Seasonal N<Subscript>2</Subscript>O emissions respond differently to environmental and microbial factors after fertilization in wheat–maize agroecosystem

Biogeochemical processes regulating cropland soil nitrous oxide (N₂O) emissions are complex, and the controlling factors need to be better understood, especially for seasonal variation after fertilization. Seasonal patterns of N₂O emissions and abundances of archaeal ammonia monooxygenase (amoA), bacterial amoA, nitrate reductase (narG), nitrite reductase (nirS/nirK), and nitrous oxide reductase (nosZ) genes in long-term fertilized wheat–maize soils have been studied to understand the roles of microbes in N₂O emissions. The results showed that fertilization greatly stimulated N₂O emission with higher values in pig manure-treated soil (OM, 2.88 kg N ha^?1 year^?1) than in straw-returned (CRNPK, 0.79 kg N ha^?1 year^?1) and mineral fertilizer-treated (NPK, 0.90 kg N ha^?1 year^?1) soils. Most (52.2–88.9%) cumulative N₂O emissions occurred within 3 weeks after fertilization. Meanwhile, N₂O emissions within 3 weeks after fertilization showed a positive correlation with narG gene copy number and a negative correlation with soil NO₃^? contents. The abundances of narG and nosZ genes had larger direct effects (1.06) than ammonium oxidizers (0.42) on N₂O emissions according to partial least squares path modeling. Stepwise multiple regression also showed that log narG was a predictor variable for N₂O emissions. This study suggested that denitrification was the major process responsible for N₂O emissions within 3 weeks after fertilization. During the remaining period of crop growth, insufficient N substrate and low temperature became the primary limiting factors for N₂O emission according to the results of the regression models.     

Novel amphiphilic temperature responsive graft copolymers PCL-<Emphasis Type="Italic">g</Emphasis>-P(MEO<Subscript>2</Subscript>MA-<Emphasis Type="Italic">co</Emphasis>-OEGMA) via a combination of ROP and ATRP: synthesis,characterization, and sol-gel transition

A series of well-defined novel amphiphilic temperature-responsive graft copolymers containing PCL analogues P(αClεCL-co-εCL) as the hydrophobic backbone, and the hydrophilic side-chain PEG analogues P(MEO₂MA-co-OEGMA), designated as P(αClεCL-co-εCL)-g-P(MEO₂MA-co-OEGMA) have been prepared via a combination of ring-opening polymerization (ROP) and atom transfer radical polymerization (ATRP). The composition and structure of these copolymers were characterized by ¹H NMR and GPC analyses. The self-assembly behaviors of these amphiphilic graft copolymers were investigated by UV transmittance, a fluorescence probe method, dynamic light scattering (DLS) and transmission electron microscopy (TEM) analyses. The results showed that the graft copolymers exhibited the good solubility in water, and was given the low critical temperature (LCST) at 35(±1) °C, which closed to human physiological temperature. The critical micelle concentrations (CMC) of P(αClεCL-co-εCL)-g-P(MEO₂MA-co-OEGMA) in aqueous solution were investigated to be 2.0 × 10^?3, 9.1 × 10^?4 and 1.5 × 10^?3 mg·mL^?1, respectively. The copolymer could self-assemble into sphere-like aggregates in aqueous solution with diverse sizes when changing the environmental temperature. The vial inversion test demonstrated that the graft copolymers could trigger the sol-gel transition which also depended on the temperature.     

Optimization of controlled ring-opening polymerization of <Emphasis Type="SmallCaps">l</Emphasis>-lactide to hydroxyl terminated polylactides using zinc acetate catalyst

