Oxygen-containing Polar Groups Research Articles

Effects and molecular mechanisms of jet ablation and fuel corrosion on separation failure of the asphalt-aggregate interface in airport asphalt pavements

To guide the improvement of asphalt pavement durability in airports, the effects and molecular mechanisms of jet ablation and fuel corrosion on separation failure of the asphalt-aggregate interface were investigated in this study using molecular dynamics simulations and density functional theory method. Firstly, tensile separation behaviors of the virgin, aged, and fuel-corroded asphalt-aggregate interfaces were simulated under different loading rates to evaluate their tensile strength and fatigue cracking resistance, and the experimental data were also used to verify the reliability of the simulation results. Subsequently, the molecular mechanisms of jet ablation and fuel corrosion on the separation failure of the asphalt-aggregate interface were analyzed by calculating the work of adhesion, work of cohesion, flowability parameters, and intermolecular binding energy. The results show that the aged specimen has higher ultimate tensile strength and fracture energy, but its flexibility and fatigue cracking resistance are significantly reduced. This is because the polar oxygen-containing groups generated during high-temperature aging enhance the intermolecular binding energy of the asphalt, but this also restricts the diffusion of asphalt molecules, resulting in greater frictional resistance and viscosity of asphalt during shear deformation, and thus loss of mobility and self-healing properties. On the contrary, since the light and medium oils soften and dilute the asphalt, and also weaken the intermolecular binding energy of asphalt, the fuel corrosion reduces the ultimate tensile strength and fracture energy of the asphalt-aggregate interface system, resulting in insufficient overall strength and load-bearing capacity.

Unifying and Suppressing Conduction Losses of Polymer Dielectrics for Superior High-Temperature Capacitive Energy Storage.

Superior high-temperature capacitive performance of polymer dielectrics is critical for the modern film capacitor demanded in the harsh-environment electronic and electrical systems. Unfortunately, the capacitive performance degrades rapidly at elevated temperatures owing to the exponential growth of conduction loss. The conduction loss is mainly composed of electrode and bulk-limited conduction. Herein, the contribution of surface and bulk factors is unified to conduction loss, and the loss is thoroughly suppressed. The experimental results demonstrate that the polar oxygen-containing groups on the surface of polymer dielectrics can act as the charge trap sites to immobilize the injected charges from electrode, which can in turn establish a built-in field to weaken the external electric field and augment the injection barrier height. Wide bandgap aluminum oxide (Al2 O3 ) nanoparticle fillers can serve as deep traps to constrain the transport of injected or thermally activated charges in the bulk phase. From this, at 200 °C, the discharged energy density with a discharge-charge efficiency of 90% increases by 1058.06% from 0.31 J cm-3 for pristine polyetherimide to 3.59 J cm-3 for irradiated composite film. The principle of simultaneously inhibiting the electrode and bulk-limited conduction losses could be easily extended to other polymer dielectrics for high-temperature capacitive performance.

Weldability improvement of immiscible polycarbonate/GFRP by femtosecond laser surface treatment

Poor miscibility is an important reason for the non-weldable performance of most dissimilar polymers and their composites, and traditional surface treatments cannot effectively improve the weldability of dissimilar polymers. Therefore, the non-weldability of dissimilar polymers is one of the important factors that limit the application of polymers and their composites. We proposed a surface modification scheme of laser ablation or etching to improve the weldability of immiscible polymers effectively. Experimental studies on femtosecond ultraviolet (UV) laser ablation/etching, mid-infrared laser transmission welding (LTW), and related characterization and mechanical tests were carried out. The experimental results showed that laser ablation induced the deposition of abundant polar oxygen-containing groups on the surface of polycarbonate (PC), which improved the miscibility of PC and polyamide 66 with a glass fibre volume ratio of 30% (PA66GF30) and reduced the weak boundary layer (WBL), thereby improving their chemical bonding performance. Using the compatibilization mechanism induced by laser ablation, the bonding strength of the PC/PA66GF30 joint obtained by LTW was 13.7 MPa, which was much higher than that of the untreated joint (1.4 MPa). However, the grooves generated by laser etching could induce macro-anchoring effect of the hybrid joint. Based on the compatibilization mechanism and macro-anchoring effect, with the selection of appropriate welding power and etching parameters, the bonding strength of the PC/PA66GF30 joint was further increased to 29.7 MPa. This work has demonstrated the feasibility of laser surface treatment (especially etching) to significantly improve the welding strength of immiscible polymers and their composites.

