Swelling Phenomena Research Articles

Preparation and characterization of uniform polyurea microspheres via an environmental-friendly synthetic process: The swelling and shrinkage phenomena

In this work, a non-toxic isocyanate HDB-LV is used for the first time to produce monodispersed polyurea microspheres with a size from 10 to 40μm via a microfluidic droplet approach. The toxic ethylenediamine which is usually necessary for the synthesis of polyurea, is found to be not adaptable for the formation of polyurea microspheres because it can either cause swelling (at low amine concentration) or deformation (at high amine concentration) of the microspheres. A theoretical mechanism for the swelling phenomenon of microspheres is elucidated. Alternatively, thermal hydrolysis of isocyanates that can generate amines is proven to be very effective for the synthesis of polyurea microspheres. A linear relationship between the sizes of microfluidic droplets and polyurea microspheres is found and discussed quantitatively. In the end, the polyurea microspheres from 2 to 40μm are characterized to have no obvious scattering effects against UV.

A Comprehensive Study of Voltage Swell and Sag in Power Distribution Systems: Characteristics, Causes, Effects, and Mitigation Strategies

Voltage variations, such as swells and sags, are prevalent disturbances in power distribution systems, posing significant challenges to system reliability and equipment performance. This research paper provides a comprehensive study of voltage swell and sag phenomena, encompassing their characteristics, causes, effects, mitigation strategies, and case studies. The study explores the magnitude, duration, and frequency of voltage variations, delving into the underlying factors contributing to their occurrence, including switching operations, faults, and load variations. Moreover, the paper examines the detrimental effects of voltage variations on electrical equipment and industrial processes, highlighting the importance of understanding and mitigating these disturbances. Various mitigation techniques, such as voltage regulation, uninterruptible power supplies (UPS), and dynamic voltage restorers (DVRs), are evaluated for their effectiveness in minimizing the impact of voltage variations. Additionally, the paper explores the use of PWM-based Distribution Static Synchronous Compensator (DSTATCOM) as a promising solution for mitigating voltage swell and sag issues, discussing principles, design considerations, control strategies, and performance evaluation. Through case studies, simulation results, and modeling approaches using MATLAB/Simulink, the research paper offers valuable insights into the complex landscape of voltage swell and sag in power distribution systems, equipping researchers and practitioners with knowledge to address these challenges effectively.

Long-term thermal aging effects in ferritic-martensitic steel HT9

The ferritic-martensitic steel HT9 is a candidate material for fuel cladding and core components in advanced nuclear reactors, such as sodium-cooled fast reactors, thanks to their high temperature mechanical properties and low susceptibility to irradiation induced swelling phenomena. However, thermal stability and elevated temperature microstructural evolution in these alloys may impact their long-term behavior and reliability. In this work, the effects of thermal aging on the microstructural and mechanical properties of HT9 have been investigated through complementary electron microscopy, synchrotron X-ray diffraction, microhardness, and thermodynamic modeling. Plates of HT9 were aged up to 50 kh at relevant sodium-cooled fast reactor operational temperatures (360 °C - 700 °C). Trends in microstructure as a function of aging time and temperature were apparent from qualitative and quantitative analysis. These observations were further supported by thermodynamic modeling of the bulk and precipitate phases. Specific phases observed include BCC Fe, FCC M23C6, HCP and FCC MX phase and Laves M2X phase. Through the application of our multi-scale and multi-modal approach, clear information on the aging mechanism of HT9 was obtained, allowing for a more informed prediction, and understanding of the long-term behavior, performance and thermal stability of ferritic-martensitic alloys exposed to elevated temperatures.

Modulation of Interlayer Nanochannels via the Moderate Heat Treatment of Graphene Oxide Membranes.

In response to the phenomenon of interlayer transport channel swelling caused by the hydration of oxygen-containing functional groups on the GO membrane surface, a moderate heat treatment method was employed to controllably reduce the graphene oxide (GO) membrane and prepare a reduced GO composite nanofiltration membrane (mixed cellulose membrane (MCE)/ethylenediamine (EDA)/reduced GO-X (RGO-X)). The associations of different heat treatment temperatures with the hydrophilicity, interlayer structure, permeability and dye/salt rejection properties of GO membranes were systematically explored. The results indicated that the oxygen-containing groups of the GO membrane were partially eliminated after heat treatment, and the hydrophilicity was weakened. This effectively weakened the hydration between the GO membrane and the water molecules and inhibited the swelling of the oxidized graphene membrane. In the dye desalination test, the MCE/EDA/RGO membrane exhibited an ultra-high rejection rate of over 97% for methylene blue (MB) dye molecules. In addition, heat treatment increased the structural defects of the GO membrane and promoted the fast passage of water molecules via the membrane. In pure water flux testing, the water flux of the membrane remained above 46.58 Lm-2h-1bar-1, while the salt rejection rate was relatively low.

