ABSTRACT Mechanically robust superhydrophobic coatings are essential for applications where surface wear and contaminants gradually diminish water repellency. This study presents a robust bilayer coating composed of reduced graphene oxide (rGO) and polytetrafluoroethylene (PTFE), applied on carbon fiber‐reinforced composite (CFRC) substrate via spray‐coating method. The bilayer design comprises a conductive epoxy–rGO base layer that generates heat via Joule heating and a superhydrophobic rGO–PTFE upper layer that prevents water penetration and provides self‐cleaning properties. The optimal composition (1 wt% rGO + 5 wt% PTFE) exhibits a water contact angle of 153° and a sliding angle of 8°, indicating adherence to the Cassie–Baxter wetting model. After undergoing 100 cycles of sandpaper abrasion and 3 M tape peel tests, the coating retains nearly superhydrophobic properties (CA > 148°). This outperforms previous systems that typically fail after 30 to 50 cycles. The coating demonstrates excellent efficacy in self‐cleaning from graphite powder contamination.

ABSTRACT Polystyrene (PS) is a widely used packaging material, but its recycling for food‐contact applications is still limited, partly due to a lack of quantitative data on the migration behavior of potential contaminants. This study investigates the diffusion behavior of organic compounds in high‐impact polystyrene (HIPS) under vacuum and controlled thermal conditions. Virgin HIPS was intentionally spiked with five organic compounds covering a broad range of molecular weights and polarities. The contaminated material was pressed to plates with various thicknesses which were then exposed to defined combinations of temperature and residence time in a vacuum oven. Initial and residual concentrations were quantified using gas chromatography, and the data were used to calibrate a one‐dimensional diffusion model based on Fick's second law including Arrhenius‐type temperature dependency. The results confirm that the model adequately describes the experimental data and allows reliable estimation of diffusion coefficients. Clear correlations were observed between the diffusion coefficients and the molecular weight, polarity, and volatility (boiling point) of the surrogates. These findings provide fundamental parameters for predicting diffusion‐driven mass transfer in HIPS processing and establish a scientific basis for future risk assessments of recycled PS in applications requiring particularly high purity standards, such as food‐contact materials.

ABSTRACT Simulation of solid conveying, melting, and melt flow in single‐screw extrusion (SSE) is essential for understanding how polymer properties, processing parameters, and screw geometry influence pressure development and throughput. Conventional numerical approaches typically model different extrusion zones separately, leading to discontinuities in the description of material evolution along the screw. In this work, a unified continuum model is developed to represent all functional regions of SSE within a single computational framework. The model combines continuum descriptions of granular flow with enthalpy‐based phase‐change formulations. Two field variables, melt fraction and solid‐bed porosity, are introduced to characterize the evolving material state, enabling a continuous transition from loosely packed pellets to fully molten polymer without explicit zone switching. Granular resistance, wall interactions, and mixture‐averaged material properties are incorporated to allow the conservation equations of mass, momentum, and energy to be solved consistently using a finite‐element method. Model predictions are evaluated against published measurements of solids‐conveying throughput and full‐process pressure and throughput, as well as extrusion experiments using Poly‐Ether‐Ether‐Ketone (PEEK) pellets with different shapes. The results demonstrate that the model provides physically reasonable predictions of pressure evolution and throughput under different processing conditions.

ABSTRACT Since the introduction of green tires for Michelin in 1992, the dispersion of silica has remained a hot topic in both academic and engineering research. Si‐69 is a silane coupling agent used in rubber materials to improve the dispersion of silica. When the Si‐69 content is too low, dispersion improvement is limited; when the content is too high, it can have a negative impact on the material. In this paper, experiments were designed to verify the properties of the materials by varying the amount of Si‐69. The experimental results show that the dispersion of filler is significantly improved and the heat build‐up is significantly reduced with the increase of Si‐69 at 0–4 phr. At 6–8 phr, the mechanical properties decreased significantly due to the high cross‐linking density. This paper investigates the heat build‐up of composites with varying Si‐69 content through finite element simulation, with the simulated results consistent with experimental findings. Unlike the previous ones, the simulation in this paper does not involve the development of complicated subroutines, and it can better reflect heat build‐up trend of different Si‐69 dosage, which is a simple, convenient and cost‐effective method. This study started from simulation, established a functional relationship between E ″/ E * 2 and the dosage of Si‐69, and performed an extremum analysis on the function to determine the optimal dosage, thereby achieving forward development of composite materials. This integrated approach coupling simulation calculations with functional processing algorithms has established a rigorous quantitative calculation framework for the design of low heat‐generating rubber products. Beyond the dosage optimization of silane coupling agent Si‐69, this method is also applicable to the quantitative optimization of a broad spectrum of other reinforcing fillers (e.g., carbon black, silica) and processing additives.

