Plasticized Poly Vinyl Chloride Research Articles

Broadening Bandwidth in a Semi-Active Vibration Absorption System Utilizing Stacked Polyvinyl Chloride Gel Actuators.

Plasticized polyvinyl chloride (PVC) gel is a new soft and smart material, whose potential in electroactive variable stiffness can be used for vibration control in soft robotic systems. In this paper, a new semi-active vibration absorber is developed by stacking PVC gel actuator units. The absorption bandwidth of a single PVC gel absorber covers the range of three natural frequencies (76.5 Hz, 95 Hz, 124 Hz) of a rectangular steel plate in vibration attenuation. The maximum reduction percentage in acceleration amplitude is 63%. With stacked PVC gel actuator units, the absorption bandwidth can be shifted and obviously broadened.

Functionalizing Carbon Substrates with a Covalently Attached Cobalt Redox Buffer for Calibration-Free Solid-Contact Ion-Selective Electrodes.

With a view to potentiometric sensing with minimal calibration requirements and high long-term stability, colloid-imprinted mesoporous (CIM) carbon was functionalized by the covalent attachment of a cobalt redox buffer and used as a new solid contact for ion-selective electrodes (ISEs). The CIM carbon surface was first modified by electroless grafting of a terpyridine ligand (Tpy-ph) using diazonium chemistry, followed by stepwise binding of Co(II) and an additional Tpy ligand to the grafted ligand, forming a bis(terpyridine) Co(II) complex, CIM-ph-Tpy-Co(II)-Tpy. Half a molar equivalent of ferrocenium tetrakis(3-chlorophenyl)borate was then used to partially oxidize the Co(II) complex. Electrodes prepared with this surface-attached CIM-ph-Tpy-Co(III/II)-Tpy redox buffer as a solid contact were tested as K+ sensors in combination with valinomycin as the ionophore and Dow 3140 silicone or plasticized poly(vinyl chloride) (PVC) as the matrixes for the ion-selective membrane (ISM). This solid contact is characterized by a redox capacitance of 3.26 F/g, ensuring a well-defined interfacial potential that underpins the transduction mechanism. By use of a redox couple as an internal reference element to control the phase boundary potential at the interface of the ISM and the CIM carbon solid contact, solid-contact ion-selective electrodes (SC-ISEs) with a standard deviation of E° as low as 0.3 mV for plasticized PVC ISMs and 3.5 mV for Dow 3140 silicone ISMs were obtained. Over 100 h, these SC-ISEs exhibit an emf drift of 20 μV/h for plasticized PVC ISMs and 62 μV/h for silicone ISMs. The differences in long-term stability and reproducibility between electrodes with ISMs comprising either a plasticized PVC or silicone matrix offer valuable insights into the effect of the polymeric matrix on sensor performance.

Application of pfg NMR diffusometry to study diffusion and ionization phenomena in plasticized polymeric membranes doped with ionic liquids

Ionic liquids (ILs) are increasingly used as promising organic solvents for a variety of applications, including electrochemical processes, novel separation techniques and innovative methods of synthesis, due to their low volatility, excellent solvation properties, high ionic conductivity and electrochemical stability. Moreover, the tunable properties of ILs determined by their composition make them favorable candidates as dopants for composite and/or functional polymeric materials, e.g. in the membranes of chemical sensors. To effectively use ILs in polymeric materials and control the characteristics of the latter, one should develop a complete understanding of the properties of ILs in the polymeric phase, such as their diffusion and ionic behavior.In our previous work, we applied pulsed field gradient (PFG) NMR technique to verify the results of a chronopotentiometric method conventionally used to determine the diffusion coefficients and electrolytic properties of electrolytes in plasticized poly(vinyl chloride) (PVC) membranes of chemical sensors. The results obtained with these two independent methods were in good agreement, confirming that PEG NMR diffusometry is a viable technique for assessing the diffusion properties of species even in highly viscous polymeric media of low polarity.Here we report a comprehensive study of the transport and ionic behavior of IL 1-hexyl-3-methyl-1H-imidazolium bis[(trifluoromethyl)sulfonyl]amide ([C6Meim][NTf2]) in a poly(vinyl chloride) matrix, performed in situ by means of PFG NMR diffusometry. A number of sets of spectra for the 1H and 19F nuclei of the [C6Meim][NTf2] ionic liquid in PVC membranes doped with the plasticizer bis(2-ethylhexyl)sebacate were registered at different amplitudes of the magnetic field gradient. The mobility of both individual ions of the IL and the formed ion associates was investigated over a broad range of IL concentrations in the PVC matrix; in addition, the ionization degree and dissociation constant of [C6Meim][NTf2] were determined and their dependence on the IL content was traced.