Hydroxyl terminated polylactide polymers with number of average molecular weights (M _n ) varying from 1625 to 3459 g mol^?1 were synthesized by ring opening bulk polymerization of lactide in the presence of zinc acetate being a potent catalyst. The use of 1,4 butanediol (BDO) initiator leads to hydroxyl terminated polylactides, thus excellent precursors for shape-memory biodegradable polyurethanes. Different reaction conditions employed for the synthesis of hydroxyl terminated polylactide polymers via activated monomer mechanism may result in differences in M _n , percentage mass conversion and percentage degree of crystallinity (%χ _c ) of the product. Influence of process parameters, i.e. catalyst concentration, initiator concentration, reaction temperature and time on characteristics of hydroxyl terminated polylactides was studied. These polymers were characterized by Nuclear Magnetic Resonance (¹H-NMR) spectroscopy, Fourier transforms infrared (FTIR) spectroscopy, gel permeation chromatography (GPC) and X-ray diffraction (XRD) techniques. FTIR and ¹H-NMR confirmed the formation of hydroxyl terminated polylactides. M _n was determined by ¹H-NMR, GPC and end group analysis. %χ _c was calculated from XRD spectra. Maximum mass conversion, M _n and %χ _c were observed at 5 mol% SnOct₂ and 5 mol% BDO concentration. At optimum temperature of 145 °C, these characteristics improved linearly with polymerization time up to 6 h and declined thereafter.     

Preparation of high surface area mesoporous nickel oxides and catalytic oxidation of toluene and formaldehyde

Mesoporous nickel oxide (NiO) nanoparticles were synthesized by the thermal decomposition reaction of Ni(NO₃)₂·9H₂O using oxalic acid dihydrate as the mesoporous template reagent. The pore structure of nanocrystals could be controlled by the precursor to oxalic acid dihydrate molar ratio, thermal decomposition temperature and thermal decomposition time. The structural characteristic and textural properties of resultant nickel oxide nanocrytals were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), N₂ adsorption–desorption isotherm and temperature programmed reduction. The results showed that the most excellently mesoporous nickel oxide particles (m-Ni-1-4) with developed wormlike pores were prepared under the conditions of the mixed equimolar precursor and oxalic acid and calcined for 4 h at 400 °C. The specific surface area and pore volume of m-Ni-1-4 are 236 m² g^?1 and 0.42 cm³ g^?1, respectively. Over m-Ni-1-4 at space velocity = 20,000 mL g^?1 h^?1, the conversions of toluene and formaldehyde achieved 90 % at 242 and 160 °C, respectively. It is concluded that the reactant thermal decomposition with oxalic acid assist is a key step to improve the mesoporous quality of the nickel oxide materials, the developed mesoporous architecture, high surface area, low temperature reducibility and coexistence of multiple oxidation state nickel species for the excellent catalytic performance of m-Ni-1-4.     

Thermal expansion and phase transitions in K<Subscript>1 − <Emphasis Type="Italic">x</Emphasis></Subscript>Rb<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>BSi<Subscript>2</Subscript>O<Subscript>6</Subscript> leucite borosilicate solid solutions

Continuous solid solutions and the reversible phase transition from the I-43d cubic phase to the Ia-3d cubic phase are revealed in the borosilicate series K_{1 ? x} Rb _x BSi₂O₆. Samples in the KBSi₂O₆-RbBSi₂O₆ system are prepared by solid-phase synthesis and crystallization of glasses and investigated using the annealing and quenching technique, high-temperature X-ray diffraction, and dilatometry. The above polymorphic phase transition is observed in all solid solutions at temperatures in the range from 330 to 430°C depending on the composition: an increase in the rubidium content in the solid solution leads to a gradual decrease in the phase transition temperature. The linear thermal expansion coefficients α are determined for solid solutions of different crystalline modifications and glasses. The linear thermal expansion coefficients α for the I-43d low-temperature phase are equal to (20–23) × 10^?6 K^?1 according to the X-ray diffraction data and (21–24) × 10^?6 K^?1 according to the dilatometric data. The values of α for the Ia-3d high-temperature phase lie in the range (4–9) × 10^?6 K^?1 according to the X-ray diffraction data and in the range (6–9) × 10^?6 K^?1 according to the dilatometric data. The linear thermal expansion coefficients for both modifications decrease with an increase in the rubidium content in the solid solutions. The linear thermal expansion coefficients for glasses α = (10–11) × 10^?6 K^?1 are close to those for the high-temperature modification and virtually independent of the sample composition. The I-43d (cubic) ai I4₁/a (tetragonal) o Ia-3d (cubic) polymorphic phase transitions in the KBSi₂O₆ compound are revealed by differential scanning calorimetry (DSC) and dilatometry. Their reversibility is confirmed by the DSC data.     