ABSTRACT Real‐time sensing has become increasingly important in injection molding for understanding melt behavior and improving part quality. Cyclo‐olefin copolymer (COC) is widely used in high‐precision optical components and medical devices due to its excellent optical clarity, low birefringence, and dimensional stability, particularly under cold‐climate and low‐temperature operating conditions, where conventional amorphous polymers may suffer from increased residual stress and optical distortion. Ensuring stable processing and reliable performance of COC components in such environments therefore requires enhanced process monitoring and control strategies. In this study, in‐mold pressure sensing combined with birefringence analysis was employed to investigate the relationship between pressure evolution and residual stress in injection‐molded COC components. Two pressure sensors were embedded at the gate and at the cavity center to characterize pressure drop behavior and a pressure‐derived viscosity index under near‐gate and far‐gate configurations. By integrating real‐time pressure data with optical stress analysis, this work demonstrates how smart sensing strategies can be used to ensure product quality, dimensional precision, and optical performance in injection‐molded COC parts. The results show that the cavity pressure drop was approximately 64% lower than the gate pressure in the near‐gate configuration, with a similar but reduced trend observed in the far‐gate configuration. Consistent variations were also identified in the viscosity index. An increased gate‐to‐cavity pressure drop was found to correlate strongly with improved geometric precision, reflected by reduced out‐of‐roundness, and with lower internal residual stress as revealed by birefringence patterns. Increasing mold and melt temperatures improved flow relaxation but introduced trade‐offs in dimensional stability between regions near and far from the gate. These findings demonstrate the coupled effects of pressure evolution and thermal conditions on part quality and highlight the importance of holistic process optimization in precision injection molding.

ABSTRACT Oil‐paper insulation, as the main dielectric medium in transformers, directly affects the operational safety and stability. To enhance the lipophilicity properties of cellulose‐based insulating paper, a palmitic acid side‐chain grafted polyimide resin (TPI‐PA) was designed and synthesized in this study, and the TPI‐PA insulating paper was fabricated via electrospinning. Through Fourier transform infrared spectroscopy (FT‐IR) and nuclear magnetic resonance (NMR) characterization and analysis, it was confirmed that the lipophilic palmitic acid long‐chain structure had been successfully grafted to the polyimide main chain. The performance test results show that when the palmitic acid content is 15 wt%, the AC breakdown field strength reaches 68.65 kV mm −1 , which is about 70.87% higher than that of the traditional lignocellulosic paper. By virtue of molecular energy band structure calculations, high‐temperature DC conductivity measurements, and surface potential decay characterizations, the TPI‐PA insulating paper/transformer oil composite system is demonstrated to suppress carrier migration dynamics and mitigate internal space charge accumulation, thereby achieving a pronounced enhancement in the electrical performance of the composite insulation assembly. Furthermore, the polyimide‐based insulating paper reinforces the wettability at the oil‐paper interface, which not only curtails the propensity for partial discharge but also endows the insulating paper with remarkably improved lipophilicity. Collectively, this work furnishes novel insights into the material optimization strategy for oil‐paper composite insulation systems in transformers, which is of considerable significance for the advancement of high‐performance insulating materials in power equipment.

