Перегляд за Автор "Mikulonok, Ihor"

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Intensification of cooling of tubular blown polymeric packing films with the flowing-down liquid film
(2018) Mikulonok, Ihor; Petukhov, Arkadii; Gapon, Viktor; Gavva, Oleksandr M.
Introduction. Analytical and natural researches of process of cooling of a packing film of low density polyethylene (LDPE; high pressure polyethylene) are conducted by the flowing-down water film. Material and methods. Pilot studies of cooling of the film are conducted at the following parameters: film type – flat; speed of the film – 0.03–0.50 m/s; sizes of the slot-hole distributor of a water film: slot size – 0.4–0.8 mm, slot width – 300 mm; temperature of the cooling water – 15–40 °C. Rational parameters of process of cooling are determined on the basis of mathematical modeling. Results and discussion. Parameters of a liquid film change only on an entrance zone and depend on liquid concentration, speed of the polymeric tube and initial distribution of speed of the liquid at the exit from a distributive ring. At high values of liquid concentration (Re>20000) only the wall layer of liquid participates in heat exchange. For the film from LDPE its external surface hardens at distance about 0.01 m from the beginning of contact with water, and an internal surface – at distance about 0.10–0.15 m. Therefore the ring for distribution of liquid needs to be established after the termination of a blowing zone of the polymeric tubular workpiece. It is also necessary to provide the steady movement of a continuous liquid film on an external surface of a polymeric tube on length to 0.2 m from the beginning of contact of liquid from the polymeric film. Temperature of the cooling water in the range of 20–60 °C significantly does not influence both intensity of cooling process, and physical-mechanical properties of the produced polymeric film. For thick films from LDPE (thickness more than 200 μm) and over 1 m wide intensity of cooling is limited to the critical liquid concentration. For practical application of the received results the nomogram for determination of volume liquid concentration of the cooling water, and also volume productivity of the technological line depending on the sizes of a ready tubular blown polymeric film is offered. Conclusion. The scientific value of results consists in definition of rational conditions of application of liquid cooling of the tubular blown polymeric films produced by extrusion. Вступ. Аналітичні та природні дослідження процесу охолодження пакувальної плівки з поліетилену низької щільності (ПВД; поліетилен високого тиску) проводяться проточною водою. Матеріал і методи. Пілотні дослідження охолодження плівки проводяться за наступними параметрами: тип плівки - плоский; швидкість плівки - 0,03–0,50 м / с; розміри щілинного розподільника водяної плівки: розмір прорізу - 0,4–0,8 мм, ширина щілини - 300 мм; температура охолоджуючої води - 15–40 ° С. На основі математичного моделювання визначаються раціональні параметри процесу охолодження. Результати і обговорення. Параметри плівки рідини змінюються тільки на вхідній зоні і залежать від концентрації рідини, швидкості полімерної труби і початкового розподілу швидкості рідини на виході з розподільного кільця. При високих значеннях концентрації рідини (Re> 20000) в теплообміні бере участь тільки стіновий шар рідини. Для плівки з ПВД її зовнішня поверхня твердне на відстані близько 0,01 м від початку контакту з водою, а також внутрішня поверхня - на відстані близько 0,10–0,15 м. Тому кільце для розподілу рідини необхідно встановлювати після закінчення зони продувки полімерної трубчастої заготовки. Необхідно також забезпечити стійке переміщення плівки безперервної рідини на зовнішній поверхні полімерної трубки по довжині до 0,2 м від початку контакту рідини з полімерною плівкою. Температура охолоджуючої води в діапазоні 20–60 ° C істотно не впливає як на інтенсивність процесу охолодження, так і на фізико-механічні властивості виробленої полімерної плівки. Для товстих плівок з ПЕНЩ (товщиною більше 200 мкм) і понад 1 м ширина інтенсивності охолодження обмежується критичною рідиною концентрація. Для практичного застосування отриманих результатів пропонується номограма для визначення об'ємної концентрації рідини охолоджуючої води, а також об'ємної продуктивності технологічної лінії в залежності від розмірів готової трубчастої видувної полімерної плівки. Висновок. Наукова цінність результатів полягає у визначенні раціональних умов застосування рідинного охолодження трубчастих видувних полімерних плівок, отриманих екструзією.
