Viscometric Method Research Articles

Spectroscopic and viscometric studies on the interaction of ionic liquid, 1-butyl-3-methylimidazolium bromide with polyvinyl pyrrolidone

Polyvinyl pyrrolidone, a nontoxic biocompatible polymer, has broad applications in pharmacy, cosmetics, and detergent industry. Although PVP is easily soluble in water, some recent findings indicate that water is not a thermodynamically good solvent for PVP. In this research, interaction of PVP with 1-butyl-3-methylimidazolium bromide ionic liquid was studied via FT-IR, UV–vis and viscometric methods. The flow activation energies were found from the linearization of Arrhenius equation and correlated in terms of polymer concentration. Thermodynamic quality of solvent was investigated using the sign of initial slope of the activation energy versus polymer concentration at zero concentration. For this purpose, viscosity and density of polyvinyl pyrrolidone in aqueous solution of ionic liquid at the temperature range of 288.15–313.15K were measured. Results suggested that the thermodynamic quality of water is increased by addition of 1-butyl-3-methylimidazolium bromide in aqueous solution of polyvinyl pyrrolidone.

Influence of Liquid Paraffin, White Soft Paraffin and Initial Hydration on Viscosity of Corticosteroid Cream

Purpose : To ascertain the influence of paraffin, white soft paraffin and pre-hydrated white soft paraffin on the viscosity of a cream formulated with a corticosteroid. Methods : The formulations were prepared via homogenization with variable velocity in the range 3300 - 4000 rpm. Individual series of preparations contained the same proportion of macrogol cetostearyl alcohol, cetyl alcohol, stearyl alcohol, sorbitan stearate, propylene glycol, metyl parahydroxybenzoate, propyl parahydroxybenzoate and water. The semi-solid preparations were assessed by viscometric and microscopic methods. Results : The viscosity of the samples measured ranged from 13050 to 15660 mPas. The particles in dispersed phase sized from 15 to 90 im. Within the multiple emulsion, the continuous phase included fine particles with diameter < 5 im. Change of the liquid paraffin used from Ondina 934 to Vara 600P significantly decreased the viscosity of the formulation. Several phases within the formulations were distinguished microscopically. Increased viscosity was observed in formulations with increasing proportion of white soft paraffin. Conclusion : Both the ratio of liquid paraffin to white soft paraffin, as well as the initial hydration of white soft paraffin influenced the viscosity of the cream as well as the diameter of particles in the dispersed phase. Keywords : Cream, Ointment, Paraffin, Emulsion, Dispersion, Viscosity, Particle diameter

Miscibility and physical properties of chitosan and silk fibroin mixtures

Miscibility investigations of chitosan (Ch) with silk fibroin (SF) mixtures with different weight percentage compositions (100/0, 80/20, 50/50, 20/80, 0/100) were studied using viscometric method. The viscosity interaction parameter of each polymer in 0.1mol·dm−3 solution as well as the ternary systems (polymer A, polymer B/solvent) has been determined. By comparing the experimental and ideal viscosity data it was clearly seen that the investigated system are miscible at the weight fraction of chitosan in the mixtures wCh≤0.5. Ch, SF and their mixture films were prepared by casting technique. The effect of mixture composition on mechanical and thermal properties was also investigated in this study. The mechanical properties such as ultimate tensile strength, Young modulus and tensile strain at break depend on the weight fraction of chitosan and were changed irregularly. The thermal properties of the film made of Ch/SF mixtures were similar to those of chitosan film.

Extraction and Characterization of Chitin and Chitosan from Parapenaeus longirostris from Moroccan Local Sources

The contents of the exoskeleton of Parapenaeus longirostris from Moroccan local sources were analyzed and the percentages of inorganic salt, protein, lipid, and chitin were determined. Chitin in the α form was extracted from Parapenaeus longirostris shells by 0.25 M HCl and 1 M NaOH treatment for demineralization and deproteinization, respectively. The obtained chitin was converted into the more useful soluble chitosan. The chemical structure and physico-chemical properties of chitin and chitosan were characterized using Fourier transform-infrared (FT-IR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, X-ray diffractometry (XRD), and scanning electron microscopy (SEM). The molecular weight (MW) of chitosan was determined by viscometric methods. The degree of acetylation (DA) of chitin and chitosan was determined by the 1H NMR technique. To the best of our knowledge this is the first report on the extraction and characterization of chitin and chitosan from Parapenaeus longirostris.