Structure of a biologically active binuclear palladium complex in the compound (bis[(μ<Subscript>2</Subscript>-2-chloroethylammonium)(1,10-phenanthroline)-palladium(I)]) · tetranitrates · hydrate

The structure of a biologically active palladium complex [(1,10-phenanthroline)Pd(μ₂-2-chloroethylammoniu)] ₂ ⁴⁺ · 4NO ₃ ^? · H₂O has been determined from the diffractometric data. The compound crystallizes in the triclinic crystal system, space group of symmetry P \(\bar 1\), with the unit cell parameters a = 12.8352(8) Å, b = 14.4040(8) Å, c = 12.1668(9) Å, α = 116.16(1)°, β = 115.72(1)°, γ = 91.09(1)°, V = 1756.3 ų, Z = 2, and ρ = 1.892 g/cm³. The final reliability factor is R ₁ = 0.0351 for 7357 nonequivalent reflections with I ≥ 2σ(I), wR ₂ = 0.0970, and S = 1.044. The asymmetric part of the unit cell contains one positively charged binuclear palladium complex, four NO ₃ ^?1 anions, and one water molecule. The nanocomplexes are involved in the stacking π-π interaction by pairs: each complex forms a stacking with only one adjacent complex. The interaction between layers and inside each layer occurs through the van der Waals interactions and a three-dimensional system of hydrogen bonds, which are formed by the N ₃ ⁺ groups and water molecules.     

Synthesis,Characterization and Surface Properties of Amidosulfobetaine Surfactants Bearing Odd-Number Hydrophobic Tail

Three amidosulfobetaine surfactants were synthesized namely: 3-(N-pentadecanamidopropyl-N,N-dimethyl ammonium) propanesulfonate (2a); 3-(N-heptadecanamidopropyl-N,N-dimethyl ammonium) propanesulfonate (2b), and 3-(N-nonadecanamidopropyl-N,N-dimethyl ammonium) propanesulfonate (2c). These surfactants were prepared by direct amidation of commercially available fatty acids with 3-(dimethylamino)-1-propylamine and subsequent reaction with 1,3-propanesultone to obtain quaternary ammonium salts. The synthesized surfactants were characterized by IR, NMR and mass spectrometry. Thermogravimetric analysis (TGA) results showed that the synthesized surfactants have excellent thermal stability with no major thermal degradation below 300 °C. The critical micelle concentration (CMC) values of the surfactants 2a and 2b were found to be 2.2 × 10^?4 and 1.04 × 10^?4 mol/L, and the corresponding surface tension (γ_CMC) values were 33.14 and 34.89 mN m^?1, respectively. The surfactants exhibit excellent surface properties, which are comparable with conventional surfactants. The intrinsic viscosity of surfactant (2b) was studied at various temperatures and concentrations of multi-component brine solution. The plot of natural logarithm of relative viscosity versus surfactant concentration obtained from Higiro et al. model best fit the surfactant behavior. Due to good salt resistance, excellent surface properties and thermal stability, the synthesized surfactant has potential to be used in various oil field applications such as enhanced oil recovery, fracturing, acid diversion, and well stimulation.     

Structure of a biologically active binuclear palladium complex,bis(bis[(μ<Subscript>2</Subscript>-cysteine)(2,2′-dipyridyl)-palladium(II)]) · hexanitrates · novemhydrates

