Processing Of Polymeric Materials Research Articles

Research on the Influence of Processing Parameters on the Specific Tensile Strength of FDM Additive Manufactured PET-G and PLA Materials.

Fused deposition modeling (FDM) is one of the most accessible additive manufacturing (AM) technologies for processing polymeric materials. It allows processing most of thermoplastic polymers, with polyethylene terephthalate glycol-modified (PET-G) and polylactic acid (PLA). AM parts tend to display anisotropic behavior because of layer-by-layer fabrication and various technological parameters that can be set for 3D print, so it is hard to predict and analyze how the manufactured parts would behave under load. This research presents results of classic tensile strength tests performed on 57 PET-G specimens and 57 PLA specimens manufactured with varying technological parameters such as: printing temperature, print orientation, layer height, and infill percentage. Afterward, a comparative analysis is performed, proposing specific tensile strength (STS) as a benchmark to determine how 3D printed parts strength is varying due to beforementioned parameters, eliminating bias induced by varying weight of specimens. The biggest relative increase of UTS and the biggest relative decrease of STS was noted for variable infill percentage (increasing infill—PLA: 37.27% UTS increase and 30.41% STS decrease; PET-G: 24.42% UTS increase and 37.69% STS decrease). The biggest relative increase of STS between examined parameters was observed for both materials as the printing temperature was increased (27.53% for PLA and 12.69% for PET-G). Similar trends in STS changes were observed for both materials. Obtained data shows which FDM AM parameters are the most important to obtain the biggest UTS of manufactured parts, and those do not overlap with parameters needed to obtain optimal strength-to-weight ratio.

Development of a Highly Efficient Environmentally Friendly Plasticizer.

The purpose of this work is the synthesis of adipic acid ester and the study of the possibility of its use as a PVC plasticizer. The resulting butyl phenoxyethyl adipate was characterized by Fourier-transform infrared spectrometry, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The compatibility, effectiveness and plasticizing effect of butyl phenoxyethyl adipate in comparison with dioctylphthalate (DOP) were determined. The new environmentally friendly plasticizer has good compatibility with PVC and high thermal stability. The effectiveness of the plasticizing action of adipate based on the glass-transition temperature was 132.2 °C in relation to pure PVC and 7.7 °C in comparison to compounds based on DOP. An increase in the fluidity of the melt of polyvinyl chloride (PVC) compounds in the temperature range of 160–205 °C by 19–50% confirms a decrease in the energy intensity of the processes of manufacturing and the processing of polymer materials containing a new additive.

Classification of Screw Cooling Devices of Single-Screw Extruders for Polymer Materials Processing (Survey of Designs)

Classification of Screw Cooling Devices of Single-Screw Extruders for Polymer Materials Processing (Survey of Designs)

Irradiation Effects in Polymer Composites for Their Conversion into Hybrids

In this paper several aspects of profound modifications caused by high energy exposures are presented as possible candidates for the efficient adjusting processing of polymer materials. The class of hybrid composites receives special attention due to the large spectrum of formulations, where the interphase interaction decisively influences the material properties. They represent potential start points for the intimate uniformity of hybrid morphologies. Their radiation processing turns composites onto hybrid morphology with expected features, because the transferred energy is spent for the modification of components and for their compatibility. The essential changes achieved in radiation processed composites explain the new material behavior and durability based on the peculiar restructuring of polymer molecules that occurred in the polymer phase. During high energy irradiation, the interaction between intermediates born in the constitutive phases may convert the primary composites into hybrids, integrating them into large applicability spheres. During the radiation exposure, the resulting hybrids gain a continuous dispersion by means of new chemical bonds. This type of compounds achieves some specific structural modifications in the polymer phase, becoming stable hybrid composites. The functional properties of hybrids definitely influence the material behavior due to the molecular changes based on the structural reasons. The radiolysis of the vulnerable component becomes an appropriate opportunity for the creation of new material with improved stability. The radiation treatment is a proper conversion procedure by which common mixtures may become continuously reorganized. This review presents several examples for the radiation modifications induced by radiation exposure that allow the compatibilization and binding of components as well as the creation of new structures with improved properties. This approach provides the reference patterns for the extension of radiation processing over the well-conducted adjustments of polymer composites, when certain material features are compulsorily required. From this review, several solutions for the adjustment of regular polymer composites into hybrid systems may become conceivable by the extended radiation processing.