Modeling of extrusion-blown molding process of polymeric package
(2018) Sokolskyi, Oleksandr; Mikulonok, Ihor; Gavva, Oleksandr M.; Gromova, Veronica
Introduction. For achievement of uniform minimum thickness of a wall of the created container and definition of the corresponding technological modes numerical researches of process of hollow polymeric products formation are conducted. Researches are conducted depending on a form of preparation and a finished product.Material and methods. In this work formation process by blowing of an axisymmetric bottle is modeled. Initial workpiece represents a cylindrical sleeve with an external radius of 10 mm. After creation of internal pressure workpiece is blown, the contact between polymer and a blown form will not be provided yet. The research is conducted on the case of formation of products from a polyethylene with low density (LDPE).Results and discussion. When the process of blowing the internal pressure is being modeled, initial thickness and outer diameter of preparation are set as constants. With an increase in the radius of a bottom corner of a bottom a wall thickness increases, however at the same time the product becomes unstable. For ensuring the minimum necessary thickness in this place it is necessary to spend excess material in other sections. Extent of thinning of a wall of a product increases with an increase in extent of blowing on a certain local site. As it follows from the results of modeling, for achievement of the minimum necessary uniform thickness of a product it is necessary to change workpiece thickness on height (in this case - to reduce it in the lower and average parts). This method of calculation of a necessary profile of thickness of preparation allows to reach uniformity of thickness of walls of the product. For this purpose workpiece on height breaks into conditional nodes, in each of which the necessary thickness of workpiece depending on the calculated product wall thickness in the corresponding point is defined by iteration.The interrelation between the workpiece, a finished product and the distribution of thickness in its walls is defined.
Modeling of melting process in a single screw extruder for polymer processing
(2018) Mikulonok, Ihor; Gavva, Oleksandr M.; Kryvoplias-Volodina, Liudmyla
A mathematical model for the melting of a single-screw extruder is developed. The model takes into account the heat transfer of the polymer with a worm and a cylinder, as well as real boundary conditions (the worm rotates, the cylinder is stationary). The parameters of the melting zone are investigated and the results of the calculation are compared with the experiment. An approach to modeling the extruder as a whole as a sequence of interconnected functional zones.
Modeling the process of polymers processing in twin-screw extruders
(2018) Mikulonok, Ihor; Gavva, Oleksandr M.; Kryvoplias-Volodina, Liudmyla
Models for the processing of polymers in co-and counter-rotating twin-screw extruders based on the generalized mathematical model of screw extrusion were developed . A base of the proposed models is the analysis of an allocated C-shaped volume, which is limited by one turn of cutting of each of screws and in which there is a certain volume of a processed polymer. Such model gives possibility to describe the process of processing both in the case of complete and partial filling of an operation channel with processed material. This is especially important in case of dosed feeding of an extruder with a polymer, which is typical for modern processing equipment.In addition, the proposed models take into account real boundary conditions on operation surfaces of rotating screws and a stationary barrel, which gives possibility to choose parameters of thermal stabilization systems of operation elements of an extruder unambiguously.The process of melting of polymer granules in an operation channel of an extruder screw was studied. The results of the study showed that it is necessary to use mixing elements at an increase of deviation of the behavior of processed material from the Newtonian behavior in an operation channel of screws. We established that intensity of energy dissipation at certain points in the volume of a processed polymer determines temperature fields in the volume of processed material. We substantiated that, firstly, an intensive external energy supply to screws and a barrel with their subsequent gradual cooling is necessary during the processing of a polymer on twin-screw extruders in contrast to single-screw extrusion.The adequacy of the developed model was verified by comparison of the results of the numerical modeling with the experimental data in processing of a composition based on high-density polyethylene filled with aluminum hydroxide in a twin-screw extruder Ø83×30 with co-rotation screws. We carried out studies for the industrial production of 50 kg/h and the rotational frequencies of screws of 25 and 40 rpm.The proposed model of twin-screw extrusion gives possibility to determine main parameters of the equipment and the process and to estimate temperature heterogeneity of melt at the design calculation for a given productivity and the required final temperature of polymer melt. The parameters include the geometry of operation elements, frequency of rotation of screws and required minimum drive power. Itis possible to determine rotational frequency of screws and thermal conditions of extruder working elements at verification calculation of an extruder for a given geometry of screws.