Amount Of Styrene Research Articles

Manganese Schiff Base Immobilized on Graphene Oxide Complex and Its Catalysis for Epoxidation of Styrene

Immobilization of metal complexes on solid supports is an efficient approach to circumvent the drawbacks of homogeneous catalysis. In this paper, using graphene oxide as carrier, manganese Schiff base supported on graphene oxide (Salen Mn-GO) was prepared through aminosilane covalent modification as well as salicylaldehyde condensation and coordination reaction. The structures and properties of the composite were examined by FT-IR, XRD, XPS, TEM, TG techniques, and the catalytic performance of Salen Mn-GO in styrene epoxidation was explored. The effects of catalyst and styrene amount as well as that of reaction time on the performance of the catalyst were investigated. The results showed that Salen Mn-GO has excellent catalytic activity and reusability for epoxidation of styrene in the presence of hydrogen peroxide. Finally, the mechanism of styrene epoxidation catalyzed by Salen Mn-GO has been preliminarily discussed.

Anionic/nonionic surfactants for controlled synthesis of highly concentrated sub-50 nm polystyrene spheres.

Polystyrene nanospheres are of great importance in 3D hard templating along with many other fields like pharmaceuticals and coatings. Therefore, it is important to be able to prepare polystyrene beads with different sphere sizes that suit each application. In this work, the emulsion polymerization method was used to prepare monodispersed polystyrene (PS) spheres with an average size of 50 nm, using styrene monomer, sodium dodecyl sulfate (SDS) and polyvinylpyrrolidone (PVP) as surfactants, and potassium persulfate (KPS) as the initiator. The average size and size distribution of the PS spheres were controlled by optimizing the synthesis parameters such as the concentration of the monomer, initiator, and surfactant, the type of surfactant, and the time and temperature of polymerization. The shape, size, and size distribution of the prepared PS spheres were characterized using dynamic light scattering (DLS) and scanning electron microscopy (SEM). The preparation of perfectly spherical PS spheres as small as 50 nm with a narrow size distribution is obtained using 8% styrene with (5% SDS and 2% KPS of the styrene amount) at 90 °C, with the monomer and surfactant molar ratio and concentration and the polymerization temperature being the dominating factors that affect the PS bead size.

Pyrolysis of waste expanded polystyrene and reduction of styrene via in-situ multiphase pyrolysis of product oil for the production of fuel range hydrocarbons

Upgraded fuel oil was produced from the waste expanded polystyrene (WEPS) using pyrolysis and in-situ selective aromatization in a specially designed reactor. The catalytic pyrolysis of WEPS was performed keeping the catalyst in three different types of catalyst arrangements inside the reactor i.e., A-type/catalyst in liquid phase, B-type/catalyst in vapour phase, and AB-type or Multiphase/catalyst in both liquid and vapour phases, respectively. The ZSM-5 ammonium powder was used as a catalyst with varying feed to catalyst ratio and 20:1 was found to be optimum. Aromatics of fuel range like benzene, toluene, and ethylbenzene (BTE) were significantly increased and styrene got reduced by many folds when AB-type/multiphase catalytic pyrolysis was performed. The thermal pyrolysis produced maximum liquid yield of 94.37 wt% at a temperature of 650 °C and a heating rate of 15 °C/min. The maximum liquid yield of 88.05 wt%, 78.85 wt%, and 75.11 wt% were obtained for the A-type, B-type, and AB-type catalytic pyrolysis at the temperature of 600 °C, 550 °C and 550 °C, respectively using the same heating rate. The liquid oil of thermal pyrolysis contains very low amount of fuel range aromatics i.e., BTE of 11.38 wt% and the highest amount of styrene (84.74 wt%). In contrarily, BTE content for the catalytic process increased progressively in the order of 18.98 wt% (A-type) < 24.27 wt% (B-type) < 28.12 wt% (AB-type). The styrene content significantly decreased to a very low value of 46.30 wt% for AB-type/multiphase pyrolysis at the temperature of 550 °C.

