Flow Of Polymer Solutions Research Articles

The effect of rotationality on nonlinear shear flow of polymer melts and solutions

By considering the rotationality of shear flow, we distinguish between tube segments created by reptation before the inception of shear flow and those created during flow. Tube segments created before inception of shear flow experience both stretch and orientation, while tube segments created after inception of flow are not stretched, but are only aligned in the flow direction. Based on this idea, the Rotation Zero Stretch (RZS) model allows for a quantitative description of the start-up of shear flow and stress relaxation after step-shear strain experiments, in agreement with data of polystyrene long/short blends and corresponding polystyrene 3-arm star polymers investigated by Liu et al. (Polymer 2023, 281:126125), as well as the shear viscosity data of poly(propylene carbonate) melts reported by Yang et al. (Nihon Reoroji Gakkaishi 2022, 50:127–135). In the limit of steady-state shear flow, the RZS model converges to the Doi-Edwards IA model, which quantitatively describes the steady-state shear viscosity of linear polymer melts and long/short blends. The assumption of “non-stretching” of tube segments created during rotational flow is therefore in agreement with the available experimental evidence. Three-arm star polymers behave in a similar way as corresponding blends of long and short polymers confirming the solution effect of the short arm in asymmetric stars. The analysis of step-shear strain experiments reveals that stress relaxation is at first dominated by stretch relaxation, followed at times larger than the Rouse stretch relaxation time by relaxation of orientation as described by the damping function of the Doi-Edwards IA model. The RZS model does not require any nonlinear-viscoelastic parameter, but relies solely on the linear-viscoelastic relaxation modulus and the Rouse stretch relaxation time.Graphical

Anti-turbulent efficiency of oil-soluble polymer solutions and colloid systems flowing through cylindrical channel

Relevance. The use of anti-turbulent additives for transporting hydrocarbon liquids through main pipelines allows reducing significantly the energy consumption of pumping power stations. Aim. Comparative analysis of the anti-turbulent efficiency of high-molecular polymers and compositions of surfactants. Methods. Laboratory-scale experimentation aimed to study the flow of dilute polymer solutions and dispersed surfactant systems through a cylindrical channel of a turbulent rheometer. Results. The author has carried out the comparative experimental studies of the anti-turbulent efficiency of extremely dilute solutions of polymers and colloidal systems. The results were obtained that suggest a higher anti-turbulent efficiency of high-molecular-weight polymers compared to micellar surfactant systems. Solutions of high molecular weight polybutadiene and aluminum polyhydroxydicarboxylates in gasoline were used as samples for the experimental comparison of hydrodynamic efficiency. The paper describes the laboratory setup, on which the studies were carried out, and introduces the formulas used for quantitative calculations. The structure of polymer solutions and colloidal systems is considered and a theoretical explanation is given for the preferential use in industrial practice of high-molecular polymers in extremely low concentrations in real pipelines. It was found out that the mechanisms of degradation of antiturbulent properties of polymer solutions and dispersed surfactant systems are different. This is due to the difference in the structure of macromolar coils of polymer with an immobilized solvent and that of micelles from low molecular amphiphilic compounds. The paper introduces the arguments that explain the degradation of the antiturbulent properties of polymers not by the destruction of carbon-chain macromolecules, but by decomposition in a turbulent flow of the original large associates, consisting of a large number of chains, into individual and smaller macromolecular coils with an immobilized solvent.

Numerical investigation on the enhanced heat transfer characteristics of non-Newtonian viscoelastic fluids in microchannel with chip arrays

Elastic turbulence is an efficient heat transfer method at microscale. In this work, we conduct a systematic investigation on the flow and heat transfer performances of viscoelastic polymer solutions in microchannels with chip arrays by means of high-fidelity numerical simulations. Focusing on the effects of fluid elasticity [i.e. polymer relaxation time (λ)] and flow Reynolds number (Re), we find that the synergistic interplay between inertial and elastic forces is strategically exploited to amplify convection, thereby facilitating an enhanced heat transfer performance. For highly elastic fluid, the Nusselt number (Nu) can be improved by 76.13 % compared to that of less elastic fluid, while the pressure drop is reduced appropriately. In addition, as the fluid elasticity increases, the pressure drop decreases and eventually converges to a constant. In the zone of elastic turbulence, the fluid reinforces the convective heat transfer, which can be ascribe to the deformation of long-chain polymer molecules. Particularly, we consider the effect of temperature-dependent λ on the heat transfer performance. Our results demonstrate that the increased temperature-dependent λ decreases the value of Nu, and the variation between values of variable and constant λ is reduced with increasing Re or λ. Hence, in some cases of large fluid elasticity or high Re, it is possible to safely ignore the impact of temperature-dependent λ with an acceptable accuracy. The present work provides important insights into the enhanced heat transfer via elastic turbulence, which could guide the applications in the field of chip cooling.