The structure of a biologically active binuclear palladium complex, namely, [(dipy)Pd(μ-cysH) (μ-cys)Pd(dipy)]³⁺ · 3NO ₃ ^? · 4.5H₂O (dipy = 2,2′-dipyridyl, C₁₀H₈N₂; cys = cysteine, C₃H₇NO₂S), has been determined from X-ray diffractometry data. The compound crystallizes in the triclinic system, symmetry space group P1, with the unit cell parameters a = 13.863(1) Å, b = 13.819(1) Å, c = 12.170(1) Å, α = 122.13(1)°, β = 103.61(1)°, γ = 91.40(1)°, V = 1887.02 ų, Z = 2, and ρ = 1.82 g/cm³. The final discrepancy factor is R1 = 0.0495 for 12884 symmetrically nonequivalent reflections with F ₀ ≥ 4σ(F ₀), wR2 = 0.1071, and GooF = 0.978. The unit cell contains two chemically equivalent but crystallographically independent positively charged binuclear palladium complexes, six NO ₃ ^? anions, and nine water molecules. The π-π stacking interaction between the nearest pyridyl rings of the neighboring layers takes place. Moreover, the interlayer and intralayer interactions occur through van der Waals interactions and a complex three-dimensional system of hydrogen bonds, which are formed by water molecules, NH ₃ ⁺ groups, and carboxyl groups.     

Crystal structure and thermal expansion of ammonium pentaborate NH<Subscript>4</Subscript>B<Subscript>5</Subscript>O<Subscript>8</Subscript>

Anhydrous ammonium pentaborate NH₄B₅O₈ has been synthesized by thermal dehydration of larderellite NH₄[B₅O₇(OH)₂] · H₂O at a temperature of 290°C for 7 h. The crystal structure has been determined from the X-ray powder diffraction data: a = 7.58667(5) Å, b = 12.00354(8) Å, c = 14.71199(8) Å, R _p = 6.23, R _wp = 7.98, R _B = 12.7, R _F = 8.95, and β-KB₅O₈ structure type. The double interpenetrating framework is formed by pentaborate groups, each consisting of a boron-oxygen tetrahedron and four triangles, in which all oxygen atoms are bridging. The thermal behavior of the NH₄B₅O₈ compound has been investigated using thermal X-ray diffraction. As for other pentaborates of this type, the thermal expansion of the NH₄B₅O₈ compound is anisotropic and reaches a maximum along the a axis. The thermal expansion coefficients are as follows: α _a = 39 × 10^?6, α _b = 6 × 10^?6, α _c = 20 × 10^?6, and α _V = 65 × 10^?6 °C^?1.     

Synthesis and characterization of thermo-responsive supramolecular diblock copolymers

In this paper, we report the synthesis and characterization of a new thermo-responsive supramolecular amphiphiles diblock copolymer, methoxy poly (ethylene glycol)-block-Poly(N-isopropylacrylamide) (mPEG-b-PNIPAM). The mPEG with β-cyclodextrin (β-CD) group and the PNIPAM with adamantine (AD) group were synthesized, respectively, and mPEG-b-PNIPAM was then obtained by the host-guest inclusion between AD and β-CD. The structure and molecular weight of mPEG-b-PNIPAM was confirmed by ¹H NMR and GPC measurements. At low temperature (T?<?33 °C), the PNIPAM block is hydrophilic. With increasing temperature, the hydrophobicity the of PNIPAM block increases. This molecular feature leads to interesting aggregation behavior of micelles in aqueous solutions at different temperatures. The self-assembly was revealed by UV, DLS measurements, and TEM observations.     

Structure of a biologically active binuclear palladium complex in the compound bis(bis[(μ<Subscript>2</Subscript>-2-chloroethylammonium) (1,10-phenanthroline)-palladium(I)]) · octanitrates · dihydrates

The structure of a biologically active binuclear palladium complex, namely, [(1,10-phenanthroline) Pd(μ₂-2-chloroethylammonium) ₂ ⁴⁺ · 4NO ₃ ^? · H₂O, has been determined using X-ray diffraction analysis. The compound crystallizes in the monoclinic system, space group of symmetry Cc, with the unit cell parameters a = 24.527(3) Å, b = 13.097(1) Å, c = 22.651(3) Å, β = 104.23(1)°, V = 7052(2) ų, Z = 8, and ρ = 1.88 g/cm³. The final discrepancy factor is R1 = 0.0316 for 15581 symmetrically nonequivalent reflections with I ≥ 2σ(I), wR2 = 0.0513, and GooF = 1.047. The palladium atoms reside in the oxidation state of 1+, which is rarely encountered in organometallic compounds. The asymmetric part of the unit cell contains two chemically equivalent but crystallographically independent positively charged binuclear palladium complexes, eight NO ₃ ^? anions, and two water molecules. The π-π stacking interaction between the nearest 1,10-phenanthroline rings of the neighboring layers takes place. Moreover, the interlayer and intralayer interactions occur through electrostatic interaction forces and a complex three-dimensional system of hydrogen bonds, which are formed by water molecules and N ₃ ⁺ groups.     

