Heat flow in polymers under high-pressure conditions is essential for a range of applications, from aerospace and deep-sea engineering to common lubricants. However, the complex relationship between pressure, P, the thermal transport coefficient, κ, and polymer architecture poses substantial challenges to both experimental and theoretical investigations. In this work, we study the pressure-dependent thermal transport properties of a widely used commodity polymer-poly(methyl methacrylate)-using a combination of all-atom molecular dynamics simulations and semi-analytical approaches. We report both classical and quantum-corrected estimates of κ, both of which show an increase with increasing pressure P. The quantum-corrected approach, which is directly comparable to experiment, reveals that as the pressure increases from 1 atm to 10GPa, κ rises by nearly a factor of four, from 0.21 to 0.80Wm-1K-1. By comparison, experimental measurements report an increase from 0.20 to 0.55Wm-1K-1 over the same pressure range. To better understand the mechanisms behind this increase, we disentangle the contributions from bonded and nonbonded monomer interactions. Our analysis shows that nonbonded energy-transfer rates increase by a factor of six over the pressure range, while bonded interactions show a more modest increase-about a factor of three. This observation further consolidates the fact that nonbonded interactions play the dominant role in dictating the microscopic heat flow in polymers. These individual energy-transfer rates are also incorporated into a simplified heat diffusion model to predict κ. The results obtained from different approaches show internal consistency and align reasonably with available experimental data. In addition, some data for polylactic acid are presented.

Abstract Fine-tuning electrospun nanofibers is crucial for producing high-quality fibers. Taguchi Design of Experiment (DOE), along with various other computational techniques, has been used to optimize the electrospinning parameters of different polymers. Taguchi DOE has proven effective in optimizing electrospun nanofibers because it reduces the number of trials needed. In this study, the electrospinning parameters of poly (butylene adipate-co-terephthalate) (PBAT) were optimized and quantified using the Taguchi-based Response Surface Methodology (RSM) approach. The average fiber diameters were measured from Field Emission Scanning Electron Microscopy (FESEM) images using ImageJ software. Within the tested range of parameters and levels, the Analysis of Variance (ANOVA) study identified polymer concentration and flow rate as the most significant factors that influenced the fiber diameter. Polymer concentration accounting 56.94% of the variation, while Flow Rate (FR) accounts for 20.82%. The optimal parameter levels were predicted to be 10 wt.% polymer concentration, 1 mL/h flow rate, 18 kV voltage, and a distance from tip to target of 15cm, which yielded fibers with an average diameter of 231 nm and an accuracy of 88.61%. Overall, the results demonstrate that Taguchi DOE, coupled with RSM, is a reliable and efficient method for identifying the optimal parameter combinations to produce uniform, fine PBAT nanofibers intended for biomedical applications.

Mold temperature control critically influences injection molding, impacting product quality and production efficiency. High mold temperatures enhance surface quality but prolong cooling, increasing cycle time, whereas low temperatures cause defects like weak weld lines and incomplete filling. This study aims to reduce cycle time and enhance tensile strength of thin-wall injection-molded products by developing an innovative mold temperature control strategy using induction heating to preheat mold inserts. The primary objective is to eliminate in-cycle heating delays while ensuring optimal mold temperatures for improved mechanical properties. However, the power consumption of this process significantly increases due to the energy-intensive nature of induction heating. Research involved numerical simulations and experimental validation. COMSOL Multiphysics analyzed thermal and electromagnetic interactions, modeling temperature distributions for heating distances (G = 5, 10, 15 mm) and times (1–8 s). Moldex3D simulated polymer flow behavior, assessing filling capabilities for materials (PC, ABS, PA6, PP). Experiments employed the external induction heating with rotational structure for mold temperature control system (Ex-IHRS), featuring a rotational mechanism to swap preheated inserts, with real-time temperature measurements via sensors and infrared cameras at points S1, S2, and S3. Tensile strength tests evaluated mechanical performance. Rapid heating within 5–8 s maintained stable mold temperatures without extending cycle time, outperforming traditional methods like resistance or steam heating. Significant tensile strength improvements occurred, with PC increasing from 111.9 MPa to 123 MPa after 6 s of heating, ABS reaching 91.3 MPa after 4 s, PA6 rising from 55.4 MPa to 62.8 MPa, and PP improving from 41.3 MPa to 47.3 MPa. Enhanced weld line integrity and reduced frozen layers drove these gains, minimizing defects in thin-wall components. Simulations showed less than 5% deviation from experimental data, validating the approach’s accuracy. Despite higher power consumption, this induction heating strategy optimizes production efficiency and enhances product quality, offering a promising advancement for thin-wall and microinjection molding applications.