Synthesis and application of environmental plasticizers based on benzene polyacid ester

AbstractUsing benzene‐1,3,5‐tricarboxylic acid, trimellitic anhydride, 2‐propylheptanol and 2‐ethylhexanol as raw materials, four kinds of environmental plasticizers were prepared, which were used as additives for polyvinyl chloride (PVC) products. Compared with commercially available di (2‐ethylhexyl) phthalate (DOP), di (2‐ethylhexyl) terephthalate (DOTP), and tributyl citrate (TBC), the application performance and plasticizing performance were compared. The structure of the target product was analyzed by fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy to verify the fingerprint region of the molecular structure of the product. The properties of plasticized PVC films were tested by thermal weight loss analysis, oven thermal aging test, migration and volatility resistance test, DMA analysis, and scanning electron microscopy. The plasticizing mechanism was confirmed through quantum chemical calculations, and the results of the calculations were in line with the migration outcomes. The results showed that compared with commercially available plasticizers, benzene polyacid ester plasticizers had better thermal stability, and better cold resistance in the polar environments, suitable for high‐temperature and water‐based environments.Highlights The four plasticizers prepared in this study were compared with reference plasticizers, and the plasticizing mechanism was validated through quantum chemical calculations. The PVC film plasticized with benzene polyacid ester prepared in this study demonstrates outstanding thermal stability, surpassing certain plasticizers reported in current literature. Benzene polyacid esters plasticized PVC film has migration stability under various conditions, it has great potential in packaging and other applications.

Enhancement in efficiency of solar photovoltaic power generation with the assistance of PVC/TiO2 reflective composite applied for double-sided power generation

Solar photovoltaic power generation is a productive and environmentally friendly technique. The results of objective evaluations show that double-sided power generation is more efficient than single-sided power generation, with a possible increase of 5 %–30 %. Hence, it is necessary to identify a composite that reflects the exact sunlight waveband (300–1100 nm) onto the backside of photovoltaic panels used for double-sided power generation. Herein, two different crystalline types of titanium dioxide (TiO2), rutile (R–TiO2) and anatase (A-TiO2), were combined with plasticized polyvinyl chloride (PVC) to create composites. A comparative analysis was conducted with other commonly utilized reflective fillers, such as barium sulfate (BaSO4) and magnesium hydroxide (Mg(OH)2). As a result, the R–TiO2 was identified as the most appropriate substance to be blended with PVC for the production of PVC/R–TiO2 composite. As the quantity of R–TiO2 increased from 0 to 100 phr, reflectance in the distinctive waveband of 300–1100 nm of the PVC/R–TiO2 rose from 5.30 % to 82.97 %. Moreover, an improvement in the thermal conductivity of PVC/R–TiO2 sample was observed, which increased by 59.2 % from 0.179 W m−1 K−1 to 0.285 W m−1 K−1, indicating a positive effect on heat transfer. The rheological measurement showed that the amount of reflective filler was inversely proportional to the compatibility of the reflective filler with plasticized PVC in the overall composite system, whereas the thermogravimetric analysis indicated that the thermal stability of the composites improved as the number of reflective fillers increased. Substantially, PVC/R–TiO2 composites exhibit better performance in enhancing the power generation efficiency of solar photovoltaic panels.