Simulation of polymer solution slip motion and composite fiber fabrication in rotary jet spinning

Composite nanofibers are widely used as a novel nanomaterial in various fields, and the key technologies of preparation methods and equipment optimization have become the focus of research. Rotary jet spinning uses the centrifugal force generated by high-speed rotation to produce slip motion of two polymer solutions in the nozzle, and as the slip velocity increases, a rotating jet is eventually formed at the nozzle to eject the composite nanofibers. The slip motion of the polymer solution is one of the important factors affecting the rotating jet composite spinning, which directly affects the velocity distribution and flow stability of the polymer solution, and ultimately affects the morphology and quality of the composite nanofibers. By simulating the flow process of polymer solution inside the nozzle, the effect of slip motion on the flow of polymer solution is verified, which further illustrates that the rotational speed has the greatest influence on the preparation of composite nanofibers. Finally, PEO/PVA composite nanofibers were successfully prepared and collected by using a rotary jet spinning device in the range of 1500–3000 rpm, and the morphology and quality of the fibers were characterized and analyzed by scanning electron microscopy (SEM), which provided experimental bases for the simulation of the slip motion of the polymer solution and the study of composite fiber preparation.

Further insights into steady three-dimensional MHD Sakiadis flows of radiating-reacting viscoelastic nanofluids via Wakif’s-Buongiorno and Maxwell’s models

AbstractKeeping in mind the stress relaxation tendency of many viscoelastic multi-phase flows (e.g., polymer solution flows and transport phenomena of red cell suspensions within blood media), the present research investigation intends principally to develop a realistic model for revealing properly the aspects of reacting-radiating Maxwell nanofluids during their laminar boundary layer flows in the steady regime over a horizontal impermeable surface under a transversal magnetic influence. For this purpose, the principal leading differential formulation is derived theoretically by linking Wakif’s-Buongiorno approach with Maxwell’s model. By invoking fundamentally the general boundary layer assumptions and the passive control strategy for the nanoparticles, the governing PDEs’ formulation is simplified accordingly and then stated properly for the case of the convective heating condition at the impermeable bi-stretching surface. By executing a feasible non-dimensionalization technique, the monitoring ODEs’ system is achieved successfully, whose solutions are presented precisely in different illustrative scenarios using Richardson’s extrapolation method. After carrying out successfully several validating tests, it is demonstrated that the weakly viscoelastic feature has generally a slight delaying effect on the nanofluid motion. This dynamical weakening can be reinforced more with the generation of thermal energy by intensifying the external magnetic field source. Additionally, these physical factors show an intensifying influence on the surface drag forces. However, a dropping impression is seen for the local heat transfer at the contact surface. Contrary to the broadening impact of the radiative heat transfer as well as the convective heating and thermophoresis mechanisms on the thermal and mass boundary layer regions, it is witnessed that the first-order chemical reaction mechanism and Brownian’s motion exhibit a shrinking impact on the mass boundary layer region.

Role of viscoelasticity in the appearance of low-Reynolds turbulence: considerations for modelling.

Inertial effects caused by perturbations of dynamical equilibrium during the flow of soft matter constitute a hallmark of turbulence. Such perturbations are attributable to an imbalance between energy storage and energy dissipation. During the flow of Newtonian fluids, kinetic energy can be both stored and dissipated, while the flow of viscoelastic soft matter systems, such as polymer fluids, induces the accumulation of both kinetic and elastic energies. The accumulation of elastic energy causes local stiffening of stretched polymer chains, which can destabilise the flow. Migrating multicellular systems are hugely complex and are capable of self-regulating their viscoelasticity and mechanical stress generation, as well as controlling their energy storage and energy dissipation. Since the flow perturbation of viscoelastic systems is caused by the inhomogeneous accumulation of elastic energy, rather than of kinetic energy, turbulence can occur at low Reynolds numbers.This theoretical review is focused on clarifying the role of viscoelasticity in the appearance of low-Reynolds turbulence. Three types of system are considered and compared: (1) high-Reynolds turbulent flow of Newtonian fluids, (2) low and moderate-Reynolds flow of polymer solutions, and (3) migration of epithelial collectives, discussed in terms of two model systems. The models considered involve the fusion of two epithelial aggregates, and the free expansion of epithelial monolayers on a substrate matrix.