Composite fiber membranes fabricated via rotational-force spinning have become widely applied in biomedicine, energy, and environmental fields owing to their excellent properties. Improving their functional performance and fabrication quality has therefore become a key research focus. Rotational-force spinning is a simple and efficient technique in which high-speed motor rotation ejects polymer solutions from a nozzle to form fibers. However, the influence of polymer flow behavior within the nozzle on fiber formation remains insufficiently understood. In this study, the flow characteristics within the micro-triangle and the liquid-liquid slip phenomenon were investigated using a core-shell spinning device. Numerical simulations were conducted to analyze velocity differences between two polymer solutions under varying motor speeds and polyoxyethylene (PEO) concentrations. The results demonstrate that increasing PEO concentration and motor speed decreases slip velocity, thereby stabilizing the flow. Complementary experiments were performed using PEO and hydroxyethyl cellulose (HEC) solutions under controlled conditions. Mechanical testing, scanning electron microscopy (SEM), and thermogravimetric analysis (TG) were employed to assess the mechanical performance, thermal stability, morphology, and fiber diameter distribution of the composite membranes. Overall, the findings highlight the critical role of liquid-liquid slip in fiber formation and provide valuable insights for the controlled fabrication of high-quality composite fibers, offering a foundation for future research.

Electrospinning is a technique that utilizes high voltage to produce polymer nanofibers with adjustable morphology, extensive surface area, and interconnected porosity, rendering them highly suitable for biomedical applications. A prominent application of these fibers is in localized drug delivery, where they enable prolonged and targeted release. This review discusses various ELS techniques, each offering distinct advantages for incorporating small molecules, proteins, nucleic acids, either during the fiber formation process or through subsequent processing. Critical formulation factors such as polymer type, solvent, molecular weight, flow rate, and environmental conditions significantly influence fiber properties and drug release patterns. The review also highlights material selections and therapeutic applications in areas such as ocular, oral, dermal, and probiotic delivery, as well as in wound healing and tissue engineering.

Modeling and analysis of non-isothermal viscoelastic polymer flow in fused filament fabrication

Processing ultra-high molecular weight polymers presents significant experimental challenges due to their high viscosity, which requires elevated shear rates and consequently increases energy demands. Here, we explore the role of the geometry of nanoparticles- spheres, rods, and tetrapods - in controlling the effective viscosity of polymer nanocomposites. Intriguingly, our combined experiments and molecular dynamics simulations reveal a significant decrease in the viscosity of composites with tetrapod nanoparticles, without compromising mechanical or thermal integrity, unlike sphere and rod, which exhibit minimal impact on the viscosity at the same level of loading. We show that the inner curvatures of the nanotetrapods impose strong physical confinement introducing an entropic cost for polymers to access this space. The inaccessible volume creates polymer packing frustration around nanotetrapod surfaces, which, in turn, increases their mobility and decreases the overall viscosity of the composite. Nanotetrapods prove to be effective flow promoters while preserving good dispersion within a polymer melt, offering significant potential for advanced polymer processing applications.

