Pressure Polyethylene Research Articles

EVALUATION OF THE ANTIOXIDATIVE EFFICACY OF FULLERENE SOOT DOPED BY C60/C70 (85/15) FOR LOW-DENSITY/HIGH PRESSURE POLYETHYLENE NANOCOMPOSITES

Fullerenes (C60-70) although effective stabilizers-antioxidants for polymeric materials they have not yet found widespread practical application because of their high cost. As such, polymer manufacturers prefer to use classical stabilizers. In order to try to overcome this situation for some useful applications here the evaluation of relatively cheap fullerene soot (FS) doped additionally by C60/C70(85/15) is undertaken. Solution kinetic studies on the inhibition of model cumene oxidation combined with the thermal and mechanical analysis of the FS+C60/C70 integrated in a low-density/high pressure polyethylene (LDPE) matrix demonstrates the obvious advantage of a such an approach. The kinetic analysis made on the model reaction of initiated oxidation of cumene showed that the antioxidant activity of samples of fullerene carbon black doped with fullerenes C60-70 exhibits inhibition rate constants with high enough values comparable to those of strong industrial antioxidants such as Irganox 1010/1076. The additional portions of C60-70 fullerenes slightly increase the commercial cost of the FS itself, while the higher efficiency of the modified fullerene samples shown by thermal and mechanical analysis prevails more and allows us to recommend them for the industrial use at a measured optimal concentration of 1%w/w in the polymer

Design of Service Life of Pressurized Polyethylene Pipes for the Transport of Fluids

Design of Service Life of Pressurized Polyethylene Pipes for the Transport of Fluids

Influence of Discharges and UV Irradiation on the Electrical Properties of High Pressure Polyethylene and Compositions on Its Base

ABSTRACT The composition and concentration of a low-molecular organic additive, leading to a significant improvement in the electrical properties of low-density polyethylene of high pressure grade 10,803-020, were experimentally determined. Phthalic anhydride and phthalic acid were used as modifying organic additives. The content of additives in the polyethylene of high pressure composition varied in the range of 0.01–0.1 wt%. It has been shown that the content of 0.05 wt% phthalic anhydride and phthalic acid in the composition polyethylene of high pressure (PEHP + 0.05 wt% PhAn + 0.05 wt% PhAc) is the optimal composition, since the electrical strength of the film has increased significantly. The dependences of the dielectric loss tangent and specific volumetric electrical resistance on temperature, as well as the kinetics of physicochemical changes in them under the influence of electrical discharges in air and UV irradiation, have been studied. It was established that the dielectric characteristics of the polymer composition PEHP + 0.05 wt% PhAn (storage life 40 years) changed slightly.

Никельсодержащие нанокомпозиты на основе изотактического полипропилена и полиэтилена высокого давления

The effect of nanofiller (NF) additives containing nickel oxide nanoparticles stabilized by a polymer matrix of high pressure polyethylene (PE) obtained by the mechanochemical method on the structure and properties of metal-containing nanocomposites based on isotactic polypropylene (PP) and high pressure polyethylene(PE) using differential thermal (DTA) and X-ray phase (XRF) and SEM analyzes. The improvement of strength, deformation and rheological parameters, as well as thermal-oxidative stability of the obtained nanocomposites was revealed, which, apparently, is associated with the synergistic effect of interfacial interaction of nickel-containing nanoparticles in the PE matrix with the components of the PP/PE polymer composition. It is shown that nanocomposites based on PP/PE/NF can be processed both by pressing method and by injection molding and extrusion methods, which expands the scope of its application.

