∆S and χN was achieved, regardless of what the crosslinking type of SBR was and what the temperature was involved. Through prediction with χN, one can get that SBR grades with higher styrene content and butadiene/vinyl ratio result in lower χN and accordingly better compatibility with N3100. One of the possible applications of χN is to select suitable SBR and antioxidant structures to design the ever‐increasing SBR‐based green tire tread formula.

Properties of styrene-ethylene-butylene styrene block copolymer/exfoliated graphite nanoplatelets nanocomposites

Three different types of styrene-ethylene-butylene-styrene block copolymer (SEBS) with varying ratios of styrene and rubber were melt-compounded with exfoliated graphite nanoplatelets at different loadings. The morphological, thermal, and mechanical properties of the nanocomposites were studied and compared. Morphological observation under SEM and AFM found that the xGnPs were dispersed at the sub-micron level throughout the SEBS matrix. Good interfacial adhesion between the xGnPs and the matrix was also observed. However, the behavior of dispersion was dependent on the styrene/rubber content. SEBS with higher styrene content showed better dispersion and strong interfacial adhesion between the xGnPs and SEBS matrix. These results contributed to the enhancement of the tensile strength of the nanocomposites. Low styrene content behaved like rubber that resulted in low tensile strength but higher elongation compared to SEBS of different amounts of styrene. The XRD patterns indicated that the melt compounding process did not change the d-spacing of xGnPs in all types of SEBS. From the thermal analysis, there was no change in the glass transition of the polymer and no improvement in the thermal stability of the nanocomposites.

Thermal and clinker‐catalyzed pyrolyses of polystyrene waste using the Portland cement solid‐base catalyst

AbstractPolystyrene is a nondegradable lightweight foamy substance that easily blows from landfills into drains and waterways. This material creates litter and water pollution and harms the wildlife who mistakenly eat it. This study investigated a cost‐effective pyrolysis approach for catalytic conversion of waste polystyrene into useful oil and gas products. The Portland cement was used as a solid base to catalyze the pyrolysis reaction for improving the product yield, lowering the reaction temperature and shortening the reaction time. Optimum reaction conditions were investigated by varying the process temperature, process time, and amount of the catalyst. The catalytic conversion of polystyrene into oil was measured about 94.98% at 400°C. In noncatalytic conversion experiments, same conversion efficiency was achieved at 600°C, which is significantly higher than the catalytic conversion. Catalytic pyrolysis produced oil with major part of volatile fractions and 42.14% styrene. The thermal pyrolysis produced oil with high styrene content (63.17%). Overall, styrene content of oil product was lower than the reported values in the literature. The noncatalytic pyrolysis produced nonreactive gases toward the copper‐I solution while catalytic pyrolysis produced highly reactive gases. The presence of olefins and acetylene in gaseous form confirmed the presence of hydrogen in the product.

Synthesis, characterization, rheological and self-assembly behavior of polyelectrolytes hydrophobically modified with high styrene content: Effect of external parameters on thickening properties and nano-associations

Acrylamide (AM)/2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS)/styrene (St) (AMAS) and AM/sodium styrenesulfonate (SSS)/St (AMSS) polyelectrolytes were synthesized by micellar copolymerization method and then characterized using 1H-NMR, rheometry, viscometry, dynamic light scattering (DLS) and water solubility analyses. It was found that polyelectrolytes are not soluble in the water due to their high length of St blocks (NH=15.4); however, a significant self-assembly behavior of St nano-sized associations was observed by adding a low amount of SDS (10 mM) to the aqueous solution, resulting in the improved rheological behavior of the corresponding solutions. Effect of the external stimuli including emulsifier (SDS) and electrolyte (NaCl) concentration and temperature on the reduced viscosity of polyelectrolyte solutions was also studied using I-optimal design. Based on the viscosity measurements, notable thickening ability for aqueous solutions of both the AMAS and AMSS samples were observed at a SDS concentration of 6.5 mM, NaCl concentration of 0.55 wt% and temperature of 25 °C, which was further confirmed using oscillatory frequency sweep and dynamic light scattering measurements. Moreover, the higher thickening ability was observed for the AMSS aqueous solution in comparison with the AMAS one.