Tracking polymer orientation and flow leading to unsteady cross-slot flow: High-speed imaging and modeling

In turbulent pipe flows, drag-reducing polymers are commonly used to reduce skin-friction drag; however, predicting this reduction in industry applications, such as crude oil pipelines, remains challenging. The skin-friction coefficient ( $C_f$ ) of polymer drag-reduced turbulent pipe flows can be related to three dimensionless parameters: the solvent Reynolds number ( $Re_s$ ), the Weissenberg number ( $Wi$ ) and the ratio of solvent viscosity ( $\eta _s$ ) to zero-shear-rate viscosity ( $\eta _0$ ), denoted as $\beta$ . The function that relates these four dimensionless numbers was determined using experiments of various pipe diameters ( $D$ ), flow velocities ( $U$ ) and drag-reducing polyacrylamide solutions. The experiments included measurements of streamwise pressure drop ( $\Delta P$ ) for determining $C_f$ , and measurements of shear viscosity ( $\eta$ ) and elastic relaxation time ( $\lambda$ ). This experimental campaign involved 156 flow conditions, each characterised by distinct values for $C_f$ , $Re_s$ , $Wi$ and $\beta$ . Experimental results demonstrated good agreement with the relationship: $C_f^{-1/2} = \widehat {A}\log _{10}(Re_sC_f^{1/2})+\widehat {B}$ , where $\widehat {A} = 27.6(Wi \beta )^{0.346}$ and $\widehat {B} = 122/15-58.9(Wi \beta )^{0.346}$ . Based on this relationship, onset and maximum drag reduction are predicted to occur when $Wi \beta$ equals $3.76 \times 10^{-3}$ and $3.40 \times 10^{-1}$ , respectively. This function can predict $C_f$ of dilute polyacrylamide solutions based on predefined parameters (bulk velocity, pipe diameter, density, solvent viscosity) and two measurable rheological properties of the solution (shear viscosity and elastic relaxation time) with an accuracy of $\pm 9.36$ %.

Effect of aspect ratio on thermal characteristics, including viscous dissipation, in pressure-driven flow of a third-grade fluid through a rectangular channel is considered. The walls of the channel are assumed to be maintained at uniform temperatures (the special case of the same upper and lower wall temperatures is also discussed). Earlier reported studies on heat transfer characteristics of third-grade fluids considered flow through large parallel plates. In actual case, however, flow occurs in channels and the parallel plate approximation results are only applicable near the central core of the channel, where, influence of the lateral walls are less. In view of this, in the present study, effect of the lateral walls are included in the governing equations and the results obtained are realistic from practical considerations. The effect of viscous dissipation is included in the energy conservation equation, and the influence of the aspect ratio is considered in the momentum and energy conservation equations. Momentum and energy conservation equations are formulated and reduced to their dimensionless forms by introducing suitable dimensionless variables and parameters. Entropy generation equation, including aspect ratio effect is deduced. The dimensionless governing equations are solved by applying the least square method (LSM), and the effects of parameters like aspect ratio, Brinkmann number, and non-Newtonian parameter on temperature, wall heat transfer, and velocity are examined. LSM is a semi-analytical technique which possesses a mixed characteristics of analytical and numerical methods and generates very accurate results. The results are validated with the results of least square homotopy perturbation method. It is important to note that heat transfer is reversed (from the upper wall to the surrounding cooling medium) at a distance of nearly 50% from the lateral walls) with rise in Brinkman number. In the region from lateral walls up to this limit (50% from the walls) heat is transferred from the upper wall to the flowing fluid. Results of the study can serve to be useful for design and analysis of heat exchangers in which lubricating oils, polymers flow takes place.