ВЛИЯНИЕ ТЕМПЕРАТУРЫ И ПРОЦЕССОВ СТАРЕНИЯ МАТЕРИАЛА НА СИЛОВЫЕ ХАРАКТЕРИСТИКИ ПОЛИМЕРНЫХ ПОГЛОЩАЮЩИХ АППАРАТОВ ВАГОНОВ

Improving the dynamic qualities, traffic safety and increasing the inter-repair mileage of cars are urgent tasks of car-building industry. The most dangerous loads acting on the car are longitudinal loads during emergency driving modes, to reduce which inter-car shock absorbers (absorbing devices) are provided; their effectiveness must be ensured throughout the whole car life. The performance of polymer car absorbing devices depends primarily on the durability of the polymer, which is a kinetically activated process accelerated by repeated deformations and elevated temperature. The mechanism of the material ageing process depends on the structure of the material. Based on experimental laboratory studies and comparative field tests, ageing of elastomers of different classes have been identified, the dependences of the power characteristics of R-5P absorbing apparatus with two types of solid elastomer (based on rubber and a mixture of elastic thermoplastic with polyvinyl chloride plastic) have been constructed at normal and low temperatures, as well as after 6 years of operation. Recommendations are given to increase the resistance to crystallization and to ageing of polymer elements of absorbing devices. It is advisable to use the characteristics obtained in the paper when modeling the operation of absorbing devices with a solid elastomer, taking into account the operating time.

PVC plasticized membranes modified with Fe3O4 nanoparticles for potentiometric sensing of sulfate

Potentiometric sensing is one of the most wide spread platforms for analysis of aqueous solutions. The development of potentiometric sensors for hydrophilic anions such as sulfate, phosphate and bicarbonate is a challenging problem, since their high hydration energy results in a low affinity for non-polar polymer membranes – a standard material for potentiometric sensor production.In this study we propose a new type of polymeric sensor membranes for ion-selective sensors with pronounced selectivity to hydrophilic anions. The membranes are based on inorganic Fe3O4 nanoparticles (NP) embedded into plasticized poly(vinyl chloride). Six different formulations of membranes with various combinations of Fe3O4 nanoparticles and other membrane-active components were synthesized and characterized with a wide range of physico-chemical methods. Contact angle measurements, FTIR spectra, SEM and AFM imaging, magnetization hysteresis curves, ZFC/FC studies were performed. The obtained results proved the formation of nanocomposites and demonstrated a structure with “cavities” in membranes with embedded nanoparticles. Potentiometric sensitivity and selectivity of the developed sensors in aqueous solutions of SO42−, HPO42−, HCO3−, H2PO4−, NO3− and Cl−anions were studied. The developed sensors showed high sensitivity to sulfate ion (-22 mV/dec in the concentration range from 10−5 to 10−3 M) and low sensitivity to the typical interfering anions – chloride and nitrate (-14 mV/dec). The optimized sensor membrane composition demonstrated sulfate selectivity higher than that of commercially available ion-selective sensor formulations. The novel sensors were tested for quantification of SO42− in real samples of natural mineral water and the obtained content of sulfate was in a good agreement with the reference data (relative error < 3 %)

Global analysis of the adverse effects of micro- and nanoplastics on intestinal health and microbiota of fish

The wide occurrence of micro- and nanoplastics (MPs/NPs) within aquatic ecosystems has raised increasing concerns regarding their potential effects on aquatic organisms. However, the effects of MPs/NPs on intestinal health and microbiota of fish remain controversial, and there is a lack of comprehensive understanding regarding how the impact of MPs/NPs is influenced by MPs/NPs characteristics and experimental designs. Here, we conducted a global analysis to synthesize the effects of MPs/NPs on 47 variables associated with fish intestinal health and microbiota from 118 studies. We found that MPs/NPs generally exerted obvious adverse effects on intestinal histological structure, permeability, digestive function, immune and oxidative-antioxidative systems. By contrast, MPs/NPs showed slight effects on intestinal microbial variables. Further, we observed that the responses of intestinal variables to MPs/NPs were significantly regulated by MPs/NPs characteristics and experimental designs. For instance, polyvinyl chloride plastics showed higher toxicity to fish gut than polyethylene and polystyrene did. Additionally, larval fish appeared to be more sensitive to MPs/NPs than juvenile fish. Collectively, this study highlights the potential impacts of MPs/NPs on intestinal health and microbiota of fish, and underscores the determinant role of MPs/NPs characteristics and experimental designs in MPs/NPs toxicity.

