On the compatibility of the IPP/PA6/EPDM blends with and without functionalized IPP I. Thermo-oxidative behaviour

Binary isotactic polypropylene (IPP)/polyamide 6 (PA6) and ternary IPP/PA6/ethylene–propylene diene terpolymer (EPDM) blends in various ratios were obtained in a Haake Rheocord mixer. Processing behaviour was changed in the presence of IPP functionalized with bismaleimide (BMI), maleic anhydride (MA) and acrylic acid (AA) as reactive compatibilizing agents. The thermal and thermo-oxidative behaviour of blends was studied by differential scanning calorimetry and thermogravimetry. The functionalized IPPs modify the crystallinity degree and the decomposition behaviour of both IPP and PA6 as a result of chemical reactions of functional groups with those of the PA6. The changes depend on the IPP/PA6 or IPP/PA6/EPDM ratio, the chemical nature and amount of the functionalized IPP. On the basis of the processing and thermal data one can conclude that the compatibilizing agent effect increases in the following order: IPP-AA 相似文献   

Sodium citrate as an eco-friendly complexing agent for the bioscouring treatment of the cellulosic/lignocellulosic fabrics

A 50% of cotton–50% of flax fabric was subjected to an enzymatic treatment (bioscouring) in ultrasound for removing the compounds which could negatively affect the further specific technological processes as whitening and dyeing. During the scouring process, some parameters of the fabrics are improved. Even EDTA is usually used as a chelating agent in the pretreatments of the fabrics, recent studies aimed to identify new biodegradable complexing agents. In this study, we present the results obtained for bioscouring treatment of the cellulosic/lignocellulosic fabrics in the presence of sodium citrate as a complexing agent. The treatments were made in 0.1 M phosphate buffer of pH 8 and ultrasound media. The samples were immersed in an aliquot containing the commercial pectinolytic product BEISOL PRO, Denimcol Wash-RGN as a surfactant and sodium citrate or EDTA (ethylenediaminetetraacetic acid). The reactions were conducted by varying the enzyme concentration and action time using a central, rotatable second-order compound program. All the parameters determined after bioscouring [weight loss, hydrophilicity, whiteness index, yellowness index, tensile strength, elongation at break, the relative absorbance (A₁₇₃₁) from FT-IR spectra, color strength (K/S) and color difference (ΔE*ab)] of the investigated samples showed in the case of sodium citrate (an eco-friendly biodegradable compound) treatments better or comparable values to treatments conducted using EDTA (non-biodegradable compound).     

Kinetics of thiophene hydrodesulfurization over a supported Mo–Co–Ni catalyst

In this study, the kinetics of thiophene (TH) hydrodesulfurization (HDS) over the Mo–Co–Ni-supported catalyst was investigated. Trimetallic catalyst was synthesized by pore volume impregnation and the metal loadings were 11.5 wt % Mo, 2 wt % Co, and 2 wt % Ni. A large surface area of 243 m²/g and a relatively large pore volume of 0.34 cm³/g for the fresh Mo–Co–Ni-supported catalyst indicate a good accessibility to the catalytic centers for the HDS reaction. The acid strength distribution of the fresh and spent catalysts, as well as for the support, was determined by thermal desorption of diethylamine (DEA) with increase in temperature from 20 to 600 °C. The weak acid centers are obtained within a temperature range between 160 and 300 °C, followed by medium acid sites up to 440 °C. The strong acid centers are revealed above 440 °C. We found a higher content of weak acid centers for fresh and spent catalysts as well as alumina as compared to medium and strong acid sites. The catalyst stability in terms of conversion as a function of time on stream in a fixed bed flow reactor was examined and almost no loss in the catalyst activity was observed. Consequently, this fact demonstrated superior activity of the Mo–Co–Ni-based catalyst for TH HDS. The activity tests by varying the temperature from 200 to 275 °C and pressure from 30 to 60 bar with various space velocities of 1–4 h^?1 were investigated. A Langmuir–Hinshelwood model was used to analyze the kinetic data and to derive activation energy and adsorption parameters for TH HDS. The effect of temperature, pressure, and liquid hourly space velocity on the TH HDS activity was studied.     

Ultrafast nuclear dynamics induced by photodetachment of Ag2- and Ag2O2-: oxygen desorption from a molecular silver surface

Femtosecond nuclear dynamics of mass-selected neutral Ag2 and Ag2O2 clusters are investigated with the 'negative ion-to neutral-to positive ion'(NeNePo) technique. For the bare silver dimer, wave packet dynamics occurring in the neutral electronic ground state and in the first excited triplet state are observed after photodetachment from the anion with 3.05 eV photon energy. While the dynamics in the ground state lead to an oscillatory structure in the NeNePo-pump-probe spectra with a vibrational constant of 185 cm-1, the dynamics in the triplet state are assigned to a bound-free transition leading to dissociation. Photodetachment from the Ag2O2- complex results in the desorption of O2. The experimental data clearly show the influence of the desorbing oxygen ligand on the nuclear dynamics of the silver dimer inducing a red shift in the vibrational frequency and an intensity enhancement of the oscillatory signal.     

HPTLC and GC-MS for Separation and Identification of Eugenol in Plants

JPC – Journal of Planar Chromatography – Modern TLC - Samples of clove, nutmeg, and cinnamon have been extracted by maceration with ethanol for 24 h and with aqueous ethanol 48 h....     

An elementary proof for the majorization principle for Wright-convex functions

We give another elementary proof for the majorization principle for Wright-convex functions. This inequality is due to Ng.     

Synthesis and Characterization of New α,ω-Bis(Maleimide-Ester) Substituted Siloxane Oligomers

Abstract

Organofunctional siloxane oligomers containing maleimide were synthesized by condensation reaction of α. ω-hydroxypropylsiloxane oligomers with n-[4-(chlorocarbonyl)phenyl]maleimide. A model compound [bis(maleimide-ester)disiloxane] was obtained to facilitate the characerization of the oligomers. Then, the heterogeneous catalyzed ring-opening cationic polymerization technique was applied to obtain an oligomer starting from the model compound and octamethylcyclotetrasiloxane.

The structures of the resulting oligomers were confirmed by elemental analysis, IR and ¹H-NMR spectroscopy. They were characterized by determining softening points, solubility and studying their thermal behavior by thermogravimetric (TGA and differential scanning calorimetry (DSC) measurements.     

Polyelectrolyte complex dispersions with a high colloidal stability controlled by the polyion structure and titrant addition rate

Three ionic/nonionic random copolymers of sodium 2-acrylamido-2-methylpropanesulfonate (AMPS) with either t-butyl acrylamide (TBA) or methyl methacrylate (MM), were used in the preparation of some polyelectrolyte complex dispersions (PCD) with two strong polycations of integral type, poly(diallyldimethylammonium chloride) (PDADMAC), and an ionene type polycation, containing 95 mol% N,N-dimethyl-2-hydroxypropyleneammonium chloride repeat units (PCA₅). The novelty of the paper is that PCDs with a high colloidal stability, both before and after the complex stoichiometry, were obtained even with hydrophilic/hydrophobic polyanions, with a high titrant addition rate (TAR), a less explored parameter, which allows a fine control of PCDs aggregation level, in salt-free aqueous solutions. The characteristics of PCDs were also correlated with the polyanion average charge density and the structure of the nonionic comonomer, at a constant TAR, the polyanion with the lowest charge density leading to the highest turbidities and the lowest colloidal stabilities. A mechanism of the PCDs colloidal stabilization as a function of TAR was suggested in the paper.