Synthesis and characterization of polyimides from 4,4′-(3-(<Emphasis Type="Italic">tert</Emphasis>-butyl)-4-aminophenoxy)diphenyl ether

A novel diamine 4,4′-(3-(tert-butyl)-4-aminophenoxy)diphenyl ether (4) was synthesized from 2-tert-butylaniline and 4,4′-oxydiphenol through iodination, acetyl protection, coupling reaction and deacetylation protection. Then some polyimides (PIs) were obtained by one-pot polycondensation of diamne 4 with several commercial aromatic dianhydrides respectively. They all exhibit enhanced solubility in organic solvents (such as NMP, DMF, THF and CHCl₃ etc.) at room temperature. Their number-average molecular weights are in the range of (2.1–3.7)?×?10⁴ g/mol with PDI from 2.25 to 2.74 by GPC. They can form transparent, tough and flexible films by solution-casting. The light transparency of them is higher than 90% in the visible light range from 400 nm to 760 nm and the cut-off wavelengths of UV–vis absorption are below 370 nm. They also display the outstanding thermal stability with the 5% weight loss temperature from 525 °C to 529 °C in nitrogen atmosphere. The glass transition temperatures (T _g s) are higher than 264 °C by DSC. XRD results demonstrate that these PIs are amorphous polymers with the lower water absorption (<0.66%). In summary, the incorporation of tert-butyl groups and multiple phenoxy units into the rigid PI backbones can endow them excellent solubility and transparency with relatively high T _g s.     

Synthesis,Surface Activities and Toluene Solubilization by Amine-oxide Gemini Surfactants

A series of amine-oxide gemini surfactants featuring amide groups [N, N’-dimethyl-N, N’-bis(2-alkylamideethyl)-ethylenediamine oxide (alkyl = C₁₁H₂₃, C₁₃H₂₇, C₁₅H₃₁, C₁₇H₃₅)] have been synthesized via a three-step synthetic route, and their chemical structures were confirmed by mass spectra, FTIR and ¹H-NMR spectra. The surface activities of these compounds have been measured. The results show that these synthesized amine-oxide gemini surfactants reduced the surface tension of water to a minimum value of approximately 26.91 mN m^?1 at a concentration of 2.92 × 10^?5mol L^?1. Furthermore, their critical micelle concentration (CMC) values and solubilization of toluene decrease with an increase of the hydrophobic chain length from 12 to 18. Isoelectric point measurements revealed that their pI values range from 4.0 to 10.5.     

Synthesis and Characterization of pH-Responsive Organic–Inorganic Hybrid Material with Excellent Catalytic Activity

Poly(N-isopropylmethacrylamide-co-methacrylic acid) [p(NipAam-Mac)] microgels were synthesized and used as microreactors to fabricate silver nanoparticles. Pure and hybrid microgels were characterized using Ultraviolet–Visible (UV/Vis) spectroscopy, Fourier transform infra-red (FTIR) spectroscopy and transmission electron microscopy (TEM). Catalytic activity of hybrid microgels and mechanism of catalysis by this system was explored using different reaction conditions. At the same temperature, apparent rate constant (k_app) was found to be varied from 0.0414 to 0.7852 min^?1 by increasing the concentration of NaBH₄ from 2.49 to 22.41 mM at constant concentration of substrate and catalyst. However upon extra increase in concentration of NaBH₄ from 22.41 to 37.35 mM reduced the value of k_app to 0.2178 min^?1. Likewise, the value of k_app was found to be increased from 0.1242 to 0.5495 min^?1 with increasing the concentration of 4-nitrophenol [Para-nitrophenol (p-Np)] from 0.063 to 0.079 mM keeping other parameters constant. Further increase in concentration of p-Np caused decline in the value of k_app. Kinetic data reveals that catalytic reduction of p-Np obeys Langmuir–Hinshelwood mechanism and p-Np is converted to p-Ap on the surface of the silver nanoparticles passing through various reaction intermediates.     