Effect of core-shell structure latex on pigment coating properties

The pore structure of the coating layer is one of the most important factors in determining the printability of coated papers. The coating pigment and binder are two principal components in paper coating, and their characteristics have a critical influence on the coating structure. The glass transition temperature (Tg) of latex binders affects the mechanical strength and pore structure of the pigment coating layer because the latex Tg influences the binding ability of latex and the shrinkage of the coating layer during the drying process. In this study, styrene-acrylate (S/A) core-shell structure latexes with different monomer compositions in the core and shell layers were designed, and their properties were compared with those of a conventional latex. These core-shell latexes were prepared using the same monomers in the same proportion and were used to investigate the effect of the core-shell structure on the structural and mechanical properties of the coating layer. The hard-shell latex with a high styrene content in the shell part yielded paper that was glossier and less rough and formed finer pores, resulting in an increased ink absorption rate into the coated paper compared to the other types of latex. The hard-shell structure showed better performance in printing uniformity and had less mottling.

Formation of Well-Defined Vesicles by Styrene Addition to a Nonionic Surfactant and Their Polymerization Leading to Viscous Hybrid Systems.

Self-assembled structures in aqueous solutions can be fixed by polymerization after adding hydrophobic monomers and can thereby be used as templates which allow to substantially alter the properties of these systems. In this work, we started from a self-assembled micellar system consisting of the nonionic surfactants tetradecyldimethylamine oxid and Pluronic L35 to which styrene was added as a polymerizable monomer. Interestingly, it was observed that styrene induces a transition from micelles to well-defined vesicles in a similar manner as a typical cosurfactant. The structural transition of the aggregates upon styrene addition as well as the structures formed after initiating a polymerization reaction were investigated by means of turbidity, dynamic and static light scattering, small-angle neutron scattering, and rheology measurements. Especially the scattering results confirmed the interesting effect of styrene on the mesoscopic structure and showed a structural evolution from rod-like micelles for low styrene concentrations to vesicles at intermediate styrene amounts, and then finally the formation of microemulsion droplets for high styrene content. Their polymerization of the vesicles again leads to a shape change to wormlike, polymerized aggregates, whose presence then results in rather viscous systems. In contrast, the microemulsions with higher styrene content then are templated and retain their size after polymerization, thereby leading to nanolattices.

Effect of tunable styrene content on achieving high-performance poly(styrene-b-ethylene-ran-butylene-b-styrene)/graphene oxide nanocomposites

In this paper, two poly(styrene-b-ethylene-ran-butylene-b-styrene) (SEBS) with different styrene segment content were adopted to explore the relationship between varying π-π stacking interaction and the mechanical performance of polymer composites. The results showed that the high styrene content on SEBS (SEBS-30, 30 wt% styrene segment) endows SEBS a stronger π-π stacking interaction with GO and a better dispersion of GO in the matrix than that in SEBS with low styrene content (SEBS-12, 12 wt% styrene segment), resulting in a high efficiency on enhancing the performance of SEBS. By adding 0.5 wt% GO, the tensile strength and modulus of SEBS-30 was increased by 44% and 64%, respectively, while that of SEBS-12 was increased by 24% and 39%. Furthermore, the GO also exhibited the ability to toughen SEBS via forming microcrack and GO-induced fibrillation of SEBS during the fracture process. The elongation at break and fracture toughness of SEBS-30 was increased by 10% and 64%, respectively. This study gives us a deep insight into the influence of varying π-π stacking interaction between graphene oxide (GO) and polymer on achieving high-performance polymer nanocomposites.