ABSTRACT Polylactic acid (PLA) is a widely used biodegradable polymer due to its non‐toxicity, good processability, and remarkable properties although its low thermal stability restricts high‐temperature applications. Halloysite nanotubes (HNTs) with a hollow tubular structure and high aspect ratio have been investigated as effective fillers to enhance polymer performance. In this study, surface‐modified HNTs were incorporated into PLA via in situ polymerization to prepare PLA/HNT nanocomposites with 0, 3, 5, 7, and 10 wt% loadings. FT‐IR spectra indicated the formation of hydrogen bonding between PLA and HNT, while SEM images confirmed homogeneous dispersion and strong interfacial adhesion. Thermal analyses revealed that the incorporation of even a small amount of HNT (3–5 wt%) effectively enhanced the thermal stability of PLA/HNT nanocomposites, increasing its degradation temperature by approximately 10°C. Among them, 5 wt% HNT provided the optimal combination of enhanced thermal stability and mechanical performance without significant loss in tensile strength. These results suggest that surface‐modified PLA/HNT nanocomposites offer improved heat resistance and processing stability, making them promising candidates for advanced packaging, electronic, and biomedical applications.

ABSTRACT This work aims to broaden the use of wood fiber‐reinforced polypropylene composites in automotive lightweighting by developing a synergistic modification system incorporating nano‐zinc oxide (nano‐ZnO) and olefin block copolymer (OBC). Alkali‐acid‐treated wood fibers (WFs) and maleic anhydride‐grafted polypropylene (MAPP) were used to improve interfacial compatibility. The effects of nano‐ZnO and OBC were evaluated relative to an unmodified system. Nano‐ZnO, functioning as a rigid nanofiller, increased stiffness, hardness, and thermal resistance, whereas OBC improved toughness by promoting energy dissipation through controlled matrix deformation. Microscopy revealed that nano‐ZnO anchors at the fiber–matrix interface while OBC forms dispersed elastomeric domains, together strengthening interfacial adhesion and enabling a cooperative reinforcement–toughening mechanism. Thermal analysis showed that this dual‐modifier system stabilizes the polymer structure during heating and promotes more uniform crystallization. A formulation combining moderate nano‐ZnO loading with low OBC content achieved the best balance of mechanical performance and thermal reliability, supporting its selection as the optimal composition. By partially replacing petroleum‐based polymers with renewable wood fibers and enabling lightweight, recyclable automotive components, this approach offers an effective and environmentally favorable route for developing high‐performance natural fiber composites.

ABSTRACT This study presents a comprehensive investigation into the influence of various inorganic fillers—namely calcium carbonate (CaCO 3 ), wollastonite (CaSiO 3 ), aluminum (Al) powder, and titanium dioxide (TiO 2 )—on the mechanical, thermal, and morphological properties of a Bisphenol‐A‐based epoxy resin matrix. The primary objective of this study was to comparatively evaluate the extent of property enhancement imparted by each inorganic filler to the Bisphenol‐A epoxy matrix, to identify filler–performance relationships that can guide industry‐specific material selection and formulation. Despite extensive studies on epoxy–inorganic filler composites, most prior works have focused on single fillers, narrow concentration ranges, or isolated property evaluations, leaving a lack of systematic, side‐by‐side comparison under identical conditions. This study addresses this gap by evaluating these four industrially relevant fillers across a wide dosage range to establish their comparative influence on the mechanical, thermal, and morphological behavior of a Bisphenol‐A epoxy matrix. Each filler was incorporated into the epoxy matrix at 2.5–20 wt%, yielding distinct, filler‐specific property responses. Calcium carbonate produced the highest lap‐shear strength (13 MPa at 15 wt%), whereas wollastonite resulted in the greatest pot‐life extension (165 min at 15 wt%). Aluminum (Al) powder generated the maximum Shore‐D hardness (86.6 at 10 wt%) but was accompanied by a reduction in thermal resistance. In contrast, titanium dioxide consistently decreased pot‐life across all loadings. FTIR confirmed effective filler incorporation, while DSC showed a progressive increase in T g with increasing filler content. TGA results indicated enhanced thermal stability, particularly for CaCO 3 . SEM micrographs revealed uniform dispersion at optimal loadings and agglomeration at higher concentrations, consistent with observed mechanical trends.