High Aromatic Content Research Articles

Influence of Aromatic Content in Rubber Processing Oils on Viscoelastic Behaviour and Mechanical Properties of Styrene-Butadiene-Rubber for Tyre Tread Applications

In the present study, experiments have been carried out to investigate the effects of aromatic and polycyclic aromatic compounds (PCAs) contents in rubber processing oils (RPOs) on the processability and mechanical properties of styrene butadiene rubber (SBR) compounds and vulcanisates. Results obtained suggest that, as expected, the presence of RPOs leads to a decreased compound viscosity, and thus an enhanced processability. By incorporating the RPOs into SBR compounds, some mechanical properties, including elongation at break and tear strength, of cured SBR can be improved, particularly for the RPOs with high aromatic content. This is believed to be attributed to the increased compatibility of aromatic containing RPOs and the SBR matrix. Nevertheless, the aromatic and PCA contents play an insignificant role on the crosslink density and bulk viscosity of the rubber compounds as well as the hardness and compression set of the rubber vulcanisates.

Synthesis and characterization of a novel epoxy resin based on cyclotriphosphazene and its thermal degradation and flammability performance

The cyclotriphosphazene-based epoxy resin hexa-[4-(glycidyloxycarbonyl) phenoxy]cyclotriphosphazene defined as CTP-EP was successfully synthesized from hexachlorocyclotriphosphazene, p-hydroxybenzaldehyde and epichlorohydrin. Its chemical structure was characterized by Fourier transform infrared (FTIR) spectroscopy, 1H NMR, 13C NMR and 31P NMR spectroscopy. The prepared compound was cured with diamino diphenyl methane (DDM), diamino diphenyl sulfone (DDS) and m-phenylenediamine (mPDA), respectively. The flame retardant properties, thermal degradation behavior and flame retardant mechanism of the cured CTP-EP were investigated. The LOI values of all cured CTP-EP samples increased from 19.9% for cured diglycidyl ether of bisphenol-A (DGEBA) to above 30% and successfully passed UL-94 V-0 rating, which demonstrated that the prepared CTP-EP thermoset exhibited excellent flame retardancy. The dynamic mechanical thermal analysis (DMA) test demonstrated that the glass transition temperature (Tg) enhanced from 155 °C for the cured DGEBA to 167 °C for CTP-EP thermoset. The results of thermogravimetric analysis/infrared spectrometry (TG-IR) tests suggested that the phosphazene group and high aromatic content in CTP-EP thermoset stimulated the dehydration of the matrix at earlier degradation process and the formation of char layer, which retarded the release of pyrolysis gas and enhanced the thermal stability of the cured CTP-EP at high temperature. The cone calorimeter tests (cone) test revealed that heat release rate (HRR), total heat release (THR), smoke production rate (SPR) and total heat production (TSP) of the cured CTP-EP decreased significantly compared with the cured DGEBA. The scanning electron microscopy (SEM) results showed that the phosphazene groups in CTP-EP obviously stimulated the formation of the intumescent, compact and stable char layer, which enhanced the flame retardancy of the matrix during combustion. Consequently, the underlying materials were protected from further degradation and combustion during a fire and result in the efficient flame retardancy of CTP-EP thermoset.

Preparation and Characterization of the Rejuvenator Seal Materials with Fluid Catalytic Cracking Flurry

Fluid catalytic cracking (FCC) slurry has a high content of aromatics. This research use three methods to prepare rejuvenator seal materials with FCC slurry and study their performance. The results showed that rejuvenator seal materials can improve the fatigue and low-temperature cracking resistance of the pavement. In addition, material 2# exhibit better performance as it has more aromatic content.