Modeling the effects of lipid contamination in poly(styrene-isobutylene-styrene) (SIBS)

Lipid uptake and subsequent degradation was characterized as a function of molecular weight and styrene content in four different formulations of poly(styrene-block-Isobutylene-block-styrene) (SIBS). Mechanical testing in uniaxial tension at varying lipid concentrations showed a consistent decrease in tensile strength for all specimens due to lipid contamination. Higher styrene content was associated with an improved resistance to lipid intrusion. A decrease in elongation at break was observed for low molecular weight formulations only; an expected result of the stiffer network and local chain motion restriction due to increased entanglements in high molecular weight SIBS. A new, coupled diffusion/finite element method was used to recover the swelling coefficient of the four different SIBS formulations. The Ogden strain-density energy function recovered from unidirectional tensile testing and diffusion properties from gravimetric analysis were used to construct the finite element model. The predicted swelling behavior matched experimental data and the swelling coefficients were recovered for all formulations tested. Results indicate that the higher lipid affinity of the isobutylene phase contributed to increased swelling, as expected. This novel method to calculate swelling coefficient effectively circumvents the inability of commonly-used thermal deswelling methods to characterize lipid and oil-induced swelling behavior; enabling better prediction of long-term in vivo performance of polymer-based biomedical devices and more accurate evaluation of lipid-induced degradation and swelling.

Stereoselective Copolymerization of Styrene with Terpenes Catalyzed by an Ansa-Lanthanidocene Catalyst: Access to New Syndiotactic Polystyrene-Based Materials

The copolymerization of bio-renewable β-myrcene or β-farnesene with styrene was examined using an ansa-neodymocene catalyst, affording two series of copolymers with high styrene content and unprecedented syndioregularity of the polystyrene sequences. The incorporation of terpene in the copolymers ranged from 5.6 to 30.8 mol % (β-myrcene) and from 2.5 to 9.8 mol % (β-farnesene), respectively. NMR spectroscopy and DSC analyses suggested that the microstructure of the copolymers consists of 1,4- and 3,4-poly(terpene) units randomly distributed along syndiotactic polystyrene chains. The thermal properties of the copolymers are strongly dependent on the terpene content, which is easily controlled by the initial feed. The terpolymerization of styrene with β-myrcene in the presence of ethylene was also examined.

A Precision Ethylene-Styrene Copolymer with High Styrene Content from Ring-Opening Metathesis Polymerization of 4-Phenylcyclopentene.

Ring-opening metathesis polymerization of 4-phenylcyclopentene is investigated for the first time under various conditions. Thermodynamic analysis reveals a polymerization enthalpy and entropy sufficient for high molar mass and conversions at lower temperatures. In one example, neat polymerization using Hoveyda-Grubbs second generation catalyst at -15 °C yields 81% conversion to poly(4-phenylcyclopentene) (P4PCP) with a number average molar mass of 151 kg mol(-1) and dispersity of 1.77. Quantitative homogeneous hydrogenation of P4PCP results in a precision ethylene-styrene copolymer (H2 -P4PCP) with a phenyl branch at every fifth carbon along the backbone. This equates to a perfectly alternating trimethylene-styrene sequence with 71.2% w/w styrene content that is inaccessible through molecular catalyst copolymerization strategies. Differential scanning calorimetry confirms P4PCP and H2 -P4PCP are amorphous materials with similar glass transition temperatures (Tg ) of 17 ± 2 °C. Both materials present well-defined styrenic analogs for application in specialty materials or composites where lower softening temperatures may be desired.

Development of group IV molecular catalysts for high temperature ethylene-α-olefin copolymerization reactions.