Gain scheduled internal model control based on the dynamic sliding mode method for the water level of nuclear steam generators

Abstract The Steam Generator (SG) is a crucial component of a nuclear power plant. Proper water level control in a nuclear steam generator is of great importance to ensure a sufficient cooling source for the nuclear reactor and to prevent damage to turbine blades. The water level control problem of steam generators has been a leading cause of unexpected shutdowns in nuclear power plants, which must be addressed for plant safety and availability. The control problem is challenging, particularly at low power levels due to shrink and swell phenomena and flow measurement errors. Furthermore, the dynamics of the steam generator vary as the power level changes. Therefore, there is a need to enhance the water level control system of the SG. In this paper, a Gain Scheduled Internal Model Control (IMC) based on the Dynamic Sliding Mode (DSMC) method is developed for the level control problem. The proposed method exhibits the desired dynamic properties throughout the entire output tracking process, independent of perturbations. Simulation results are presented to demonstrate the effectiveness of the proposed controller in terms of performance, robustness, and stability. The simulation results confirm the improvement in transient response achieved by using the proposed controller.

The die swell eliminating mechanism of hot air assisted 3D printing of GF/PP and its influence on the product performance

Abstract For eliminating the die swell phenomenon in 3D printing of GF/PP, a hot air assisted 3D printing method is proposed and its mechanism is studied. A two-phase flow model consisting of compressible gas and in-compressible melt is established, and the process of polymer filament extrusion is simulated. A series of experiments are conducted to compare the differences between traditional printing and gas-assisted printing in terms of extruded filament, temperature, and morphology. The simulation and experiment results show that the addition of gas effectively mitigates the melt die swell, and increases the extrusion filament temperature to more than 70°C. The extrusion pressure is reduced about two orders of magnitude, and the first normal stress is decreased from 400,000 to 20,000 Pa. The surface morphology of printed product is smoother and more refined. This study provides valuable information for understanding the principles of gas-assisted printing and demonstrates its potential for improving printing quality and efficiency.

Index swelling prediction of clayey soils

In civil engineering, statistical studies are widely used in risk studies of landslides, seismic, swelling-shrinking and other hazard studies. This study deals with a volumetric deformation of the clayey soil by water absorption, which is the phenomenon of swelling. It is a serious problem for lightweight structures such as highways. This phenomenon is characterized by two mechanical parameters measured by an oedometric test carried out in the laboratory, which takes a long time and is expensive, why scientists have always looked for other quick and less expensive alternatives to estimate these parameters. They developed models between classical parameters, easily determined in the laboratory, such as water content, dry density, percent of clay particles, plasticity index and mechanical properties of clay soils. The developed models are based on descriptive statistics, a neural network, or multiple regressions. To estimate the risk of swelling and to verify the applicability of the models of the literature on the Algerian soils, a database was collected from the geotechnical reports carried out on the sites of certain projects in Algeria. The objective of the present study consists of estimating the mechanical parameter of swelling, which is the swelling index from a set of physical tests carried out in the laboratory.

Wet continuous mixing technology and extrusion rheological properties of carbon black/natural rubber composites

AbstractIn order to solve the problems of dust, low mixing efficiency, and poor quality stability in dry mixing and continuous mixing, this study combined the flocculation extrusion technology with continuous mixing technology of carbon black/additives/natural rubber composites. The flocculation of latex was achieved by carbon black itself and the shearing of the twin screw. The continuous mixing was carried out in a double‐rotor continuous mixer, which was composed of functional elements such as the exhaust section and extrusion section. The results showed that the technology promoted the formation of the filler‐rubber network, the sensitivity of viscosity to temperature was weakened, and the rubber was closer to a Newtonian fluid, with less extrusion swell phenomenon and no obvious spiral distortion. Compared with the dry mixing, the tensile strength, rebound rate, and abrasion resistance of the rubber composites prepared by this technology were increased by 11%, 31%, and 9%, respectively, providing theoretical and technical guidance for the green production and continuous production of high‐performance natural rubber composites.Highlights The process is achieved by a twin‐screw extruder and a twin‐rotor continuous mixer. The process promotes the formation of the filler‐rubber network. The sensitivity of viscosity to temperature is weakened, with no spiral distortion. The tensile strength, rebound rate, and abrasion resistance are increased by 11%, 31%, and 9%.