Nonlinear rheological models and their application to describe the mechanical behavior of highly oriented polymer materials

The nonlinear viscoelasticity of uniaxial oriented polymer materials is considered. To explain the deformation mechanisms of oriented polymers and the possibility of predicting their mechanical behavior in various operating modes, new nonlinear rheological models have been proposed. The application of the simplest rheological model of a real viscoelastic solid to the description and explanation of the recovery process in polymer materials is studied. From the standpoint of rheology, a model of an ideal viscoelastic solid is introduced. Using the balance equation for the number of transitions through energy barriers, a method for calculating the new nonlinear rheological model has been proposed. To eliminate the shortcomings of the ideal viscoelastic solid model associated with the impossibility of predicting creep and stress relaxation modes for long times, a generalized rheological model of a real viscoelastic solid was obtained. In the corrected model, the simplest elements are connected in parallel, which means the presence of not one, but several energy barriers in the materials, the transmission through which have their own relaxation times. To describe the recovery processes in polymer materials, the model of an ideal viscoelastic solid is supplemented by a parallel connected elastic spring. An additional Hooke spring replaces the interfibrillar interaction between the individual elements of the structure and is responsible for possible obstacles during jump-like transitions through the energy barrier. Using the method of rheological models and describing interfibrillar bonds within the framework of the theory of elasticity, a constitutive equation was obtained for the case of recovery processes. Based on the constitutive equation of viscoelasticity for uniaxial oriented polymer materials, a new nonlinear highly elastic element is introduced, which replaces the Maxwell’s element in the theory of linear viscoelasticity. A new rheological model of parallel connection of elastic elements is shown. An explanation of the retardation of the recovery process in polymers is given. The simplest rheological model of a real viscoelastic solid is proposed, in which an elastic spring is responsible for interfibrillar bonds. A constitutive equation is obtained that describes the recovery process in polymers. This equation can be integrated by quadratures and gives a solution that is an analogue of the Newton-Leibniz formula for the proposed model. It is shown that the deformation recovery process in polymer does not depend on the level of initial deformation and the loading method. The obtained result is confirmed by experimental data for polyamide and polyethylene film yarns. When specifying a certain initial level of deformation, generalized recovery curves of these materials are obtained. The proposed simplest rheological model of a real viscoelastic solid makes it possible to predict the reducing properties of polymer materials. And also makes it possible to determine the height of the energy barrier and the magnitude of the elastic modulus in the model. Based on the new rheological models, it is planned in the future to consider the issues of modeling and forecasting different modes of deformation.

Influence of Extruder's Nozzle Diameter on the Improvement of Functional Properties of 3D-Printed PLA Products.

The dynamic growth of the use of polymer construction parts manufactured individually and in a small series makes it necessary to improve additive methods in the areas of materials, equipment and processes. By observing selected phenomena occurring during the processing of polymer materials in other production technologies (e.g., extrusion and injection molding), it is possible to obtain solutions that positively affect the final performance properties of the products obtained in additive manufacturing technologies using thermoplastic filament. The aim of this research was to determine the effect of the diameter of the print head nozzle on the spatial structure (path width) and selected mechanical properties of samples produced by the FFF method with PLA material. The obtained results were compared to the samples with a solid structure produced using injection molding technology. In the experiment, the RepRap device for additive manufacturing was used, with the use of nozzles with diameters of 0.2 mm, 0.4 mm, 0.8 mm and 1.2 mm. The test objects were produced with a layer height of 0.2 mm, full filling (100%) and with constant remaining printing parameters. The conducted research allowed us to conclude that the use of layer heights lower than the standard ones gives favorable results for selected mechanical properties. The use of an extruder nozzle diameter of 0.8 mm allows one to obtain a macrostructure with a high degree of interconnection of layers and paths and favorable mechanical properties. The test results can be used in the construction of functional elements that are produced by fused deposition modeling (FDM) and fused filament fabrication (FFF) methods in prototype, unit and small-lot production.