Multiplex vortex instability in the flow of non-Newtonian fluids through microcavity arrays

Complex fluids always possess obvious non-Newtonian properties that facilitate the occurrence and development of vortex instability in porous media, which is of critical significance in many natural and industrial processes. It is widely known that this flow instability is regulated by both fluid flow and solid structure. However, the quantitative understanding of how structural characteristics of porous space affect the evolution of vortex instability is still nascent, especially in the case of fluids with varying rheological properties. Herein, the flow of polymer solutions with distinct non-Newtonian properties through microcavity arrays is experimentally studied, by which we systematically explore the effect of structural parameters of the cavity array on vortex instability. We find that, for both Newtonian and shear-thinning fluids with negligible elasticity, the vortex evolution behavior in each cavity of the cavity array is identical to those in an isolated cavity. In contrast, for viscoelastic fluids, the vortex instability is visibly affected by cavity number and cavity–cavity interval, and this effect exhibits different forms when the fluid shear-thinning participates or not. Multiplex vortex instabilities are observed under these tested conditions. By multiplex, we mean the vortex formation dynamics and evolution patterns are diversified. These unusual evolution phenomena are then interpreted in terms of the interplay between the elongation and relaxation of polymers as they navigate among neighboring cavities. These results can help us to further understand the flow instability of complex fluids in porous media and evoke new strategies for microfluidic applications of efficient mixing.

Some experimental results for converging flow of dilute polymer solution

This paper presents the results of experimental studies of the flow of a dilute polymer solution in a converging pipe. Three geometries with restriction rates are considered: 2.41, 3.92, and 5.65. A water–glycerin solution of 0.1% polyacrylamide was used as a working fluid. Point velocity measurements are made by using the smoke image velocimetry technique, which previously was proved by the construction of velocity profiles corresponding to the laminar viscoelastic flow in a straight pipe. The influence of the Weissenberg number and the restriction rate of the channel on the velocity profiles are established for both transverse and longitudinal directions. For small Weissenberg numbers, the experimental results are compared with the numerical results obtained using the Giesekus and exponential form of Phan-Thien–Tanner rheological models. Three flow regimes are identified: flow without vortex, vortex enhancement, and divergent flow, which is consistent with published results on the abrupt contraction and converging flows. Vortex length for a wide range of Weissenberg numbers is well predicted by a logarithm function. Modified expression of stretch rate with location of detachment plane can predict the flow regimes and the onset of unsteady flow in converging channels.

A web of sticky strands: how localized stress controls spatio-temporal fluctuations in viscoelastic flows through a lattice of obstacles

Recent microfluidic experiments have evidenced complex spatio-temporal fluctuations in low-Reynolds-number flows of polymer solutions through lattices of obstacles. However, understanding the nonlinear physics of such systems remains a challenge. Here, we use high performance simulations to study viscoelastic flows through a hexagonal lattice of cylindrical obstacles. We find that structures of localized polymer stress – in particular birefringent strands – control the stability and the dynamics. We first show that, at steady state, strands act as a web of sticky flow barriers that induce channelization, multistability and hysteresis. We then demonstrate that a spontaneous destabilization of the strands drives the transition to unsteady flow with regimes of self-sustained oscillations, travelling waves and strand pulsations. We further show that these pulsations, which result from the destabilization of envelope patterns of stress with strands wrapped around multiple obstacles, are integral to the transition towards elastic turbulence in our two-dimensional simulations. Our study provides a new perspective on the role of birefringent strands and a framework for understanding experimental observations. We anticipate that it is an important step towards unifying existing interpretations of the nonlinear physics of viscoelastic flows through complex structures.

Theory of flow-induced covalent polymer mechanochemistry in dilute solutions

It is crucial to consider both solvent strain and strain rate when predicting mechanochemistry of polymer solutions in arbitrary flows.