Characterization and Refining Pathways of Straight-Run Heavy Naphtha and Distillate from the Solvent Extraction of Lignite

Coal liquids were produced by solvent extraction of Bienfait lignite at 415 °C and 4 MPa H2 for 1 h with a hydrotreated coal tar distillate in a 2:1 solvent to coal ratio. Detailed characterization was performed on four straight-run distillation fractions of the coal liquids in the 120–370 °C boiling range. It was found that the coal liquids contained very little aliphatic material. Most of the compounds were aromatics, with aromatic compounds having no alkyl substituents dominating the composition. The aromatic carbon content increased with boiling fraction from 80 wt % in the 120–250 °C fraction to 94 wt % in the 343–370 °C fraction. Major compounds identified in the coal liquids were acenaphthene, phenanthrene, fluoranthene, and pyrene, which constituted 62 wt % of the total product. The coal liquids also contained heteroatom species. Interestingly, the nitrogen content did not monotonically increase with an increase in boiling point. The maximum nitrogen content was found in the 300–343 °C boiling fraction as a result of a high concentration of carbazole. The refining pathways for transportation fuel production were evaluated. It was found that the naphtha fraction could be upgraded to a motor gasoline blending component just by hydrotreating. No subsequent catalytic reforming was necessary because of the low aliphatic content of the naphtha. The kerosene required severe hydrotreating in order to be acceptable as a jet fuel blending component, mainly because of the high dinuclear aromatic content of the straight-run kerosene. The distillate made a poor feed material for diesel fuel and required severe hydrotreating to achieve an acceptable cetane number. In general, the coal-derived distillate would benefit from ring opening to reduce its density. The prognosis for transportation fuel production from the coal liquids was not favorable. The production of aromatic chemicals was a better fit with the properties of the coal liquids.

Thermotropic Polyesters from 2,5-Furandicarboxylic Acid and Vanillic Acid: Synthesis, Thermal Properties, Melt Behavior, and Mechanical Performance

In this work, we address the synthesis of novel aromatic–aliphatic biobased polyesters showing thermotropic behavior in the melt. Successful incorporation of different biobased monomers such as 2,5-furandicarboxylic acid (2,5-FDCA), suberic acid (SuA), and vanillic acid (VA) in thermotropic liquid crystalline polymers (TLCPs) is made possible by performing synthesis at low temperatures. The chemical structures, molecular weights, phase transitions, thermal behavior, and mechanical performance of the synthesized polymers are studied using polarization optical microscopy, WAXD, DSC, TGA, DMTA, solid-state NMR spectroscopy, rheology, and tensile tests. It is shown that the incorporation of the rigid, aromatic 2,5-FDCA moiety enhances the formation of blocky copolymers, whereas the VA moiety tends to decrease the block formation. However, when combined, nonblocky TLCPs containing 2,5-FDCA and VA with high aromatic content can be obtained. These materials show a low temperature transition from the crystalline ...

Influence of SBS and asphalt on SBS dispersion and the performance of modified asphalt

Styrene–butadiene–styrene (SBS) modified asphalt (PMA) was prepared by high shear method. Four asphalts with different components and four types of SBS copolymers with different S/B ratio and types were selected in this study. The influences of the asphalt components and SBS structure as well as SBS contents on the particle size distribution of SBS and properties of the SBS modified asphalt were investigated. Fluorescence microscope and the Image-Pro Plus program were chosen to characterize the microstructure and count the particle size distribution of SBS. The results show that the asphalt components, SBS structure and content had significant impacts on the particle size distribution of SBS polymer in asphalt and the performance of SBS modified asphalt. The high aromatics content and the low asphaltenes content could improve the dispersion of SBS in asphalt. When the S/B ratio is 30/70, the particle size distribution curve was the narrowest and the performance of modified asphalt was improved. With the content of SBS increasing, the particle size distribution curve became wide and the softening point of the modified asphalt was increased, while the penetration and the ductility were decreased. The viscosity at 135°C of modified asphalt was increased with the range of the particle size distribution curves becoming narrow.

Neurobehavioral performance in volunteers after inhalation of white spirits with high and low aromatic content