Switchable Pickering emulsions stabilized by polystyrene-modified magnetic nanoparticles

Switchable Pickering emulsions were prepared using polystyrene-modified magnetic nanoparticles (PS-MNPs) as stabilizers in mixtures consisted of a polar solvent, such as chloroform, and water. For this purpose, bare magnetic nanoparticles (bMNPs) were firstly synthesized but they were not able to stabilize emulsions prepared with chloroform. Consequently, the surface of the bMNPs was modified with polystyrene via radical polymerization to provide the nanoparticles more hydrophobic character. This resulted in stable water-in-oil (W/O) and oil-in-water (O/W) Pickering emulsions from water/chloroform mixtures. Variables affecting the coating step, including reaction time and amount of styrene in the polymerization mixture, were studied. The resulting material was characterized in terms of composition and size by infrared spectroscopy (IR-ATR), transmission microscopy (TEM) and dynamic light scattering (DLS). Next, different percentages of aqueous and oil phases were tested obtaining switchable W/O and O/W Pickering emulsions, depending on the percentages of each phase. To demonstrate what type of emulsion was formed with each percentage, the emulsions were observed under the optical microscope and both the drop and the methylene blue tests were performed. Finally, to evaluate the stability and morphology of the Pickering emulsions obtained by the PS-MNPs, the effect of the temperature, pH value and salt was also investigated in detail.

Synthesis of Graphene Oxide-Polystyrene Graft Polymer Based on Reversible Addition Fragmentation Chain Transfer and Its Effect on Properties, Crystallization, and Rheological Behavior of Poly (Lactic Acid)

Graphene oxide-polystyrene graft polymer (SGO-PS) was prepared by reversible addition-fragmentation chain transfer radical polymerization method. Orthogonal experiments indicated that the optimum synthesis reaction conditions for SGO-PS were as follows: the millimole ratio of chain transfer agent to initiator was 0.15 : 0.3, and the amount of styrene was 8 mL at 80°C for 12 hours. The products were characterized by Fourier transform infrared spectroscopy and thermal weightlessness analysis, and the highest grafting rate of SGO-PS was 62.46%. Then, PLA/SGO-PS nanocomposites were prepared using SGO-PS as fillers by melt intercalation method, and its crystallinity, mechanical properties, and thermal stability were significantly improved. Compared with pure PLA, the crystallinity of PLA/SGO-PS (0.3 wt%) nanocomposites was increased by 5 times. Multiple melting behavior tests showed that the introduction of SGO-PS caused the PLA molecular chain to be discharged into the unit cell in time, and the melting temperature shifted to a higher temperature, which ultimately made the grain structure of PLA composites more complete and stable than pure PLA. The rheological performance test showed that the uniform dispersion of SGO-PS in the PLA matrix inhibited the free movement of the PLA molecular chain and caused higher flow resistance, resulting in an increase in the complex viscosity, storage modulus, and loss modulus of PLA/SGO-PS.

The effects of low-profile additives on shrinkage and mechanical properties of cultured marble materials

ABSTRACT Cultured marble is a blend of unsaturated polyester and calcium carbonate that is combined with pigments and additives to produce a wide range of colours and realistic, natural-looking patterns. This study aims to investigate process conditions (catalyst, temperature, cured time, etc …) of cultured marble at high temperatures. The optimized process conditions are obtained by thermal analysis from DSC with a temperature of 110°C and curing time of 20 min, respectively. The optimum catalyst for process conditions in a bulk moulding compound (BMC) machine is 2 phr of benzoyl peroxide (BPO). The styrene amount in UP resin is determined at 37.40% by the Gas chromatography-mass spectroscopy – headspace (GCMS-HS) technique. Anhydride maleic (MA) is found to improve outstanding mechanical properties in terms of flexural properties, the strength of impact, and the resistance of volume shrinkage of UP resin in cultured marble material.