Effectiveness of activated zeolite adsorber in decreased soot emission and increased oxygen concentration from combustion smokes of polyvinyl chloride plastic

Polyvinyl Chloride plastic waste is becoming an increasingly urgent global environmental issue. Combustion PVC plastic waste can have significant negative impacts on human health. To overcome these problems, this research was conducted by utilizing zeolite as an adsorbent for PVC combustion smokes. The research methodology is zeolite activation, adsorber design and gas adsorption process through dry adsorption method which is the core of this research. This study will evaluate oxygen concentration and soot emissions. Before being given a zeolite adsorbent, the oxygen concentration produced in PVC combustion smokes was only 17.2% with high soot levels as evidenced by the blackened smoke color. Furthermore, after being given an adsorbent in the form of activated zeolite as much as 283.5 grams, the oxygen concentration produced increased significantly to 20.9% followed by a decrease in soot emission levels as evidenced by changes in the color of whitened smoke. Based on the test results related to the increase in oxygen concentration and the decrease in soot emission levels, it can be concluded that activated zeolite has a high effectiveness in carrying out the PVC combustion smoke adsorption process by producing particles of carbon and oxygen within the normal threshold in the air.

Flow resistance of phloem sieve plates revisited using an experimental model

Flow resistance of phloem sieve plates revisited using an experimental model

Application of ionic liquids in ion-selective electrodes and reference electrodes: A review.

Ionic liquids (ILs) are organic chemical compounds that are composed only of ions, a large organic cation and a smaller inorganic or organic anion. These are salts whose melting point is lower than the boiling point of water. ILs have many interesting properties, thanks to which they find great practical applications in analytics, electrochemistry, separation techniques, catalysis and others. One of the many areas of application of ionic liquids is sensors especially electrochemical sensors including ion-selective electrodes. In this case, the properties of ILs that are particularly useful include very good electrical conductivity, high electrochemical stability, good extraction properties, hydrophobic character and compatibility with other materials, e. g. polyvinyl chloride plasticizers or carbon nanomaterials. ILs were used as components of ion-selective membranes, both polymeric ones based on PVC and membranes in carbon paste electrodes. ILs performed various functions in these membranes, including lipophilic ionic additive, ionophore/ion exchanger, plasticizer, transducer media and matrix. They were also used as a component of the intermediate layer in solid contact ISEs. The last chapter presents examples of the use of ILs in reference electrodes. This review discusses the use of ionic liquids in ion-selective electrodes (ISEs) and reference electrodes over the last ten years.

Pollution characteristics, sources, and health risks of phthalate esters in ambient air: A daily continuous monitoring study in the central Chinese city of Nanchang

In recent years, the atmospheric pollution caused by phthalate esters (PAEs) has been increasing due to the widespread use of PAE-containing materials. Existing research on atmospheric PAEs lacks long-term continuous observation and samples from cities in central China. To investigate the pollution characteristics, sources, and health risks of PAEs in the ambient air of a typical city in central China, daily PM2.5 samples were collected in Nanchang from November 2020 to October 2021. In this study, the detection and quantification of six significant PAE contaminants, namely diethyl phthalate (DEP), di-n-butyl phthalate (DnBP), diisobutyl phthalate (DIBP), Di-2-ethylhexyl phthalate (DEHP), di-n-octyl phthalate (DnOP), and diisodecyl phthalate (DIDP), were accomplished using gas chromatography and mass spectrometry. The results revealed that the concentrations of DEP, DnBP, DEHP, and DnOP were relatively high. Higher temperatures promote the volatilization of PAEs, leading to an increase in the gaseous and particulate PAE concentrations in warm seasons and winter pollution scenarios. The results of principal component analysis show that PAEs mainly come from volatile products and polyvinylchloride plastics. Using positive matrix factorization analysis, it is shown that these two sources contribute 67.0% and 33.0% in atmosphere PAEs, respectively. Seasonally, the contribution of volatile products to both gaseous and particulate PAEs substantially increases during warm seasons. The residents in Nanchang exposed to PAEs have a negligible non-cancer risk and a potential low cancer risk. During the warm seasons, more PAEs are emitted into the air, which will increase the toxicity of PAEs and their impact on human health.