2,6-Bis-benzimidazolylpyridines as new catalyst in copper-based ATRP

The ligands, 2,6-bis(NH-benzimidazol-2-yl)pyridine (L1) and 2,6-bis(N-methyl-benzimidazol-2-yl)pyridine (L2), were synthesized by a one-step reaction of 2,6-pyridinedicarboxylic acid with a diamine (o-phenylenediamine or N-methyl-1,2-phenylenediamine), respectively, in syrupy phosphoric acid at ca. 200 °C. Their efficiency as a catalyst in Cu-based atom transfer radical polymerizations (ATRP) of methylmethacrylate (MMA) was investigated. The linear first-order kinetic plots were observed; indicating that the number of active species is constant during the polymerization and termination reactions are limited. The apparent rate constant values of ATRP of MMA with CuCl/L1 catalyst system at 90 °C in acetonitrile were found to be between 3.83 × 10^?5 and 1.33 × 10^?4 s^?1, while they were between 1.86 × 10^?4 and 4.40 × 10^?4 s^?1 in the case of CuCl/L2 catalyst, indicating the presence of lower radical concentration throughout the polymerization of MMA using CuCl/L1 catalyst system. In both the cases, low apparent rate constant values are obtained. This indicates that ATRP proceeded at reasonable rates and a good control over ATRP in general. Apparent rate constant vs [ligand]/[catalyst] ratio plots showed a maximum at the [ligand]/[catalyst] ratio of two. M _n,GPC values increased slightly linearly with conversion and molecular weight values were closer to M _n,th in the case of ATRP of MMA using CuCl/L2 catalyst complex. Cyclic voltammetry measurements confirmed that CuCl/L1 and CuCl/L2 complexes in acetonitrile give reversible redox couples and copper(I) centers in CuCl/L1 and CuCl/L2 catalyst complexes that are readily oxidized and they potentially suit to facile ATRP.     

Impedance sensor for the early failure diagnosis of organic coatings

A miniature impedance sensor used for field diagnosis of the early failure of coatings has been developed based on microelectronics and electrochemical impedance spectroscopy (EIS). The aging process of polyurethane-based coatings in salt spray test chamber was studied using the impedance sensor. Several critical indexes related to EIS such as phase angle (θ_10Hz, θ_15kHz), breakpoint frequency (f_b), specific capacitance (C_10Hz, C_15kHz), and impedance modulus (Z_0.1Hz) were proposed to evaluate the severity of coating degradation. The results indicated that the impedance sensor could accurately monitor the degradation process of coatings, and once Z_0.1Hz?<?10⁶ Ω cm², f_b?>?100 Hz, or θ_10Hz?<?20°, the coating may be regarded as completely degraded and fails to protect the metal substrate.     

Amorphous polyamide coating resins from sugar-derived monomers

In this article, the synthesis of bio-based polyamides for powder coating applications and their evaluation in a solventborne coating system are reported. The M _n values of the resins were between 3000 and 4000 g mol^?1 and the resins displayed T _g values from 60 to 80°C. Both amine and carboxylic acid functionalities (total ~0.6 mmol g^?1) were introduced for curing purposes. The resins were cured with triglycidyl isocyanurate (TGIC) or N,N,N′,N′-tetrakis(2-hydroxyethyl)adipamide (Primid XL-552). The curing reaction was followed using rheology which indicated that TGIC achieved higher reaction rates and higher gel contents. The DSC analysis of the cured disks showed that all cured samples were amorphous as is desired for the targeted coating application. The resins required a curing temperature higher than 150°C. Aluminum panels were coated using a solventborne approach and the coatings were cured at 180°C during 1 h. Dewetting was observed on all panels. Network formation was adequate for an amine-functional resin cured with TGIC as indicated by solvent resistance testing. In conclusion, the developed bio-based polyamide resins are promising materials to be used as binder resins in powder coating applications.     