Exploring multi-stability in three-dimensional viscoelastic flow around a free stagnation point

Fluid elements passing near a stagnation point experience finite strain rates over long persistence times, and thus accumulate large strains. By the numerical optimization of a microfluidic 6-arm cross-slot geometry, recent works have harnessed this flow type as a tool for performing uniaxial and biaxial extensional rheometry (Haward et al., 2023 [5,6]). Here we use the microfluidic ‘Optimized-shape Uniaxial and Biaxial Extensional Rheometer’ (OUBER) geometry to probe an elastic flow instability which is sensitive to the alignment of the extensional flow. A three-dimensional symmetry-breaking instability occurring for flow of a dilute polymer solution in the OUBER geometry is studied experimentally by leveraging tomographic particle image velocimetry. Above a critical Weissenberg number, flow in uniaxial extension undergoes a supercritical pitchfork bifurcation to a multi-stable state. However, for biaxial extension (which is simply the kinematic inverse of uniaxial extension) the instability is strongly suppressed. In uniaxial extension, the multiple stable states align in an apparently random orientation as flow joining from four neighbouring inlet channels passes to one of the two opposing outlets; thus forming a mirrored asymmetry about the stagnation point. We relate the suppression of the instability in biaxial extension to the kinematic history of flow under the context of breaking the time-reversibility assumption.

Transition to turbulence in viscoelastic channel flow of dilute polymer solutions

The transition to turbulence in a plane Poiseuille flow of dilute polymer solutions is studied by direct numerical simulations of a finitely extensible nonlinear elastic fluid with the Peterlin closure. The range of Reynolds number ( $Re$ ) $2000 \le Re \le 5000$ is studied but with the same level of elasticity in viscoelastic flows. The evolution of a finite-amplitude perturbation and its effects on the transition dynamics are investigated. A viscoelastic flow begins transition at an earlier time than its Newtonian counterparts, but the transition time appears to be insensitive to polymer concentration in the dilute and semi-dilute regimes studied. Increasing polymer concentration, however, decreases the maximum attainable energy growth during the transition process. The critical or minimum perturbation amplitude required to trigger transition is computed. Interestingly, both Newtonian and viscoelastic flows follow almost the same power-law scaling of $Re^\gamma$ with the critical exponent $\gamma \approx -1.25$ , which is in close agreement with previous studies. However, a shift downward is observed for viscoelastic flow, suggesting that smaller perturbation amplitudes are required for the transition. A mechanism of the early transition is investigated by the evolution of wall-normal and spanwise velocity fluctuations and flow structure. The early growth of these fluctuations and the formation of quasi-streamwise vortices around low-speed streaks are promoted by polymers, hence causing an early transition. These vortical structures are found to support the critical exponent $\gamma \approx -1.25$ . Once the transition process is completed, polymers play a role in dampening the wall-normal and spanwise velocity fluctuations and vortices to attain a drag-reduced state in viscoelastic turbulent flows.

ИССЛЕДОВАНИЕ РЕОЛОГИЧЕСКИХ СВОЙСТВ РАСТВОРОВ ПОЛИВИНИЛБУТИРАЛЯ В СМЕСИ МОНОМЕРОВ ТРИ(1-МЕТАКРИЛОКСИ-3-ХЛОРПРОПОКСИ-2-)ФОСФАТА И ГЛИЦИДИЛМЕТАКРИЛАТА

The method of rotation viscometry is used to study the rheological properties of various proportions of polyvinyl butyral solutions in tris(1-methacryloxy-3-chloropropoxy-2-) phosphate and glycidyl methacrylate. It is established that the dynamic viscosity of polymer solutions ranges from 101 to 3995 mPa∙s as a function of temperature and different proportions of the monomers.The polymer solution flow complies with a two-phase mechanical model comprising viscous as well as plastic and creep deformation. The analyzed polymers can be used as binders to produce polymer composites by vacuum and thermal vacuum infusion.