This Account describes our research related to the development of molecular catalysts for solution phase olefin polymerization. Specifically, a series of constrained geometry and nonmetallocene (imino-amido-type) complexes were developed for high temperature olefin polymerization reactions. We have discovered many highly active catalysts that are capable of operating at temperatures above 120 °C and producing copolymers with a useful range of molecular weights (from medium to ultrahigh depending on precatalyst identity and polymerization conditions) and α-olefin incorporation capability. Constrained geometry catalysts (CGCs) exhibit very high activities and are capable of producing a variety of copolymers including ethylene-propylene and ethylene-1-octene copolymers at high reactor temperatures. Importantly, CGCs have much higher reactivity toward α-olefins than classical Ziegler-Natta catalysts, thus allowing for the production of copolymers with any desired level of comonomer. In search of catalysts with improved performance, we discovered 3-amino-substituted indenyl-based CGCs that exhibit the highest activity and produce copolymers with the highest molecular weight within this family of catalysts. Phenanthrenyl-based CGCs were found to be outstanding catalysts for the effective production of high styrene content ethylene-styrene copolymers under industrially relevant conditions. In contrast to CGC ligands, imino-amido-type ligands are bidentate and monoionic, leading to the use of trialkyl group IV precatalysts. The thermal instability of imino-amido complexes was addressed by the development of imino-enamido and amidoquinoline complexes, which are not only thermally very robust, but also produce copolymers with higher molecular weights, and exhibit improved α-olefin incorporation. Imido-amido and imino-enamido catalysts undergo facile chain transfer reactions with metal alkyls, as evidenced by a sharp decrease in polymer molecular weight when the polymerization reactions were conducted in the presence of diethylzinc, an essential requirement for use in the production of olefin block copolymers via chain shuttling polymerization. Overall, the excellent characteristics of imino-amido-type catalysts, including high catalytic activities and ultrahigh molecular weight capabilities, make them good candidates for high temperature syntheses of block and random ethylene-α-olefin copolymers. Additionally, trialkyl imino-enamido complexes react quickly with various protic and unsaturated organic fragments, leading to a library of dialkyl precatalysts that, in several instances, resulted in superior catalysts. In conjunction with the development of transition metal catalysts, we also synthesized and evaluated activators for olefin polymerization. We found, for example, that, when conducted in coordinating solvents, the reaction between aluminum alkyls and tris(pentafluorophenyl)borane leads to the exclusive formation of alumenium borates, which are excellent activators for CGC complexes. Additionally, we developed a series of highly effective new activators featuring a very weakly coordinating anion composed of two Lewis acids coordinated to an imidazole fragment.

The Properties of a Styrene Butadiene Block Copolymer with a High Styrene Content

The structure and properties of block copolymers (BCPs) of styrene and butadiene of grade StiroTEP-70 (styrene:butadiene = 70:30, Mw/Mn= 1.43–1.45) are discussed. Analysis of IR spectra enables the BCP to be treated as polystyrene-stat-copoly(butadiene/styrene/1,2-butadiene)-polystyrene. It is suggested that the absorption band at 542 cm-1be considered as characteristic when identifying polymers with extensive polystyrene phases. At temperatures of 190–230°C, the BCP is partially crosslinked, and at 260°C it breaks down. The BCP is processed well at temperatures up to 200°C.

Preparation of microcellular thermoplastic elastomer foams from polystyrene‐b‐ethylene‐butylene‐b‐polystyrene (SEBS) and their blends with polystyrene

AbstractA microcellular foam was prepared from a thermoplastic elastomer by a batch physical foaming with CO2. Two hydrogenated polystyrene‐b‐polybutadiene‐b‐polystyrene (SEBS) copolymers with different styrene ratios were used as an elastomer basis and blended with polystyrene (PS) to control their rigidity and gas permeability. The end‐blocks of the SEBS form a physical cross‐link and provide a rubber‐like elasticity when cooled. SEBS alone, with its lower styrene content, cannot be physically foamed while retaining a stable‐shape dimension because of its higher gas permeability and lower rigidity. SEBS with higher styrene contents were used, or the PS blend ratio was increased to 80/20 or 50/50, and batch physical foaming experiments were conducted at three temperature levels (60, 100, and 120°C) while the sorption CO2pressure was maintained at 10 MPa. Increasing the styrene content or blending PS with SEBS increased the storage modulus and decreased the gas permeability. As a result, the shrinkage of the foam was controlled, and stable microcellular elastomer foams could be prepared. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Adesivos poliméricos à base de SBR: influência de diferentes tipos de agentes promotores de adesão

Neste trabalho, foi desenvolvido um novo adesivo não estrutural à base de copolímero de SBR com alto teor em estireno (SBR-53). O objetivo deste novo produto é avaliar a possibilidade de sua utilização no segmento moveleiro, em substituição ao adesivo de policloropreno (CR-M), cujo polímero-base é importado. Diferentes formulações de adesivos foram desenvolvidas, específicas para a indústria moveleira, e o desempenho do elastômero SBR-53 foi comparado ao dos elastômeros SBR-23 comercial (SBR tradicional - baixo teor de estireno) e CR-M, quanto à estabilidade em solução, viscosidade e propriedades mecânicas.