Surface Activities of Three Anionic Gemini Surfactants Derived from Cyanuric Chloride: Effect of a Branched Hydrophobic Chain

Sodium 4,6-(2-(N,N-bis-ethylhexylamino)-1,3,5-triazine-4,6-yl-amino) ethane sulfonate (IXC₈), Sodium 4,6-(2-(N,N-bis-octylamino)-1,3,5-Triazine-4,6-yl-amino) ethane sulfonate (XC₈) and 2,2′-(6,6′-(ethane-1,2-diylbis(azanediyl) bis(4-(octylamino)-1,3,5-triazine-6,2-diyl)) bis(azanediyl))diethane sulfonate (C₈-2-C₈) were synthesized from cyanuric chloride. The surface activity and application properties of these surfactants (XC₈, IXC₈ and C₈-2-C₈) were discussed. The values of CMC, γ _CMC, pC₂₀, Γ_max, and A_min calculated from surface tension measurement at 30 °C indicate that the surface activity of IXC₈, which has two branched hydrophobic carbon chains, has lower γ _CMC (26.8 mN m^?1) than the other investigated surfactants and excellent wetting ability.     

Buckypapers of 4,4′-oxydianiline-modified polyvinylchloride and functional nano-filler obtained by resin infusion method

This study provides information on the fabrication and characterization of polyvinylchloride (PVC) buckypaper composite using resin infusion method. PVC modified with 4,4′-oxydianiline (ODA) was infiltrated through buckypapers made of purified multi-walled carbon nanotubes (P-MWCNTs) and functionalized MWCNTs (F-MWCNTs). The increases in P-MWCNT and F-MWCNT contents were investigated on the physical properties of BP-PVC-ODA/PEG (polyethylene glycol)/P-MWCNT and BP-PVC-ODA/PEG/F-MWCNT buckypaper composites. Fourier transform infrared spectroscopy was used for the functional group confirmation which proved the PVC modification and functionality of MWCNTs. The scanning electron micrographs of BP-PVC-ODA/PEG/F-MWCNT showed that intercalation of cross-linked polymer with nanotube produced a polymer-coated F-MWCNT mesh. The maximum degradation temperature (T _max) of functional composite BP-PVC-ODA/PEG/F-MWCNT 0.05 (484 °C) was higher than that of non-functional BP-PVC-ODA/PEG/P-MWCNT 0.05 (473 °C). The glass transition temperature (T _g) of BP-PVC-ODA/PEG/F-MWCNT 0.05 was 225 °C, while BP-PVC-ODA/PEG/F-MWCNT 0.03 yielded a lower T _g of 214 °C. Tensile strength of the functional buckypaper was also found to increase to 37.3 MPa with filler loading. According to X-ray diffraction, the amorphous character of buckypaper showed a trend towards crystal formation with filler loading. P-MWCNT-based buckypaper showed an electrical conductivity up to 4.12 × 10^?1 S/cm; lower than the electrical conductivity of functional buckypaper (1.98 S/cm). The results demonstrated that the resin infusion technique was a successful method to achieve high performance buckypapers compared with F-MWCNTs.     

Thermogravimetric characteristics of <Emphasis Type="Italic">α</Emphasis>-cellulose and decomposition kinetics in a micro-tubing reactor

The pyrolysis characteristics and kinetics of α-cellulose were investigated using thermogravimetric analyzer (TGA) and micro tubing reactor, respectively. Most of the α-cellulose decomposed between 250 and 400 °C at heating rate of 5–20 °C/min. The apparent activation energy was observed in the range of 263.02 kJ mol^?1 to 306.21 kJ mol^?1 at the conversion of 10-80%. The kinetic parameters were determined by nonlinear least-squares regression of the experimental data, assuming first-order kinetics. It was found from the kinetic rate constants that the predominant reaction pathway was A(α-cellulose) to B(bio-oil) rather than A(α-cellulose) to C(gas; C₁-C₄) and/or to B(bio-oil) to C(gas; C₁-C₄) at temperatures of 340-360 °C.