Capillary Viscometry Research Articles

Topological structure and antioxidant properties of macromolecules of lignin of hogweed Heracleum sosnowskyi Manden

This article presents the study of topological and chemical structure of lignin macromolecules isolated from stems of hogweed Heracleum sosnowskyi Manden. The chemical structure was characterized by 13C and 2D NMR-spectroscopy, chemical analysis and pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS). The methods of sedimentation-diffusion analysis and capillary viscometry were used to study the hydrodynamic properties of macromolecules in solutions and to reveal the features of the topological structure. The molecular mass of the fractions, the macromolecular radii and the hydrodynamic invariants were determined. The analysis of the scaling dependences within the framework of Mark-Kuhn-Houwink equation was performed. The obtained results showed that the behavior of hogweed lignin macromolecules corresponded to high-molecular weight compounds with chaotically branched topological structure. It was determined that the hogweed lignin had high antioxidant activity comparable to that of recognized antioxidants. The sorption properties of several lignins were studied and the significant adsorption capacity to T-2 mycotoxin and naturally occurring long-lived thorium radionuclide (Th232) was determined.

Apparent molal volumes and hydration numbers from viscosity studies for microemulsions with a nonionic surfactant derived from castor oil and a series of polar oils

The cloud point of a nonionic surfactant is related to the hydration of its polar shell. Viscosity data can be used to determine the total amount of water associated with micelles. The aim of this study was to apply this model to a more complex system comprising a series of oil-in-water microemulsions. These consisted of the nonionic surfactant, Kolliphor® RH 40, with and without polar oils. The oils used were isopropyl myristate (IPM), neopentyl glycol diethylhexanoate (NGDO), diisopropyl sebacate (DIS) and diisopropyl adipate (DIA) while the alcoholic solvents ethanol, 2-propanol and diethylene glycol monoethyl ether (DEG) were the co-surfactants. The apparent molal volumes were determined from the densities using a pycnometric method while the viscosities were measured using capillary viscometry. The partial excess volumes with IPM ranked as DEG>2-propanol>ethanol while the excess volumes varied as IPM>NGDO>DIS>DIA. These results were most likely related to the effect of the co-surfactant on the size and curvature of the micellar pseudophase and to the site of oil solubilization, respectively. The presence of oil induced increases in the intrinsic viscosities, the Huggins constants and the hydration numbers. The magnitudes of the latter two parameters were in excellent agreement with the values reported for micelles of nonionic surfactants. With DIS, the changes in the hydration numbers showed a good relationship with the excess volumes. Therefore, meaningful hydration values for microemulsions may be obtained with polar oils which are solubilized in the palisade layer rather than in the core as occurs with hydrophobic oils.

Competitive Surface Activity of Monoclonal Antibodies and Nonionic Surfactants at the Air-Water Interface Determined by Interfacial Rheology and Neutron Reflectometry.

Interfacial stresses can destabilize therapeutic formulations containing monoclonal antibodies (mAbs), which is proposed to be a result of adsorption and aggregation at the air-water interface. To increase protein stability, pharmaceutical industries add surfactants, such as Polysorbate 20 (PS20), into protein formulations to minimize mAb adsorption at the interface but rarely quantify this process. We determine that mAb adsorption in surfactant-free solutions creates a monolayer with significant viscoelasticity, which can influence measurements of bulk mAb solution viscosity. In contrast, PS20 absorption leads to an interface with negligible interfacial viscosity that protects the air-water interface from mAb adsorption. These studies were performed through a combined study of surface tensiometry, interfacial rheology, capillary viscometry, and neutron reflectometry to determine the surface activity of a model surfactant, PS20, and mAb system, which can be useful for the successful formulation developments of biotherapeutics.