Simultaneous amphiphilic polymer synthesis and membrane functionalization for oil/water separation

This work scrutinizes a versatile process during which amphiphilic copolymers (made of styrene and sulfobetaine methacrylate, ethylene glycol methacrylate or vinylpyrrolidone) are simultaneously copolymerized and coated on microporous poly (vinylidene fluoride) (PVDF) membranes. Changing the nature of the hydrophilic monomer and the reaction conditions, it is possible to regulate the wetting properties of the membranes by water and oil. The main surface physical properties of the membranes were not modified for a reaction/deposition bath containing up to 50% styrene monomer, but larger styrene amounts led to aggregate formation. A 50% molar ratio in hydrophobic/hydrophilic unit led to a suitable balance between stability and hydration, resulting in optimized water permeation and oil repellence. Gravity-driven separation of oily wastewaters was doable with all selected membranes (St50S50, St50P50 and St50V50) and oils tested (toluene, hexane, diesel). Nevertheless, it is highlighted that PEGylated surfaces offer the best overall compromise between separation kinetic and separation efficiency. Results also suggested that zwitterionization with larger amounts of zwitterionic monomers is not practical, possibly because it leads to a hydration layer too tight, which slows down the gravity-driven separation. This study demonstrates the effectiveness/versatility of this surface modification method to quickly hydrophilize PVDF membranes applied to energy-efficient separation of emulsions.

Glass Fiber Reinforced Polycarbonate Composites for Laser Direct Structuring and Electroless Copper Plating

Glass fiber (GF) reinforced polycarbonate (PC) composites were prepared for laser direct structuring (LDS) applications. A small amount of styrene–maleic anhydride (SMA) was introduced to enhance GF/PC interfacial interactions. The PC/SMA/GF LDS composites using metal complex as LDS additive were investigated for applicability in copper circuit development. Rough surface patterns by laser irradiation under different laser parameters were measured by microscopy and Fourier infrared spectrometry. Copper particles and plating layer by subsequent electroless copper plating procedure was observed using microscopy. Thickness of plating layer and adhesion between layer and matrix were also evaluated. The results showed that laser repetition and scanning speed led to different resolutions and ablated surfaces without structural changes of composites. Copper particles gradually deposited, grew, and interconnected during metallization procedure. Plating layer was successfully formed at an optimum LDS additive loading, and appropriate scanning speed and repetition of laser. In addition, the plating layer displayed disparate thickness and distribution, owing to different activated surfaces by irradiation. Severe ablation or unetched parallel regions resulted in leaky or discontinuous plating layer. Better plating microstructure and higher adhesion were obtained for the composite material with 1.0 wt% LDS additive loading, supporting its extensive development and practical application in LDS technology. POLYM. ENG. SCI., 60:860–871, 2020. © 2020 Society of Plastics Engineers

Chemical composition and porous structure of polymer‐derived silicoboron carbonitride ceramics prepared via a monomer route

Polymer‐derived silicoboron carbonitride (SiBCN) ceramics were facilely prepared using organosilicon monomers tris(dichloromethylsilylethyl)borane and bis(trimethylsilyl)carbodiimide as the starting materials. The polymer precursors were obtained either without adding styrene or by adding an appropriate amount of styrene into the mixture of the organosilicon monomers, followed by heat treatment and purifying. The chemical composition and pore structure of the polymer‐derived SiBCN ceramics were studied. It was found that styrene diluted the monomers and hindered their chemical reaction from forming the polymeric network. The polymer precursor prepared with styrene was composed of boron‐modified polysilylcarbodiimide as the matrix and dispersed polystyrene mainly of sizes 20–50 μm. Accordingly, a polymer‐derived SiBCN ceramic with a three‐dimensional continuous macroporous structure containing pores mainly of 20.9–58.1 μm with a total porosity of 74% was achieved. The B/N atomic ratio reached 0.58 with low oxygen content of 2.81 wt%, which satisfied the requirement for high‐temperature application.