In-situ construction of cellulose acetate propionate-based hybrid gel polymer electrolyte for high-performance lithium metal batteries

Quasi-solid-state gel polymer electrolytes (GPEs) have a great deal of promise for usage in future energy systems due to their high safety. However, ex-situ prepared GPEs still suffer from interfacial incompatibility. Herein, to create stable electrolyte-electrode interfaces and ensure adequate contact, a novel GPE was prepared by in-situ polymerization using pentaerythritol tetraacrylate (PETEA) and cellulose acetate propionate (CAP) as raw materials. PETEA and CAP with a certain mass ratio were added into liquid electrolyte, and the in-situ polymerization of PETEA and CAP was initiated by azobisisobutyronitrile (AIBN). The multi-side chain structure of PETEA and the hydrogen bonding interaction between PETEA and CAP contributed to a robust cross-linked framework, while CAP improved Li+ transport through its polar oxygen-containing groups. The obtained GPE 1:1 exhibited high ionic conductivity (1.03 ×10−3 S/cm at 25 ℃), superior Li+ transference number (0.73), and good stability to Li metal. Meanwhile, a stable SEI film with rich LiF was established, ensuring a long-term cycling lifespan. After 500 cycles at 1 C, the assembled LiFePO4/GPE 1:1/Li cell revealed a high capacity retention of 90.6%. These results provide a guideline for the future design of novel cellulose-based GPEs for high performance lithium metal batteries.

Biochar pyrolyzed with concentrated solar radiation for enhanced nitrate adsorption

Biochar has been recognized as an effective soil amendment for reducing nitrogen leaching in agriculture, but its large-scale implementation is impeded by the costly production process due to high energy requirements for thermal decomposition of feedstock. This study aimed to develop a novel pyrolysis system utilizing concentrated solar radiation to produce biochar and explore the potential of solar-pyrolyzed biochar for nitrate adsorption. Results showed that the solar-pyrolyzed biochar exhibited a maximum adsorption capacity of 35.59 mg/g for nitrate, significantly higher than two out of the three commercially available biochars in America that are selected for comparison. The Fourier-transform infrared (FTIR) analysis suggested a variety of oxygen-containing polar functional groups present in the solar-pyrolysis biochar, which enhances its affinity for nitrate and other hydrophilic ions. The X-ray diffraction (XRD) analysis revealed that the solar pyrolysis biochar was an amorphous material with a poorly crystalline, carbon-rich phase, indicating a high degree of carbonization and recalcitrance, as confirmed by Raman spectroscopy and scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS) analysis. The porous structure of the solar-pyrolysis biochar suggested a larger specific surface area, which could benefit adsorption. Although further experiments are required to determine the stability and cost-effectiveness of a scaled-up solar-pyrolysis apparatus, these findings provide hope for a more sustainable and high-performing biochar production process in the future.

How to Make Plastic Surfaces Simultaneously Hydrophilic/Oleophobic?