Modification and study decommissioned high pressure polyethylene

Modification and study decommissioned high pressure polyethylene

Obtaining and studying the properties of composites based on high pressure polyethylene with nickel-containing nanofillers

The effect of nickel nanoparticles stabilized by a polyethylene matrix on the physical-mechanical and thermal properties of nanocomposites based on high-pressure polyethylene was studied by X-ray phase (XRD) and differential thermal (DTA) analyzes.An improvement in the strength and deformation parameters, as well as the thermal-oxidative stability of the obtained nanocomposites was revealed, which can be attributed to the effects of structural modification of the polymer matrix.Small amounts of nanofiller introduced into the polymer play the role of structure-forming agents - artificial nuclei of crystallization, which contributes to the formation of a small-spherolite structure in the polymer, characterized by improved physical, mechanical and thermal properties of the obtained nanocomposite.fi

Contact mechanical behavior and leakage prediction of metal lenticular gaskets in bolt flange joints of ultrahigh pressure pipelines

Metal lenticular gaskets have been widely applied in the bolt flange joints of high and ultrahigh pressure pipelines due to their semi-self-tightening sealing properties. However, research on the leakage prediction of the metal lenticular gaskets is still lacking, which limits their further optimal design and sealing performance improvement. In this paper, an elastoplastic contact mechanics analysis of a metal lenticular gasket used in the bolted flange joint of ultra-high pressure polyethylene pipelines was firstly carried out. The analytical formulas of contact stress and contact width were derived and compared with corresponding numerical results. Then, based on the surface topography measurement, a leakage model was established, in which the pipe surface was simplified to a smooth rigid flat surface, and the gasket surface was simplified to an equivalent rough surface composed of identical wedges. Finally, an analytical leakage prediction formula for the metal lenticular gasket was proposed. In addition, the effects of influence factors on leakage rate were discussed. It is shown that the analytical formulas can accurately calculate the contact stress and contact width in elastoplastic contact. The leakage rate increases with the decrease of the bolt load and the increase of internal pressure. For the ultrahigh pressure pipeline with internal pressure of 200 MPa, the minimum bolt load should be ensured to be higher than 120 kN in order to meet the T5 tightness level. In addition, the initial contact diameter is basically proportional to the leakage rate, while the change of gasket inclination angle has little effect on the leakage rate. Therefore, the contact diameter can be designed to be as small as possible within a reasonable range. This work can provide a theoretical basis for the sealing optimal design of metal lenticular gaskets.

Factors Influence on Electrophysical Parameters of the Composite Varistors

Purpose. Evaluation influence structural state polymer phase on the response voltage and coefficient nonlinearity of a multilayer varistor based on zinc oxide. Methodology. Zinc oxide consisted of 97% zinc oxide and 3% total oxides of Bi2O3, Co3O4, MnO2, B2O3, SbO3, ZrO2, Al2O3. At a temperature of 1573°K, the synthesis of semiconductor ceramics based on Zinc oxide was carried out. For composite of thermoplastic polymers and Zinc oxide, non-polar and polar polymers, high pressure polyethylene and polyvinylidene fluoride were used. The composites were obtained by hot pressing at the melting temperature of the polymer phase and a pressure of 15 MPa. After that, using silver paste, measuring electrodes 10 mm in diameter were applied to the surface of the synthesized samples, and then current–voltage characteristics were measured. Modification of composites under action of gas-discharge plasma was carried out in a special cell that creates a dielectric-gas-composite system. The structure of the composites was studied by X-ray diffraction analysis and IR spectroscopy. Findings. The obtained experimental results show that the size of the particles of the inorganic phase significantly affects the current-voltage characteristics of the composite varistor: at a given thickness of the composite varistor, the operation voltage decreases markedly, and the nonlinearity coefficient increases. Numerous experimental results obtained by us show that the impact of electric discharge plasma on the polymer Zinc oxide-composite leads to a significant change in the permittivity and the concentration of local levels at the interface of the composite. The results research showed that effect electrical plasma on the opening voltage depends on the polarity of polymer matrices. Moreover, plasma processing itself significantly changes the structure of the polymer phase at composite. Originality. The magnitude of the potential barrier at phase boundary is mainly determined by the volume fraction and size of the main structural element of ZnO ceramics. Changing the structural state of the polymer matrix allows the adjust response voltage and coefficient nonlinearity of volt-ampere characteristic of the multilayer varistor. Practical value. The discovered development of electron-ion processes at polymer phase of the varistor indicates the need to take into account change in its service characteristics from the duration and intensity of use. The result obtained has a certain practical significance, since it indicates not only the reason for the change in properties, but also the need to develop measures to increase the service life of the varistor.