Simulation and Optimization of Polystyrene Free Radical Polymerization Process

A model for bulk polymerization of styrene was established by using the POLYMER module of ASPEN PLUS. The effects of the chain initiator (TBP), solvent (ethylbenzene) and the chain transfer agent (DDM) on the yield, number average degree of polymerization(DPN), weight average degree of polymerization(DPW), number average molecular weight(Mn), weight average molecular weight(Mw) and the polydispersity index(PDI) of polystyrene were investigated. Through the analysis, we can first consider the amount of styrene to obtain roughly the parameters of the polystyrene process. As the use of initiator in polymerization has the optimal value, we must strictly control the amount of TBP according to the amount of monomer styrene, and adjust the amount of chain transfer agent to control the product quality accurately.

Abrasive wear behaviour of SBR/HIPS (%35–55) polymer blends

Styrene Butadiene Rubber (SBR), being the most widely produced synthetic rubber, is a random copolymer of styrene and butadiene. The physical properties of SBR are related to the amount of styrene in copolymer chains and styrene/butadiene ratios in the copolymer. SBR is used in many areas such as tires, conveyor belts, mats, shoe soles, and heels, while Polystyrene, due to its brittle nature, its usage is limited. This study examines the abrasive wear behavior of SBR and High-Impact Polystyrene (HIP) polymer blends. For the experiments, SBR /HIPS polymer blends were prepared by adding HIPS at different ratios (35%–55%) to SBR. Using emery paper of 240 G and 500 G, wear tests were carried out on a pin-on disc wear test apparatus under the load value of 5 N, for sliding distances ranging from 25 to 100 m and at a sliding speed of 1 m s−1. Density and hardness measurements of the samples were carried out. The worn surfaces of the pin were examined using an optical microscope. It is clearly shown that the wear coefficients of polymer blends are dependent on both abrasive nature and the ratio of blends.

Tuning the molecular design of random copolymers for enhancing the biofouling mitigation of membrane materials

Although a lot has been done on the making of antifouling membranes using PEGylated materials, numerous molecular design improvements can still be made on fine-tuning of both composition and chain length. Here, an antifouling copolymer made of styrene and ethylene glycol methacrylate units (PS-co-PEGMA) was used and the results demonstrate that by altering the molar ratio and chain length PS/PEGMA, it can turn the membrane from low-biofouling to almost entirely fouling resistant. At first, a set of 7 copolymers with a molecular weight in a same range but different compositions was prepared, characterized and was used to modify poly(vinylidene fluoride) (PVDF) membranes by vapor-induced phase separation (VIPS) process. Membranes were fully characterized, and antifouling tests carried out with Escherichia coli, Stenotrophomonas maltophilia and fibrinogen all showed that a 30 mol% polystyrene content in the copolymer (PS30P70) led to the best antifouling properties. Increasing or decreasing the styrene amount resulted in increasing the hydrophobicity of the material or decreasing the stability of the modification, respectively, which outcome in both cases was a higher biofouling. Then, 5 copolymers with a fixed composition but different Mws were prepared, and antifouling tests indicated that the longer the chain, the better the antifouling properties. The chain length is essential to the strength of the hydration layer as supported by both mapping FT-IR and DSC measurements.

Volatile non-intentionally added substances (NIAS) identified in recycled expanded polystyrene containers and their migration into food simulants