Hydrophilic/oleophobic surfaces are desirable in many applications including self-cleaning, antifogging, oil-water separation, etc. However, making plastic surfaces hydrophilic/oleophobic is challenging due to the intrinsic hydrophobicity/oleophilicity of plastics. Here, we report a simple and effective method of making plastics hydrophilic/oleophobic. Plastics, including poly (methyl methacrylate) (PMMA), polystyrene (PS), and polycarbonate (PC), have been coated with a perfluoropolyether (PFPE) (i.e., commercially known as Zdol) via dip coating and then irradiated with UV/Ozone. The contact angle measurements indicate that the treated plastics have a lower water contact angle (WCA) and higher hexadecane contact angle (HCA), i.e., they are simultaneously hydrophilic/oleophobic. The Fourier transform infrared (FTIR) results suggest that UV/Ozone treatment introduces oxygen-containing polar groups on the plastic surfaces, which renders the plastic surfaces hydrophilic. Meanwhile, more orderly packed PFPE Zdol molecules, which is due to the UV-induced bonding between PFPE Zdol and the plastic surface, result in the oleophobicity. Moreover, the simultaneous hydrophilicity/oleophobicity of functionalized plastics does not degrade in aging tests, and they have superior antifogging performance and detergent-free cleaning capability. This simple method developed here potentially can be applied to other plastics and has important implications in the functionalization of plastic surfaces.

Effect of Flame Treatment on Bonding Performance of GF/EP Pultrusion Sheets Used for VARI Process

This paper presents an easy and low-cost flame treatment method to improve the bonding performance of GF/EP (Glass Fiber-Reinforced Epoxy) pultrusion plates, which are using widely for large size wind blades. In order to explore the effect of flame treatment on the bonding performance of the precast GF/EP pultruded sheet vs. the infusion plate, the GF/EP pultruded sheets were treated with different flame treatment cycles and were embedded in the fiber fabrics during the vacuum-assisted resin infusion process (VARI). The bonding shear strengths were measured by tensile shear tests. It is found that after 1, 3, 5, and 7 flame treatments, the tensile shear strength between the GF/EP pultrusion plate and infusion plate increased by 8.0%, 13.3%, 22.44%, and -2.1%, respectively. This indicates that the maximum tensile shear strength can be obtained after five times of flame treatment. In addition, DCB and ENF tests were also adopted to characterize the fracture toughness of the bonding interface with the optimal flame treatment. It is found that the optimal treatment gives increments of 21.84% and 78.36% for G I C and G II C, respectively. Finally, the surficial topography of the flame-treated GF/EP pultruded sheets were characterized by optical microscopy, SEM, contact angle test, FTIR, and XPS. The results show that flame treatment plays an impact on the interfacial performance through the combination of physical meshing locking and chemical bonding mechanism. Proper flame treatment would remove the weak boundary layer and mold release agent on the surface of the GF/EP pultruded sheet, etch the bonding surface and improve the oxygen-containing polar groups, such as C-O and O-C=O, to improve the surface roughness and surface tension coefficient of pultruded sheet to enhance the bonding performance. Excessive flame treatment destroys the integrity of epoxy matrix on bonding surface which results into the exposure of the glass fiber, and the carbonization of release agent and resin on the surface loosen the surficial structure, which reduces the bonding properties.

Wettability Alteration of a Thiolene-Based Polymer (NOA81): Surface Characterization and Fabrication Techniques

Wettability plays a significant role in controlling multiphase flow in porous media for many industrial applications, including geologic carbon dioxide sequestration, enhanced oil recovery, and fuel cells. Microfluidics is a powerful tool to study the complexities of interfacial phenomena involved in multiphase flow in well-controlled geometries. Recently, the thiolene-based polymer called NOA81 emerged as an ideal material in the fabrication of microfluidic devices, since it combines the versatility of conventional soft photolithography with a wide range of achievable wettability conditions. Specifically, the wettability of NOA81 can be continuously tuned through exposure to UV-ozone. Despite its growing popularity, the exact physical and chemical mechanisms behind the wettability alteration have not been fully characterized. Here, we apply different characterization techniques, including contact angle measurements, X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM) to investigate the impact of UV-ozone on the chemical and physical properties of NOA81 surfaces. We find that UV-ozone exposure increases the oxygen-containing polar functional groups, which enhances the surface energy and hydrophilicity of NOA81. Additionally, our AFM measurements show that spin-coated NOA81 surfaces have a roughness less than a nanometer, which is further reduced after UV-ozone exposure. Lastly, we extend NOA81 use cases by creating (i) 2D surface with controlled wettability gradient and (ii) a 3D column packed with monodisperse NOA81 beads of controlled size and wettability.