ИССЛЕДОВАНИЕ ВЯЗКОСТИ БРОМСОДЕРЖАЩЕГО ПЛАСТИФИКАТОРА ИЗ ОТХОДОВ ПРОИЗВОДСТВА

The importance of studying the viscosity parameters of liquid ingredients of plastics and elastomers for solving a number of technological issues related to taking into account the energy costs required to perform basic and auxiliary production operations in the processing of polymer materials is noted. The influence of the degree of halogenation of unsaturated mixed plasticizer obtained from industrial waste on its viscosity in the temperature range corresponding to the technological parameters of processing polymer materials 273-393 K. It is shown, that with an increase in the degree of bromination at a constant temperature the viscosity of the bromine-containing plasticizer increases by 63.3%, 52.0% and 46.8%, respectively. With an increase in temperature to 353-393 K, a decrease in the maximum viscosity values for samples with a mass fraction of bromine of 14.4% by 26% was found. It is shown that in the studied range of the degree of bromination, the viscosity drop with an increase in temperature to 393 K is 96%. An equation is proposed to evaluate the effect of the degree of bromination and temperature on the viscosity of a mixed bromine-containing plasticizer of the phthalate type, obtained from production waste. The values of its coefficients in a given temperature range are established, which characterize the change in the intensity of intermolecular interaction with an increase in the bromine content in the plasticizer. It is shown that the activation energy of the viscous flow decreases by 12% with an increase in temperature and an increase in bromine content. The heat of evaporation of the plasticizer components within 100 kJ/mol was determined. The value of a complex indicator is obtained, taking into account the combined effect of bromine content and temperature on viscosity in the range of 25-26 kJ/mol, which confirms the provisions of the activation theory for linear low-molecular hydrocarbons. It was found that the degree of influence of the bromine content in the plasticizer on its viscosity in the established temperature range is 3.3 – 4.1%. It is shown that an increase in the degree of bromination of a phthalate-type plasticizer contributes to an additional intermolecular interaction that contributes to an increase in kinematic viscosity.

AUTOMATED CONTROL OF HF ELECTROTHERMY OF ORGANIC AND POLYMERIC MATERIALS TAKING INTO ACCOUNT RESONANT PHENOMENA

The paper presents an overview of existing technological systems designed for ultra-high-frequency and high-frequency electro-thermal and dielectric processing of polymer, organic and biological materials. A comparative analysis of electrothermia and other types of heating and theirs advantages are described. Deficiencies in control systems and automation capabilities of existing high-frequency industrial equipment have been identified. The optimal industrial frequency of high-frequency exposure allowed for industrial use has been evaluated. The main controlled parameter for non-intrusive heating was determined in order to improve and activate (seeding) the processed material. (Research purpose) The research purpose is developing a method of electrothermal treatment of organic and polymer materials and its automated control, excluding the influence of various little-studied processes. (Materials and methods) The theoretical justifications showing the uneven heating of the samples were confirmed by field tests. Heating is mainly carried out on the surface of the samples, which often leads to their melting. The method of heating with the use of high-frequency electrothermia, which is free of these disadvantages, was studied. Industrial high-frequency equipment of the UZP 2500 model was used in the experiment. (Results and discussion) The paper presents the results of the use of the electrothermia process and the analysis of the technological process of controlling high-frequency processing on the example of samples of polymer composites similar to natural organic materials. A resonant phenomenon manifested when exposed to high-frequency electrothermia was described. The paper presents the solution of its accounting in the organization of the management process. We have developed technical equipment, selected processing modes for organic and polymer materials. (Conclusions) The practical possibilities of the proposed method of automated control of high-frequency electrothermia of organic and polymer materials used in industry and agriculture during transportation and preparation for their operation, as well as prolongation of their residual life during storage, have been revealed.

