Low molecular weight liquid rubber (ATBN = amine terminated butadiene acrylonitrile copolymer or CTBN = carboxyl terminated butadiene acrylonitrile copolymer)–DGEBA (diglycidyl ether of bisphenol A) blends indicated upper critical solution temperature (UCST) behavior. The phase separation behavior of the neat and crosslinked rubber (ATBN, CTBN)–epoxy blends was analyzed by a laser light scattering experiment. Lauryl peroxide (LPO) was employed to crosslink the rubber during the initial annealing stage. The onset point of the phase separation in the crosslinked ATBN–epoxy system occurred later than in the case of the neat ATBN–epoxy system. However, the onset point of the phase separation process started earlier in the case of the crosslinked CTBN–epoxy system. The domain correlation length of the crosslinked rubber-added system was smaller than that of the neat rubber-added system. 相似文献
FeN -co-doped TiO2 photocatalysts are prepared by sol–gel method using titanium tetraisopropoxide, urea and iron(II) acetylacetonate as precursors of titania, nitrogen and iron, respectively. The prepared samples are analysed from chemical-physical point of view by X-ray diffraction (XRD), Raman spectroscopy, UV–Vis diffuse reflectance spectroscopy (UV–Vis DRS), specific surface area measurements and scanning electron microscopy (FESEM). UV–Vis DRS spectra evidence that the co-doping of TiO2 with N and Fe leads to the narrowing of the band gap value (2.7 eV) with respect to Fe-doped TiO2 (2.8 eV) and N-doped TiO2 (2.9–3 eV). XRD patterns show that photocatalysts are mainly in anatase phase and Fe and N ions are successfully incorporated into the TiO2 lattice. The average crystallite size of Fe-N co-doped TiO2 is slightly lower than the other samples and equal to about 7 nm and the specific surface area of the co-doped sample results to be 117 m2 g−1. Photocatalytic performances of all prepared samples are evaluated by analysing the degradation of Acid Orange 7 azo dye under visible light irradiation. Photocatalytic efficiency obtained using FeN co-doped TiO2 strongly increases compared to undoped TiO2, N-doped TiO2 and Fe-doped TiO2 photocatalysts. In detail, using the co-doped photocatalyst, dye discoloration and mineralization result equal to about 90 and 83% after 60 min of LEDs visible light irradiation, underlining the best performances of the FeN co-doped TiO2 photocatalyst both in terms of treatment time and electric energy consumption. 相似文献
Optical methods are appropriate tools to detect organic micro-pollutants in fluids. A new technique is introduced which uses the decay of interaction processes like fluorescence and elastically scattered radiation by a fluid. Principally two different parameters are determined:
1. (i) the decay-time of the conventional interaction τC, which occurs at relatively short path-lengths of the incidence beam in the fluid, and
2. (ii) the decay-time τMP of the multi-path-saturation interaction originating at long path-lengths, e.g. in multi-path-reflection cuvettes, where the incidence beam is fully absorbed by the fluid.
A relation between the decay-time and the absorption coefficient of a fluid is theoretically derived. A simple preliminary experiment is performed considering distilled water polluted with non-fluorescent azobenzene and fluorescent quinine-sulphate. A nitrogen laser has been used to generate the fluorescence and scattering signals. The reciprocal value of the difference between the decay-time of the multi-path and conventional signals, 1/(τMP − τC), yields the total absorption coefficient directly. In comparison to the conventional absorption technique the decay-time method is characterized by a higher sensitivity. 相似文献
Mixtures of dioctadecyldimethylammonium chloride (DODAC) cationic vesicle dispersions with aqueous micelle solutions of the anionic sodium cholate (NaC) were investigated by differential scanning calorimetry, DSC, turbidity and light scattering. Within the concentration range investigated (constant 1.0 mM DODAC and varying NaC concentration up to 4 mM), vesicle → micelle → aggregate transitions were observed. The turbidity of DODAC/NaC/water depends on time and NaC/DODAB molar concentration ratio R. At equilibrium, turbidity initially decreases smoothly with R to a low value (owing to the vesicle–micelle transition) when R = 0.5–0.8 and then increases steeply to a high value (owing to the micelle–aggregate transition) when R = 0.9–1.0. DSC thermograms exhibit a single and sharp endothermic peak at Tm ≈ 49 °C, characteristic of the melting temperature of neat DODAC vesicles in water. Upon addition of NaC, Tm initially decreases to vanish around R = 0.5, and the main transition peak broadens as R increases. For R > 1.0 two new (endo- and exothermic) peaks appear at lower temperatures indicating the formation of large aggregates since the dispersion is turbid. All samples are non-birefringent. Dynamic light scattering (DLS) data indicate that both DODAC and DODAC/NaC dispersions are highly polydisperse, and that the mean size of the aggregates tends to decrease as R increases. 相似文献
The synthesis, optical, and electrochemical properties of semi-conducting co-oligomers of biphenyl/oligothiophenes and homo-oligophenylenes derived from a precursor 4-bromo-4′-(n-butyl)-2,2′-biphenyl, which was synthesized by a direct alkylation from 4,4′-dibromo-2,2′-biphenyl using n-butyl lithium, are reported. 相似文献