Novel Dinuclear Half‐Titanocene‐Producing Styrene/Ethylene Copolymers Containing Syndiotactic Styrene/Styrene Sequences

AbstractThe synthesis and characterization of a novel titanium complex, {[C5(CH3)5]ClTi}2O2C2(CH3)4(µ‐O) (2), which has two titanium metal centers linked by heteroleptic bridges, oxo and pinacolato, is described. The compound shows good stability under air. The 2/modified methylalumoxane (MMAO) catalytic system produces ethylene/styrene interpolymers (ESIs) containing syndiotactic styrene/styrene sequences (syndiotactic polystyrene blocks) with a high styrene content. To the best of our knowledge, this is the first example of a group‐4‐based catalytic system producing an ESI with syndiotactic polystyrene blocks. magnified image

Analysis of Thiol-sensitive Core-cross-linked Polymeric Micelles Carrying Nucleoside Pendant Groups using 'On-line' Methods: Effect of Hydrophobicity on Cross-linking and Degradation

Amphiphilic block copolymers were prepared via reversible–addition fragmentation chain transfer (RAFT) polymerization and their synthesis, cross-linking, and degradation were studied using on-line monitoring. The focus of this work is the systematic alteration of the hydrophobic block using copolymers based on 5′-O-methacryloyluridine (MAU) and styrene at different compositions to determine the effect of the copolymer composition on the properties of the micelle. A poly(poly(ethylene glycol) methyl ether methacrylate) (PEGMA) macroRAFT agent was chain extended with a mixture of styrene and MAU. In both systems, an increasing fraction of styrene was found to reduce the rate of polymerization, but the functionality of the RAFT system was always maintained. The amphiphilic block copolymers were dialyzed against water to generate micelles with sizes between 17 and 25 nm according to dynamic light scattering (DLS). Increasing styrene content lead to smaller micelles (determined by DLS and transmission electron microscopy) and to lower critical micelle concentrations, which was measured using surface tensiometry. The micelles were further stabilized via core-cross-linking using bis(2-methacroyloxyethyl) disulfide as crosslinker. NMR analysis revealed a faster consumption of crosslinker with higher styrene content. These stable cross-linked micelles were investigated regarding their ability to degrade in the presence of dithiothreitol as a model reductant. Increasing the styrene content resulted in a faster degradation of the cross-linked micelles into unimers.

Influence of fillers on NR/SBR/XNBR blends. Morphology and wear

The blends of carboxylated acrylonitrile butadiene rubber (XNBR), styrene-butadiene rubber with high styrene content (SBR) and natural rubber (NR) were prepared with different types of carbon black. The effect of filler on morphological and wear characteristics was studied. Intermediate super abrasion furnace (ISAF) carbon black showed improve result on curing study and mechanical properties by reacting at the interface between XNBR, SBR and NR matrix. Blends containing ISAF carbon black showed high abrasion resistant properties against Du-Pont abrader, DIN abrader and different mining rock surfaces and also was found to be the toughest rubber against all types of rock.

Effects of rubber type on the curing and physical properties of silica filled rubber compounds

AbstractAs environmental regulations are getting stricter, tire industries for automobiles have shown much interest in substituting silica for conventional carbon black partially or entirely. To take full advantage of silica as fillers for rubbers, it is essential to find a reasonable rubber system that shows an excellent performance with silica reinforcement. Therefore, in this study, several different rubber compounds comprising the same amount of silica were prepared with several different rubber systems, respectively. The processability, curing characteristics, and mechanical and viscoelastic properties of the rubber compounds were investigated to analyze the performance of the rubber compounds as tire tread materials. Among the rubber compounds studied, SBR1721 compound comprising natural rubber (NR) and styrene butadiene rubber (SBR) with high styrene content was considered the most appropriate for application to tire tread materials. Copyright © 2008 John Wiley & Sons, Ltd.