Abstract Recycled materials such as expanded polystyrene (EPS) are increasing in the food market and some hazardous chemicals may exist in recycled PS resins. Therefore, a method of solid-phase microextraction and gas chromatography coupled to mass spectrometry followed by chemometric tools applied to the data obtained allowed the identification of markers for virgin and recycled EPS. The multivariate statistical analysis was developed to characterize the profile of volatile organic compounds (VOCs) in virgin and recycled EPS containers, and identify the potential VOCs markers responsible for EPS containers discrimination. A total of 99 compounds were identified in virgin and recycled EPS containers. Among these, 17 compounds contributing the most to the discrimination, were selected based on their variables importance in the projection (VIP) values, including o-xylene, acetophenone, ethylbenzene, α-ethylstyrene, 2-phenylpropenal, propylbenzene, 2-phenyl-1-propene, undecanal, benzoic acid ethyl ester, 2-ethyl-1-hexanol, decanal, benzylcarboxaldehyde, isopropylbenzene, 2,4-diphenyl-1-butene, dodecanal, benzaldehyde and nonanal. To evaluate the health risk of EPS containers, migration tests from EPS containers into two food simulants (10% ethanol, 3% acetic acid) were conducted. It should be highlighted that high amount of styrene was detected. Nevertheless, analysed materials accomplish with current EU Regulation No.10/2011. The proposed method finds the differentiation markers and provides a reliable tool to discriminate virgin and recycled EPS containers, which could be an additional tool for quality control of EPS containers.

Shape memory polymer networks based on methacrylated fatty acids

In this study, bio-based materials were prepared from fatty acid precursors and variable amounts of styrene or divinylbenzene by free-radical polymerization. The obtained materials were highly translucent and resulted insoluble in common organic and aqueous solvents. They exhibit a complex microstructure due to the formation of highly cross-linked arrangements (micro/nanogels) closed packed into clusters. The bio-polymers prepared with divinylbenzene (a tetra-functional monomer), due to their excessive cross-linkage, resulted in brittle samples whose mechanical response could not be obtained. On the other hand, bio-based polymers obtained from styrene (a bi-functional monomer) resulted in materials with a moderate cross-linking density, a sharp glass-rubber transition and acceptable mechanical properties, leading to polymers with interesting shape memory response (switching temperature, fixity and recovery ratios) that could be tailored by changing the composition. In these materials it was corroborated that higher (but not excessive) cross-linking density led to a greater shape recovery, since cross-links are the responsible for memorizing the original shape of the material.

PERFORMANCE OF RECYCLED ASPHALT MIXTURES FORMULATED WITH MODIFIED BITUMEN

The maintenance of flexible roads or roads at end of life service generates high quantities of reclaimed asphalt pavement every year. The reuse of these materials, considered for a long time as waste, allows a substantial saving in transport, energy, and maintains dwindling natural resources. Recycling of asphalt also helps to reduce inert waste storage volumes, and conserve valuable landfill space. The applicability of recycled asphalt was tested in laboratory, and asphalt mixtures containing 20%, 40% and 50% of reclaimed asphalt pavement (RAP) were designed. Marshall and Duriez tests have been performed on various formulations using paving grade bitumen and modified bitumen as binders, the latter contains a quantity of Styrene /Butadiene / Styrene (SBS) polymer. This investigation led to the conclusion that the performance of recycled asphalt mixture containing 20% of RAP is significantly closer to those obtained with virgin asphalt mixture without recycled materials. In addition, the use of SBS polymer improves the properties of recycled asphalt mixtures even with high amounts of reclaimed asphalt pavement.

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 nature and extent of functional group modification on properties of thermosets from methacrylated epoxidized sucrose soyate