Effect of ionic liquids on structure and electromechanical properties of plasticized polyvinyl chloride (PVC) gels

Polyvinyl chloride (PVC) gels, as electroactive polymers, have various applications in the fields of soft actuators and sensors. The relationship between the structure and electromechanical properties of PVC gels, however, has not been fully understood so far. In this work, the effect of different alkyl chain length of 1-allyl- imidazolium cations of tetrafluoroborate (BF4)-based ionic liquid (IL) on structure, mechanical and dielectric properties, bending actuation, sensing and electroadhesion properties of plasticized polyvinyl chloride/dibutyl adipate (PVC/DBA) gel were investigated. The interaction between DBA and ILs in PVC/DBA/IL gels leads to the disruption of interactions between inter-DBA molecules and subsequent formation of DBA-rich phases with DBA/IL complexes. The number of DBA-rich phases in PVC/DBA/IL gels increases as the alkyl chain length of the cation in IL increases, due to an enhanced interaction between DBA and ILs with an increase in the alkyl chain length of the cation in IL. The Young's modulus of the PVC/DBA gel was slightly reduced, while the dielectric constant significantly increased when IL was added. Additionally, the bending actuation properties and capacitance pressure sensing sensitivity of the PVC/DBA/IL gel increased with an increase in the alkyl chain length of the cation of IL. However, there was an opposite trend observed for electroadhesion peel strength. Among the studied PVC/DBA/IL gels, the bending displacement, pressure sensing sensitivity, and electroadhesion peel strength of PVC/DBA/IL gel with 3.2 wt% of 1-allyl-3-butylimidazolium tetrafluoroborate ([ABIM]BF4) increased by 2.6 times, 7.5 times, and 1.7 times compared to PVC/DBA gel, respectively. These results provide new insights into understanding the relationship between structure and electromechanical properties of PVC gels for their application in actuation, sensing, and electroadhesion integrated soft grippers.

Poly(vinyl chloride)/Nanocarbon Composites for Advanced Potentiometric Membrane Sensor Design.

Polymer nanocomposites filled with carbon nanoparticles (CNPs) are a hot topic in materials science. This article discusses the current research on the use of these materials as interfacial electron transfer films for solid contact potentiometric membrane sensors (SC-PMSs). The results of a comparative study of plasticized poly (vinyl chloride) (pPVC) matrices modified with single-walled carbon nanotubes (SWCNTs), fullerenes-C60, and their hybrid ensemble (SWCNTs-C60) are reported. The morphological characteristics and electrical conductivity of the prepared nanostructured composite films are reported. It was found that the specific electrical conductivity of the pPVC/SWCNTs-C60 polymer film was higher than that of pPVC filled with individual nanocomponents. The effectiveness of this composite material as an electron transfer film in a new potentiometric membrane sensor for detecting phenylpyruvic acid (in anionic form) was demonstrated. Screening for this metabolic product of phenylalanine in body fluids is of significant diagnostic interest in phenylketonuria (dementia), viral hepatitis, and alcoholism. The developed sensor showed a stable and fast Nernstian response for phenylpyruvate ions in aqueous solutions over the wide linear concentration range of 5 × 10-7-1 × 10-3 M, with a detection limit of 10-7.2 M.

Effect of spontaneous degradation of ion-selective optodes receptor materials on sensors performance. Where is the catch?

Interest in application of biodegradable polymers as matrix for ion-selective sensors, including optodes is likely to increase. However, finding an alternative for plasticized poly(vinyl chloride) or polyacrylates, requires among others consideration if spontaneous changes in these materials affect the analytical performance of sensors. In this work we study ion-selective optodes prepared using biodegradable matrix: p-polycaprolactone and acetyl tributyl citrate using classical constituents: optically silent ionophore and chromoionophore as optical transducer. The effect of spontaneous changes of sensor constituents on its performance was studied. It was confirmed that hydrolysis of receptor is occurring leading to change of the matrix composition. Surprisingly it was found that the key factor affecting performance of sensor is spontaneous transformation of the dye embedded within it, typically considered as stable within the sensor matrix. N-octadecanoyl-Nile blue, i.e. chromoionophore I, undergoes acidic hydrolysis leading to formation of Nile blue and Nile red, and ultimately resulting in decreased sensor performance. The hydrolysis of chromoionophore in plasticized polycaprolactone matrix is significantly affected by incorporation of carbon dioxide to the solution containing nanoprobes. As model sensors hydrogen or potassium ions selective optodes were tested.