ABSTRACTWhen evaluating single‐screw extruder design and troubleshooting in plant settings, many times the production issue is black specks and gels in the product. It is necessary to determine if the metering section of the screw is in control by accurately predicting the flow rates. The metering section temperature calculation is accurately predicted to determine polymer viscosity. These calculations are strongly affected by the screw channel depth, the role of the different components of the screw, and the shear thinning characteristics of the polymer. It is a goal of this paper to bring these issues together in one publication so the practitioner may determine how he/she wishes to proceed as a design evaluator or troubleshooter. The historic Barrel Rotation theory is compared with Screw Rotation theory for polymer flow and temperature rise, documenting analysis tradeoffs. The issue of how polymer shear thinning affects the predictions of flow and pressure drop in the screw metering section is also addressed. A set of experiments on a specially designed glass‐barrel extruder should help the troubleshooter understand how each element of the screw affects the pumping capacity and their effect on predictions of screw residence time and chaotic mixing.

This study focuses on the performance evaluation of silicone rubber (SR) nanocomposites fabricated using industry-standard molding and thermal compression techniques. Nanocomposite insulator specimens were synthesized with nano-TiO2 doping concentrations of 0%, 1%, 3%, 5%, and 7% by weight. The DC resistance measurements of the nanocomposites exhibited a distinct range from 211.33 GΩ to 161.16 GΩ with increasing nano-filler content. Notably, a 7% nano-TiO2 loading yielded the highest dielectric constant at both 0 Hz and 2 MHz. Partial discharge (PD) testing indicated that the 5% nano-TiO2 composite exhibited a 24.1% increase in inception voltage, signifying improved resistance to electrical stress due to the enhanced charge distribution and stabilization effects introduced by nano-filler incorporation. The observed variations in PD inception voltage were attributed to the interplay between doping levels and local charge diffusion dynamics, which modified the electric field distribution. Thermal stability assessments revealed significant modifications in degradation kinetics upon TiO2 nanoparticle inclusion, as determined via thermogravimetric analysis (TGA). Differential scanning calorimetry (DSC) demonstrated a 38% reduction in polymer flow rate between − 50 °C and 100 °C, indicative of endothermic transitions. Mechanical property evaluations showed that the 5% TiO2-filled composite exhibited the lowest tensile force durability (41.2 N) and tear strength (18.72 kN/m). A comprehensive performance assessment highlights the enhanced operational reliability and longevity of HTV-SR nanocomposites, making them viable candidates for outdoor high-voltage insulator applications.

ABSTRACTA novel method was developed to characterize thermal contact resistance (TCR) at the polymer/mold interface under injection molding conditions. The study emphasizes the design and validation of an experimental setup that accounts for variations in material type, surface finish, and process conditions. The goal is to establish a model for computing variable TCR values, moving beyond the conventional assumption of constant resistance. This advancement aims to improve the accuracy of temperature distribution predictions in injection molding simulations, which are critical for modeling polymer flow, shrinkage, and warpage. TCR measurements were performed using a specialized compression molding setup comprising two stack configurations with differing numbers of identical mold‐polymer interfaces. Comparing the heat transfer behavior between the two stacks enables a precise calculation of TCR. Statistical techniques, including multivariate regression and principal component analysis, identified polymer temperature as the most influential factor affecting TCR. Measured values ranged from 0.0003 to 0.0015 m2·K/W under the tested conditions. The thermal conductivity of the mold metal exhibited a moderate influence, while surface roughness, polymer thermal conductivity, and part thickness had minimal effects on thermal performance.

This paper presents an experimental study of a novel automated manufacturing process that integrates cold embossing to add complex features, such as micro-Fresnel lens designs, onto a 3D-printed ABS polymer component. The research demonstrates that precise control over process parameters, including embossing time (Et) and velocity (Ev), is critical for successful feature replication. Gloss analysis confirmed that surface softening as a crucial prerequisite for embossing was successfully achieved using a vapour smoothing (VS) chamber that was developed and optimised for the process. High-speed automation using a 6-axis KUKA robot allowed 48 embosses to be completed in just over one minute, highlighting its efficiency over conventional hot embossing (HE) methods. Results showed that an Et (0.01 s) prevented feature replication as there was insufficient time to allow for polymer flow, while an optimal Et (0.1 s) produced high-quality embosses across all test segments. Additionally, this study identified that while insufficient cycle times hinder polymer flow, extended durations can lead to surface hardening, prohibiting replication. These findings pave the way for integrating Diffractive Optical Elements into 3D-printed parts, potentially enhancing precision, functionality, and productivity beyond the capabilities of standard 3D-printing processes.