A study was carried out to evaluate the impact of modification of epoxidized sucrose soyate using a combination of methacrylate and inert esters (acetate propionate, butyrate) on the properties of the resins as well as the thermosets. Previous studies have shown that methacrylated epoxidized sucrose soyate (MESS) can yield thermosets having high glass transition temperature (Tg) and good mechanical properties, but had high resin viscosity due to hydrogen bonding of the hydroxyl groups. Further functionalization to yield dimethacrylated epoxidized sucrose soyate (DMESS) resulted in reduced resin viscosity, but some of the thermosets were brittle. In this study, to maintain low resin viscosity and improve thermoset ductility, replacement of some methacrylate groups with various ester groups was explored. The synthesis of these resins was carried out in a one-pot process involving the sequential slow addition of anhydrides of the acids mixed prior to addition. The synthesized resins were characterized for their viscosity with and without styrene diluent. Formulations were made using varying amounts of styrene and free-radically cured using peroxyesters as initiators. The bio-based resins with 30% styrene gave much lower viscosities compared to commercial resins containing higher amounts of styrene (33% and 45%). The thermosets produced had improved flexibility and toughness with only a slight reduction in the glass transition temperature. The inclusion of the non-functional esters in the resin structure acted as internal plasticizers for the polymer system. The new sets of thermomechanical properties demonstrated the tunability of the bio-based resin system and opens up different avenues for end-use applications.

An evaluation of the impact of SG1 disproportionation and the addition of styrene in NMP of methyl methacrylate

A kinetic modeling study is presented for batch nitroxide mediated polymerization (NMP) of methyl methacrylate (MMA; nitroxide: N‐tert‐butyl‐N‐[1‐diethylphosphono‐(2,2‐dimethylpropyl)] (SG1)). Arrhenius parameters for SG1 disproportionation (A = 1.4 107 L mol−1 s−1; Ea = 23 kJ mol−1) are reported, based on homopolymerization data accounting for unavoidable temperature variations with increasing time, that is, nonisothermicity. For low targeted chain lengths (TCLs ≤ 300), this nonisothermicity is also relevant for NMP of MMA with a small amount of styrene. Parameter tuning to copolymerization data confirms a penultimate monomer unit effect for activation (sa2 = ka12/ka22=6.7; 363 K; 1: MMA; 2: styrene). To obtain, for a broad TCL range (up to 800), a dispersity well below 1.3 an initial styrene mass fraction of ca. 10% is required. An interpretation of the comonomer incorporation is performed by calculating the fractions of activation‐growth‐deactivation cycles with a given amount of monomer units and the copolymer composition distribution. © 2018 American Institute of Chemical Engineers AIChE J, 64: 2545–2559, 2018

Agglomeration-Free Preparation of Modified Silica Nanoparticles for Emulsion Polymerization-A Well Scalable Process.

To prepare modified silica nanospheres for emulsion polymerization, a new agglomeration-free change of dispersion media has been developed. Nanosized silica spheres were synthesized by the Stöber method and directly modified with a silane coupling agent. To prepare these particles for subsequent polymerization, the dispersion medium was changed in a two-step process from ethanol to water without agglomeration of the particles. The emulsion polymerization leads to hemispherical single-core-structured silica-polystyrene composite particles. The thickness of the polymer shell can be altered by varying the amount of styrene. The developed change of dispersion media provides nonagglomerated modified silica particles for the encapsulation with polystyrene and enables the synthesis of narrowly distributed single-core composite particles. The developed process is a promising approach for the preparation of nanoparticles for subsequent polymerization and can be scaled-up for industrial applications.

On the Size‐Determining Role of the Comonomer in the Nucleation and Growth of Cationic Polystyrene Latex via Emulsion Polymerization

AbstractThe formation of positively charged polystyrene latex particles via the surfactant‐free emulsion polymerization of styrene with cationic initiator is investigated. Using the comonomer (vinylbenzyl)trimethyl‐ammonium chloride (VBTMAC) it is shown that the particle size can be tuned rather precisely between above 350 nm and below 70 nm. The simple functional dependence of the particle size on the inverse cube root of the comonomer concentration leads to propose, with reasonable assumptions, that VBTMAC comonomer addition allows the separation of nucleation and growth for this reaction. Thereby the comonomer concentration determines the nucleation rate and number of particles produced, while the styrene amount determines by how much the nucleated particles grow. Support for this model is obtained through zeta potential measurements at different pH values. The latter confirmed that the surface density of cationic groups resulting from the comonomer relative to that of groups resulting from the initiator decreases with decreasing comonomer concentration.