Molar mass determination of microwave initiated polycondensation produced PLLA by capillary viscometry method

The microwave initiated polycondensation is a new approach for polylactic acid production. The time need of this process is quite less compared to the standard polycondensation process, but the progress and improvement of the molar mass is the most important basic factor.In my earlier work the standard polycondensation has already been investigated, so to be able to compare both methods PLLA has been produced by microwave initiated polycondensation too. The measurement of molar weights is a crucial point of polymer synthesis. According to my earlier work a rheology-based method was used again to define the molar masses during the polymerization process and make the comparison reliable.During my experiments PLLA has been synthesized by microwave initiated polycondensation method. According to the relevant literature, by standard polycondensation 104-105 g·mol−1 molar mass can be reached, so the main question was that how long should be the microwave process run to result the same level of molar mass. During the experiments PLLA samples have been taken according to a special time plan, then solved in chloroform prepared samples with different concentrations for further analysis. To measure the flow-times Ubbelohde capillary viscometer was applied at this time too. Based on the data of viscometry measurements the intrinsic viscosities have been graphically defined then the molar masses of polylactic acid polymers were calculated according to the correlation of Mark – Houwink relation.

Molar mass determination of polylactic acid alternatives by capillary viscometry method

The molar mass of polymers is a basic property that defines the appropriate processing method and the field of application of polymers. Therefore, the measurement of molar weights is a crucial point of polymer synthesis. In absence of modern but expensive equipment a rheology-based method can be used to define the molar mass with reliable result. By evaluation of molar mass, the entire polymerization can be monitored and controlled.During my experiments polylactic acid alternatives (PLLA, PDLA, PDLLA) have been synthesized by direct polycondensation methods. According to the relevant literature, by this method and with the adequate setup of its parameters 104-105 g·mol−1 molar mass can be reached. The two most important parameters are the process time and temperature that strongly effects on the value of molar mass of polymer. In this work standard polycondensation method has been used to produce the mentioned polylactic acid alternatives then the molar masses of polylactic acid polymers were calculated by followed the correlation of Mark – Houwink relation.

DETERMINACIÓN DE LA CONCENTRACIÓN DE QUITOSANO EN POLVO POR VISCOSIMETRÍA CAPILAR

El objetivo de este trabajo ha sido desarrollar un procedimiento para la determinación de la concentración de quitosano en muestras en polvo, por viscosimetría capilar de Ostwald (capilar de 0,55 ± 0,02 mm de diámetro interno). Se prepararon soluciones de quitosano patrón entre 461 mg/litro hasta 9138 mg/litro y pH 1,24 para todos los casos. Se realizaron también ensayos a temperaturas entre 20° a 50°C observándose linealidad con la concentración hasta antes de 9138,36 mg/litro. La dependencia más importante fue la de viscosidad relativa (ηr) frente a la concentración (concordante con la ecuación de Poiseuille) que en el rango de 461 mg/litro a 2808 mg/litro dio una dependencia lineal con r2=0,995, posibilitando el análisis de muestras para el contenido de quitosano con resultados consistentes y equiparables con los referenciales.

Features of structure and properties of hemp cellulose nitrates

Comprehensive studies of the structural, molecular and physico-chemical properties of cellulose nitrates from hemp fiber were carried out using modern research methods: capillary viscometry, IR Fourier spectroscopy, X-ray diffraction, gel permeation chromatography. The results of the study revealed features of the influence of inter- and intramolecular interactions in cellulose macromolecules from various types of fiber, the degree of crystallinity of the initial material, and the degree of polydispersity on the formation of qualitative characteristics of hemp cellulose nitrates.

Thermal gelation of partially hydrolysed polyacrylamide/polyethylenimine mixtures using design of experiments approach

Polyethylenimine crosslinked polymer gels are gaining a huge interest in conformance control applications in oilfields. They are used to reduce the production of undesirable fluids (water & gas) by blocking the fractures that connect injection and production wells. In this paper, a statistical analysis on the thermal gelation of well characterized reactants namely partially hydrolysed polyacrylamide (PHPA) (Mw = 5.1 million Daltons and hydrolysis degree = 6%) and polyethylenimine (PEI) (Mw = 19.2 kilo Daltons and branching degree = 59%), was conducted using response surface methodology (RSM). A four factor doehlert matrix was employed in designing the experiments and evaluating the gelation time as function of salinity (0–8 g/L NaCl), polymer (PHPA) and crosslinker (PEI) concentrations, temperature (70 °C–90 °C) and their corresponding combinations. As a result, the gelation time was found to strongly vary with salinity, temperature and PHPA concentration following a nonlinear mathematical model. The analysis of variance (ANOVA) of this model revealed its significance in a 95% confidence level against experimental data. In a second part, an experimental investigation was carried out to understand the interaction between PHPA and PEI. To do so, the viscosity variations of analogue mixtures prepared with low molecular weight (Mw) polymers, such as polyacrylamide (PAM) and polyacrylic acid (PAA), were monitored using capillary viscometry at different conditions of temperature, pH and reaction time. The PAM/PEI mixtures showed a remarkable viscosity increase at typical pH of around 10 when cured at 80 °C. While, the PAA/PEI mixtures underwent precipitation at pH of around 6 revealing the strong interaction between PAA and PEI at this condition.