Improved thermal stability and heat-aging resistance of silicone rubber via incorporation of UiO-66-NH2

The metal-organic frameworks (MOFs) as emerging materials have attracted worldwide attention. In this study, a novel strategy by blending classic MOFs material UiO-66-NH2 to efficiently enhance the thermal stability and thermal aging resistance of silicone rubber (SR) was proposed. The experimental results indicated that very low dosage (0.25–1.5 part) of UiO-66-NH2 addition could effectively increase the thermal-oxidative stability of SR, which was proved by that the values of T5 (temperature at 5% weight loss) and Tm (the maximum thermal decomposition rate temperature) of SR were greatly increased by 43.4 °C and 97.9 °C, respectively. Moreover, the retention rate of elongation at break and tensile strength of SR with 1.5 part UiO-66-NH2 could remain about 72% and 57% after 288 h treatment in 210 °C. The possible heat resistance mechanism was explored by processing torque (PT) and thermogravimetry-mass spectrometry (TG-MS), whose results suggested that even very low addition of UiO-66-NH2 could efficiently inhibit degradation of SR chains and obstruct heat transfer due to its low thermal conductivity. This study provided a novel strategy to enhance thermal stability of rubber materials, and might open up new filed for polymer material processing.

Recent Advances in Elongational Flow Dominated Polymer Processing Technologies.

The continuous development of plasticizing conveying methods and devices has been carried out to meet the needs of the polymer processing industry. As compared to the conventional shear-flow-dominated plasticizing and conveying techniques, a new method for processing polymers based on elongational flow was proposed. This new method and the related devices such as vane extruders, eccentric rotor extruders and so on, exhibited multiple advantages including shorter processing time, higher mixing effectiveness, improved product performance and better adaptability to various material systems. The development of new techniques in the field of polymer material processing has opened up a broad space for the development of new plastic products, improved product performance and reduced processing costs. In this review, recent advances concerning the processing techniques based on elongational flow are summarized, and the broad applications in polymer processing as well as some future opportunities and challenges in this vibrant area are elucidated in detail.

Estimation of chemical safety of environmental protection technologies for atmosphere pollution reduction (a case study of processess of laser treatment of polymer materials)

Introduction. One way to protect atmospheric air from industrial pollution is the use of environmental protection technologies aimed at emissions purification. As a result of the man-induced impact, the industrial emissions can change the composition of air medium, while the resulting products of physical and chemical transformations with other, sometimes more toxic properties, can influence on the quality and chemical safety of atmospheric air in comparison with the initial substances entering it as part of industrial emissions. Materials and methods. Studies of the impact of various technologies of treatment the industrial atmospheric emissions of organic glass and polymer materials processing plants with laser systems were carried out using a chromato-mass spectrometric system Focus GC with DSQ II (USA). Results. We have established the change in the qualitative-quantitative composition of emissions from organic glass laser treatment processes using various cleaning devices. Estimation of electrostatic purification technology efficiency based on plasma-catalytic oxidation with atomic oxygen revealed an increase in the transformation products - aldehydes. The cleaning devices seems ineffective and chemically unsafe concerning one of the primary pollutants included in the emissions of organic glass and polymer materials processing plants with laser systems - methyl methacrylate. Conclusion. The use of new environmental protection technologies for emissions purification can cause a change in their qualitative-quantitative composition, which requires chemical-analytical control. It is advisable to use chromatography-mass spectrometry to identify and quantify up to 100 substances simultaneously in the air with an unknown composition of pollutants to assess the efficiency and chemical safety of new technologies for emissions purification adequately. It will certainly reduce and minimize health risks and allow considering the possibility of man-induced formation of transformation by-products.