The content of aromatic hydrocarbons in solvent mixtures, such as white spirits (WS), has been assumed a major contributor to the neurotoxic effects of these compounds. Hence, dearomatized WS have been introduced to the market rapidly in the last decade. Studies investigating other aromatic hydrocarbons (toluene) and animal models have supported the aforementioned assumption, but the current study is the first one to compare acute neurobehavioral effects of exposure to aromatic and dearomatized WS (aWS, daWS) content in human volunteers at current occupational exposure limit values. In a pseudo-randomized crossover design, six female and six male healthy volunteers were exposed to aWS and daWS at two concentrations (100 and 300mg/m(3)) and to clean air for 4h at rest. During each of the five exposure conditions, volunteers performed five neurobehavioral tasks that were selected following a multidisciplinary approach that accounted for findings from the cognitive neurosciences and mechanisms of solvent toxicity. Two of the tasks indicated performance changes during aromatic WS exposure, the working memory (WM) and the response shifting task, but both effects are difficult to interpret due to low mean accuracy in the WM task and due to a lack of dose-response relationship in the response shifting task. Healthy human volunteers showed weak and inconsistent neurobehavioral impairment after 4-h exposures to 100 and 300mg/m(3) aromatic or dearomatized WS. Our multidisciplinary approach of selecting neurobehavioral test methods may guide the test selection strategies in future studies.

Physicochemical Characterization of Organic Matter in Bayer Liquor

Organic matter in Bayer liquor from an alumina production facility in Australia was characterized in terms of its molecular weight distribution and molecular structure using a suite of complementary chromatographic, spectroscopic, and thermal and chemical degradation methods. The organic matter was characterized using high-performance size-exclusion chromatography with UV–vis detection (HPSEC–UV), Fourier transform infrared (FTIR) spectroscopy, and solid-state 13C nuclear magnetic resonance (13C NMR) spectroscopy. These techniques provided information on the apparent molecular weight distribution of the organic matter contained in the Bayer liquor, its alkyl/aromatic characteristics, and the presence of specific functional groups. The techniques of microscale sealed vessel (MSSV) pyrolysis–gas chromatography–mass spectrometry (GC–MS), flash pyrolysis–GC–MS, and online tetramethylammonium hydroxide (TMAH) thermochemolysis–GC–MS provided detailed information at a molecular level. Information on individual low-molecular-weight organic acids in the sample was also obtained using liquid chromatography–tandem mass spectrometry (LC–MS–MS). The novelty of this work is the molecular identification of nitrogen compounds, pyridines, pyrenes, quinolones, benzoquinolines, indoles, carbazoles, bipyridines, and phenylpyridines that derive from organic matter in the bauxite or its transformation products. The results from the other analysis techniques largely confirm the high aromatic content of the liquor, with varying degrees of alkyl (predominantly methyl), carboxylic, ketone, nitrile, and hydroxyl substitution. Aromatic acids were found to be abundant, although they were poorly detected using pyrolysis methods, highlighting the importance of using a suite of complementary techniques for the analysis of Bayer liquor samples.

Component Characteristics of Coal-Based Jet Fuel and Petroleum-Based Jet Fuel

There are mainly four pathways to get liquid fuels from the coal including the direct liquefaction process, the Fischer-Tropsch process, coal-tar refining, and pyrolysis process. The characteristics of these four processed have been described. As the first two pathways are considered to be promising, the characteristics of these two types of coal-based jet fuels are discussed and the component characteristics of coal-based synthesis fuels are investigated, respectively. The component characteristics of coal-based jet fuels are compared with the traditional petroleum-based jet fuels. There are large differences between the properties of the coal-based jet fuel via direct and indirect liquefaction pathways. Comparing with the conventional petroleum-based jet fuel, the coal-based jet fuel via direct liquefaction pathway has the higher aromatics content, while the fuel via indirect pathway (F-T process) has more paraffin and nearly no naphthenes or aromatics. In additional, the carbon numbers of the coal-based synthesis jet fuels are compared with the conventional petroleum-based jet fuel.

Depolymerization of organosolv lignin using doped porous metal oxides in supercritical methanol

An isolated, solvent-extracted lignin from candlenut (Aleurites moluccana) biomass was subjected to catalytic depolymerization in the presence of supercritical methanol, using a range of porous metal oxides derived from hydrotalcite-like precursors. The most effective catalysts in terms of lignin conversion to methanol-soluble products, without char formation, were based on copper in combination with other dopants based on relatively earth-abundant metals. Nearly complete conversion of lignin to bio-oil composed of monomers and low-mass oligomers with high aromatic content was obtained in 6h at 310°C using a catalyst based on a Cu- and La-doped hydrotalcite-like precursor. Product mixtures were characterized by NMR spectroscopy, gel permeation chromatography, and GC-MS.