Модификация полимерных смесей с сополимерами для получения полимерных композиций с улучшенными деформационно-прочностными характеристиками

Утилизация многослойных полимерных материалов затруднена, из-за сложности в процессах сортировки и разделения смешанных отходов, поэтому чаще всего они попадают на свалки, полигоны или сжигаются, что приводит к экологической и экономической проблеме в стране. В настоящее время существуют способы переработки отходов упаковки с исключением стадии сортировки при помощи химико-физической модификации. Статья посвящена проведению процесса модификации полиолефиновых смесей на основе полиэтилена и полипропилена, а также проведению комплексного исследования полученного вторичного сырья, которое направлено на увеличение технологической совместимости полимерных материалов для разработки технологии рециклинга с перспективой возврата полимерных композиций в производственный цикл. В работе были поставлены следующие задачи: провести комплексное исследование полимерных композиций на основе полиолефинов, которые модифицированы сополимером этилена с пропиленом в различном соотношении компонентов; изучить влияние модификатора на физико-механические свойства полимерных смесей; изучить влияние реологических свойств полимерных композиций, модифицированных сополимером; предложить технологию повторной переработки вторичных полиолефиновых композиций в производственный цикл. В качестве объектов исследования использовали полиэтилен, полипропилен и сополимер этилена с пропиленом, как связующее звено, в разном соотношении компонентов. Образцы получали на лабораторном одношнековом экструдере при многократной переработке. Научные исследования проведены с использованием метода капиллярной вискозиметрии, пикнометрического метода для определения реологических свойств, метода одноосного растяжения для изучения физико-механических свойств полимерных композиций. Установлено, что введение модификатора (сополимер этилена с пропиленом) приводит к увеличению относительного удлинения при разрыве у полимерных композиций в соотношении 70% полиэтилена 30% полипропилена и разрушающее напряжение для композиций на основе полиэтилена и полипропилена в соотношении 50:50 и 30:70 соответственно. В результате проведенных исследований предложена технология получения многослойных упаковочных материалов с использованием отходов упаковки в среднем слое для контакта с пищевыми продуктами; предложена технология переработки полиолефиновых смесей различной химической природы без предварительной сортировки, с получением упаковки технического назначения и предметов бытового использования.

Development of dose-response functions for historic paper degradation using exposure to natural conditions and multivariate regression

Many collections of documents, manuscripts, and works of art on paper are prone to degradation due to a complex interplay of extrinsic and intrinsic factors. The aim of this study was to examine the simultaneous effect of multiple degradation agents on selected non-model types of paper in natural environments, and the relative effect of environmental parameters (heat, humidity, light and pollution) compared to material parameters (pH, fibre composition and presence of additives). An exposure experiment was set up to investigate visual and chemical changes of 12 different types of paper in real time in different environmental conditions over a 1.5-year period at 11 sites across Europe and North Africa, sheltered from UV light and precipitation. Suitable environmental monitoring equipment, such as data loggers and gas samplers, and analytical methods to characterise sample degradation, specifically spectrocolorimetry and capillary viscometry, were used to estimate alterations in visual appearance and degree of cellulose polymerisation, which are the most important properties of paper in the heritage context. Multiple linear regression and principal component regression were used to interpret the large volume of data and calculate a set of dose-response functions. The results of this study not only suggested that most of the considered variables are of significance in relation to changes in colour and in average molecular weight, but also revealed a number of meaningful interactions between these variables. Based on the assessment of the relative contributions of environmental and material-related variables to the natural ageing processes of paper, the dose-response functions proposed in this study enable prioritisation of degradation factors in environmental management of paper-based collections and in historic paper degradation studies; however, further work is required to increase accuracy and understanding of the chemistry of degradation.