АНАЛІЗ ЗАСТОСУВАННЯ ПЛАЗМОВИХ ТЕХНОЛОГІЙ В ТЕКСТИЛЬНІЙ ТА ЛЕГКІЙ ПРОМИСЛОВОСТІ

Analysis and determination of the most promising and economical plasma technologies for processing polymeric textile materials to obtain materials with specifi ed properties. Methodology. The article uses analytical methods for the study of diff erent types of plasma treatment of polymeric textile materials and their impact on the properties and structure of these materials. Results. Diff erent types of plasma treatment of polymeric textile materials are analyzed. Of the physical methods of modifi cation, the most promising are plasma technologies that can reduce environmental pollution. Thermal plasma has extremely high temperatures and cannot be used to modify and treat the surface of PTM fi bers. The choice of a certain type of cold plasma for the treatment of PTM depen ds on the speed of their processing, the sample size and the degree of the proposed modifi cation. The infl uence of diff erent types of plasma treatment of polymeric textile materials on the change of their structure and properties, as well as the causes and features of such changes are determined. Practical value. The application of plasma technologies in the textile and light industry allows to replace the technological operations of processing polymeric textile materials that require high consumption of water and chemical reagents, for the processes of their dry processing. This reduces the consumption of chemical materials and reduces energy costs. Installation and maintenance of atmospheric pressure equipment is much simpler and cheaper than low pressure plasma equipment

Application of natural zeolite for recycling of polymer waste

Recently, the ways of obtaining alternative energy resources in the production of gasoline and diesel fuels have been considered. Using physico-chemical methods, nitrogen and sulfur-containing compounds in gasoline, diesel distillates obtained from polymer residues can be determined. Currently, a promising method is the processing of polymer materials into liquid fuel fractions and organic products. In this method, the destruction of the polymer series with the formation of low-molecular hydrocarbons occurred. The process was carried out at a temperature of 400-450°C at atmospheric or elevated pressure in the presence or in the absence of a catalyst. Both pure polymers and various polymer wastes, containing organic orinorganic waste that does notrequire special cleaning, were used. This technology allows you not only to eliminate wastes, but also to obtain a large number of commercial products.

Pulse-to-pulse evolution of optical properties in ultrafast laser micro-processing of polymers

Polymers were one of the first materials to be processed by ultrafast lasers. However, the nature of absorption for near-infrared laser beams is not fully understood, and therefore it remains challenging to process polymeric materials with high energy efficiency. In this study, the pulse-to-pulse evolution of optical properties (reflectance, transmittance, and absorptance) of polypropylene (PP), which is an important polymeric material widely used in many industrial applications, is determined by performing time-resolved measurements for a wide range of pulse energies. The goal is to differentiate between linear and nonlinear absorption in different laser-matter interaction regimes and select the processing condition that yields the highest energy efficiency. The experiment is performed by recording the reflection and transmission of each laser pulse in an ellipsoidal mirror-based setup, which enables the collection of scattering reflection with nearly full coverage. Absorption is calculated from the experimental data, and a model consisting of linear and nonlinear absorption is used to analyze the results. It is found that PP undergoes a dramatic morphological change from pulse to pulse, which is accompanied by changes in optical properties, that is, the tuning of the laser condition to fully utilize the laser energy. Their results could help increase energy efficiency in ultrashort-pulsed laser processing of polymers toward the high-throughput operation.

Numerical Study of a Williamson Fluid Past a Semi-Infinite Vertical Plate with Convective Heating and Radiation Effects

In the present paper, we investigated mathematical model of the magnetohydrodynamic flow and heat transfer in an electro-conductive polymer on the externalsurface of a semi-infinite vertical plate under radial magnetic field. Thermal radiation andconvective heating effects are considered at the semi-infinite plate surface with modifiedboundary conditions. The Williamson viscoelastic model is employed which isrepresentative of certain industrial polymers. The non-dimensional, transformedboundary layer equations for momentum and energy are solved with the second orderaccurate implicit Keller box finite difference method under appropriate boundaryconditions. Validation of the numerical solutions is achieved via benchmarking withearlier published results. The influence of Williamson viscoelastic fluid parameter,magnetic body force parameter, convective heating, radiation parameter, stream wisevariable and Prandtl number on thermos-fluid characteristics are studied graphically. Themodel is relevant to the simulation of magnetic polymer materials processing.

Optimization of Mathematical Modeling of Functional-Consumer Processes in Special and Dual-Purpose Polymer Materials

An approach for optimizing mathematical modeling of functional-consumer processes in special purpose polymer materials is considered. The presented optimization is carried out on the basis of the integral forecasting reliability criterion for relaxation-recovery processes.

Surface Characteristics of Polymers with Different Absorbance after UV Picosecond Pulsed Laser Processing Using Various Repetition Rates.