Highly stable, antiviral, antibacterial cotton textiles via molecular engineering.

Cotton textiles are ubiquitous in daily life and are also one of the primary mediums for transmitting viruses and bacteria. Conventional approaches to fabricating antiviral and antibacterial textiles generally load functional additives onto the surface of the fabric and/or their microfibres. However, such modifications are susceptible to deterioration after long-term use due to leaching of the additives. Here we show a different method to impregnate copper ions into the cellulose matrix to form a copper ion-textile (Cu-IT), in which the copper ions strongly coordinate with the oxygen-containing polar functional groups (for example, hydroxyl) of the cellulose chains. The Cu-IT displays high antiviral and antibacterial performance against tobacco mosaic virus and influenza A virus, and Escherichia coli, Salmonella typhimurium, Pseudomonas aeruginosa and Bacillus subtilis bacteria due to the antimicrobial properties of copper. Furthermore, the strong coordination bonding of copper ions with the hydroxyl functionalities endows the Cu-IT with excellent air/water retainability and superior mechanical stability, which can meet daily use and resist repeated washing. This method to fabricate Cu-IT is cost-effective, ecofriendly and highly scalable, and this textile appears very promising for use in household products, public facilities and medical settings.

One-pot synthesis of porous N-doped hydrochar for atrazine removal from aqueous phase: Co-activation and adsorption mechanisms

KOH-activated N-doped hydrochar (KHCN) was synthesized via co-activation method to eliminate atrazine (AT) in water efficiently. Compared to primitive HC, KHCN had advantages of splendid specific surface area (1205.82 m2/g) and developed microsphere structures on the surface. Specially for KHCN, the extra melamine added strengthened and preserved partial structure of polar oxygen-containing groups that were decomposed in the process of pore making. Besides, the estimated uptake amount of AT onto KHCN (216.50 mg/g) was remarkably superior to KHC (114.25 mg/g). KHCN exhibited the pH-dependence for AT removal, and presented excellent uptake capacity at a relatively neutral environment. Notably, the proposed mechanisms for AT removal by KHCN included electrostatic attraction, pore filling, π-π EDA, H-bond as well as hydrophilic effect. Hence, the porous N-doped hydrochar was a kind of adsorbent which was easy to prepare and had the application prospect for AT removal in natural water.

Understanding the Accelerated Sodium-Ion-Transport Mechanism of an Interfacial Modified Polyacrylonitrile Separator

Sodium-ion batteries (SIBs) are considered as the most attractive candidates for large-scale energy storage systems owing to their low cost and abundant reserves. They need a special separator with rapid Na+ transport for a satisfactory power performance. Herein, an alkaline-solution-treated electrospun polyacrylonitrile separator with an in situ chemical-grafted graphene oxide (denoted as M-PAN-GO) is prepared via regulating the interfacial group. The increased amount and variety of oxygen-containing polar groups −COO–, −COOH–, and −OH in the M-PAN-GO separator not only increase the number of active sites for bonding and transferring Na+ but also produce more H-bonds that impede the migration of PF6–. The obtained M-PAN-GO separator displayed accelerated transmission of Na+ and Li+, and the Na+ transference number is larger than that of Li+ owing to a more efficient binding that can be formed between oxygen-containing functional groups and Na+. DFT calculations demonstrate that a greater binding energy is favorable to binding and promoting ion transport in a certain range. Along with the M-PAN-GO separator’s desolvation capability, high Na+ transference number (0.70) and ion conductivity (4.53 mS cm–1) of the M-PAN-GO separator in 1 M NaPF6 EC DMC electrolyte are obtained. The Na|Na3V2(PO4)3 cells assembled with the M-PAN-GO separator have a superior polarization voltage of 0.76 V rather than 0.97 V at 4 C in SIBs. This work provides a potential high-performance separator for SIBs and lithium-ion batteries.

