Density and Viscosity of the Binary Mixtures Formed by p-Xylene with Methanol,n-Propanol and n-Butanol+

Abstract

Density and viscosity measurements on the binary mixtures of methanol+p-xylene, n-propanol+p-xylene and n-butanol+p-xylene at 303.15, 313.15 and 323.15K are reported The representation of the data by common mixing rules is also studied.     

Some Physical Properties of Binary Liquid Systems: (2-Butanone + n-Propionic Acid or n-Butyric Acid)

Abstract

Density, viscosity and surface tension of two binary liquid systems: 2-butanone + n-propionic acid, 2-butanone + n-butyric acid have been determined at 20, 30 and 40°C, over the whole compositional range. The excess values of molar volume, viscosity, Gibbs free energy for the activation of flow and surface tension were evaluated. These excess values were fitted to a Redlich-Kister type of equation. The Grunberg-Nissan parameter, d, was also calculated. The binary viscosity data were fitted to the models of McAllister, Heric, Auslander and Teja and Rice. Surface tension data were fitted to the models of Zihao and Jufu, Rice and Teja, and an empirical two-constant model proposed in this study.     

Analysis of Excess Molar Volumes of the Ternary Systems Containing a Propyl Alkanoate and Two Alkanes with Some Predictive Methods

Abstract

Excess molar volumes at 298.15 K of the ternary mixtures (propyl ethanoate + n-heptane + n-decane), (propyl propanoate + n-heptane + n-decane) and (propyl butanoate + n-heptane + n-decane) were determined using a DMA 60/602 Anton Paar densimeter. All the experimental values were compared with the results obtained with empirical expressions for estimating ternary properties from binary data and with the Nitta-Chao group-contribution model. For these ternary mixtures the same behaviour that had been observed in ester + n-alkane binary systems was found: excess volumes decrease when the ester length increases.     

Multi-arm Star Polyisobutylenes. V. Characterization of Multi-arm Polyisobutylene Stars by Viscometry,Pour Points,Electron Microscopy,and Ultrasonic Shear Degradation

Abstract

Structure/property relationship of multi-arm star polyisobutylenes [?-(PIB) _n s] were characterized by a variety of techniques, including vis-cometry, pour points, electron microscopy, and ultrasonic degradation. The intrinsic viscosity of ?-(PIB) _n s changes very little with temperature in the 30 to 100°C range, whereas that of linear PIBs of the same molecular weight increases strongly with temperature. Kinematic viscosity measurements of select ?-(PIB) _n s gave viscosity indices in excess of 130. The viscosity of ?-(PIB) _n s is mainly determined by the molecular weight of the arms and much less by the number of arms or overall molecular weights. Electron microscopy of ?-(PIB) _n s indicates a compact spherical morphology, a conclusion that was substantiated by radius of gyration measurements. Pour points of ?-(PIB) _n s are ?27°C. Ultrasonic studies gave insight into the mechanism of shear degradation of ?-(PIB) _n s. These characteristics render ?-(PIB) _n s of interest as rheology control additives for motor oils.     

Effect of alkoxy-chain length proportionation on the mesophase behaviour of terminally di-substituted phenylazo phenyl benzoates

A series of 4-alkoxyphenylazo-4′-phenyl-4′′-alkoxybenzoates bearing two terminal alkoxy groups (I m + n), where m and n denote the number of carbon atoms in the alkoxy groups attached to the phenylazo and benzoate moieties, respectively, was synthesised, and the molecular structures were established via elemental analyses, IR, NMR and mass spectroscopy. First, the thermal transitions and mesophase characteristics of any two isomeric molecules, having the same molecular length but with differently proportionated alkoxy groups, were investigated by differential scanning calorimetry and polarised-light microscopy. All compounds investigated proved to have a wide smectic C and nematic liquid crystalline ranges, except for the lower homologous (I 6 + 8 and I 8 + 6) where they are purely nematogenic. Mesophases were confirmed by the miscibility method, using dodecyloxybenzoic acid as the mesophase reference. Second, the mesophase behaviours of binary mixtures of isomeric compounds, bearing the same total alkoxy-chain length (m + n) but differ in the individual values of m and n, were studied and discussed. It was found that the smectic C and nematic phases behaved ideally in their binary mixture with the 4-alkoxy benzoic acid, independent of either n or m.     

Liquid–Liquid Equilibria of Oxygenate Fuel Additives with Water at 298.15 K: Ternary and Quaternary Aqueous Systems of Diisopropyl Ether and Hydrocarbons with 2-Propanol

Experimental tie-line data were determined for one ternary system, water + diisopropyl ether + n-heptane and two quaternary systems, water + diisopropyl ether + 2-propanol + n-heptane or toluene at 298.15 K and ambient pressure. The experimental liquid–liquid equilibrium data were successfully correlated using a modified UNIQUAC model with ternary and quaternary mixture parameters, in addition to the binary ones. The calculated results were also compared with those obtained from an extended UNIQUAC model of Nagata [Fluid Phase Equilib. 54, 191 (1990)].     