Trash into treasure: Chemical upcycling of poly(ɛ-caprolactone) waste plastic to plasticizer with excellent plasticizing performance and migration resistance

In recent years, with the increasingly serious environmental pollution, the achievement of a truly circular materials economy approach to sustainability has attracted the attention of scientists. In this paper, we proposed an approach that combined the chemical recycling of poly(ɛ-caprolactone) (PCL) plastic with the synthesis of a green plasticizer to promote the development of plastics' reutilization. An efficient alcoholysis strategy was employed to achieve the precise chain scission of PCL into short-chain PCL (sc-PCL), which was subsequently blended with polyvinyl chloride (PVC). The excellent compatibility of PVC/sc-PCL blend was characterized through differential scanning calorimetry (DSC) and solubility parameters. Thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA) confirmed that the thermostability and plasticity of the plasticized PVC samples were superior to those of most commercial plasticizers' plasticized samples. Meanwhile, the exceptional extraction and migration resistance of PVC/sc-PCL implied that sc-PCL was capable to modify PVC as an ideal plasticizer. The flexible macromolecular structure of sc-PCL and the high percentage of polar ester groups made sc-PCL closely entangled with PVC, thus exhibiting excellent plasticizing properties. This trash into treasure strategy was also applicable to commercial PCL products, which will open up a new direction for chemical recycling of plastics as well as design and synthesis of green plasticizers.

Optimization of innovative optical sensor for zirconium determination and capturing from environmental samples

A highly sensitive bulk optode membrane, specifically engineered for the identification of zirconyl (ZrO2+) ions, has been successfully created. The membrane is composed of plasticized polyvinyl chloride (PVC), dibenzodylmethane (DBM) acting as the chromoionophore, 2-amino-4-(3-chlorophenylazo)pyridine-3-ol (ACPAP) serving as the ionophore, and sodium tetraphenylborate (NaTPB) included as an ionic additive. The sensing membrane undergoes a color change from orange to blue when exposed to ZrO2+ ions at pH 6.5. The preparation parameters of the sensor and the determination of ZrO2+ ions were meticulously optimized. In addition to showcasing reproducibility, extended stability, and a comparatively long lifespan, the suggested sensor membrane displays remarkable selectivity for ZrO2+ ions, effectively discerning them from a spectrum of alkaline earth, heavy and transition metal ions, and actinides. The sensor delivers a calibration response tailored for ZrO2+ ions across a concentration spectrum spanning 7.5–185 ng mL−1, establishing limits of quantification and detection at 7.3 and 2.2 ng mL−1, respectively. Demonstrating a rapid response within a timeframe of under 5.0 min. The sensor consistently delivered highly reproducible results, as evidenced by relative standard deviation (RSD) of 1.67 % and 1.55 % for Zr4+ concentrations at 100 and 150 ng mL−1.This underscores the precision and reliability of the sensor. Regeneration of the optode can be easily accomplished by employing 0.05 M HCl. Effectively employed across a spectrum of samples, including water, soil, plant materials, and ore solutions, the proposed optical sensor proves to be a valuable instrument for determining ZrO2+ ions in diverse environmental and analytical scenarios.

Application of a dual depressant system and microwave irradiation for flotation-based Separation of Polyethylene Terephthalate, Polyvinyl Chloride, and Polystyrene Plastics

Application of a dual depressant system and microwave irradiation for flotation-based Separation of Polyethylene Terephthalate, Polyvinyl Chloride, and Polystyrene Plastics

High-efficiency co-liquefaction of low-rank coal and PAEs-rich PVC waste in supercritical water: Products upgrading and dechlorination