Amphiphilic polysaccharide based on curdlan: Synthesis and behaviour in aqueous solution

Amphiphilic polyelectrolyte based on curdlan derivative containing quaternary ammonium groups with a degree of substitution up to 0.4 was synthesized and characterized. The chemical structure of the amphiphilic curdlan derivative was confirmed by FTIR, 13C and 1H NMR spectroscopy. The 2D NMR homo- and heteronuclear correlations were used to attribute the ambiguous 1D NMR signals from 1H and 13C spectra. The hydrodynamic properties of this new derivative were studied by capillary viscometry. The non-linear Wolf equation was used to determine the intrinsic viscosity and the scaling theory was used to delimitate the concentration domains. The self-aggregation of the amphiphilic derivative was studied by fluorescence spectroscopy using pyrene and N-phenylnaphthylamine as micropolarity sensitive probes, and by surface tension measurements.The results obtained from the antibacterial and antifungal tests performed on E. coli, P. aeruginosa bacteria, and C. albicans fungi recommend this new amphiphilic derivative to be used either as a soluble biopolymer or as a precursor for the preparation of new biomaterials with antimicrobial properties.

Разработка многослойного упаковочного материала на основе полиолефиновых смесей, модифицированных сополимером этилена с пропиленом, для хранения пищевых продуктов

The research features a comprehensive study aimed at increasing the technological compatibility of multilayer packaging materials. The paper describes a recycling technology with the prospect of returning the resulting secondary raw materials to the production cycle. The research included the following tasks: to conduct a comprehensive study of polyolefin mixtures modified by ethylene propylene copolymer; to study the effect of the copolymer on the rheological and physicomechanical properties of polymer compositions; to propose a technology for the recycling of secondary polyolefin mixtures. The research involved the following methods: the capillary viscometry method was used to determine the rheological properties of polymer compositions; the tensile test method was employed to define the physicomechanical properties of the compositions; the pycnometric method was used to assess the density of the mixtures. The study featured such polymers as polyethylene, polypropylene, and ethylene-propylene copolymer, which was chosen as a link between the polymers. The authors obtained polymer compositions in various ratios of polyethylene, polypropylene, and ethylene-propylene copolymer: 70:30:0; 68.5:28.5:3; 65:25:10; 30:70:0; 28.5: 68.5: 3; 25:65:10. The article describes the process of modifying polyolefin compositions based on polyethylene and polypropylene by ethylene-propylene copolymer on a single-screw extruder. The authors defined the rheological properties and the deformation-strength characteristics of the polymer mixtures. Repeated processing proved to lead to a decrease in the physicomechanical properties of polyolefin mixtures, with the exception of compositions based on polyethylene and polypropylene in the ratio of 30:70, where the breaking stress increased. The number of processing cycles increased the melt flow rate of the mixtures. The proposed technology is meant for producing multilayer packaging materials using packaging waste in the middle layer for contact with food.

Тhe Viscosity Study of Naftifine Hydrochloride Solution with a Combination of Polyethylene Glycols