Synthesis of condensed polynuclear aromatic resin from furfural extract oil of reduced-pressure route II

As an industrial byproduct of oil refining, furfural extract oil from reduced-pressure route II with high aromatic content was used to prepare heat-resistant condensed polynuclear aromatic (COPNA) resin for the first time. The basic properties of furfural extract oil and the resultant COPNA resin were characterized by infrared spectroscopy (FT-IR), nuclear magnetic resonance spectroscopy (1H-NMR), thermogravimetric analysis (TGA) and elemental analysis (EA). The result showed that heat treated furfural extract oil was successfully used for the synthesis of heat-resistant COPNA resin. The average structural parameters of raw materials and prepared resin were calculated by the improved Brown-Ladner method, and the averaged molecular structure of the resin was obtained. The reaction mechanism for the synthesis of COPNA resin was suggested as an acid-catalyzed positive ion type polymerization.

Influence of Aromatic Content in Rubber Processing Oils on Viscoelastic Behaviour and Mechanical Properties of Styrene-Butadiene-Rubber (SBR) for Tyre Tread Applications

In recent years, the increasing concern on the toxicity of highly aromatic oils has been incentive to the development of rubber process oils (RPOs) which are more environmentally-friendly. Many alternative eco-friendly RPOs have been tested with the aims of selecting the most suitable replacement for these highly aromatic oils. As a consequence, in order to achieve both environmental friendliness and effective rubber compounding, the aromatic content in RPOs must be optimised. In the present study, the experiments have been carried out to investigate the effects of aromatic and polycyclic aromatic compounds (PCAs) contents in RPOs on processability and mechanical properties of styrene butadiene rubber (SBR) compounds and vulcanisates. Results obtained suggest that the presence of RPOs leads to a decreased compound viscosity, and thus an enhanced processability. By incorporating the RPOs into SBR compounds, some mechanical properties including elongation at break and tear strength of cured SBR can be improved, particularly for the RPOs with high aromatic content. It is believed to be attributed to the increased compatibility between RPOs and SBR matrix. Nevertheless, the aromatic and PCA contents play little or insignificant role on the crosslink density and bulk viscosity of rubber compounds as well as hardness and compression set of vulcanisates.

The synthesis of humic acids graft copolymer and its adsorption for organic pesticides

humic acid graft copolymer (PSt-g-HA) was prepared by graft copolymerization of Humic acid (HA) with styrene and the sorption of three selected organic pesticides, parathion-methyl, carbaryl and carbofuran by PSt-g-HA acid and untreated humic were also examined, respectively. The PSt-g-HA had relatively high aromatic carbons content because the grafted copolymerization of polystyrene entered into condensed domains in HA, whereas the removal of the polar function groups, such as carboxyl and phenolic hydroxyl group, was performed. For above reasons, the sorption capacity of three organic pesticides (parathion-methyl, carbaryl and carbofuran) on PSt-g-HA increased by 64.1% to 95.2%.

A screening study on the fate of fullerenes (nC60) and their toxic implications in natural freshwaters

Increasing usage of fullerenes (C60 ) increases their opportunities to be released into the environment. For risk assessment, it is important to understand the environmental fate and ecotoxicological effects of C60 . In the present study, fullerene settling was measured during a 1-yr period with 4 different lake waters and an artificial freshwater, and Daphnia magna immobilization and fullerene accumulation was also measured in each of the lake waters. Depending on the characteristics of the lake waters, fullerenes either exhibited extended water stability or settled rapidly; in all waters, there was a fraction that remained stable after 1 yr. Water stability was affected by the quality and molecular size distribution of dissolved natural organic matter (DNOM). Increasing DNOM molecular sizes with high aromatic content enhanced water stability. Immobilization of D. magna was generally quite low (under 20%) and highly variable after 24 h and 48 h at initial fullerene concentrations up to 10 mg/L. Substantial settling occurred during the time period for acute toxicity assays (i.e., 48 h), which should be anticipated when conducting toxicity assays. There were no significant differences in the quantity of accumulated fullerenes among the different lake waters at fullerene concentrations of 0.5 mg/L, but there were differences at 2 mg/L.