INVESTIGATION OF CORROSIVE EFFECT ON METAL OF A BROAD FUEL FRACTION OBTAINED FROM SECONDARY POLYMER RAW MATERIAL

A research of the corrosion effect on the metal (copper plate) of a broad fuel fraction (FPF) - a liquid product of thermal destruction of secondary raw materials made of low pressure polyethylene (LDPE) at temperatures up to 380 ° C and a pressure of 0,12-0,15 MPa. is conducted. Determination of the corrosion effect on the copper FFT plate was carried out in accordance with the standard ASTM D 130-10 at a temperature of 50 ° C for 120 minutes for both the dehydrated FFT sample and in the presence of 1% water. It was found that the copper plates, which were in the FFT and FFT + 1% water in the visual evaluation, had a light orange color, close to the color of the original plate. This, in turn, indicates that the investigated FFT samples have withstood the test, and the corrosive effect on the copper plate can be attributed to a slight fading, class 1.a. Also, together with the study under standard conditions, the corrosion effect on the copper plate of the products of combustion of FFT at different temperatures at which it was found that in the temperature range 180-230 ° C the surface of the copper plate becomes pale purple, and the corrosion effect on the copper plate can be attributed to moderate dimming, class 2.b; at temperatures of 230-290 ° the surface of the copper plate already has a silver color, and the corrosive effect on the copper plate corresponds to a moderate blackout, class 2.d. Therefore, when the combustion products of the FFT on the copper plate only oxygen corrosion occurs, which is due to the presence of oxygen in the area of the copper plate and the temperature of the combustion products. Thus, it was concluded that there is no corrosive elements in the FFT, which makes it suitable for use as a cheap component of motor, furnace and boiler fuels, improving their performance (e.g., reducing sulfur content).

Influence of Nature of Pigments and Dyes on Coloring Properties of Polymeric Superconcentrates

The article considers methods of manufacturing non-toxic films of a given color that meet technological requirements. The problem of reducing the shrinkage of the colored polymer in the casting mould during cooling and maintaining its technical characteristics is experimentally solved. To this end, the influence of the nature of pigments on the degree of polymer coloring is studied, and ways to improve the quality of color are investigated. The object of the study was selected pigment concentrate based on high pressure polyethylene brand 15803-003. The pigment has chosen technical carbon grades N220, P803. Surfactants were modifying additives. Tests of samples to determine the light fastness of dye, migration resistance, the number of agglomerates of pigments, toughness and strength, physical and mechanical properties showed that the most effective additive to improve the coloring properties of soot pigment brand N220 and improve the appearance of finished products introduced into the superconcentrate calcium stearate, which at the stage of mixing in the extruder acts as a surfactant and prevents the adhesion of the pigment and the formation of agglomerates in the polymer melt.

Polymer Composites Supported on Polyolefins and Dried Barley Grass

Benchmark results of physical, rheological and biodegradable properties of low (HDPE 273-83) and high (LDPE 15303-003) pressure polyethylene mixture by a factor of 1:1 supported on dried barley grass flour (200 microns maximum) ( 5–30 % by weight) enhanced by compatibilizer of 10 % (method functionalized with ultrathene alkaline alcohol exchange (ethylene-vinyl acetate copolymer 12206-007) and 1 % processing aid (polyethylene glycol (PEG-115 (4000)). It was concluded that the Young modulus and tensile strength do not decrease significantly with increase in vegetable reinforcement (up to 30 %). To compare the composite properties in terms of biodegradability, moisture uptake, chemical oxygen demand, and weight loss, a 12-month study was performed in laboratory soil. It is shown that an increase in the content of plant reinforcement increases the biodegradability of the composite. Resulting composites can be used in the production of various packaging materials.