Analysis of Natural Aging Behavior of Asphalt Binder in Cold and Arid Region

With extremely bad climate and poor geographical environment in cold and arid region, the deterioration and failure of road materials are serious. In order to analyze the characteristics of natural aging behavior of asphalt binder in cold and arid region, the experiments were carried out based on the exposure field test base. The multiscale characterization of virgin asphalt under different natural aging conditions was carried out by means of macromechanical analysis and microchemical composition analysis. The results showed that the effects of natural aging and laboratory simulated aging on asphalt binder properties were similar. There was little effect on the performance of asphalt binder after natural aging one year. The effect of natural aging on asphalt binder in one year was similar to that of laboratory short-term aging. However, the strong UV radiation was a great challenge for asphalt pavement in Northwest China. Wind, dust, rain, and other factors have little effect on asphalt binder aging. Affected by the natural environment, macromolecular structures such as oxygen-containing polar functional groups will form in asphalt binder. The molecular weight of asphalt binder was increased, and the internal molecules of asphalt binder were subjected to large internal friction resistance in the process of movement. The macroscopic physical properties and road performance of asphalt binder become poor.

Hydrophilization of polytetrafluoroethylene using an atmospheric-pressure plasma of argon gas with water–ethanol vapor

This paper presents an approach to improve the surface wettability of polytetrafluoroethylene (PTFE) using an atmospheric-pressure plasma of argon gas with water–ethanol vapor. Plasma is generated by the dielectric barrier discharge of argon gas bubbled into a water-ethanol solution. Quadrupole mass analysis revealed that the plasma promoted the decomposition of ethanol and production of H2, CH4, and CO, which saturated at low ethanol concentrations. The modified PTFE surface was strongly influenced by the ethanol concentration in the solution and treatment time. Plasma treatment with 3%, 5% and 9% ethanol resulted in a significant reduction in the water contact angle from 115° to 16.5 ± 2.8° after 10 s of treatment. X-ray photoelectron spectroscopy showed that oxygen-containing functional groups (hydroxyl, carbonyl, and carboxyl groups) formed on the plasma-treated PTFE surface, reflecting the hydrophilization of PTFE. At the beginning of the plasma treatment, the water vapor induced the breaking of the CF2 chain, and the additional ethanol vapor generated oxygen-containing polar groups on the PTFE surface. In addition to the modification of the PTFE surface itself, a low-molecular-weight oxidized material layer was deposited over the surface, which prevented further surface modification, and the deposited layer exhibited excellent wettability. The deposited low-molecular-weight oxidized material layer was easily removed by immersion in deionized water, and the exposed modified PTFE surface exhibited stable wettability with water contact angle of 52.7 ± 3.5°.

Enhancing ink adhesion of specialty paper using an interpenetrating polyvinyl alcohol-blocked polyurethane polymer network sizing system.

The printing quality and strength of specialty papers such as money, maps, newspapers and bank notes have been a significance challenge in recent years. The adhesive effect between ink and paper is depend on both the secondary binding force between the molecules and the mechanical anchoring effect of the ink on the paper. Also, the porous and fibrous structures of base paper restrain its application in printed products because of the strong capillary effect leading to the diffusion of ink particles. To address the problems involved in ink diffusion and mechanical reinforcement, surface sizing is an attractive choice from the perspective of paper handling. Herein, the surface sizing system of specialty paper with an interpenetrating polyvinyl alcohol-blocked polyurethane polymer network was applied to fabricate paper of high ink adhesive properties. In the case of the same external factors (gluing temperature, drying time, etc.), the surface sizing effect of paper samples (sizing with TBPU, polyvinyl alcohol and TBPU/PVA system) were evaluated by infrared spectroscopy, X-ray photoelectron spectroscopy, water contact angle measurements and scanning electron microscopy. Some of the pure cotton pulp paper with surface sizing treatment was treated via adhering inks to paper by spraying, smearing and soaking. The bonding strength was tested by peel-off tape tests, soaking tests, and simulated washing tests. The results showed that the water contact angle of the sized-paper increased from 67.6° to 89.7°. The mechanical properties had been greatly improved after treatment and SEM, AFM and XPS analyses indicated an increase in surface roughness and the oxygen-containing polar groups (C Created by potrace 1.16, written by Peter Selinger 2001-2019 ]]> O, C–OH, –NH–COO– and COOH) enhanced the fixation of ink particles on the fiber surface. These tests indicated that the novel composite system of TBPU/PVA could endow specialty paper with superb mechanical properties and more than 90% ink retention rate. All these advantages of this composite system may contribute to its wide application in the fields of papermaking and printing.