Total Aromatic Content in Petroleum Solvents Modifies Headspace Benzene Vapor Concentrations: Implications for Exposure Assessments

ABSTRACT This study evaluates how equilibrium vapor concentrations above petroleum solvent mixtures are affected by total aromatic content and the implications for estimating benzene vapor exposures. Headspace vapor concentrations over mixtures with liquid benzene content ranging from 0.001 to 1.0% and varying percentages of 1,2,4-trimethylbenzene and n-nonane were studied using a direct-injection gas chromatography/flame ionization detection method that showed good precision. The measured values were compared to predictions based on Raoult's Law, with and without non-ideality corrections using activity coefficients. Ratios of vapor to liquid benzene concentrations decreased with increasing total aromatic content; that is, mixtures with 10% to 20% trimethylbenzene simulating non-hydrotreated mineral spirits had much lower ratios compared to the ≥99% aliphatic mixtures that simulate hydrotreated mineral spirits. Positive deviations from Raoult's Law were greatest at liquid benzene concentrations less than 0.1%, particularly in the predominantly aliphatic mixtures. Correcting for non-ideality using activity coefficients resulted in predicted vapor concentrations that were closer to measured values. The data indicate that higher aromatic content and higher liquid benzene content suppress benzene vapor concentrations due to benzene's greater affinity for similar aromatic molecules in solution. Benzene exposure reconstructions should consider actual composition of the historic material with respect to aromatic content.

Feedstocks for fuels and chemicals from algae: Treatment of crude bio-oil over HZSM-5

Crude bio-oil produced from hydrothermal liquefaction of Nannochloropsis sp was reacted over HZSM-5 catalyst with high pressure H2. The effects of reaction temperature (400–500°C), reaction time (0.5–4h), and catalyst loading (5–50wt.%) on the composition and yields of the oil and gas products were determined. Treatment greatly reduced the heteroatom (N, O, and S) content in the oil. S was reduced to below detection limits (<0.1wt.%) at all reaction conditions investigated. The lowest N/C ratio achieved is about 25% of the original N/C ratio in the crude bio-oil. The O/C ratio of the oil treated at 450 and 500°C was an order of magnitude lower than that in the crude bio-oil. The carbon content of the oil increased at all reaction conditions investigated, but the H/C ratios of the oils treated at 450 and 500°C fell below that of the crude bio-oil due to their high aromatic content and the migration of H atoms into the gaseous products. This study demonstrates the opportunities to engineer the composition of the products that emerge from this catalytic treatment of the crude bio-oil. Catalytic processing at 400°C produced a paraffinic oil that was 95wt.% C and H and retained 87% of the energy content of the crude bio-oil. This product would be useful as a feedstock for liquid transportation fuels. Catalytic processing at 500°C, on the other hand, produced a freely flowing liquid mixture composed of aromatic hydrocarbons in 44wt.% yield along with a hydrocarbon gas stream in 19wt.% yield. These products, which could be useful as feedstocks for industrial chemicals, contained 70% of the carbon originally present in the crude bio-oil.

Cyanate ester resins – 'old newcomers' among high performance composite materials

resistant thermosetting polymer materials, cyanate ester resins offer numerous advantages over the widely used commodity resins. Due to the high aromatic content of the monomer and the cured polymer, they possess higher glass transition temperatures (Tg) than epoxy resins (up to 400°C), while the triazine ring formed during addition polymerization is responsible for high thermal stability, high char yield and low smoke generation. Balanced dipoles in the cured state and absence of hydrogen bonding functionality provide further important advantages as low dielectric properties and low moisture absorption. This latter is one of the most significant advantages, as high water uptake would plasticize the resins, lower the Tg value and thus limit the hot/wet service temperature of it. As for the mechanical properties, the relatively low crosslink density and high free volume is responsible for appropriate toughness. These properties can be further fine-tuned through backbone structure (using different linking groups between the aromatic rings of the monomer) or by blending them with other polymers as epoxy resins, phenolic resins, bismaleimides, benzoxazines. Further advantage of the cyanate ester resins is that they can be processed using the same composite preparation methods (resin transfer moulding (RTM), vacuum-assisted resin transfer moulding (VARTM), moulding, filament winding, prepregging) as epoxy resins. But in comparison to epoxy resins, they offer greater dimensional stability due to reduced outgassing during the addition type polymerization reaction. Despite the listed advantages and the fact that they were commercialized already in 1976, cyanate esters are still considered as relative newcomers in the composite industry. The reason behind is not only their relatively high cost (approximately twice as high performance epoxy resins), but also lack of formulation knowledge (moisture sensitivity of the uncured resin, toughness). Moisture sensitivity of the cyanate ester curing process is a known issue: the hydrolysis of the cyanate function leads to formation of carbamates, decomposing to amine and CO2 over 190°C, resulting in voids in the composite structure, decrease in mechanical properties, lower crosslink density and Tg. The use of rapidly developing process analytical technologies during composite preparation (e.g. in-line fibre-optic-coupled Raman spectrometric monitoring of the curing reaction and moisture uptake with possible feedback to process parameters itself) may offer a key to overcome these problems and facilitate the headway of cyanate esters in high-tech composite applications.