Аналитическое представление зависимостей коэффициента трения от температуры при фрикционном взаимодействии стального шара с термопластами

A mathematical model describing the dependence of the coefficient of friction on temperature during the frictional interaction of a steel ball with thermoplastics is proposed. Verification of the developed mathematical model is implemented by processing experimental data obtained during the frictional interaction of a slide made of steel SHX15 on such thermoplastics as low and high pressure polyethylene, polypropylene, polyformaldehyde, polymethylmethacrylate, polystyrene. A number of new tribotechnical characteristics have been introduced, which make it possible to characterize the frictional interaction in the metal-thermoplastics system in more detail.

Теплофизические свойства полимерных компаундов на основе вторичного полипропилена и полиэтилена

The relevance of the problem under study is due to an increase in the amount of polymer waste based on synthetic polymers, which determines the feasibility of its involvement in recycling in relation to thermoplastic polyolefins. A significant proportion of plastic waste falls on plastic products made of polypropylene, while the processed raw materials almost always contain a mixture of polypropylene with different polyethylene content. The aim of the work was to study the thermal characteristics of polymer compounds based on secondary polypropylene filled with high and low pressure polyethylene. The leading approach to the study of this problem is the use of methods of thermogravimetry and differential scanning calorimetry, which make it possible to identify patterns of changes in temperature and thermal characteristics of phase transitions, as well as thermal stability of polymer compounds. It is shown that the presence of two peaks of melting and crystallization on thermograms of differential scanning calorimetry of polypropylene-polyethylene mixtures indicates the incompatibility of polymers, while the polymer system is heterophase. In the presence of polyethylene, the crystallization rate of polypropylene changes, while its melting temperature decreases and the crystallization temperature increases compared to a pure polymer. Filling the compound with polyethylene of both low and high pressure reduces the rate of decomposition of secondary polypropylene and shifts the decomposition process of compounds to higher temperatures. The mass of the dry residue when heated to 400°C and 600°C for a polymer compound with low-pressure polyethylene is higher compared to high-pressure polyethylene. The materials of the article can be useful for the creation of polymer composites based on recycled polypropylene in the presence of polyethylene, as well as the development of technological modes of their processing.

Obtaining and studying the properties of composites based on high pressure polyethylene with cobalt-containing nanofi llers

The effect of cobalt nanoparticles stabilized by a polyethylene matrix on the physical-mechanical and thermal properties of nanocomposites based on low density polyethylene was studied using X-ray phase (XRD) and differential thermal (DTA) analyzes.An improvement in the strength and deformation parameters, as well as the thermal-oxidative stability of the obtained nanocomposites was revealed, which can be attributed to the effects of structural modification of the polymer matrix.Small amounts of nanofiller introduced into the polymer play the role of structure-forming agents - artificial nuclei of crystallization, which contributes to the formation of a small-spherolite structure in the polymer, characterized by improved physical, mechanical and thermal properties of the obtained nanocomposite.

PROPERTIES OF BOILER FUEL COMPOUNDED BY NARROW FUEL FRACTIONS

In order to improve the performance properties, in particular viscosity-temperature, of boiler fuel, it is proposed to combine them with narrow fuel fractions obtained by thermal destruction of secondary polymer raw materials (low pressure polyethylene and polypropylene).
 When compounding grade 100 fuel oil with narrow fuel fractions, the values ​​of density are reduced to 865 (873) kg / m3, conditional viscosity to 2.50 (2.63) deg. um., pour point up to 8 (13) °C), sulfur content up to 0.17 wt%. and the lower heat of combustion increases to 43606 (43850) kJ / kg. At the same time, there is a gradual decrease in the value of the flash point to 114 (127) °C.
 This reduction is a negative point, which leads to increased fire safety of fuel oil during its use, storage, pumping and transport. However, the values of the flash point, according to the requirements of regulatory documentation, are within acceptable limits. That is, the value of this indicator can limit the content of fuel oil in narrow fuel fractions.
 It is determined that the rational concentration of narrow fuel fractions in the composition of fuel oil grade 100, is within 30% of the mass. Within these limits, there is a permissible decrease in flash point values – an indicator that characterizes the fire hazard of fuel oil during its use, storage, pumping and transportation against the background of improving other performance properties of fuel oil.
 The production of the proposed compound boiler fuel on the one hand allows to expand the raw material base of the process by involving in the production process secondary polymer raw materials – solid waste subject to mandatory disposal, on the other – to meet existing demand for boiler fuel by increasing its production.