Introduction. Naftifin hydrochloride is an antifungal drug from the allylamine group, which is used as a drug for external use in the treatment of onychomycosis. Quickly penetrates the skin and nails. It has antifungal, antibacterial and anti-inflammatory effects. It has a wide range of actions against many fungi that cause onychomycosis (dermatophytes, molds and yeast). In addition, it has an antibacterial effect in the ratio of gram-positive and gram-negative bacteria, reduces the risk of complicated course of the disease. It has a pronounced anti-inflammatory effect. Polyethylene glycols belong to the class of organic polymers of ethylene glycol. Polyethylene glycols are safe and widely used in pharmaceutical production, due to the variety of applications. The object of the study is a number of solutions of naftifin hydrochloride in different combinations and with different ratios of polyethylene glycols.Aim. The purpose of the work is to choose the optimal composition of the solution of naftifin hydrochloride. Achieve due to the viscosity of the prolonging action of the solution. Depending on the molecular weight of polyethylene glycol to determine the flow time of solutions. Choose among a number of samples with different ratios of polyethylene glycols, a solution with maximum viscosity.Materials and methods. To determine the viscosity of this solution, a capillary viscometry method was used on the vpzh-2 apparatus. «Exoderil» solution was chosen as a reference formulation.Results and discussion. Alternating different combinations of polyethylene glycol, we have increased the viscosity of the fluid naftifine hydrochloride, which has achieved a more accurate method of application of medicinal substances. During the study, it was determined that the solution «Exoderil» has a minimum viscosity, compared with all samples of the studied solutions.Сonclusion. The optimal viscosity of the solution of naftifin hydrochloride provides a prolonged action of the drug, due to a longer stay on the nail plate. Viscosity allows for more accurate application to the damaged nail, and reduces the loss of concentration of the active substance. Moisturizing properties of polyethylene glycols will help to reduce the severity of side effects (dryness, rarefaction), and provide a longer and more comfortable treatment of onychomycosis.

Chain conformation of xanthan in solution as influenced by temperature and salt addition

The capillary viscometry and Fourier transform infrared spectroscopy in attenuated total reflection (ATR-FTIR) were used to investigate the conformation of xanthan gum (XG) chains in aqueous solutions, in the absence/presence of NaCl and in the temperature range from 25 to 90 °C. The content of acetate and pyruvate groups per side of XG was determined by 1H NMR spectroscopy. The viscometric parameters (the intrinsic viscosity, [η], and the hydrodynamic interaction parameter, B) were determined by modeling the experimental data according to the new Wolf model. The viscosity for XG solution in the absence/presence of NaCl as temperature rises has an ascendent evolution which takes place with slope variations. These changes were attributed to conformational transition of the chains from the ordered to disordered form affecting the polymer-polymer and polymer-solvent interactions. Salt addition diminishes the electrostatic repulsions between COO− groups, the ordered conformation is stabilized and the temperature at which conformation changes occur is shifted to higher values (above 55 °C for XG solution with 10−2 mol/L NaCl). The ordered-disordered transition of the chains was also observed in ATR–FTIR spectra. Significant shifts in the regions 1750–1550 cm−1, corresponding to vibration of COO− groups, indicate changes in the hydrogen bonding network.

Hydrodynamic behavior of chitosan hydrochloride macromolecules in aqueous solutions of D- and l-ascorbic acid

The hydrodynamic behavior of chitosan hydrochloride macromolecules in aqueous solutions of D- and l-ascorbic acid in a temperature range 25–45°C was studied by capillary viscometry. The intrinsic viscosity, the Huggins constant, and the temperature coefficient of viscosity were estimated. The effect of the ionic strength of the solvent mixture, predetermined by varying the acid concentration or introducing NaCl, on the hydrodynamic volume of macromolecules and their manifestation of polyelectrolyte properties was revealed. It was established that an increased temperature had led to the macromolecular coils getting more compact and the thermodynamic quality of the water-acid medium as a polymer solvent getting poorer. Despite the close values of pH and ionic strength of the aqueous solutions of D- and l-ascorbic acid, chitosan hydrochloride in the d-ascorbic acid solution is characterized by larger macromolecules and the polymer interaction with the solvent mixture components is energetically more favorable. It is suggested that the conformational state of chitosan hydrochloride is affected not so much by the macrochain stiffness as by the isomeric form of ascorbic acid. A comparison was made of the viscometric parameters of the aqueous solution of the aminopolysaccharide in ascorbic acid with its traditional solvent media, namely: water, acetic and hydrochloric acids, and sodium acetate buffer.

Physico-chemikal properties of a system H2O-H2SO4-Al2(SO4)3×18H2O

In this paper, the concentration and temperature dependences of the density and the viscosityof a system H2O-H2SO4-Al2(SO4)3 × 18H2O in the temperature range of 20-50°C were studied. The sulfuric acid concentration was varied from 2 to 40 wt %, the aluminum sulfate content in the system was varied from 5 to 30 wt %. The viscosity was determined by high precision capillary viscometry, the density was determined by pycnometry. The formulated regression equations can be used for the calculation of the density and the viscosity at different salt and acid concentrations and at different temperatures with the accuracy sufficient for practical purposes, and the results can be presented as reference data.