Study of the influence of some polymeric additives as viscosity index improvers and pour point depressants – Synthesis and characterization

Abstract Homopolymers of decyl acrylate and isooctyl acrylate and copolymers of each of them with 1-decene were synthesized and characterized by viscosity measurement, thermogravimetric and spectral analysis. Viscometric methods were used to determine the intrinsic viscosity of each of them. Pour point depressant (PPD) and viscosity index improver (VII) properties were tested with additive doped base oil in terms of pour point (PP) and viscosity index (VI), respectively. Although the decyl acrylate polymers were thermally more stable than the isooctyl acrylate polymers, the latter showed higher VI and pour point depression efficiency. VI and PP values of the additive doped base oils depend on the nature of mineral base oils as well as on the type and concentration of VI improvers.

Polyhydroxybutyrate and hydroxyvalerate production by Bacillus megaterium strain A1 isolated from hydrocarbon‐contaminated soil

ABSTRACTIn this study, we attempted to find an alternative microbial resource as a bioplastic producer. Among all of the isolates, the A1 strain produced 44% poly(β‐hydroxybutyrate) (PHB) in proportion to its dry cell weight. The molecular identification of the 16S RNA gene showed that this bacterium was a strain of Bacillus megaterium with the accession number KC579390. The optimization studies led us to the conclusion that the highest poly(β‐hydroxybutyrate‐co‐hydroxyvalerate) (PHBV) production was 78% when 5% molasses was used as the carbon source at pH 6 and 35°C after 60 h of incubation. Attenuated total reflectance Fourier transform infrared (FTIR) spectroscopy and H‐NMR were used for chemical characterization. Differential scanning calorimetry was used to determine the thermal properties of the PHB and PHBV that were synthesized with sucrose and molasses as carbon sources, respectively. The FTIR spectra of the polymers were characterized by typical absorption bands at 1715–1720 cm−1 for amide‐bound CO bands and 1261–1279 cm−1 for an ester‐bound CO band. The molecular weights of PHB and PHBV synthesized with sucrose and molasses were calculated as 428 and 498 kDa, respectively, according to the viscometric method. This study indicated that the B. megaterium strain A1 is an alternative microbial resource as a bioplastic producer. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40530.

Physico-Chemical Studies on the Interaction of Bacterial Polysaccharide- Surfactant Aggregates with Special Reference to their Hydrodynamic Behavior.

Capsular polysaccharides (SPS) are the integral component of gram-negative bacteria, and also have potential uses as vaccines. In this paper, interaction of anionic SPS, isolated from Klebsiella K28, K43, K51 and K20, with cationic surfactants and cationic-nonionic mixed surfactants were investigated by turbidimetric titration, viscometric method. Variation of size and zeta-potential was measured using dynamic light scattering method. Due to binding of the surfactants size enhancement and charge reversal takes place. The interaction between oppositely charged polymer-surfactants are governed by the nature of the charged head group and of the counter ion, charge density and rigidity of the polymer architecture, CMC of the surfactant systems, concentration of surfactant (Cs). The binding is influenced both by electrostatic and hydrophobic interaction.

Cellulose Nanofiber Reinforced Ecofriendly Green PMMA Nanocomposites

Recently, the polymeric composites from renewable resources have attracted great interest. The trend to develop novel eco-friendly green materials from various renewable resources leads to the full or partial replacement of synthetic materials towards a sustainable world also. With a high modulus of elasticity, low density, low production cost and energy consumption, easy processability, renewable nature and recyclability, cellulose nanoparticles have attracted considerable attention as reinforcing filler in polymer matrix composites for exploring new applications. Polymethylmethacrylate (PMMA)/cellulose nanocomposite films were prepared by in-situ polymerization with 10 weight% loading of cellulose nanofibers (CNF) and chemically modified cellulose nanofibers with maleic anhydride (M1CNF) and MMA (M2CNF) respectively to increase their interfacial compatibility with PMMA. The presence of the nanofiller increased the thermal stability of the nanocomposites, as measured by thermogravimetric analysis (TGA) and their glass transition temperature, measured by differential scanning calorimetry (DSC), as well as their average molecular weight measured by viscometric method. Mechanical test results showed that surface treatment of cellulose nanofibers significantly improved the tensile properties of PMMA nanocomposites. Biodegradation study was performed with soil burial method to analyze the effect of cellulose nanofibers on biodegradation.