Rotation of a fibre in simple shear flow of a dilute polymer solution

The motion of a freely rotating prolate spheroid in a simple shear flow of a dilute polymeric solution is examined in the limit of large particle aspect ratio, $\kappa$ . A regular perturbation expansion in the polymer concentration, $c$ , a generalized reciprocal theorem, and slender body theory to represent the velocity field of a Newtonian fluid around the spheroid are used to obtain the $O(c)$ correction to the particle's orientational dynamics. The resulting dynamical system predicts a range of orientational behaviours qualitatively dependent upon $c\, De$ ( $De$ is the imposed shear rate times the polymer relaxation time) and $\kappa$ and quantitatively on $c$ . At a small but finite $c\, De$ , the particle spirals towards a limit cycle near the vorticity axis for all initial conditions. Upon increasing $\kappa$ , the limit cycle becomes smaller. Thus, ultimately the particle undergoes a periodic motion around and at a small angle from the vorticity axis. At moderate $c\, De$ , a particle starting near the flow–gradient plane departs it monotonically instead of spirally, as this plane (a limit cycle at smaller $c\, De$ ) obtains a saddle and an unstable node. The former is close to the flow direction. Upon further increasing $c\, De$ , the saddle node changes to a stable node. Therefore, depending upon the initial condition, a particle may either approach a periodic orbit near the vorticity axis or obtain a stable orientation near the flow direction. Upon further increasing $c\, De$ , the limit cycle near the vorticity axis vanishes, and the particle aligns with the flow direction for all starting orientations.

Macro–Micro-Coupled Simulations of Dilute Viscoelastic Fluids

Modeling the flow of polymer solutions requires knowledge at various length and time scales. The macroscopic behavior is described by the overall velocity, pressure, and stress. The polymeric contribution to the stress requires knowledge of the evolution of polymer chains. In this work, we use a microscopic model, the finitely extensible nonlinear elastic (FENE) model, to capture the polymer’s behavior. The benefit of using microscopic models is that they remain faithful to the polymer dynamics without information loss via averaging. Their downside is the computational cost incurred in solving the thousands to millions of differential equations describing the microstructure. Here, we describe a multiscale flow solver that utilizes GPUs for massively parallel, efficient simulations. We compare and contrast the microscopic model with its macroscopic counterpart under various flow conditions. In particular, significant differences are observed under nonlinear flow conditions, where the polymers become highly stretched and oriented.

Rheology mediates transition of vortex evolution patterns in microcavity flow of polymer solutions

Vortex instability in cavity flow is a fundamental component of microfluidic applications such as flow mixing, nanoparticle synthesis, and cell/particle manipulation. In contrast to Newtonian fluids, non-Newtonian fluids exhibit significantly different flow behaviors due to their non-linear flow dynamics. This study experimentally investigates the flow dynamics of polymer solutions with distinct rheological properties through a microcavity and quantifies the influence of the rheological degree on the evolution dynamics of vortices. We find three typical vortex evolution patterns in the cavity flow of polymer solutions and show that the rheological degree mediates the transitions among these patterns. The vortex evolution in the cavity flow of all polymer solutions tested in this study shifts from a basic increasing logistic function to one of three typical patterns as the polymer concentration increases. It is clarified that the pattern transition is related to the elasticity number and shear-thinning index of the fluids, and the phase difference between identical patterns is due to differences in the viscosity and elasticity of the fluids. These results extend our understanding of the vortex dynamics of complex fluids in cavity flow and provide theoretical guidance for enhancing the working efficiency of cavity-structured microfluidic applications using polymer solutions. The results of this study may also inspire developments in the flow regulation of drug delivery in blood through the vascular system.

Development of Novel Electrospun Fibers Based on Cyclic Olefin Polymer.

For the first time, a systematic study to investigate the electrospinnability of cyclic olefin polymer (COP) was performed. Different solvents and mixtures were tested together with different electrospinning parameters and post-treatment types to prepare bead-free fibers without defects. These were successfully obtained using a chloroform/chlorobenzene (40/60 wt.%) solvent mixture with a 15 wt.% COP polymer, a 1 mL/h polymer solution flow rate, a 15 cm distance between the needle and collector, and a 12 kV electric voltage. COP fibers were in the micron range and the hot-press post-treatment (5 MPa, 5 min and 120 °C) induced an integrated fibrous structure along with more junctions between fibers, reducing the mean and maximum inter-fiber space. When the temperature of the press post-treatment was increased (from 25 °C to 120 °C), better strength and less elongation at break of COP fibers were achieved. However, when applying a temperature above the COP glass temperature (Tg = 138 °C) the fibers coalesced, showing a mechanical behavior similar to a plastic film and a low elongation at break with a high strength. The addition of a high dielectric constant non-solvent, N,N-dimethylacetamide (DMAc), resulted in a considerable reduction in the COP fiber diameter. Based on the cloud point approach, it was found that the use of DMAc and the solvent chloroform or chlorobenzene improved the electrospinnability of COP polymer solution.