Density and Viscosity of Methanol + Trichloroethylene,n-Propanol + Trichloroethylene and n-Butanol + Trichloroethylene Mixtures

Abstract

Density and Viscosity measurements on the binary mixtures of methanol + trichloro-ethylene, n-propanol + trichloroethylene, and n-butanol + trichloroethylene binary mixtures at 303.15, 313.15 and 323.15K are reported. The representation of the data by simple mixing rules is also studied.     

Preparation of optically active N-bornyl maleimide and poly(N-bornyl maleimide)

Optically active N-bornyl maleimide (NBMI) was prepared with maleie anhydride and d-camphor amine and the polymerizations of N-bornyl maleimide were carried out with benzoyl peroxide (BPO), α,α′-azobisisobutyronitrile (AIBN) and n-butyllithium. The specific rotations of the polymers obtained by BPO, AIBN, and n-BuLi were +5.1 to +8.4, +10.0 to +10.1 and ?7.0 to ?9.0, respectively. The results of the x-ray analysis for the above polymers showed that these polymers had the same structure. The specific rotation of the polymer initiated by BPO increased with increasing intrinsic viscosity. The effect of the polymer endgroup on the specific rotation was discussed.     

Synthesis,characterization, and DNA-binding properties of copper(II), cobalt(II), and nickel(II) complexes with salicylaldehyde 2-phenylquinoline-4-carboylhydrazone

Salicylaldehyde 2-phenylquinoline-4-carboylhydrazone (H₂L), and its novel copper(II), cobalt(II), and nickel(II) complexes MHL · Cl · nH₂O [M=Cu n = 3 (1), M=Co n = 2 (2), M=Ni n = 3.5 (3)] have been synthesized and characterized by elemental analysis, molar conductivity, spectroscopic, and thermal analysis. The interaction of these complexes with calf thymus DNA was investigated by UV absorption spectroscopy, fluorescence spectroscopy, cyclic voltammetry, and viscosity measurements. The results suggest that these complexes bind to DNA via an intercalation binding mode and their affinity to DNA follows the order of 3 > 1> 2. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Einfluß der Polarität und Viskosität des Lösungsmittels auf die Deaktivierung des S1-Zustandes von Donator-Akzeptor-substituiertentrans-Stilbenen

The dependence of the fluorescence constantsk _f ⁿ and the adiabatic twisting constantsk _tpof the S₁-State upon the solvent polarity, the capacity of hydrogen-bonding, as well as the solvent viscosity, were investigated for donor-acceptor substitutedtrans-stilbenes [4-dimethylamino-4-cyano-stilbene (1 g), 4-dimethylamino-4-diphenylphosphinyl-stilbene (1 b), 4-dimethylamino-4-brom-stilbene (1 h) and 4-dimethylamino-4-methoxistilbene (1 k)] by using the multiparameter model. An increase of the solvent polarity results in the decrease of the fluorescence ratek _f ⁿ for all these compounds. The specific interaction between the strongly polar stilbenes such as1 g and1 b and a solvent leads to additional decrease ink _f ⁿ but in the case of a relatively weak polar compound1 k to its growth. The linear combination of universal and specific solvent-solute interactions yields distinct relations fork _tp. Both interactions have an influence onk _tpfor1 g,1 b, and1 k to an equal degree. The twisting observed for1 g and1 b due to the interaction with solvent is hindered, however it is being supported for1 k. The influence of the investigated small range of viscosity onk _tpat simultaneous variable solvent polarity (pure solvent) is only visible for the weak polar1 k. In the other cases the effect of solvent-polarity is predominant.The viscosity dependence ofk _tpwas also experimentally proved for1 g,1 b and1 k by applying the obtained different dimethylformamid-acetonitril mixtures. According previous results the radiationless deactivation process is caused by twisting around ethyl-bonding, thereforek _tpevidently decreases with an increase of viscosity.

     

Viscosities and Densities of Solutions of n-Decane, or n-Tetradecane with Several Esters at 25°C

Viscosity and density data are reported for n-decane + propyl ethanoate, propyl propanoate, propyl butyrate, and n-tetradecane + propyl ethanoate, propyl propanoate, and propyl butyrate at 25°C and atmospheric pressure. Kinematic viscosities were determined using a capillary viscosimeter and densities were measured using vibrating-tube densimetry. The equations of Grunberg–Nissan, McAllister, Auslander, and Teja were fitted to the viscosity data. Excess molar Gibbs free energies of activation for flow were also evaluated. The experimental values obtained for excess volumes were compared with the Nitta et al. group contribution model.     

