The ternary system H2O–Fe(NO3)3–Co(NO3)2 isotherms 0 and 15 °C

The solid–liquid equilibria of the ternary system H₂O–Fe(NO₃)₃–Co(NO₃)₂ were studied by using a synthetic method based on conductivity measurements.

Two isotherms were established at 0 and 15 °C, and the stable solid phases which appear are the iron nitrate nonahydrate (Fe(NO₃)₃·9H₂O), the iron nitrate hexahydrate (Fe(NO₃)₃·6H₂O), the cobalt nitrate hexahydrate (Co(NO₃)₂·6H₂O) and the cobalt nitrate trihydrate (Co(NO₃)₂·3H₂O).     

Etude de l’isotherme 25°C du système quasi quaternaire H2O-Zn(NO3)2·6H2O-Cu(NO3)2·3H2O-NH4NO3;I- Isoplèthes 4 masse% NH4NO3, 8 ma

The solid-liquid equilibria of the quasi-quaternary system H₂O-Zn(NO₃)₂·6H₂O-Cu(NO₃)₂·3H₂O-NH₄NO₃ were studied at 25°C by using a synthetic method based on conductivity measurements. Three isoplethic sections has been established at 25°C and the stable solid phases which appear are: NH₄NO₃(IV), Zn(NO₃)₂·6H₂O, anhydrous Cu(NO₃)₂, Cu(NO₃)₂·3H₂O and metastable Cu(NO₃)·2.5H₂O. Neither double salts, nor mixed crystals are observed at these temperatures and composition range.     

Cellulosic nanoparticles from alfa fibers (<Emphasis Type="Italic">Stipa tenacissima)</Emphasis>: extraction procedures and reinforcement potential in polymer nanocomposites

The microstructure and chemical composition of alfa (Stipa tenacissima) were investigated. The polysaccharide and lignin contents were around 70 and 20 wt%, respectively. From the bleached and delignified fibers, two types of nanosized cellulosic particles were extracted, namely cellulose nanocrystals and microfibrillated cellulose (MFC). The former correspond typically to the elementary crystallite units of the cellulose fibers, with a rod-like morphology and an aspect ratio of about 20. The latter, mechanically disintegrated from oxidized bleached fibres, presents an entangled fibrillar structure with widths in the range 5-20 nm. The reinforcing potential of the ensuing nanoparticles was investigated by casting a mixture of acrylic latex and aqueous dispersion of cellulose nanoparticles. Thermo-mechanical analysis revealed a huge enhancement of the stiffness above the glass transition of the matrix. Significant differences in the mechanical reinforcing capability of the nanoparticles were reported.     

Water Activity and Freezing Points in Aqueous Solutions of Manganese Nitrate: Experimental and Modeling

The water activities of manganese nitrate solutions were measured using a humidity sensor instrument up to almost the saturation molality at 298.15 K; the thermodynamic properties of the system were described by the Pitzer model and specific interaction theory (SIT). The evaluation of the ion interaction parameters for the Pitzer model and SIT were carried out using experimental freezing points and osmotic coefficients of manganese nitrate aqueous solutions, collected from the open literature, and the water activity data measured in this work. A set of Pitzer and SIT parameters were estimated using a temperature dependency, that enables us to cover wider temperature ranges, and consequently calculate system properties to higher molalities. Both approaches represent very satisfactorily, and with similar accuracy, the experimental data and the calculated manganese nitrate molal activity coefficients are comparable to those already published for analogous systems. Additionally, the Pitzer model was also able to calculate the ice curve and the solubility branch of manganese nitrate hexahydrate up to a salt solution 6.5 mol·kg^?1.     

Biopolymer electrolytes based on carboxymethyl ҡ-carrageenan and imidazolium ionic liquid

Novel biopolymer electrolytes based on carboxymethyl kappa-carrageenan (CM?-carrageenan) and ionic liquid 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) have been successfully developed. Strong coordination and hydrogen bonding interaction of [Bmim]Cl with the biopolymer were detected by Fourier transform infrared (FTIR) spectroscopy. The efficient function of [Bmim]Cl as the charge carrier in the system was reflected by electrochemical impedance spectroscopy (EIS) where the highest ionic conductivity (σ) of (5.76 ± 0.20) × 10^?3 S cm^?1 was achieved at ambient temperature (298 K) upon 30 wt.% of [Bmim]Cl inclusion. X-ray diffraction (XRD) analysis confirmed that the addition of ionic liquid did not alter the prominent amorphous phase of CM?-carrageenan. Analysis of scanning electron microscopy (SEM) proved the strong interaction of [Bmim]Cl with the biopolymer matrix. The highest conducting biopolymer electrolyte showed an electrochemical stability up to 3.0 V, whereas the transference number measurement revealed that ions are the major elements that contribute to the conductivity with 0.970 ion transference number.     