Evolution of coal permeability during gas/energy storage

Both carbon dioxide and hydrogen can be stored in coal seams as two enabling components of energy transition from fossil-based systems to renewable sources. In both cases, understanding the evolution of coal permeability under the influence of gas adsorption is extremely important. The gas sorption-induced deformation is commonly treated by analogous calculation of thermal expansion. This assumption has long been proved to be inconsistent with observations as reported in the literature. In this study, we hypothesize that the difference between the assumption and the reality is due to self-constrained/facilitated swelling phenomena during gas injection. Under this new hypothesis, coal could be constrained or facilitated depending on coal internal structures and processes. A concept of fictitious stress is introduced to quantify coal self-constrained or facilitated degree and converted into the equivalent effective stress. This conversion has transformed the conventional effective stress principle to unconventional one. This has led to new generic coal permeability model, which has been validated by experimental data. An analysis of stress state evolution during gas storage process is conducted. Our results suggest that our coal permeability model is a valuable tool for evaluation of gas storage in coal seams.

A multiscale approach in modeling of chemically reactive porous media

Chemical reactions occur in geotechnical, biological and synthetic porous media. Swelling and shrinkage phenomena can be observed in clays, shales and gels, when they are in close contact with water. In petroleum engineering, wellbore-stability problems are caused by swelling or shrinking of the wellbore. Thus, it is significant to model the Chemo-Hydro-Mechanical (CHM) processes in porous media that include different physical and geometrical heterogeneities. In this paper, a multiscale computational homogenization approach is developed for the analysis of CHM problems. In this manner, the first-order homogenization technique is adopted for the two-scale formulation. The heterogeneities are assumed in the microscale level and a homogeneous domain is considered for the macroscale level, where the constitutive behavior is derived from the microscopic level. The governing equations and constitutive equations of the CHM processes are presented in the coupled manner. The primary variables are taken as the displacement, pore pressure, and solute concentration fields. Moreover, the transient terms are included in the microscale level to increase the accuracy of computations. Consequently, a generalized form of Hill-Mandel principle of macro-homogeneity is defined between the two scales. Appropriate microscopic boundary conditions, i.e. the linear and periodic boundary conditions, are employed to satisfy the averaging constraints. Finally, the accuracy and efficiency of the proposed computational multiscale method are illustrated through several numerical examples.

Study of xenon evolution in UO[formula omitted] using multi-grain cluster dynamics modeling

The behavior of fission gas is a key issue for the performance of UO2 fuel, which is the most widely used fuel type in GEN-III reactors. Fission gas will lead to lower thermal conductivity and affect the microstructure of fuel, gradually cause swelling and other phenomena. It seriously affects the performance and safety of nuclear reactor. The numerical simulation method based on physical model is an important means to study fission gas. In this paper, in order to study the key parameters affecting the behavior and evolution of fission gas xenon in UO2 fuel, a multi-grain parallel cluster dynamics model is designed and implemented. The model can describe the multi-grain structure characteristics of UO2, and establish the correlation for the physical process of intra- and inter-granular bubbles. Furthermore, the model is extended to a larger temporal and spacial scale through parallelization, so as to simulate the fission gas behavior closer to the actual situation, and expand the applicable conditions and range of the model. Based on the modeling work, the long-term evolution processes of xenon under different initial grain radius and temperature conditions are analyzed, the results show that the initial grain radius has a much bigger effect on the inter-granular gas concentration than the intra-granular gas, while temperature has a large effect on both intra- and inter-granular gas concentrations. The model and analysis results provide theoretical support for understanding fission gas behavior and improving UO2 fuel performance.