Copolyesters Containing Polyisobutylene Soft Segments and Polybutylene Terephthalate as the Crystalline Segments

Abstract

The preparation and characterization of multiblock copolymers consisting of polyiso-butylene (PIB) soft segments connected to dimethyl terephthalate (DMT) plus 1,4-butane diol (BD) hard segments (PIB-b-PBT)_n are described. Syntheses involved solution poly-condensation of DMT + BD + hydroxyl ditelechelic PIB (HO-PIB-OH). The overall block composition, and the lengths of the soft segments were varied in the M_n,PIB=1,400–10,000 g/mol range. The presence of PIB in the multiblocks was demonstrated. The solubility in THF and other solvents, and extractability of the polymers with n-hexane were studied. Efforts to determine solution viscosity remained unsuccessful due to the insolubility of the polar and nonpolar segments in a common solvent. Mechanical testing gave unacceptable results, however, the multiblocks showed good thermal stability (up to 367°C in air) and melt processibility appears to be feasible.     

New isothiocyanatotolane liquid crystals with terminal but-3-enyl substitute

Four kinds of new but-3-enyl-based isothiocyanate liquid crystals composed of tolane core and but-3-enyl terminal group (A1–A4) were synthesised via seven step reactions based on 2-(4-bromophenethyl)-1,3-dioxolane, and four n-butyl analogues B1–B4 as comparison structures were also prepared. The mesomorphic properties and physical properties of the compounds were investigated. Single fluorinated compounds A2 and A3 exhibit monotropic nematic phase, and they have lower melting enthalpy and higher clearing points than those of the comparison compounds B2 and B3. The non-fluoro-substituted compound A1 and difluorinated compound A4 exhibit no nematic phase. Replacement of n-butyl chain by but-3-enyl as terminal group is enabled to increase birefringence (Δn ~ 0.394–0.430) and reduce rotational viscosity. These isothiocyanatotolanes with terminal but-3-enyl substitution have potential application for high birefringence mixtures.     

Structurally different cadmium(II) and lead(II) supramolecular polymers with the same benzene-1,2,3,4-tetracarboxylate dianion as bridging ligands from hydrothermal reactions

Two crystalline metal-organic frameworks, [Cd₂(o-BTC)(H₂O)₂] _n (1) and [Pb₂(o-BTC)] _n (2) (o-BTC?=?benzene-1,2,3,4-tetracarboxylic), were synthesized under hydrothermal conditions and characterized by analytical, spectroscopic and single crystal X-ray diffraction studies, which reveal three-dimensional reticular structures via M²⁺ and carboxylate ligands. All carboxyl groups of o-BTC are deprotonated, in agreement with the IR data. The Cd²⁺ centers of 1 have one coordination environment, while Pb²⁺ centers of 2 have two coordination environments. Both 1 and 2 form 3D interpenetrated grid structures along the b and c axes, respectively.     

Polymerization by oxidative coupling. IV.. Synthesis and properties of poly(2-methyl-6-phenylphenylene ether)

Copper-amine catalyst systems which polymerize 2-methyl-6-phenylphenol to high molecular weight polymer are described. With CuCl and N,N,N ′,N′-tetramethyl-1,3-butanediamine (TMBD), an intrinsic viscosity of 1.56 dl/g was obtained. Faster rates of polymerization resulted with a CuBr-TMBD catalyst. Catalysts from other tertiary amines and mixtures of tertiary amines also produced high polymer. Pyridine and diethylamine catalyst were less active. Samples of polymer were isolated at different stages of the polymerization. Measurements of viscosity, osmotic pressure, light scattering, gel permeation, hydroxyl groups, nitrogen content, and chemical reactivity were made on the samples. Below a molecular weight value of M?_n 60,000, M?_n/M?_w was 2.0. At higher molecular weights, there was a broadening in molecular weight distribution. No major change in the molar concentration of the “;head” endgroups with increasing molecular weight was detected by infrared analysis. However, nitrogen analyses, chemical reactivity studies, and the M?_n/M?_w ratio suggested the chemical nature of the “head” end had changed. The relationships between intrinsic viscosity in chloroform at 25°C and M?_n and M?_w for unfractionated polymer samples are log [η] = ?4.26 + 0.84 log M?_n and log [η] = ?3.86 + 0.70 log M?_w.     

Hydrothermal syntheses, crystal structures and luminescent properties of two novel silver (I) complexes with 5-methyl-2-pyrazinecarboxylate

The self-assembly of 5-methylpyrazine-2-carboxylate (Hmpca) with silver nitrate generated two coordination polymers [Ag₂(Hmpca)(mpca)(NO₃)] _n (1) and [Ag(mpca)] _n (2) in the presence of Er³⁺ or Mn²⁺ via hydrothermal synthesis. The complexes have been characterized by IR, elemental analyses and single-crystal X-ray diffraction. Complex 1 possesses a novel 1D looped-chain topology structure. Complex 2 shows an extended honeycomb-like 3D framework. The luminescent properties of complexes 1 and 2 were investigated.     

