Development of an in-line magnetometer for flow chemistry and its demonstration for magnetic nanoparticle synthesis

Despite the wide usage of magnetic nanoparticles, it remains challenging to synthesise particles with properties that exploit each application's full potential. Time consuming experimental procedures and particle analysis hinder process development, which is commonly constrained to a handful of experiments without considering particle formation kinetics, reproducibility and scalability. Flow reactors are known for their potential of large-scale production and high-throughput screening of process parameters. These advantages, however, have not been utilised for magnetic nanoparticle synthesis where particle characterisation is performed, with a few exceptions, post-synthesis. To overcome this bottleneck, we developed a highly sensitive magnetometer for flow reactors to characterise magnetic nanoparticles in solution in-line and in real-time using alternating current susceptometry. This flow magnetometer enriches the flow-chemistry toolbox by facilitating continuous quality control and high-throughput screening of magnetic nanoparticle syntheses. The sensitivity required to monitor magnetic nanoparticle syntheses at the typically low concentrations (<100 mM of Fe) was achieved by comparing the signals induced in the sample and reference cell, each of which contained near-identical pairs of induction and pick-up coils. The reference cell was filled only with air, whereas the sample cell was a flow cell allowing sample solution to pass through. Balancing the flow and reference cell impedance with a newly developed electronic circuit was pivotal for the magnetometer's sensitivity. To showcase its potential, the flow magnetometer was used to monitor two iron oxide nanoparticle syntheses with well-known particle formation kinetics, i.e., co-precipitation syntheses with sodium carbonate and sodium hydroxide as base, which have been previously studied via synchrotron X-ray diffraction. The flow magnetometer facilitated batch (on-line) and flow (in-line) synthesis monitoring, providing new insights into the particle formation kinetics as well as, effect of temperature and pH. The compact lab-scale flow device presented here, opens up new possibilities for magnetic nanoparticle synthesis and manufacturing, including 1) early stage reaction characterisation 2) process monitoring and control and 3) high-throughput screening in combination with flow reactors

Self-healing polyurethane-polypropylene oxide copolymers for the protection of carbon and glass fiber-reinforced composites

Polyurethane-polypropylene oxide block copolymers containing fragments of an adduct capable of self-healing by the Diels-Alder reaction mechanism have been synthesized and studied for the first time. All obtained polyurethane copolymers were characterized by IR spectroscopy. The temperature transitions and thermal stability of copolymer melts were determined by using the methods of differential scanning calorimetry and thermogravimetric analysis. The self-healing effect was confirmed using a thermal cycling procedure on pre-damaged samples of modified polyurethanes and surface morphology studies. The perspective of the work begun on the creation of self-healing protective polyurethane coatings are shown

Current trends in the synthesis of soluble and hot-melt polyimides

The work is devoted to a review of works published in recent years on the development of the chemical structure of soluble and hot-melt copolyimides, including a brief description of their synthesis and properties

Prospects for the synthesis and application of copolyimides based on tetracarboxylic acid dianhydride mixtures

The process of obtaining copolyimides by polycondensation based on 3,6-diaminoacridine, 9,9-bis-(p-aminophenyl)fluorene, dianhydride of 2,2-bis-(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane and dianhydride of 3,3',4,4'-tetracarboxydifenyloxide are described. The main physico-chemical properties of the obtained products are discussed and the prospects for the use of these soluble and fusible products as a polymer base for the preparation of composite materials are shown

Pharmacological correction of formation of connective tissue with mesh hernia repair in experiment

The use of foreign materials in modern herniology, on the one hand, reduces the number of recurrences, and on the other - increases the risk of several complications: profuse exudation and possible infection in the postoperative wound, extensive cicatricial deformation of a zone of operations, persistent pain syndrome and possible reduced fertility in men. In the experiment 30 rats were studied influence of drugs «mesogel®» and «iodopiron» in the course of wound process during operations using mesh explant. Histological methods were evaluated the usefulness of the formation of connective tissue, degree of involvement in cicatricial process is located in the area of operation of tissues and structures. Compared with the control group of animals is set to a relatively low density and fewer collagen fibers. In the control group of animals had a marked proliferative response in the surrounding tissue prosthesis, gross deformity and involvement in the scar process near structures

Selection of antioxidants to improve the thermal-oxidative stability of polyarylates

Using the method of thermogravimetric analysis, the selection of synergistic mixtures of antioxidants for the synthesized polyarylate-polysulfone block copolymer F-230/30 with a glass transition temperature of 260°C was made

Synthesis and study of block copolymer polyarylates

In order to reduce the viscosity of a polyarylate melt based on phenolphthalein and terephthalic acid dichloride with a glass transition temperature of 280°C, polyarylate-polysulfone block copolymers with a glass transition temperature of 240 to 260°C capable of processing through a melt at 340°C were synthesized and studied

Influence of coloring on the properties of epoxy binders and fiberglass rebar based on them