Abstract Viscoelastic fluid flows are widely described by elastic dumbbell models such as Oldroyd-B and FENE-P. However, these constitutive equations can yield significantly different predictions, which may contradict experimental observations. In this work, we analyze the fully developed flow of a viscoelastic fluid in a straight channel and present a theory based on the lubrication approximation for calculating the elastic stresses and flow rate for four elastic dumbbell models, including various microstructurally inspired terms. We compare the predictions of different models and elucidate the impact of (i) the finite extensibility, (ii) conformation-dependent friction coefficient, and (iii) conformation-dependent non-affine deformation on the polymer stresses, velocity, and flow rate. We demonstrate that including all three microstructurally inspired terms in a constitutive equation can significantly affect the response of a viscoelastic fluid even in a fully developed flow, thus highlighting their potential necessity for accurate modeling of viscoelastic channel flows with mixed kinematics.

Water injection is the most widely used secondary recovery method, but its low viscosity limits sweep efficiency in heterogeneous carbonate reservoirs, especially when displacing heavy crude oils. Polymer flooding overcomes this by increasing the viscosity of the injected fluid and improving the mobility ratio. In this work, we compare three biopolymers (i.e., Xanthan Gum, Scleroglucan, and Guar Gum) using a core flood test on Indiana Limestone with 16-19% porosity and 180-220 mD permeability at 60 °C and 30,905 mg/L of salinity. We injected solutions at 100-1500 ppm and 0.5-6 cm3/min to measure the Resistance Factor (RF), Residual Resistance Factor (RRF), in situ viscosity, and relative injectivity. All polymers behaved as pseudoplastic fluids with no shear thickening. The RF rose from ~1.1 in the dilute regime to 5-16 in the semi-dilute regime, and the RRF spanned 1.2-5.8, indicating moderate, reversible permeability impairment. In-site viscosity reached up to eight times that of brine, while relative injectivity remained 0.5. Xanthan Gum delivered the highest viscosity boost and strongest shear thinning, Scleroglucan offered a balance of stable viscosity and a moderate RF, and Guar Gum gave predictable but lower viscosity enhancement. These results establish practical guidelines for selecting polymer types, concentration, and flow rate in reservoir-condition polymer flood designs.

A novel model of polymer flow with processing aid (PPA) is developed to predict the start-up of pressure transient in capillary flow. The gradual coating dynamics of the die surface with PPA are predicted with the pressure transient and the gradual change in polymer slip velocity. This model includes several physical parameters that can lead to developing/identifying appropriate polymer processing aids and optimizing them in terms of concentration, performance, and operational conditions. The model is validated using experimental results to address the effects of die length, apparent shear rate, and PPA (fluoropolymer) concentration on the flow dynamics and melt fracture performance of PPAs.