Sodium alginate crosslinked oxidized natural rubber supramolecular network with rapid self-healing at room temperature and improved mechanical properties

Rubbers with dynamic covalent bonds generally require external stimuli to trigger the healing process, e.g. high temperature, which caused inconvenience to utilize. In contrast, rubbers based on noncovalent supramolecular networks can be spontaneously repaired under mild conditions, but usually exhibit kPa level on the mechanical properties. In this paper, a rapid self-healing composite film with considerable mechanical properties was developed based on sodium alginate (SA) crosslinked oxidized natural rubber (oNR) supramolecular hydrogen bonding network. The NR latex was firstly modified to equip oxygen-containing polar groups and then blended with SA solution. After film-formation, regenerated SA formed a frame-like network and simultaneously participated in formation of a reversible supramolecular network via hydrogen bonding with rubber matrix. The composite film with 20 phr SA showed improved tensile strength of 6.5 MPa, meanwhile, its self-healing efficiency could reach 60% after self-healing 2 min and reach 80% after 10 min at room temperature.

Improved lithium-ion battery performance by introducing oxygen-containing functional groups by plasma treatment

Metal sulfides are often used as cathode materials for lithium-ion batteries (LIBs) owing to their high theoretical specific capacity; however, excessively fast capacity decay during charging/discharging and rapid shedding during cycling limits their practical application in batteries. In this study, we proposed a strategy using plasma treatment combined with the solvothermal method to prepare cobalt sulfide (Co1−x S)-carbon nanofibers (CNFs) composite. The plasma treatment could introduce oxygen-containing polar groups and defects, which could improve the hydrophilicity of the CNFs for the growth of the Co1−x S, thereby increasing the specific capacity of the composite electrode. The results show that the composite electrode present a high discharge specific capacity (839 mAh g−1 at a current density of 100 mA g−1) and good cycle stability (the capacity retention rate almost 100% at 2000 mA g−1 after 500 cycles), attributing to the high conductivity of the CNFs. This study proves the application of plasma treatment and simple vulcanization method in high-performance LIBs.

Synthesis of polyaniline nanowires wrapped yolk-shell structured S@RGO composite material and its improved lithium-storage performance

To accommodate volume change of sulfur particles, confine lithium polysulfides (LiPSs) within conductive matrix, as well as accelerate transference of electrons/ions, the sulfur@reduced graphene oxide (S@RGO) yolk-shell particles wrapped by polyaniline (PANI) nanowires were prepared in this work. Meanwhile, PANI nanowires are synthesized by in situ polymerization of aniline monomers. Importantly, many nanoscale holes are generated on the RGO nanosheets forming three-dimensional channels for ion transportation within the obtained composite material. LiPSs can be firmly confined in the composite material by the polar oxygen-containing groups on the surface of the RGO shells and the protonated nitrogen-containing groups on the PANI nanowires. Benefiting from the unique structure, the S@RGO/PANI particles exhibit an improved electrochemical performance. It can deliver an initial capacity of 1021 mAh·g−1 at 0.1C rate and a high initial coulombic efficiency up to 95.4%. Even at 2.0C rate, a discharge capacity of 501 mAh·g−1 can be retained after 500 cycles. Results indicate that the S@RGO/PANI can be promisingly exploited as a kind of high-energy density cathode material for rechargeable lithium batteries.