At present, polymer composite materials are widely used in the construction and automotive industries, products for which must meet not only operational, but also aesthetic requirements. Since color is one of the most important design elements, much attention is paid to the coloring of structural composites. There is a fairly wide range of different methods for coloring polymer composites, but each method has both advantages and disadvantages. This article discusses two methods for coloring a hot amine-cured epoxy composition, which is used for the manufacture of composite fiberglass reinforcement: by adding pigment and organic dyes to the epoxy composition. It has been found that organic dyes dissolve in all components of the epoxy composition, but become colorless upon heat treatment. When adding an insoluble dispersed pigment, the color remains unchanged even after the thermal curing of the epoxy matrix. The addition of up to 0.5 mass parts of iron oxide pigment (“red FEPREN TP-303”) to the epoxy binder slightly reduces the mechanical strength of the composite and significantly increases its thermal stability

Дослідження та обґрунтування параметрів замкових з'єднань паркетних дощок

Three-layer parquet boards are becoming increasingly popular on the market of wooden flooring in Ukraine. Demand for flooring is caused by rapid growth of the construction industry, particularly in the residential sector. The purpose of the work is to study and substantiate the design features and operating parameters of parquet boards for consistency with the geometry of the profile, the magnitudes of the differences and gap between the ends of the parquet boards at the 5G-C lock joint. The statistical processing of the experimental studies confirmed the validity of the results obtained and the permissible deviation of the parameters of the boards' geometry in accordance with the established standards. The statistical analysis of the experimental studies on the differences and gap between the ends of the parquet boards at lock joint between adjacent boards during the "4&nbsp;boards" test showed that a small part of joints does not meet the regulatory requirements. The experimental studies and statistical processing of their data made it possible to detect the deviation of the parameters of parquet boards and to plot graphs for comparing the characteristics of the differences and gap values during the tests "4&nbsp;boards", "Tongue", "Groove" and with various widths of boards with inserts from HDF and veneer for the 5G-C end joint. As a result of the analysis of comparative graphs, it is established: the change in the magnitude of differences and the size of the gap depends on the type of test used; during the "4&nbsp;boards" test, the values for the differences and the size of the gap are minimal; the influence of the insert material on the size of the gap and the values of the differences is insignificant; the size of the gap increases during the "Tongue" test, and exceeds the tolerance for boards of 130&nbsp;mm and 180&nbsp;mm wide; the differences value increases during the "Groove" test and exceeds the tolerance for boards of 130&nbsp;mm in width; A gap with a board width of 207&nbsp;mm has the slightest deviation for all tests. The conducted studies and statistical data processing made it possible to establish deviations of the parameters of the parquet board profile and to construct a polygon and distribution curves, graphs for comparing the characteristics of the differences and the gap size in the "4&nbsp;boards" tests, at the loads in the tests of "Tongue", "Groove" and with the inserts from HDF and veneer for the 5G-C lock joint. The processing of experimental data showed that the frequency of distribution of the values for the differences between adjacent parquet boards during the "4&nbsp;boards" tests can be described by a second order polynomial, the frequency of distribution of the gap size between adjacent parquet boards can be described by a logarithmic function. The insignificant percentage of reject items (up to 5&nbsp;%) with the excess of the differences values is due to inaccurate adjustment of the tool in calibration operations on the thickness of the boards, milling of the longitudinal and transverse profiles and partial wear of the tool. Deviations of the differences values and the gap size for the tests of "Tongue" and "Groove" are within the tolerance field. The obtained results of the study confirmed the fact that parquet boards with veneer and PVC inserts are more reliable in operation and can be used on premises where there is an increased level of loads, temperature and humidity variations (public rooms, assembly halls, gyms, etc.).Встановлено параметри відповідності контролю профілю з'єднання та геометрії паркетних дощок після фрезерування. Виконано статистичний аналіз показників параметрів геометрії паркетних дощок та параметрів контролю сучасного профілю поперечного (торцевого) замкового з'єднання 5G-C відповідно до лекал оптичного проектора та розподілу величин параметрів перепаду і щілини від тестових навантажень. Досліджено показники міцності з'єднання профілю при вертикальних навантаженнях залежно від матеріалу вкладки та положення пластикової вставки. Зроблено практичні висновки згідно з дослідженнями контролю профілю з'єднання 5G-C та дошки загалом після фрезерування в технологічному потоці. Встановлено відповідність значень параметрів при контролі профілю з'єднання та геометрії дошки після фрезерування на проекторі, за шаблоном, за тестами складання і навантаження дощок до нормативних показників та якості. Запропонований перелік заходів щодо економії сировини у виробництві сучасних і традиційних паркетних виробів дасть змогу контролювати питання з раціонального та ефективного використання деревинної сировини, запровадити у виробництво науково обґрунтовані прогресивні норми

Alkali resistant epoxy binders for pultrusion

Alkali-resistant hot-curing epoxy binders based on ED-20 and new amine hardeners “Amikrost” have been developed, intended for the production of glass-composite fittings for construction purposes. The rheological properties of epoxy compositions were determined, using differential scanning calorimetry and thermogravimetric analysis, the temperature dynamics of the curing process of epoxy compositions and the thermal-oxidative resistance of cured samples were studied. The alkali resistance of cured epoxy compositions and specimens of composite reinforcement in 40% alkali aqueous solution was evaluated. It is shown that the developed amine hardeners provide high alkali resistance of composite reinforcement in comparison with the currently used anhydride hardener iso-MTHPA, which is especially important for reinforcing buried and hydraulic concrete