Numerical and experimental studies on design of multi-lumen tube extruded with drawing and air flow

This study represents the design and optimization procedure of a multi-lumen tube used for endoscopic retrograde cholangiopancreatography (ERCP) catheter. The geometry of tip and die for the multi-lumen tube is designed based on numerical analysis of molten polymer and air flow. In particular, this numerical study consider the interaction between the molten polymer and the air flow in the lumen which is the main process variable of extrusion, and analyze the heat transfer and pressure distribution through the air flow for the first time. In addition, to reflect the reality of the multi-lumen extrusion process, the velocity is controlled at the end of the tube ejected to the free surface in consideration of the extrusion process, which is drawn by the puller downstream of the extruder. The shear rate and temperature dependent viscosity of PEBAX 7233 SA01 MED is measured for non-isothermal numerical simulations. The extrusion process for multi-lumen tubes with drawing is simulated using ANSYS Polyflow. The profile of extrudate is numerically predicted with the initial design of the tip and die with the manufacturing parameter is optimized. The predicted profile of extrudate is compared to the target profile with dimensional requirements. The design of the tip and die is modified based on numerical results following the design procedure. To suppress the die swell phenomena, the flow area of molten polymer is increased, and the velocity difference is reduced. Finally, the multi-lumen tube with the optimized tip and die is experimentally extruded and compared to the target profile of the extrudate. It has a good agreement with the target profile and satisfies the dimensional requirements. This design procedure and numerical analysis help achieve the desired target profile of extrudate.

Modelling the gradual through thickness porosity formation and swelling during the thermal aggression of thermoplastic based laminates

Impacting thermoplastic-based laminates by a high thermal energy -e.g. a flame—essentially causes the progressive deterioration of the matrix, involving solid-state transformations and dramatic variations of the thermomechanical properties. Throughout this process and because it is associated with significant through thickness gradients, the laminates retains a substantial capacity to sustain a mechanical load, even after matrix has melted. For temperatures higher than the melting temperature, the dominant mechanism of the matrix thermal decomposition is the formation of voids. Whereas they constitute a weakness from the mechanical point of view, they act as thermal insulators and contribute to the protection of the matrix on the side opposite to thermal aggression. Thus, describing accurately the kinetics of their formation is the key to a reliable control of the laminates thermomechanical properties evolution under fire conditions. As a prerequisite to this objective, the formation process was experimentally investigated. Results have evidenced the strong dependence of the porosity content and of the related swelling phenomenon to the time and temperature of thermal exposure. A mesoscopic Finite Element model representing porosities at a structural level was developed based on these observations. The porosity nucleation and the induced swelling were reproduced using a probabilistic approach to drive the progressive transformation of elements into porosities according to their thermal state.

A Direct AC–AC Switched-Capacitor Converter With Input-Series Output-Parallel and In-Phase/Out-of-Phase Capabilities

In this paper, a bidirectional transformerless multi-level direct ac-ac switched-capacitor converter (SCC) is proposed with both in-phase and out-of-phase output voltage capabilities. This converter can be used for series compensator applications, such as dynamic voltage restorers (DVRs), to compensate grid voltage sag and swell phenomena by incorporating its input-output common ground. Its input-series output-parallel capabilities reduce voltage and current stresses of the converter components in multi-level configurations, which lead to higher efficiency and lower manufacturing costs for high-power applications. Furthermore, proper utilization of an interleaving control scheme can provide lower input and output currents ripples values and smaller filter sizes. The proposed SCC operation principle and its mathematical analyses are given, in detail. Additionally, its switching patterns have been developed with a safe-commutation strategy to obtain various output voltages. Subsequently, both single- and two-level SCC prototypes are implemented as series compensators for DVR applications. Moreover, experimental results are given to generate in-phase and out-of-phase regulated output voltages. The experimental results at 2 kW show that the output voltage changes are less than 3% under the steady-state conditions, despite the large input voltage changes from 140 to 300V. The converter maximum efficiency value is equal to 95.4% at maximum output power value.

Diffusive transport phenomena of lactoferrin from gelatin gels crosslinked with genipin

In order to examine the effects of crosslinking and structure on the swelling and diffusive phenomena in a hydrogel, low-solid gelatin gels were crosslinked with a range of genipin proportions. The ninhydrin assay showed high levels of successful crosslinking within the gels whilst FTIR and WAXD showed successful entrapment of the bioactive molecule lactoferrin within the matrix. Rheological analysis further assessed the effects of crosslinking on the system with an increase in network strength at greater genipin additions. SEM illustrated the successful incorporation of lactoferrin and how the pronounced changes in gel morphology influences entrapment. Experimental evidence supported theoretical estimations of the gel morphology using the Flory-Rehner theory. Analysis of the diffusive transport of lactoferrin from each crosslinked system suggested that densely bound matrices hinder the free movement of molecules. Pairing aspects of the Flory-Rehner theory with the diffusion data allowed for the calculation of the critical molecular weight between crosslinks (M*c) for diffusion to occur and the coupling parameter (ξ) for the gelatin and lactoferrin chain segments.