Chitosan and Carboxymethyl Chitosan from Fish Scales of Labeo rohita

Chitin was extracted from the fish scales of Labeo rohita and chitosan was successfully prepared from it by deacetylation reaction. The prepared chtiosan was characterized by FT-IR spectral analysis and degree of decetylation was determined by pH-metric titration. The molecular weight of chitosan was estimated by viscometric method. Chitosan was converted into its carboxymethyl derivative using alkali and monochloroacetic acid. The prepared carboxymethyl chitosan was characterized by FT-IR spectral analysis and degree of substitution was estimated. Dhaka Univ. J. Sci. 61(1): 145-148, 2013 (January) DOI: http://dx.doi.org/10.3329/dujs.v61i1.15116

Probing solute–solute and solute–solvent interactions in (l-arginine + d-xylose/l-arabinose + water) solutions at different temperatures by using volumetric and viscometric methods

Densities, ρ of l-arginine in water and in aqueous–d-xylose/l-arabinose (2.5% and 5% of d-xylose/l-arabinose, w/w in water) mixed solvents were measured at temperatures (293.15, 298.15, 303.15, 308.15, 313.15 and 318.15)K, and viscosities, η of these solutions at temperatures (298.15, 303.15, 308.15, 313.15 and 318.15)K were measured at atmospheric pressure. From the density values, the apparent molar volume, Vϕ, limiting apparent molar volume, Vϕ°, slope, Sv and transfer volume, Vϕ,tr° and hydration number, nH were calculated. The viscosity values have been analysed on the basis of the Jones–Dole equation; and Falkenhagen Coefficient, A and Jones–Dole coefficient, B were calculated. The Gibbs energies of activation of viscous flow per mole of solvent, Δμ1°# and per mole of solute, Δμ2°# were also calculated. The results indicate that there exist strong solute–solvent interactions in these systems, which increase with increase in carbohydrate concentration in both the solvents. It is observed that l-arginine act as a structure-maker in both these solvent systems.

Polyurethane adhesive composition cured at room temperature

The influence of polyfunctional hydroxyl-containing oligomer on the rheological, physicomechanical, and adhesive properties of polyurethane composite based on multicomponent oligomer blend and polyisocyanate is investigated. The kinetics of curing is investigated by the viscometric method, and the composition lifetime is determined. It is shown that the polyurethanes under investigation can be used as fast-curing adhesive composites of cold curing operating in a temperature interval of up to +90°C.

Nickel(II) complexes with Schiff bases derived from 2-acetylpyrazine and tryptophan: synthesis, crystal structures and DNA interactions

A pair of stereoisomers of nickel Schiff base complexes, namely [Ni(C17H15N4O2)2·2CH3OH]n (1) (C17H15N4O2 = 2-acetylpyrazine-l-tryptophan) and [Ni(C17H15N4O2)2·2CH3OH]n (2) (C17H15N4O2 = 2-acetylpyrazine-d-tryptophan), were synthesized and characterized by physico-chemical and spectroscopic methods. The X-ray diffraction single-crystal analyses indicate that the structure of 2 is essentially 0D monomeric, while a 2D layer structure is formed through N–H…O intermolecular hydrogen bonds for 1. The interactions between complex 1 and calf thymus DNA were investigated by spectroscopic and viscometric methods. The results indicate that complex 1 interacts with DNA very strongly (K b = 1.01 × 107 mol−1 L and K sq = 1.11). The nature of the binding seems to be mainly an electrostatic interaction between DNA and the complex. However, other binding modes, such as hydrogen bonding, may also be present in this system.

Synthesis, Characterization, and Performance Evaluation of Some Multifunctional Lube Oil Additives

Eight polymers (two homopolymers and six copolymers with 1-decene) of isodecyl acrylate and isooctyl acrylate were synthesized using benzoyl peroxide as initiator and characterized by spectral analysis, viscometric, and thermogravimetric measurements. Intrinsic viscosity obtained from the viscometric method was used to determine the viscometric molecular weight of the polymers. Pour point (PP) and viscosity index (VI) of the additive-doped base oils were evaluated to check the efficiency of the polymers as pour point depressant (PPD) and viscosity index improver (VII), respectively. Analysis of different properties indicates that the isooctyl acrylate polymers have better lube oil additive property than that of isodecyl acrylate polymers. VI and PP values of the polymers doped in base oils depend on the nature of mineral base oils, polymer type, and also on the concentration of the additives.

