The intrinsically high melt viscosity of ultra-high-molecular-weight polyethylene (UHMWPE) originates from severe topological confinement and restricted chain mobility, which significantly limits its melt processability. In this study, UHMWPE is blended with high-density polyethylene (HDPE), and calcium stearate (CaSt₂) is introduced as a low-content processing additive. A combined experimental and molecular dynamics (MD) investigation is performed to establish a multiscale structure–dynamics–property relationship. MD simulations demonstrate that 0.5 wt% CaSt₂ promotes the redistribution and enlargement of local free volume and enhances segmental mobility, as evidenced by a 27.17% increase in diffusion coefficient and an 8.06% increase in fractional free volume. These changes are accompanied by a redistribution of entanglement constraints and intermolecular interactions, indicating partial release of topological confinement. Experimentally, the modified blends exhibit significantly improved melt processability and extrusion stability, with a 19.05% increase in melt flow rate, while tensile strength increases by 4.01% alongside a 5.18% improvement in crystallinity, suggesting that enhanced processability is achieved without compromising mechanical integrity. The simulation results provide molecular-level mechanistic support for the experimentally observed macroscopic improvements.

Abstract Personal thermal management materials are increasingly in demand under intensifying outdoor heat exposure and global warming. However, simultaneously achieving efficient radiative cooling, rapid thermal conduction, mechanical flexibility, and sustainability within a simple wearable architecture remains challenging. Here, biobased PLA/Al2O3 composite fibrous films were fabricated by electrospinning for synergistic thermal conduction and radiative cooling. By regulating the Al2O3 loading and film thickness, optical scattering, thermal emissivity, and thermal conduction were coordinately optimized. The optimized PFA-30 film with a thickness of 400 μm exhibited 95.7% solar reflectance, 95.47% average emissivity within 8–13 μm, and a thermal conductivity of 0.46 W·m–1·K–1. In outdoor tests, PFA-30 delivered a maximum daytime temperature reduction of 9.8 °C and an average daytime reduction of 3.8 °C relative to ambient temperature. This work establishes a versatile platform for sustainable wearable thermal management systems, advanced smart textiles, and next-generation energy efficient personal cooling technologies.

Molecular dynamics can predict and analyze polyethylene's mechanical properties, thermodynamic quantities, and other macroscopic properties at the molecular level. However, the molecular modeling of polyethylene is still not fully developed, the simulated systems often involve relatively low molecular weights and single components, and it cannot be well combined with the experiment to study the mechanical properties of UHMWPE/HDPE blends. Therefore, this paper combined experimental analysis with simulations to investigate the flow modification and tensile properties of UHMWPE/HDPE blends and established a semicrystalline UHMWPE/HDPE model. The result shows that the flow modification effect of HDPE is more pronounced at lower screw rotational speeds, and the UHMWPE/HDPE mass ratios of 6/4 and 5/5 can produce as-spun filaments with better surface quality at a screw speed of 5 r/min. As the HDPE content increases, the blends' molecular chain mobility and disentanglement capability improve. However, an excessively high HDPE content hinders the enhancement of blend orientation. When the UHMWPE/HDPE mass ratio is 6/4, the system achieves the highest degree of orientation, the fewest internal void defects, and the longest duration of strain hardening during drawing.

The high melt viscosity and poor flowability of ultrahigh molecular weight polyethylene (UHMWPE) hinder its spinning production efficiency and industrial-scale processing. In this study, a blend of UHMWPE and high-density polyethylene (HDPE) was modified by incorporating silicone powder and polyethylene glycol (PEG). By integrating experimental characterization with molecular dynamics simulations, this study investigates the effects and underlying mechanisms of flow modification induced by the individual and synergistic incorporation of PEG and silicone powder into UHMWPE/HDPE blends at both macroscopic and molecular levels. Experimental results showed that 1 wt % PEG provided the most significant modification effect on the UHMWPE/HDPE blend. Compared to the unmodified UHMWPE/HDPE blend, the processing torque and flow activation energy decreased by 22.1% and 34.57%, respectively, and the melt flow rate increased by 48.04%. However, a slight reduction in tensile properties was observed, with the tensile strength decreasing by 5.09%. Molecular dynamics simulations revealed that the addition of 1 wt % PEG notably enhanced the overall mobility of the molecular chains in the UHMWPE/HDPE blend, leading to the highest free volume fraction and diffusion coefficient, thus improving flowability. However, the intermolecular interactions within the blend were relatively weak, resulting in lower cohesive energy density and interaction energy, which, in turn, reduced mechanical properties. The experimental and simulation results are in good agreement and provide valuable insights into the modification effects and mechanisms of different flow additives, offering guidance for the selection and optimization of modification formulations for UHMWPE.