Shape optimization of thermal shape memory epoxy resin and its mechanism for improving the self-healing of asphalt mixtures

Thermal shape memory epoxy resin (T-SMER) is a novel smart material. The shape memory effect of T-SMER is stimulated by sensing and responding to temperature changes in the asphalt mixtures. The shape memory effect of T-SMER can be used to repair initial cracks in the asphalt mixtures. T-SMER’s shape can influence its shape memory effect and ability to improve the self-healing property of the asphalt mixtures. It also affects the performance of asphalt and asphalt mixtures. Therefore, granular T-SMER and filamentous T-SMER were prepared in this study, and their basic properties were examined. To determine the T-SMER shape with better shape memory effect, the three major indicators and elastic recovery performance of asphalt with granular T-SMER were tested, AC-5 asphalt mixture and AC-10 asphalt mixture with granular T-SMER were formed. Although the granular T-SMER improved the self-healing property of asphalt, its compatibility with asphalt was poor, and there existed a swelling phenomenon in AC-5 and AC-10 asphalt mixture. The adhesiveness between the asphalt and filamentous T-SMER, Marshall indexes, and preliminary study on self-healing property of the asphalt mixtures with the filamentous T-SMER were also investigated. The addition of the filamentous T-SMER significantly increased the consistency of asphalt, improving its strength and self-healing. Thus, the filamentous T-SMER was more suitable for application in the asphalt mixtures. To study the mechanism of the filamentous T-SMER for improving the self-healing property of the asphalt mixtures, the visualization of asphalt mixtures with filamentous T-SMER self-healing process by ANSYS were analyzed. The shape memory ability of the T-SMER can be stimulated to enhance the self-healing property of asphalt mixtures.

Prevention of Swelling Phenomenon of Alginate Beads To Improve the Stability and Recyclability of Encapsulated Horse Liver Alcohol Dehydrogenase.

Horse Liver Alcohol Dehydrogenase (HLADH) has been immobilized on calcium-alginate beads and used for both oxidation and reduction reactions. To avoid swelling of the beads and their subsequent breakage, calcium ions were added to both reaction and storage solutions, allowing the beads to maintain the initial structural features. The techniques used for this purpose revealed that 2 mM Ca2+ is the optimal concentration, which does not significantly change the weight of the beads, the amount of water in them, and their external and internal structure. The optimized experimental procedure has been used to verify the properties of the enzyme in terms of reusability, storage, and thermal stability. The addition of calcium ions allows the enzyme to retain more than 80% of its initial activity for fourteen cycles and approximately 50% at the twentieth cycle. Moreover, when the biocatalyst has been stored in a buffer solution containing 2 mM Ca2+, the retention of enzyme activity after 30 days was 100%, compared to that measured before incubation. The encapsulated enzyme exhibits greater thermal stability than free HLADH up to at least 60 °C, preventing dimer dissociation into the two subunits.

A Microwave Voyage into Swelling Phenomenon: Investigation of Polydimethylsiloxane and VOCs Interaction.

When exposed to specific gases, polymers undergo swelling, leading to physiochemical changes that can significantly affect their performance. Monitoring this swelling phenomenon requires innovative approaches. This study focuses on investigating the real-time resonant microwave behavior of two polydimethylsiloxane (PDMS) structures (solid and porous) in interaction with tetrahydrofuran (THF) and acetone, which are primary swelling agents. A microwave measurement method is proposed using an 8.63 GHz planar split ring resonator (SRR). The device's resonant frequency downshifts to 7.75 and 8.42 GHz when solid and porous PDMS blocks are placed on the split ring gap. Interaction of the solid PDMS and porous PDMS with target gases caused a change in PDMS structure resulting in alterations in the dielectric properties of the PDMS/gas system, as evidenced by the resonator's transmission amplitude and resonant frequency shifts. The magnitude of these shifts depends on the type and concentration of the solvent gas. The PDMS-integrated SRR exhibits a sensitivity of 25.3 MHz/1 ppt THF and 7 MHz/1 ppt acetone. Additionally, the solid block demonstrates response times of 6800 and 4200 s for swelling and deswelling, respectively, when in exposure to 25 ppt concentrations of THF and acetone. Overall, this study underscores the substantial potential of microwave resonators as versatile tools for investigating the physical changes in polymers during their interaction with gases, contributing to the understanding of polymer-gas interactions and opening avenues for further research and diverse applications.