Abiotic association of phthalic acid esters with humic acid of a sludge landfill

The abiotic association between phthalic acid esters (PAEs) and humic substances (HS) in sludge landfill plays an important role in the fate and stability of PAEs. An equilibrium dialysis combined with 14C-labeling was used to study the abiotic association of two abundant PAEs (diethyl phthalate and di-n-butyl phthalate) with humic acid (HA) isolated from a sludge landfill with different stabilization times and different molecular weights. Elemental analysis and Fourier Transform Infrared Spectrophotometer (FTIR) suggested that high KA value of HA was related to the high aromatic content and large molecular weight of HA. The results indicated that the association strength of PAEs with HA depended on both the properties of the PAEs and the characteristics of HA. The KA values of the association were strongly dependent on solution pH, and decreased dramatically as the pH was increased from 3.0 to 9.0. The results suggested that nonspecific hydrophobic interaction between PAEs and HA was the main contributor to the association of the PAEs with HA. The interactive hydrogen-bonds between the HA and the PAEs molecules may also be involved in the association.

Changes in character of organics in the receiving environment of effluent from a sulphite pulp mill

The characteristics of organics in sulphite pulp mill effluent and in the receiving environment of effluent discharge were investigated to assess the basis for the persistence or attenuation of colour. Characterization of organics was conducted through determination of SUVA, specific colour, and molecular weight distribution of organics using high performance size exclusion chromatography and by solid-state (13) C cross polarization (CP) NMR. The characteristics of organics from mill wastewater before and after secondary aerobic treatment, followed by lime treatment and from the receiving environment, an enclosed brackish lake were compared. Changes in the character of organics in lake water over a period of 14 years were studied in the context of changes in mill processing and climate impacts. High colour in mill effluent and in receiving waters correlated with high SUVA and specific colour levels, high molecular weight range and aromatic content. Conversely, lake waters with low colour had UV absorbing compounds of much lower molecular weight range and low relative abundance of aromatic compounds. Attenuation of colour and changes in the character of organics in the receiving environment coincided with increased concentrations of metal cations. These increased concentrations appear to be due to the effects of climate change, lake management and their presence in mill effluent, with subsequent discharge to the lake. Attenuation of colour was found to be predominantly through removal of high molecular weight aromatic compounds where the removal processes could be through adsorption and co-precipitation with divalent metals, as well as through dilution processes.

High-Throughput Screening of Catalytic Materials for JP-8 Fuel Cracking to Liquefied Petroleum Gas

ABSTRACTA high-throughput methodology is applied for the discovery and optimization of novel catalyst formulations to convert readily available hydrocarbon-based JP-8 fuel directly into a lighter hydrocarbon product suitable for portable power applications utilizing LPG-powered fuel cells. In addition to catalytic cracking challenges, JP-8 cracking poses other challenges including high sulfur content (up to 3,000 ppmw) and significant concentration of aromatics, which are precursors to coking. An existing 16-channel high-throughput reactor system was modified for the JP-8 catalytic cracking studies. The catalyst support material was of primary importance in determining cracking activity. Alumina-based catalytic materials demonstrate the greatest activity for conversion of JP-8 to LPG during catalytic cracking at reactor temperatures above 600°C. This is attributed to the importance of acidic reaction sites within the structure of the catalytic support. The addition of noble metals to the alumina-based materials does not yield significant improvements in JP-8 conversion.