Removal of volatile organic compounds from the coal-fired flue gas by adsorption on activated carbon

Removal of volatile organic compounds (VOCs) from coal-fired power plants is the key to reducing VOCs emissions to the atmosphere. Adsorption on activated carbon (AC) is considered to be an economical and environment-friendly method for removal of these low-concentration VOCs. The VOCs adsorption behaviors on AC were investigated under coal-fired flue gas environment by a fixed-bed reactor. Investigations showed that adsorption capacity of the five aromatic compounds ranged from 12.3 to 52.7 mg/g at 120 °C. The lower concentrations and the higher adsorption temperature resulted in the lower VOCs adsorption capacity on AC. Physical adsorption accounted for a large proportion in VOCs removal. VOCs adsorption capacity was reduced by 20.1–26.9% when the SO2, water vapor, and fly ash coexisted. Competitive adsorption was present among the SO2, water vapor, and VOCs. SO2 and water vapor preferentially occupied the polar oxygen-containing groups, inhibiting the electron donor-acceptor interaction between VOCs and the functional groups. The stronger the VOCs polarity, the greater the inhibition. The fly ash adhered to the AC external surface and blocked the macropores on the surface, which not only reduced the VOCs adsorption capacity but also lowered the adsorption rate. Selecting AC with large micropore volume and increasing adsorption time are conducive to the VOCs removal.

SEBS effect on 60Co radiation resistance behavior of PP/HDPE matrix for medical device applications

Radiation resistant polypropylene (PP) has become more and more critical in the medical industry. Composites of PP were synthesized by melting process in the presence of high-density polyethylene (HDPE) and styrene–ethylene–butylene–styrene triblock copolymer (SEBS). Under 60Co γ-ray irradiation, all samples were characterized by mechanical properties, thermal analysis, contact angle (CA), FT-IR analysis, and SEM. Under a 20 kG y dose irradiation, mechanical properties results show that the impact strength rose from 3.28 kJ/m2 to 4.40 kJ/m2, and the tensile strength decreased by 3.52 MPa. At the same time, CA's results show that a much higher irradiation dose makes CA lower, but the higher content of SEBS, the higher CA. To confirm the presence of polar oxygen-containing groups, the FT-IR was used, and the results show that the characteristic peak intensity of carbonyl groups decreased gradually. SEM images indicate that the number of cracks and plastic particles reduced gradually, and the radiation resistance of samples enhanced by the aromatic ring structure of SEBS.

Polarity-Based Sequential Extraction as a Simple Tool to Reveal the Structural Complexity of Humic Acids

A sequential chemical extraction with a defined series of eluotropic organic solvents with an increasing polarity (trichloromethane < ethyl acetate < acetone < acetonitrile < n-propanol < methanol) was performed on peat-bog humic acid. Six organic fractions were obtained and subjected to a physicochemical characterization utilizing methods of structural and compositional analysis. Advanced spectroscopic techniques such as Attenuated Total Reflectance (ATR-FTIR), total luminescence, and liquid-state 13C NMR spectrometry were combined with elemental analysis of the organic fractions. In total, the procedure extracted about 57% (wt.) of the initial material; the individual fractions amounted from 1.1% to 19.7%. As expected, the apolar solvents preferentially released lipid-like components, while polar solvents provided organic fractions rich in oxygen-containing polar groups with structural parameters closer to the original humic material. The fraction extracted with acetonitrile shows distinct structural features with its lower aromaticity and high content of protein-like structural motifs. The last two—alcohol extracted—fractions show the higher content of carbohydrate residues and their specific (V-type) fluorescence suggests the presence of plant pigment residues. The extraction procedure is suggested for further studies as a simple but effective way to decrease the structural complexity of a humic material enabling its detail and more conclusive compositional characterization.