Effect of different injection fluids scenarios on swelling and migration of common clays in case of permeability variations: a micromodel study

Swelling and migration of present clays make damage to the oil reservoirs due to low salinity waterflooding (LSWF) can induce serious problems in the case of oil recovery improvement and researchers are trying to solve this problem. The purpose of this work is to investigate the mechanism of two phenomena of swelling and migration clays in the porous media of a reservoir rock by injecting a different composition of LSWF using a glass micromodel and providing the appropriate composition and pattern of injection with the removal of damage. Proper water flooding design, application of efficient swelling inhibitors, and migration control are among the most important methods to overcome the problem of formation damage due to swelling and migration of clays. A series of static (bulk or bottle test) and dynamic tests were carried out using a micromodel with a coating of kaolinite and montmorillonite clays in the vicinity and injection of different low salt water compositions. The type and amount of these clays were selected based on the results of XRD and SEM mineralogical tests on real reservoir rock, FW and diluted FW, SW and diluted SW, solution of 1% zirconium oxychloride in 20 times diluted seawater (SI), and composition of nanofluid MgO, SiO2, and Al2O3 in 20 times diluted. In the studies conducted by the micromodel, only the images taken were used in the analysis of the mechanisms, but here, the input and output pressures of the micromodel were recorded with high-precision pressure transmitters, and by using the differential pressure, the permeability was calculated and the formation damage index was introduced. The overlap of the interpretation of the captured images and the changes of the numerical parameter of the damage index in all stages of injection of smart water composition was considered to evaluate the simultaneous and separate mechanisms of swelling and migration of clays. The results of the experiments in this research show that clay swelling has destructive effects on permeability, and migration due to the transfer of clays from the porous medium can have promising effects on reducing the damage index in some conditions. And it is necessary to use the swelling control compound during the flooding process, but the migration inhibitor compound is not always suitable. Gradual reduction of salinity is also introduced as a pattern to prevent swelling damage or clay migration.In general, in this study, the best design and fluid engineering for smart water injection with the least damage in the micromodel scale was presented.

Sequential Solid-Phase Microextraction with Biocompatible Coating Materials to Address Displacement Effects in the Quantitative Analysis

Solid-phase microextraction (SPME) is a simple and effective sample-preparation technique for the analysis of complex samples. However, sample matrices containing high concentrations of nonpolar substances or spiked analytes in free form can cause swelling, saturation, and/or competition phenomena in the coating material. This results in a displacement effect wherein polar analytes with low affinities for the solid coating material are displaced by nonpolar substances in the matrix or spiked analytes with a high affinity. Therefore, the quantitative analysis of polar analytes can be challenging, as the displacement effect causes non-linearity in the calibration curves. This paper presents a comprehensive investigation of the conditions under which the displacement effect occurs and how it influences the quantitative analysis of polar analytes. To remedy this issue, a sequential SPME strategy using two SPME blades with different selectivities is applied. SPME blades offer a large surface area and coating volume─and thus, greater extraction capacity─which may mitigate the displacement effect. In addition, the biocompatible coatings on the SPME blades are comprised of small amounts of sorbent particles embedded by a polyacrylonitrile (PAN) binder, which allows them to be directly immersed into complex matrixes such as biological and food samples, as the PAN acts as a barrier that prevents the adsorption of large macromolecules (e.g., cells and proteins). As such, a C18/PAN-coated blade was applied for the first extraction step, which significantly decreased the concentrations of nonpolar compounds in the sample. In the second step, a hydrophilic-lipophilic balanced (HLB)/PAN-coated blade was employed to extract the polar analytes and any remaining nonpolar analytes. The proposed sequential SPME strategy successfully enabled the quantitative determination of polar and nonpolar drugs of abuse with log P values ranging from 0.16 to 4.98 in biological matrices while also providing good linearities.