This study systematically investigated the hot compression behavior of Ti-5Mo-5V-8Cr-3Al alloy, commonly referred to as TB2 alloy, within the temperature range of 800-950 degrees C and strain rates of 0.001-1 s-1. Using transmission electron microscopy (TEM) and electron backscatter diffraction (EBSD) techniques, the microstructural evolution and dynamic recrystallization (DRX) mechanisms were thoroughly analyzed. Based on the relationship between flow stress and deformation conditions, the apparent activation energy of TB2 alloy was calculated to be 497.6 kJ/mol using the Arrhenius equation. The high-precision constitutive model was then developed to describe the complex interactions between stress, strain rate, and temperature. The hot processing map was constructed using the dynamic materials model (DMM), identifying optimal processing parameters of 900 degrees C and 0.001 s-1 . Under these optimized conditions, the alloy achieved complete DRX, forming a fine and uniformly distributed equiaxed grain structure, significantly enhancing its mechanical properties. Additionally, the study identified two primary DRX mechanisms in TB2 alloy: continuous dynamic recrystallization (CDRX) and discontinuous dynamic recrystallization (DDRX). The synergistic effect of these two mechanisms promotes dislocation rearrangement and grain refinement during dynamic deformation. These findings provide critical theoretical and practical guidance for the optimization of the hot working process of TB2 alloy.

The Cr-Co-Ni particle-reinforced AZ31 magnesium matrix composite (CrCoNi/AZ31) was manufactured by powder metallurgy. Through the use of microscopic analysis, the emergence of the new Al13Cr2 phase within the composite material was observed. The hot deformation characteristics of the CrCoNi/AZ31 magnesium matrix composites were examined with hot compression testing. The experimental parameters were established within the temperature range of 250-400 degrees C and the strain rate range of 0.001-1 s-1. The analysis focused on the flow stress and micro-deformation mechanisms of the CrCoNi/AZ31 magnesium matrix composites during the hot deformation. The constitutive equation model was developed for the CrCoNi/AZ31 magnesium matrix composites. The hot deformation activation energy Q was calculated to be 137.06 kJ/mol based on this model. The correlation coefficient between the constitutive model and the experimental data was determined to be R2 = 0.9608. The processing map for the CrCoNi/AZ31 magnesium matrix composites was created. The optimal deformation conditions for the CrCoNi/AZ31 magnesium matrix composites were identified as follows: the deformation temperature of 350-400 degrees C and strain rate of 0.001-0.01 s-1. During the hot compression process, continuous dynamic recrystallization (CDRX) is the primary recrystallization mechanism. The Al13Cr2 phase promotes dislocation accumulation, triggers the particle-stimulated nucleation (PSN) mechanism, and creates particle deformation zones (PDZs), accelerating the dynamic recrystallization process and thereby enhancing the microstructural uniformity of the composite material.

Due to the lack of melt processability in ultra-high molecular weight polyethylene (UHMWPE), the melt spinning technology of UHMWPE has yet to be industrialized. This study employed a melt blending technique, using silicone powder as a flow aid. The melt processing performance of silicone powder-modified UHMWPE pellet materials was systematically analyzed through torque measurements and rheological property tests. Additionally, the impact of silicone powder on the surface energy of UHMWPE was evaluated. The influence of silicone powder and hot drawing processes on the mechanical properties of UHMWPE melt-spun monofilaments was further analyzed through tensile strength testing, creep behavior analysis, differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). The results indicate that the addition of silicone powder significantly improves the melt flowability and extrusion stability of UHMWPE, with a slight increase in its surface energy. Under extrusion conditions of 270 degrees C and a screw speed of 5 rpm, silicone powder-modified UHMWPE can be continuously extruded into as-spun filaments, with molecular chains oriented along the drawing direction during the hot drawing process, thereby enhancing the creep resistance of the monofilaments. When the silicone powder content is 3 wt% and the draw ratio is 36, the tensile strength of the modified UHMWPE monofilament reaches 1565.21 MPa.