With the extensive use of phthalates (PAEs)-rich polyvinyl chloride (PVC) plastic products, the recycling of PAEs-rich PVC waste has become a great challenge. Meanwhile, the efficient utilization of low-rank coal is important in China due to the abundant reserves. In this study, a high-efficiency co-liquefaction treatment of PAEs-rich PVC waste and low-rank coal (Inner Mongolia lignite) was developed by using supercritical water (SCW) process based on the interaction between the two kinds of waste. The effects of temperature, time, solid-to-liquid ratio (MCoal+PVC:MH2O), and mass ratio of coal-to-PVC (MCoal:MPVC) on the co-liquefaction conversion, composition of liquefied oil and dechlorination of PVC waste were investigated. The co-liquefaction of low-rank coal and PAEs-rich PVC waste had a significant positive synergistic effect with a maximum synergistic efficiency of 7.53% in the temperature range of 350–450 °C. The conversion ratio of low-rank coal and PAEs-rich PVC waste by SCW co-liquefaction increased from 59.71% to 74.92% with the increase of reaction temperature from 350 to 450 °C. PAEs-rich PVC waste could be almost completely dechlorinated (>98%) by the SCW co-liquefaction process, and more than 90% of the DEHP could be decomposed. The addition of PAEs-rich PVC waste resulted in a significant decrease of the percentage of heteroatom-containing compounds in the oil products by the co-liquefaction. At 450 °C, the co-liquefaction oil contained 69.16% of hydrocarbons and 6.14% of phenolic compounds. Different from supercritical water gasification, the purpose of SCW co-liquefaction in this study is to improve the coal liquefaction conversion ratio and oil quality by introducing the PAEs-rich PVC waste. The synergistic SCW treatment of PAEs-rich PVC waste and low-rank coal has good application prospects in products upgrading of low-rank coal and safe recycling of PAEs-rich PVC waste plastics.

EVALUATION OF THE THERMAL-OXIDATIVE STABILITY OF A HALOGEN-CONTAINING PLASTICIZER-FIRE RETARDANT

The importance of assessing the indicators of thermal-oxidative stability of plasticizers that are part of polymer compositions for ensuring high performance indicators during their processing and operation of finished products is noted. When using brominated organic compounds of the aromatic series, a short burning time of polymer compositions and a significant smoldering time have been established. The use of flame retardants containing a halogen in the aliphatic radical leads to a decrease in the smoldering time and an increase in the duration of combustion due to a decrease in the thermal stability of the material at the stage of decomposition. It is indicated that bromine-containing compounds give the best inhibition effect compared to chlorine-containing compounds due to a decrease in the carbon-bromine bond breaking energy compared to the carbon-chlorine bond energy. The decomposition parameters of the brominated plasticizer-fire retardant have been established. It is shown that the thermal decomposition of the brominated plasticizer occurs in two stages, corresponding to the elimination of bromine from the aliphatic radical in the temperature range 473 K – 573 K and the decomposition of phthalic acid esters in the range 603 K – 623 K. The beginning of intensive decomposition corresponds to 443 K. The maximum of the first stage of decomposition is at the point corresponding to 501 K, the second - 606-623 K. It was noted that the bromine-free plasticizer decomposes intensively, starting from 503 K and reaches the maximum decomposition rate at 611 K. The maximum loss of the bromine-free plasticizer was established at 27%, brominated - 50.9% of the mass of the sample. It has been confirmed that the presence of bromine atoms in the plasticizer adversely affects its thermal stability. The influence of the degree of halogenation of an unsaturated plasticizer on the nature of its thermal-oxidative degradation in the temperature range corresponding to the technological parameters of processing polymeric materials at elevated temperatures of 413-443 K has been studied. It is shown that an increase in the content of bromine in the plasticizer when performing technological operations for the processing of polymer compositions in the specified temperature range and the duration of exposure to elevated temperatures within one hour does not significantly affect the mass fraction of bromine in the plasticizer. A kinetic equation for the reaction of thermal decomposition of a bromine-containing plasticizer-flame retardant of the phthalate type, accompanied by the elimination of hydrogen bromide, is proposed. The activation parameters of the hydrogen bromide evolution reaction were determined for the temperature range of maximum decomposition of a brominated phthalate plasticizer with a bromine content in the range of 5% – 25%. It is shown that the activation energy of hydrogen bromide elimination depends on the bromine content in the plasticizer and decreases by 23% with an increase in the degree of bromination. It is shown that the temperature range of maximum decomposition of the brominated fire retardant plasticizer, corresponding to 473 K – 573 K, allows using it as a secondary plasticizer for polyvinyl chloride without reducing the thermal stability of the base.