Production Technology and Damping Properties of Aerated Polymer Coatings

The process of obtaining aerated (filled with air bubbles) polymer coatings has been developed and investigated by the method of flame spraying with an assessment of their ability to damp vibrations. A technology for the controlled formation of aerated polymer coatings has been developed while using the capabilities of the ОИМ (OIM) 050 polymer thermal atomizer design which consists in providing a concurrent air flow between the flame torch and the jet of powder material. The experiments have been carried out with such thermoplastic polymers as polyethylene terephthalate, high pressure polyethylene, ultra high molecular weight polyethylene, polyamide. It has been found that the aeration coefficient grows almost in direct proportion with an increase in the amount of air in the concurrent flow for all investigated polymer coatings. It is noted that the aeration process is influenced by the rheological properties of liquid polymers, or rather, the value of the polymer melt flow rate. The limiting values of air in the concurrent flow have been determined, which make it possible not to reduce the adhesion of polymer coatings to steel substrates by less than 6 MPa and not to decrease their hardness by more than 25–30 %. Studies of the damping properties of samples with polymer coatings have been carried out on a stand, the kinematic diagram of which is based on loading the free end of a cantilever sample, abrupt removal of the load and registration of free damped oscillations by an induction-type contactless sensor connected to a computer. It is shown that the use of aeration when forming noise-absorbing coatings on steel samples can increase their logarithmic damping decrement by 18–26 %.

Using the method of pyrolytic mass spectrometry in the study of biodegradable polymeric materials

The results of pyrolytic mass spectrometry studies of biodegradable polymeric materials based on polyolefins and segmented polyurethanes with various functional additives are summarized. The structure and composition of initial and after exposure in soil, climate chamber and after exposure to microorganisms (bacteria, yeast) composites are characterized. In the research presented, influence of acetates and complexonates of metals, including cobalt, copper and zinc, on the structural changes in the high pressure polyethylene (HPPE) occurring under the impact of factors such as temperature, humidity and UV-radiation is investigated. It was established, that samples of HPPE, modified by cobalt acetate and cobalt and copper complexonates are responsive and most sensitive to the action of above-mentioned physical factors. Investigation of a segmented polyurethanes (SPU) of a different chemical structure influenced by a factors, modeling of the environmental conditions was conducted. It was shown using pyrolytic mass-spectrometry method and monitoring of samples’ weight loss that under the influence of above-mentioned environmental factors in the SPU occurs processes, resulting to changing its micro heterogeneous structure. It is established that SPU having ester links in its structure and being exposured in soil for 120 days is predominantly attacked by microorganisms, then the main active factor appears to be soil’ pH value – after 300 days in soil with alkaline or acid solution SPU sample decomposes into a separate fragments. Features of the chemical structure of urethane polymers synthesized on the base of hydroxylated rapeseed oil (polyol) were examined. Analysis of the results showed that the macromolecular compounds obtained are segmented polyurethanes which thermal degradation occurs in two stages: hard blocks are destroyed at the first stage, while polyol part (soft blocks) decomposes at the second stage, allowing to identify the temperature area of polymer destruction and thus its temperature region of operation. It is shown that the most suitable from the viewpoint of environmental friendly is polyurethane composition containing more than 50% of polyol. Thermal mass-spectrometry (TMS) has been employed to investigate processes of thermal destruction of segmented polyurethane and it’s compositions filled by polysaccharides: starch, dextrin, chitosan. The features of thermal destruction for segmented polyurethane and related compositions before and after their storage in a soil have been determined. Application TMS is shown to permit the processes of biodegradation of polymeric materials to investigate.