We experimented with two polymer materials with different ultraviolet (UV) wavelength absorption characteristics, which are commonly used in flexible devices, by applying an ultrashort-pulsed laser of a 355-nm UV wavelength for 10 ps. The laser parameters studied were pulse repetition rate, laser irradiation method, and laser power condition. Previous studies using polyethylene terephthalate (PET), which does not exhibit linear absorption at a UV wavelength, have focused on processing trends resulting in minimal collateral damage around the laser-induced ablation. However, our results showed a trend of accumulating such damage irrespective of the laser parameters. Meanwhile, polyimide (PI) exhibited a completely different behavior depending on the laser parameters. At low pulse repetition rates, minimal collateral damage was observed, whereas at high repetition rates, the morphology varied considerably. The electrical characteristics of the laser-processed materials were found to be correlated with the variations in morphology. In the case of PI, such variations in electrical resistance and morphology indicated that the material was carbonized. The findings of this study are expected to provide a useful reference when selecting parameters for the laser processing of similar polymer materials.

ANALYSIS OF APPROACHES TO THE RESEARCH OF MECHANICAL PROCESSING OF POLYMER MATERIALS

The article presents the results of analysis of modern approaches to research and improvement of methods of mechanical processing of polymer materials. The article illustrates the fact that scientific works on the mechanical processing of composite materials based on polymers are currently relevant due to the lack of data on the properties of materials that characterize their workability.

Darcy flow of polymer from an inclined plane with convective heat transfer analysis: a numerical study

An analytical model is developed to study the Darcy flows in viscoelastic convection from an inclined plate as a simulation of electro-conductive polymer materials processing with Biot number effects. The Jeffery’s viscoelastic model describes the non-Newtonian characteristics of the fluid and provides a good approximation for polymers, which constitutes a novelty of the present work. The normalized nonlinear boundary value problem is solved computationally with the Keller Box implicit finite difference technique. Extensive solutions for velocity, surface temperature, skin friction and heat transfer rate are visualized numerically and graphically for various thermophysical parameters. Validation is conducted with earlier published work for the case of a vertical plate in the absence of non-Newtonian effects. The boundary layer flow is accelerated with increase in Deborah number, whereas temperatures are decelerated slightly. Temperatures are boosted with increase in inclination parameter, whereas velocity is lowered. A reverse trend is seen for increasing mixed convection parameter. Increase in Biot number enhances both velocity and temperature. Increasing Darcy number is found to enhance velocity, whereas it suppresses temperature. This particle study finds applications in different industries like reliable equipment design, nuclear plants, gas turbines and different propulsion devices.

The effect of materials' rheology on process energy consumption and melt thermal quality in polymer extrusion

AbstractPolymer extrusion is an important but an energy intensive method of processing polymeric materials. The rapid increase in demand of polymeric products has forced manufactures to rethink their processing efficiencies to manufacture good quality products with low‐unit‐cost. Here, analyzing the operational conditions has become a key strategy to achieve both energy and thermal efficiencies simultaneously. This study aims to explore the effects of polymers' rheology on the energy consumption and melt thermal quality (ie, a thermally homogeneous melt flow in both radial and axil directions) of extruders. Six commodity grades of polymers (LDPE, LLDPE, PP, PET, PS, and PMMA) were processed at different conditions in two types of continuous screw extruders. Total power, motor power, and melt temperature profiles were analyzed in an industrial scale single‐screw extruder. Moreover, the active power (AP), mass throughput, torque, and power factor were measured in a laboratory scale twin‐screw extruder. The results confirmed that the specific energy consumption for both single and twin screw extruders tends to decrease with the processing speed. However, this action deteriorates the thermal stability of the melt regardless the nature of the polymer. Rheological characterization results showed that the viscosity of LDPE and PS exhibited a normal shear thinning behavior. However, PMMA presented a shear thickening behavior at moderate‐to‐high shear rates, indicating the possible formation of entanglements. Overall, the findings of this work confirm that the materials' rheology has an appreciable correlation with the energy consumption in polymer extrusion and also most of the findings are in agreement with the previously reported investigations. Therefore, further research should be useful for identifying possible correlations between key process parameters and hence to further understand the processing behavior for wide range of machines, polymers, and operating conditions.