Abstract Cold sintering enables the fabrication of ceramic matrix‐polymer composites through low temperature densification by employing a transient solvent under moderate pressure to drive diffusional processes. This innovative processing allows the integration of seemingly incompatible components in a single step to provide new possibilities for tailored multifunctional composites. However, the microstructure of these cold‐sintered composites is controlled by a complex interplay between solubility, evaporation, plastic flow and compaction of the inorganic particles. Pressure solution creep process densifies the inorganic particulates through the dissolution, transport and precipitation at the interfaces of the particulates under applied stresses and slightly elevated temperatures. Through selection of ceramic (gypsum and MgO) and polymer (polypropylene and polymethyl methacrylate) materials that differ in densification mechanisms, new insights are gleaned about how material selection impacts the morphology and mechanical behavior of cold‐sintered composites. Cold sintering of gypsum leads to a well‐densified ceramic, while rapid hydration of MgO leads to minimal densification of the inorganic phase. This difference in ceramic densification affected characteristics of the composites, including the polymer distribution, phase connectivity, and mechanical performance. The high compaction of gypsum during cold sintering facilitated polymer infiltration between particles to form co‐continuous phases on cold sintering. In contrast, the limited densification of MgO did not promote flow of polymer and produced isolated polymer domains that led to poor mechanical performance in the cold sintered composites. Although the cold sintering temperature impacts the rheology of the polymer phase to alter the infiltration of the plastic between the inorganic phase during processing, the primary factor dictating the formation of co‐continuous phases and corresponding good mechanical performance is signficant densification of the ceramic during cold sintering. The processing temperature and material interactions between the polymer and inorganic phases also impact the morphology of cold sintered ceramic‐polymer composites. The combination of materials selection and cold sintering processing parameters provide routes to control morphology for engineering composites with cold sintering with a key heuristic identified here that the inclusion of the polymer cannot overcome poor sintering of the ceramic and densification (compaction) during cold sintering appears to drive the flow and developed connectivity of the polymer phase.

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 222035, “Selecting Injected Viscosity in Polymer Flood Projects: A Controversial and Critical Question,” by Eric Delamaide, SPE, IFP Technologies. The paper has not been peer reviewed. _ Polymer injection is now a mature enhanced-oil-recovery process, and numerous large-scale expansions are currently underway while new projects are being designed globally. Some practitioners advocate injecting very high viscosities, while others advocate the opposite. The paper explains why the question of polymer-viscosity selection remains without a clear answer and describes the arguments of both positions using case studies. Paper Scope The complete paper is a comprehensive review of global projects in which the issue of injected-polymer viscosity has been explored by the author in a variety of scenarios and contexts. Because of the detailed nature of the review of these studies, this portion of the paper, which makes up its majority, is not included here; instead, the discussion and conclusions reached by this paper’s author are preserved and included in this synopsis. The aspects of the issue detailed in the complete paper include the following: - Polymer viscosity and recovery factor ---- Microscopic displacement efficiency ---- Areal sweep efficiency ---- Vertical sweep efficiency --------- Multilayer reservoirs with crossflow --------- Multilayers with no crossflow ---- Field experience --------- Monolayer reservoirs --------- Multilayer reservoirs with crossflow --------- Multilayer reservoirs without crossflow - Concentration and adsorption - Injectivity and fracturing ---- When fracturing is not desired/expected ---- When fractures are desired/expected ---- Field cases - In-depth polymer flow ---- Field cases - Surface facilities issues - Operations Discussion This paper discusses the effect of injected-polymer viscosity on various aspects of a project, from recovery to surface facilities. The review includes both theoretical arguments and practical field experience because these do not always align. In theory, increasing polymer viscosity to achieve a favorable mobility ratio is preferable and would lead to the highest recovery, particularly in the case of multilayered reservoirs with crossflow. Increasing polymer viscosity to achieve mobility ratios below 0.1, however, seems difficult to justify. In multilayered reservoirs with no crossflow, vertical sweep efficiency will, in practice, be limited, even with an infinite polymer viscosity, unless significant volumes of polymer are injected. Finally, field experience has shown that increasing polymer viscosity does not always result in increased recovery. In the case of polymer injection, theory can be misleading and should be considered with caution. Discussion on viscous crossflow, and field experience in heavy oil, has shown hidden complexity. Increasing injected-polymer viscosity in heavy-oil fields, as suggested by some authors, ignores the economic realities of heavy-oil operations. Heavy oil is sold at a significant discount compared with West Texas Intermediate, and reducing operating costs is paramount. Increasing injected viscosity did not guarantee an increase in recovery as shown in Tambaredjo and a field case in Saskatchewan, though polymer cost increased significantly. In addition, in western Canadian fields, injection pressure is regulated—injecting 0.5 pore volumes can take almost 20 years. Thus, many factors must be considered besides theory, which is what operators are doing.

Pore-network modeling of polymer flow in porous media