AbstractThe challenging melt processing of ultrahigh‐molecular‐weight polyethylene (UHMWPE) melt spinning hinders its efficiency and quality, which can be improved by processing aids that enhance its flowability. Building upon modifications of UHMWPE with high‐density polyethylene (HDPE), this article studies the effects of CaSt2, polyethylene glycol (PEG), silicone powder, and their compound additives on the processing performance of UHMWPE/HDPE blends. The modification effects and mechanisms are studied by analyzing processing torque, melt flow rate, viscoelastic activation energy, and rheological performance. The research results indicate that 1 wt% PEG significantly improves the processing flowability of UHMWPE/HDPE blends, and PEG mainly plays an internal lubrication role on the molecular chains of the blends. The combination of 0.5 wt% CaSt2 and 0.5 wt% silicone powder exhibits a synergistic effect of internal and external lubrication on the UHMWPE/HDPE blends melt processing, further improving the processing performance of UHMWPE/HDPE blends. Compared with unmodified blends, the maximum screw speed for obtaining qualified as‐spun filaments of UHMWPE/HDPE blends modified with CaSt2/silicone powder compound additives increases from 5 to 20 rpm, which means that the critical shear rate of the modified UHMWPE/HDPE blend melt processing is significantly improved. Meanwhile, the processing torque decreases by about 22%.

In this paper, the effect of heat treatment on the microstructure and mechanical properties of SLMed corrax (CX) stainless steel was investigated. The results showed that solution treatment (ST) promoted the transformation of residual austenite to martensite, and the lath martensite structure was formed during solution treatment, with a preferred orientation of crystal face (111). Meanwhile, the solution treatment led to the obvious grain growth and dissolution of NiAl precipitates into the matrix, which weakened the mechanical performance of SLMed samples. Furthermore, the NiAl precipitates in nanoscale were formed again during the subsequent aging treatment (AT). At the aging temperature above 580 °C for 3 h, some martensite was transformed into the reversed austenite, resulting in the occurrence of overaging. The highest hardness and strength were obtained in the parameters of ST 900 °C/ 1 h + AT 530 °C/ 3 h. The maximum hardness, yield stress (YS) and ultimate tensile strength (UTS) reached 526.3 HV, 1486 MPa and 1598 MPa, respectively, all of which were improved by about 50

The challenging melt processing of ultrahigh-molecular-weight polyethylene (UHMWPE) melt spinning hinders its efficiency and quality, which can be improved by processing aids that enhance its flowability. Building upon modifications of UHMWPE with high-density polyethylene (HDPE), this article studies the effects of CaSt(2), polyethylene glycol (PEG), silicone powder, and their compound additives on the processing performance of UHMWPE/HDPE blends. The modification effects and mechanisms are studied by analyzing processing torque, melt flow rate, viscoelastic activation energy, and rheological performance. The research results indicate that 1 wt% PEG significantly improves the processing flowability of UHMWPE/HDPE blends, and PEG mainly plays an internal lubrication role on the molecular chains of the blends. The combination of 0.5 wt% CaSt(2) and 0.5 wt% silicone powder exhibits a synergistic effect of internal and external lubrication on the UHMWPE/HDPE blends melt processing, further improving the processing performance of UHMWPE/HDPE blends. Compared with unmodified blends, the maximum screw speed for obtaining qualified as-spun filaments of UHMWPE/HDPE blends modified with CaSt(2)/silicone powder compound additives increases from 5 to 20 rpm, which means that the critical shear rate of the modified UHMWPE/HDPE blend melt processing is significantly improved. Meanwhile, the processing torque decreases by about 22%.

The extremely low melt flowability of ultra-high molecular weight polyethylene (UHMWPE) is the primary obstacle to its melt processing. Particularly in melt spinning processes, the extremely high molecular weight of UHMWPE and the density of entangled molecular chains severely limit its production efficiency and monofilament performance. This study investigates the effect of flow modifiers on the melt spinning process of UHMWPE/HDPE blends, focusing on CaSt(2), PEG, and CaSt(2)/silicone powder composite additives, and their impact on the standard tensile samples and monofilament tensile properties of UHMWPE/HDPE. The mechanism of additive influence on the tensile properties of UHMWPE/HDPE blends is analyzed through tensile strength testing, thermal analysis, and microscopic morphology observation. The results show that in standard tensile samples, CaSt(2) or CaSt(2)/silicone powder composite additives can enhance the crystallinity of the blend, thereby improving its tensile strength. Conversely, adding PEG significantly reduces the crystallinity and tensile strength of the blend. The maximum tensile strength of CaSt(2)-modified UHMWPE/HDPE monofilament is 1236.61 MPa. This enhancement is attributed to the lubricating effect of CaSt(2), which simultaneously assists the molecular chains in the amorphous region, and the reorientation of the stress-induced molten lamellar structure under tension, greatly promoting the formation of straight-chain crystals in the monofilament. During hot drawing, PEG inhibits the formation of straight-chain crystals in the monofilament, resulting in a 3.06% decrease in maximum crystallinity compared with standard tensile samples. When CaSt(2) is combined with silicone powder, the additives tend to aggregate during hot drawing, and these larger aggregate particles hinder the orientation of molecular chains along the drawing direction, resulting in a 30.75% decrease in maximum tensile strength of the monofilament compared with the standard tensile samples.