Hybrid Nanofluid Flow with Multiple Slips Over a Permeable Stretching/Shrinking Sheet Embedded in a Porous Medium

Including slip boundary conditions in the study involving the flow of foams, emulsions, polymer solutions, and suspensions over moving surfaces are crucial for real-life applications. The current study analysed the multiple slips effects on the magnetohydrodynamics (MHD) flow of Ag-CuO/water hybrid nanofluid past a permeable stretching/shrinking sheet embedded in a porous medium. Appropriate similarity variables are introduced for transforming the governing equations and boundary conditions into ordinary differential equations before being solved using the bvp4c solver. Dual solutions are yielded from the numerical computation of flow over a shrinking sheet, and the first solution is identified as stable through a stability analysis. It is found that the imposition of velocity, thermal, and mass slips promotes the reduction of momentum, thermal, and concentration boundary layer thickness, respectively. The hybrid nanofluid around the sheet is observed to flow at a different velocity from the sheet due to the imposition of velocity slip. Thermal and mass slips, meanwhile, obstruct the flow's ability to transport heat and mass. An increased suction parameter, however, can aid in enhancing the rates of heat and mass transfers.

Efekty lepkosprężyste w warunkach nawadniania kolektora szczelinowo-porowego cieczą wodno-polimerową

The work is devoted to the numerical simulation of the flow of simple and viscoelastic (polymer solution) fluids through a fracture by using polymer solutions for enhanced oil recovery from a reservoir. Polymer solutions have viscoelastic properties. Therefore, when polymer solution flows through the slot, we use the well-known Maxwell’s fluid model with the Jaumann derivative to evaluate deformation characteristics of the flow (stream functions, distributions of the longitudinal velocity gradient and normal stress) resulting in the manifestation of abnormal (compared with the behaviour of the ordinary fluid) effects. The case of slow flow is considered. In this case, the inertial terms can be neglected, the velocities, stresses, and stream functions can be written as the decomposition by Weisenberg number, and we can assume that the Weissenberg number is less than one. The determined regularities of viscoelastic (polymer solution) liquid behaviour with longitudinal velocity gradient and the elastic deformations effects manifested in this case have a decisive meaning in understanding the mechanism of anomalously high oil recovery capacity of a reservoir by using water-polymer flooding of the fractured-porous reservoir. Understanding the nature of the effects of elastic deformations under the conditions of water-polymer flooding of the fractured-porous reservoir enables hydrodynamic calculations of the optimal flow of the polymer solution. One of the main issues that need to be solved when developing the technology for increasing oil recovery from formations using polymer solutions is to determine the optimal flow regime in the fractured-porous reservoir. The calculation results verify the ideas obtained from the experimental solution of this problem concerning the strain-stress state of polymer macromolecules (liquid elements) during polymer flow in the inlet area of the fracture in the oil reservoir and confirm the possibility of using numerical analysis of convergent polymer flow for calculating longitudinal velocity gradients in the inlet area of the fracture and can also serve as additional substantiation of the proposed earlier mechanism for increasing oil recovery from reservoirs by using polymer solutions.

Analysis and Prediction of Electrospun Nanofiber Diameter Based on Artificial Neural Network

Electrospinning technology enables the fabrication of electrospun nanofibers with exceptional properties, which are highly influenced by their diameter. This work focuses on the electrospinning of polyacrylonitrile (PAN) to obtain PAN nanofibers under different processing conditions. The morphology and size of the resulting PAN nanofibers were characterized using scanning electron microscopy (SEM), and the corresponding diameter data were measured using Nano Measure 1.2 software. The processing conditions and corresponding nanofiber diameter data were then inputted into an artificial neural network (ANN) to establish the relationship between the electrospinning process parameters (polymer concentration, applied voltage, collecting distance, and solution flow rate), and the diameter of PAN nanofibers. The results indicate that the polymer concentration has the greatest influence on the diameter of PAN nanofibers. The developed neural network prediction model provides guidance for the preparation of PAN nanofibers with specific dimensions.