Peroxide crosslinking of poly(n-alkyl methacrylates)

The action of dicumyl peroxide on poly(n-butyl methacrylate) and poly(n-nonyl methacrylate) produces degradation and crosslinking reactions in both polymers. Crosslinking and degradation of poly(n-alkyl methacrylates) are influenced also by the initial molecular weight of the polymer as well as by the type of alkyl group. The ratio of degradation to crosslinking p/q determined on the basis of the equation of Charlesby and Pinner, S + S^0.5 = (p/q) + (1/qP_n) is for poly(n-butyl methacrylate) of viscosity molecular weight 0.923 × 10⁶ and 2.16 × 10⁶ of 0.78 and 0.60, respectively; for poly(n-nonyl methacrylate) of weight average molecular weight 3.83 × 10⁵, p/q is 0.16. Crosslinking efficiencies (moles of crosslinks per mole of decomposed dicumyl peroxide) of the above polymers are relatively very low: 0.014, 0.005, and 0.039, respectively. The critical concentration of dicumyl peroxide necessary for the formation of gel, provided it undergoes complete decomposition, is for the above polymers 1.82, 1.65, and 0.98 wt.-%, respectively. Under the critical concentration of dicumyl peroxide the limiting viscosity number of poly(n-butyl methacrylate) increases with increasing concentration of dicumyl peroxide. An initial decrease of the value of the limiting viscosity number, which is characteristic for polymers undergoing simultaneous degradation and crosslinking, was not observed.     

Viscosity of Aqueous Solutions of n-butylamine,sec-butylamine and tert-butylamine

Abstract

Viscosities of the systems, water (W) + n-butylamine (NBA), W + sec-butylamine (SBA) and W + tert-butylamine (TBA) have been measured in the temperature range 298.15–323.15K. The viscosities (η) and excess viscosities (η^E) have been plotted against mole fraction of amines (X ₂). On addition of amines to water, viscosities first increase rapidly, then pass through maxima at 0.2 mole fraction of amines and then decline continuously as the addition of amines is continued. η^E show large positive values, with maxima also at 0.2 mole fraction of amines. The maxima of the curves of η and η^E vs. mole fraction of butylamines follow the order, W + TBA > W + SBA > W + NBA. The ascending part of the η vs. X ₂ curves in the water-rich region is explained by the hydrophobic hydration caused by the hydrocarbon tails and the hydrophilic effect due to — NH₂ group of amines. Following the maxima, amine - amine association is preferred, which accounts for the steady decrease of viscosity up to the pure state of amines.     

An Empirical Relation for the Evaluation of the Dielectric Constants of Some Miscible Aqueous-Organic Solvent Mixtures at 298.15 K

Abstract

Dielectric constants of some miscible aqueous-organic solvent mixtures at 25°C have been analyzed by an equation analogous to Tamura and Kurata equation for viscosity. The hydration numbers n_h found out from the plots of Δ? vs. x₂ are explained in terms of H-bonding both in water-rich and alcohol-rich medium.     

Universal Calibration and Molecular Weight Averages in Gel Permeation Chromatography Illustrated by Cellulose Nitrate and Poly(oxypropylene)

Abstract

The nature of the averaging process in the analysis of gel permeation chromatograms was examined for cases where the molecules in the detector cell of the apparatus were of different molecular weight and of the same molecular weight. When the molecules have the same molecular weight, the hydrodynamic volume (1), [?]M, averaged across a chromatogram was found to become KM^a+1 for any molecular weight average at the elution volume corresponding to that average. [η] is intrinsic viscosity, M is molecular weight, and K and a are the appropriate Mark-Houwink constants. Thus when size separation is by molecular weight, the universal GPC calibration functions include KM_n ^a+1 where M_n is the number average molecular weight.

Cellulose nitrate and poly(oxypropylene) were analyzed using three sets of columns and two GPC instruments. KM_n ^a+1, KM_w ^a+1, and [η]M_w were found to represent the hydrodynamic volume since these functions fell on the universal calibration plot for nearly nono-disperse polystyrene standards. The function [η]M_n was displaced from the polystyrene universal calibration plot by factor which equaled M_w/M_n. The slopes and intercepts of the universal calibration plots were found to be completely consistent with the slopes and intercepts of the molecular weight calibration plots showing that the Mark-Houwink constants were correct. Intrinsic viscosity - molecular weight relations were presented for 12.0–12.6%N cellulose nitrate and for low molecular weight poly(oxypropylene), the latter relation being a correction of that of Sholtan and Lie (18).