The effect of induction heating temperature on the microstructures and properties of GH4169 nickel-based superalloy was investigated. Both electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) were applied to analyze the microstructure. The results showed that the induction heating temperature had a promoting influence on the evolution of static recrystallization (SRX) and the optimization of grain boundary characteristics distribution (GBCD). After induction heating, the coincidence site lattice (CSL) boundaries were mainly Σ3 boundaries, and the main formation mechanism was the growth accident model. With the increasing heating temperature, the SRX behavior was well developed with a gradual increase in the fraction of Σ3 boundaries. This indicates a 'symbiotic relationship' between the SRX grains and Σ3 boundaries. Moreover, it was found that the ductility and corrosion resistance of the alloy were improved with the increasing temperature. This is mainly due to the fact that the SRX behavior can effectively improve the uniformity of the microstructure and eliminate the residual stresses. Meanwhile, the high fraction of Σ3 boundaries disrupts the connectivity of the random grain boundary network, ultimately enhancing the corrosion resistance of the GH4169 alloy.

The microstructural evolution and corrosion performance in chloride environments of as-cast AlCrFeNi3Mox (x = 0, 0.1, 0.2, 0.3, and 0.4 in molar ratio) high-entropy alloys (HEAs) were investigated. Results indicated that the microstructures of AlCrFeNi3Mox HEAs were transferred from FCC+B2 dual-phase eutectic microstructures (x = 0, 0.1, and 0.2) to bimodal eutectic microstructures (x = 0.3, 0.4), and the corrosion resistance of Mo-containing HEAs was superior to that of Mo-free HEA and 316L SS. The AlCrFeNi3Mo0.3 HEA exhibited the superior anti-corrosion properties attributed to dense passive film enrichment of Cr2O3 and MoO3. Additionally, all HEAs displayed micro-galvanic corrosion behavior, with the B2 phase dissolving preferentially.

The vanadium particles reinforced AZ31 matrix composite (VP/AZ31) was prepared using the powder metallurgy method. Subsequently, hot deformation behavior of VP/AZ31 composite was studied through hot compression trials. The experimental parameters were set in a temperature range of 250-400 °C and a strain rate range of 0.001-1s-1. Based on the experimental results, a strain-compensated Arrhenius constitutive model was developed to accurately forecast the flow behavior of VP/AZ31 composite. Moreover, the thermal activation energy was calculated to be 138.605kJ/mol and the processing map was delineated according to the dynamic material model theory. The processing map revealed that the optimal processing area existed under 363-400 °C/0.001-0.004s-1, where the efficiency of power dissipation exceeded 23%. Notably, the highest efficiency of power dissipation occurred at 400 °C/1s-1, which exceeded 30%. Under these conditions, dynamic recrystallization (DRX) was sufficiently developed, indicating the enhancement of workability. It is estimated that the instability region for VP/AZ31 composites occurred within the conditions of 250-325 °C/0.16-1s-1, characterized by crack formation. The DRX of VP/AZ31 composite is predominantly governed through the mechanism of discontinuous DRX (DDRX).