The discharge selectivity in an atmospheric pressure helium–argon dielectric barrier discharge

In this paper, an atmospheric pressure polyethylene terephthalate dielectric barrier discharge is produced in a helium–argon mixture. The influences of the electrode voltage on the discharge mode are experimentally investigated. The results show that, at a fixed argon content of 50%, the discharge transits from local uniform, through the isolated pattern, to whole uniform with the increase in the electrode voltage. Both the peak value of current pulse and argon spectra (696.54, 763.13, 772.09, 811.17, and 911.81 nm) intensities are captured to clarify the characteristics of the discharge mode transition. The different discharge characteristic regions are obtained by varying the argon content. In addition, the influence of the argon content on the above-mentioned argon spectra intensities is also researched. The spectra intensities enhance at 696.54, 763.13, and 772.09 nm but weaken at 811.17 and 911.81 nm with the increase in the argon content when the discharge operates in the whole uniform mode. The physical reasons for these results are discussed.

Цинксодержащие нанокомпозиты на основе изотактического полипропилена и полиэтилена высокого давления

The effect of nanofiller (NF) additives containing zink oxide nanoparticles stabilized by a polymer matrix of high pressure polyethylene obtained by the mechanochemical method on the structure and properties of metal-containing nanocomposites based on isotactic polypropylene (PP) and high pressure polyethylene (PE) using differential thermal (DTA) and X-ray phase (XRF) analyzes. The improvement of strength, deformation and rheological parameters, as well as thermal-oxidative stability of the obtained nanocomposites was revealed, which, apparently, is associated with the synergistic effect of interfacial interaction of zink — containing nanoparticles in the PE matrix with the components of the PP/PE polymer composition. It is shown that nanocomposites based on PP/PE/NF can be processed both by pressing method and by injection molding and extrusion methods, which expands the scope of its application.

Microalgae colonization on some artificial polymers in experimental conditions

The present work demonstrates the results of experimental studies of the character of microphyte fouling on the surface of plastic materials. The work is based on two laboratory experiments I and II and the field one (experiment III). Experiments I and II were established in laboratory conditions in crystallizers for 4 and 7 weeks. As a model for the experiment I, polyethylene terephthalate (PET) plates of two types were used: the plates taken from the marine environment from coastal decomposition (rough, EP) and untreated PET plastic (smooth, KP); for experiment II – low pressure polyethylene (LDPE) plates and untreated PET plastic. Glass plates were used as controls. The field experiment took place for 7 days in the coastal zone of the Gulf of Odessa. PET plates of different transparency and surface were used as a model. As a result of experiment I, the plates of rough plastic (EP) and glass (K) had the best fouling, the lowest parameters of the fouling on the plates with a smooth surface (KP). Significant differences in quantitative indicators of microalgae on the plates were detected only during the first exposure. As a result of changes in the properties of the plastic surface after being in the marine environment, it becomes more suitable for the formation of fouling in the laboratory (experiment I), forming a biomass of from 0.2·10‑2 mg·cm-2 to 4.0·10‑2 mg·cm-2. Laboratory experiment II showed a gradual increase in the quantitative indicators of phytoperiphyton on PET plates (from 0.01·10‑2 mg·cm-2 to 0.18·10‑2 mg·cm-2), and a decrease on LDPE plates (from 0.03·10‑2 mg·cm-2 to 0.001·10-2 mg·cm-2). These data are confirmed by the correlation coefficient: +0.9 (for PET) and -0.9 (for LDPE) for biomass. The development of microalgae was regulated by ciliates, which began to develop actively on 2–3 weeks of the experiment and used microphytes as food. The maximum number of ciliates was observed on LDPE plates. Weekly exposure of PET in field experiment III demonstrated that the primary settlements of microphytes are quite diverse and reached 28 species. The obtained data make a significant contribution to understanding the processes of interaction of plastic materials with microalgae and will be the basis for future research.