PROCESSING ADDITIVES AND RHEOLOGICAL PROPERTIES OF MOLDED PHENOLIC PLASTICS

By the method of capillary viscosimetry, the melt flow curves of the molded phenolic resin and its compositions with lubricant, plasticizer and their mixture were obtained. It was shown that the size (diameter) of the capillary channel influences the dependence of the effective shear rate on the shear stress (flow curves) of the studied compositions. Such rheological behavior of the compositions during flow is associated with the effect of sliding along the surface of the capillary wall. According to the Mooney method, the dependences of the effective shear rate at given values of shear stress on the reciprocal of the capillary radius are plotted. The function of the slip velocity on the shear stress on the capillary wall is characterized in terms of the slip coefficient, which relates the shear stress on the capillary wall to the velocity of the composition along it. For the studied compositions, the total flow through the capillary was divided into volume fractions, one of which is associated with a shear flow; the other is determined by the slip effect. It has been shown that the introduction of both a lubricant and a plasticizer into the composition leads to an increase in the fluidity of the compositions. At the same time, adding of lubricant increases the volume fraction of the slip flow. The greatest effect of increasing the fluidity of the composition gives the use of complex modifying additives containing both lubricant and plasticizer.

Enzymatic Depolimerization of Chitosan for the Preparation of Functional Membranes

This work reports the study of chitosan depolymerization through the synergy of the Celuzyme® XB enzyme complex; it is composed of cellulase, xylanase, andβ-glucanase. The optimal conditions of temperature, pH, and concentration were determined to verify the depolymerization reaction. The specificity of the enzymes at theβ(1-4) glycosidic link site was checked. Low molecular weight chitosan (64 × 103 g·mol−1) with degree of acetylation 15% was obtained. The depolymerized chitosan products were characterized by infrared spectroscopy, the degree of acetylation was obtained by UV-Vis spectroscopy, and the determination of the molecular weight was obtained by capillary viscosimetry. With the depolymerized chitosan, membranes were formed and their antioxidant and antimicrobial functionality was determined; results show that these properties are dependent on the molecular weight and on the acetylation degree of chitosan.

ВПЛИВ НАНОНАПОВНЮВАЧА НА РЕОЛОГІЧНІ ВЛАСТИВОСТІ РОЗПЛАВІВ ПОЛІМЕРІВ ТА ЇХ СУМІШЕЙ

Studying the influence of additives of nano-sized aluminium oxide on the patterns of Polypropylene (PP) and mixture PP/CPA (copolyamide) melt flow. The mixtures were obtained by the prior injection of the nano-filler to the PP melt with the further mixing of granula with CPA on the worm-disk extruder. Viscosity (η) of melts was examined by the method of capillary viscometry and the elasticity was studied by value of extrudate equilibrium swelling. The melts ability to longitudinal deformation was evaluated by the maximum stretch rating.

Nanostructure of organic-inorganic composite materials based on polymer hydrogels

The initial stage of gelation of organic-inorganic hybrid hydrogels based on poly(N-vinylpyrrolidone) and the products of hydrolytic polycondensation of tetramethoxysilane has been studied by capillary viscometry. The development of strong bonds between polymer molecules and silica particles in aqueous solutions is proved by the electrokinetic sonic amplitude method. The molecular mass of poly(N-vinylpyrrolidone), the concentration of starting components, and their total amount affect the onset time of gelation in poly(N-vinylpyrrolidone)-water-tetramethoxysilane systems. The general scheme of formation of three-dimensional networks in such systems under the conditions of mutual penetration of poly(Nvinylpyrrolidone) coils is suggested. According to this scheme, nanoparticles of the general formula SiOx(OH)y(OR)z linking poly(N-vinylpyrrolidone) macromolecules serve as junctions of the gel network due to the formation of hydrogen bonds between hydrogens of silanol groups of organosilanes and oxygens of carbonyl groups of poly(N-vinylpyrrolidone).