This investigation delves into the thermal deformation behavior of TC9 titanium alloy. Compression tests at isothermal conditions were performed on a Gleeble thermal simulator under conditions spanning 700-1200 degrees C and strain rates of 0.001-1 s- 1. The true stress-true strain curves indicated that stress increases with rising strain rate and decreasing temperatures. The softening mechanisms in the biphasic and monophasic regions were discussed. By correcting errors caused by friction, the strain-compensated Arrhenius-type constitutive equation, which accurately describes the flow behavior of TC9 titanium alloy, has been established. A processing map at a strain of 0.7 was constructed based on the power dissipation factor, revealing an unstable region at 700-800 degrees C/ 0.01-1 s-1 and 800-900 degrees C/0.1-1 s-1, where microcrack defects were observed, suggesting that processing should be avoided in this region. Efficiency values as high as 60-70 % indicate superplasticity deformation, with corresponding m values within this efficiency range of approximately 0.4-0.5, reaching the strain rate sensitivity index range of superplasticity titanium alloys. Tensile tests conducted at 900 degrees C and a deformation rate of 0.001 s-1 showed elongation exceeding 100 %. The sample compressed at 900 degrees C and 0.001 s-1 exhibits small grain size, uniform orientation, the lowest dislocation density, and a uniform two-phase mixture. These microstructural features indicate the material's good machinability.

The widespread application of biodegradable polylactide (PLA) is hindered by its brittleness. Polyethylene glycol (PEG) is commonly utilized as a plasticizer because of its favorable compatibility with PLA. However, the incorporation of PEG considerably diminishes the tensile strength of PLA. To address this issue, reactive isocyanate-modified graphene oxide (mGO) was synthesized and used as an enhancer in PLA/PEG blends. By virtue of the reaction between the isocyanate group in mGO and the terminal hydroxyl groups of PLA and PEG, graphene-based polyurethane (PU) in-situ formed and enhanced the interface between GO and the matrix. Consequently, the PLA/PEG/mGO composites exhibit simultaneously improved tensile and impact strengths, achieving an increase of 20.6% and 29.4%, respectively, compared to PLA/PEG blends. Moreover, the in situ formed PU reduces the relaxation time of the molecule motion and improved the entanglement density, thereby improving the shape-memory recovery rate and final recovery degree of the composites. This work provides a facile method to simultaneously improve the dispersion of GO and enhance its interface with polymer, thereby supplying well comprehensive properties of PLA and extending the applications of biodegradable polymers.

以连续玻璃纤维(GF)增强聚乙烯(PE)复合管为研究对象,设计了一种适用于复合管道的新型非金属管道接头,该接头采用对焊和热熔缠绕的方式对管道进行连接,通过理论公式计算了管道接头处的接头厚度和GF带缠绕长度.建立了内压载荷下管道接头的有限元模型,对接头处的受力和流体流动情况进行模拟分析.模拟结果表明,GF带与管端接触的截面受力最大,最大应力出现在增强层.管道接头处的最大应力为环向应力,除最外层外,管道接头处各层受力由内向外呈现递减趋势.接头等通径的设计能够有效避免接头处物料粘结和应力集中的发生.对新型管道接头进行静液压实验,验证了管道接头的安全性与可靠性.

A facile technique was reported for fabricating high conductivity and improved strength of linear low-density polyethylene/multi-walled carbon nanotubes (LLDPE/MWNTs) composite films by the ultrasonication anchoring technique and compression molding treatment. Thermal property, mechanical property, electrical conductivity, microstructures, optical property, and organic vapor sensing behaviors of the MWNTs/LLDPE composite films were studied. The MWNTs are uniformly anchored onto the surface of LLDPE matrix, and the conductive networks are easily formed by the ultrasonication anchoring technique. After compression molding treatment, the incorporation of MWNTs causes an easier formation of LLDPE extended-chain, which is wrapped around of MWNTs shish. The MWNTs/LLDPE composite films exhibit an excellent conductivity of 2.79 × 10 5 Ω∙cm with 0.15 wt % MWNTs. Meanwhile, the tensile strength of the composite films reaches 18.9 MPa. Interestingly, the transparency is not significantly reduced. The sensitivity and reproducibility of vapor sensing behaviors have been demonstrated during immersion-drying runs toward two representative solvents, i.e., acetone and xylene. This work opens up a new direction for the conductivity optimization of MWNTs/LLDPE composite films with a broad prospect in the field of vapor sensor.

The thermal deformation behavior of a novel CrFeNiSi0.15 medium entropy alloy (MEA) was studied via isothermal compression experiments, with the processing parameter range of 900–1200 °C and 0.001–1 s−1. According to experimental data, the modified constitutive equation had been obtained, which precisely predicted the flow behavior of CrFeNiSi0.15 MEA during thermal deformation. At the same time, the processing map was established on the basis of the dynamic material model (DMM) theory. According to the map, the optimal processing parameters were determined at 1130–1200 °C/0.06–1 s−1, under which the power dissipation efficiency could reach above 34