Investigation of biosourced carboxymethyl cellulose-ionic liquid polymer electrolytes for potential application in electrochemical devices

Biosourced carboxymethyl cellulose polymer electrolytes have been studied for potential application in electrochemical devices. The carboxymethyl cellulose was obtained by reacting cellulose derived from kenaf fibre with monochloroacetic acid. Films of the biosourced polymer electrolytes were prepared by solution-casting technique using ammonium acetate salt and (1-butyl)trimethyl ammonium bis(trifluoromethylsulfonyl)imide ionic liquid as charge carrier contributor and plasticizer, respectively. The shift of peak of carboxyl stretching in the Fourier transform infrared spectra confirmed the interactions between the host biosourced polymer with the ionic liquid. Scanning electron microscopy indicated that the incorporation of ionic liquid changed the morphology of the electrolyte films. The room temperature conductivity determined using impedance spectroscopic technique for the film without ionic liquid was 6.31 × 10^?4 S cm^?1 while the highest conductivity of 2.18 × 10^?3 S cm^?1 was achieved by the film integrated with 20 wt% (1-butyl)trimethylammonium bis(trifluoromethanesulfonyl) imide. This proved that the incorporation of ionic liquid into the salted system improved the conductivity. The improvement in conductivity was due to an increase in ion mobility. The results of linear sweep voltammetry showed that the electrolyte was electrochemically stable up to 3.07 V.     

Design and characterization of cellulose fibers with hierarchical structure for polymer reinforcement

This paper describes an approach to manufacture hierarchical composites from environmentally friendly materials by grafting cellulose whiskers onto regenerated cellulose fibers (Cordenka 700). Fourier Transform Infrared spectroscopy, Scanning Electron Microscopy and X-ray diffraction analysis were performed to verify the degree of modification. The mechanical properties of the unmodified and modified fibers were analyzed using fiber bundle tensile static and loading–unloading tests. To show the effect of cellulose whiskers grafting on the Cordenka fibers, epoxy based composites were manufactured and tensile tests done on transverse uni-directional specimens. The mechanical properties were significantly increased by fiber modification and addition of the nano-phase into composite reinforced with micro-sized fibers.     

Novel Copolymers of Difluoro Ring-substituted 2-Phenyl-1,1-dicyanoethylenes with 4-Fluorostyrene: Synthesis,Structure and Dielectric Study

Copolymerization of fluorine ring-substituted 2-phenyl-1,1-dicyanoethenes, RC₆H₃CH?C(CN)₂ (R is 2,3-F,F, 2,4-F,F, 2,5-F,F, 2,6-F,F, and 4-CF₃) with 4-fluorostyrene were prepared in the presence of a radical initiator (ABCN) at 70°C. The composition of the copolymers was calculated from nitrogen analysis, and the copolymers were characterized by IR, ¹H and ¹³C-NMR, GPC, DSC, and TGA. The monomer reactivity ratios for 4-fluorostyrene (M₁), r₁ = 0.6 and 2-(2,4-difluorophenyl)-1,1-dicyanoethene (M₂), r₂ = 0 were determined from Fineman-Ross plot. The order of relative reactivity (1/r₁) for difluoro-substituted monomers is 2,4-F,F (0.31) > 2,3-F,F (0.25) > 2,5-F,F (0.22) > 2,6-F,F (0.10). DSC curves showed that the copolymers were amorphous with high T _g in comparison with that poly(4-fluorostyrene) indicating a substantial decrease in chain mobility of the copolymer due to the high dipolar character of the trisubstituted ethylene monomer units. From the thermogravimetric analysis, the copolymers began to degrade in the range 214–260°C. The copolymer of 4-fluorostyrene and 2-(2,4-difluorophenyl)-1,1-dicyanoethene and poly(4-fluorostyrene) were dielectrically characterized in the range 25–200°C. The dominating relaxation process detected in both materials was the α-relaxation, associated with the dynamic glass transition. The relationship polarity-permittivity was discussed.     

H2O + Fe(NO3)3 + Ni(NO3)2 ternary system isotherms at 0 °C and 30 °C

H₂O + Ni(NO₃)₂ binary system were investigated in the temperature range from −25 °C to 55 °C. The solid-liquid equilibria of the ternary system H₂O + Fe(NO₃)₃ + Ni(NO₃)₂ were studied using a synthetic method based on conductivity measurements. Tow isotherms were established at 0 °C and 30 °C, and the appearing stable solid phases are iron nitrate nonahydrate (Fe(NO₃)₃·9H₂O), iron nitrate hexahydrate (Fe(NO₃)₃·6H₂O), nickel nitrate hexahydrate (Ni(NO₃)₂·6H₂O) and nickel nitrate tetrahydrate (Ni(NO₃)₂·4H₂O).     

Studies of dielectric relaxation in natural fiber–polymer composites

Polymer composites of a polyester resin matrix filled with short palm tree lignocellulosic fibers were studies by means of dielectric spectroscopy in the frequency range 0, 1–100 kHz and temperature interval from 40 °C to 200 °C. Three relaxations processes were identified, namely the orientation polarization imputed to the presence of polar water molecules in Palm fiber, the relaxation process associated with conductivity occurring as a result of the carriers charges diffusion noted for high temperature above glass transition and low frequencies, and the interfacial relaxation that is attributable to the accumulation of charges at the Palm fibers/polyester interfaces.