Study of solute–solute and solute–solvent interactions of l-threonine in aqueous-glucose solutions at different temperatures by using volumetric and viscometric methods

Densities, ρ of solutions of l-threonine in water and in aqueous-glucose solvents (5, 10, 15 and 20% of glucose, w/w in water) at T=(293.15, 298.15, 303.15, 308.15, 313.15 and 318.15)K and viscosities, η of these solutions at (298.15, 303.15, 308.15, 313.15 and 318.15)K were measured at atmospheric pressure. From these experimental results, the apparent molar volume, Vϕ, limiting apparent molar volume, Vϕ∘ and the slope, Sv, transfer volume, Vϕ,tr∘, Falkenhagen coefficient, A, Jones–Dole coefficient, B, temperature derivative of B-coefficients, dB/dT, Gibbs free energies of activation of viscous flow per mole of solvent, Δμ1∘# and per mole of solute, Δμ2∘# and hydration number, Hn were calculated. The results are interpreted in terms of solute–solvent and solute–solute interactions in these systems. It has been observed that there exist strong solute–solvent interactions in these systems, which increase with increase in glucose concentration. It is also observed that l-threonine acts as structure-breaker in these aqueous-glucose solvents. The thermodynamics of viscous flow are also discussed.

Investigating the miscibility of polystyrene/poly(styrene-co-acrylonitrile) blend in tetrahydrofuran by simple physical techniques at various temperatures

The miscibility of polystyrene and poly(styrene-co-acrylonitrile) blend in tetrahydrofuran was investigated by viscometric, density, and refractometric methods over an extended range of concentration, composition, and temperature. The miscibility of the polymer blend was investigated on the basis of the sign of the interaction parameters α, β, μ, ΔB, and Δ[η]m. The results from the viscosity method were correlated with the miscibility data obtained for the same blend by refractive index and density methods. These investigations indicated that the examined blend was immiscible over the investigated composition and temperature range.

Evaluation of DNA-binding, radical scavenging and cytotoxic activity of five coordinated Cd(ii) complexes containing 2-acetylpyridine-N4-substituted thiosemicarbazone

A series of new five coordinated Cd(II) complexes of the type [Cd(Ln)Cl2] (n = 1–3) have been isolated and characterized using analytical, spectral and structural methods. The single crystal X-ray structure of one of the complexes [Cd(L2)Cl2] (2) has been determined and a distorted square pyramidal geometry has been found, in which Cd(II) is coordinated with two nitrogens, one sulfur and two chlorine atoms. The interactions of the complexes with calf thymus DNA (CT-DNA) have been explored by absorption, competitive, thermal denaturation and viscometric methods, which revealed that the compounds could interact with CT-DNA through groove binding. Investigation of the antioxidant properties showed that the Cd(II) complexes have a strong radical scavenging tendency against DPPH˙, OH˙ and NO˙ radicals. Further, the cytotoxic effect of the compounds examined on a human breast cancer cell line (MCF-7) showed that the complexes exhibited substantial cytotoxic activity.

Role of critical concentration of PEI in NMP solutions on gas permeation characteristics of PEI gas separation membranes

In preparation of polymeric gas separation membranes by phase inversion method, polymer concentration is one of the most important variables which can change membrane morphology and behavior. In this research, critical concentration of the polyetherimide (PEI) solutions in N-methyl-2-pyrrolidone (NMP) as a solvent was determined by viscometric method. The influence of temperature on critical concentration was studied. Three asymmetric PDMS/PEI membranes with different concentrations of PEI were prepared and characterized for H2/CH4 separation. The results showed that the membranes with higher concentrations than critical concentration were more suitable for gas separation. In addition, the viscosity data were fitted by appropriate equations and the densities were satisfactorily correlated by a simple first-order polynomial with respect to temperature and the PEI mass fraction. The prepared membrane showed the selectivity of 26 for H2/CH4 separation at 1bar and 25°C for pure gas and 24.8 for mixed gas. The influence of the pressure on the H2 and CH4 permeance and the selectivity for a mixed binary gas showed that the permeance of both gases declined by pressure enhancement and the selectivity increased.

Molecular Weight Determination and Correlation Analysis of Dalbergia sissoo Polysaccharide with Constituent Oligosaccharides

Mucilaginous polysaccharide extracted from Dalbergia sissoo Roxb. leaves has a number of medicinal applications. Molecular weight studies and correlation analysis of the structure of polysaccharide with oligosaccharides can be helpful for further utilisation, modification and structure-activity relationship for biological applications. To determine molecular weight of medicinally important polysaccharide. To establish an unequivocal correlation of the polysaccharide monosugars with constituting oligosaccharides and glucuronic acid content based on gas-liquid chromatography (GLC) with the spectrophotometric method. Complete and partial hydrolytic studies of pure polysaccharide yielded constituting monosugars and oligosaccharides. The ratio of sugars in polysaccharide and oligosaccharides was studied by preparation of alditol acetates and analysed using GLC. The uronic acid content was studied by GLC analysis and spectrophotometry. Molecular weight of the polysaccharide was determined using the viscometric method. Dalbergia sissoo leaves yielded 14.0% pure polysaccharide, containing 15.7% of glucuronic acid. Complete hydrolysis and GLC analysis of alditol acetate derivatives of reduced and unreduced monosugars indicated the presence of L-rhamnose, D-glucuronic acid, D-galactose and D-glucose in 1.00:1.00:2.00:2.33 molar ratios. Partial hydrolysis followed by monosugar analysis of oligosaccharides established the monosugar ratio in complete agreement with polysaccharide, thereby corroborating the sugar ratio. Similar uronic acid content was obtained by GLC and spectrophotometry. The polysaccharide had an average molecular weight of 1.5 × 10⁵ Da. The study has established an obvious correlation of the structure of polysaccharide with oligosaccharides, leading to unambiguous identification of monosaccharides, which normally is not studied conclusively while reporting the polysaccharide structure. The molecular weight of the polysaccharide was determined.

Solvodynamic Properties of Sodium Polystyrenesulfo‐nate in Methanol‐Water Mixed Solvent Media in Absence and in the Presence of a Salt Using Viscometric Method

AbstractLinear extrapolation of the reduced viscosity values of uncharged polymer solutions as the concentration approaches zero constitutes the basis for the traditional method for the determination of the intrinsic viscosities of polymer solutions. While this method works well for uncharged polymer solutions, it fails completely for polyelectrolyte solutions especially in absence and also in presence of small amount of an added electrolyte. A very convenient method has recently been proposed by Wolf (Wolf, Macromol. Rapid Commun. 2007, 28, 164) to determine the intrinsic viscosities of polyelectrolyte solutions on the basis of the laws of phenomenological thermodynamics applied to the viscosity of polymer solutions. In spite of the success and the convenience of this method, this has so far been applied to a limited number of polyelectrolyte systems by the Wolf group alone (Wolf, Macromol. Rapid Commun. 2007, 28, 164; Eckelt et al., Macromolecules 2008, 41, 912; Badiger et al., Macromol. Chem. Phys. 2008, 209, 2087; Ghimici et al., J. Phys. Chem.B. 2009, 113, 8020). In order to improve the situation, we have measured the viscosities of an anionic polyelectrolyte, sodium polystyrenesulfonate, in methanol‐water mixed solvent media both in absence and in the presence of an electrolyte, sodium chloride. The results show that the experimental data fit well with the Wolf model and thus allow the calculation of intrinsic viscosities, which provide important insight about the dependence of the polyion conformation on solvent composition as well as on the concentration of the added electrolyte. This new evaluation method, thus, proves to be very useful to a better understanding of the rheological behaviour of the polyelectrolyte system investigated.

Physicochemical Study of Bile Salt-Polymer Micellar Aggregates

Abstract The micellar behavior of Sodium Deoxycholate (NaDC), a bile salt in presence of a neutral water soluble polymer Poly(vinylpyrrolidone) (PVP) has been investigated at four different temperatures (10–40 ºC) using conductometric, tensiometric, viscometric and fluorometric methods. NaDC is found to associate co-operatively with the polymer beyond a critical concentration, saturate the polymer completely and then undergo micellization at a higher concentration. The counter-ion binding capacity to the micelles is considerably reduced in presence of PVP. The thermodynamic properties of micellization and interfacial adsorption depend on the polymer concentration and the entropic contributions are observed to control the complexation process. The NaDC-PVP aggregate exhibits polyelectrolytic behavior. The aggregation number (N) and polarity index (I1/I3) of the NaDC-PVP mixed entities have been explored by pyrene fluorescence probing technique. The values of N and I1/I3 are found to be affected by [PVP] and temperature: the N values decrease with temperature while those of I1/I3 show increasing trend. The dependence of N and I1/I3 values on [PVP] and temperature reveal interesting insights into the NaDC-PVP complexation phenomenon.