Polymer Alloys Research Articles

Evolution from micropinned to polymeric alloy structure of XLPE‐PS: Improving electrical properties and mechanism

AbstractThis research investigates the transition from a micropinned to a polymeric alloy structure in crosslinked‐polyethylene‐polystyrene (XLPE‐PS). Incorporating 2 wt% 10 μm PS particles into low‐density polyethylene (LDPE) and crosslinking with 2 wt% dicumyl peroxide (DCP) forms XLPE‐PS structures. The polymeric alloy structure, formed at 220°C extrusion, contrasts with the micropinned formed at 150°C. Morphological, thermo‐structural, chemical, and crystal properties are examined to understand their impact on electrical properties and charge transport mechanisms. Results indicate that the polymeric alloy effectively resolves void/crack issues, whereas the micropinned exhibits phase separation. Both structures exhibit a benzene‐crosslinked network, and variations in these structures lead to significant changes in thermo‐structural, chemical, and crystalline properties. The polymeric alloy XLPE‐PS shifts the polyethylene (PE) hkl crystal planes, confirming phase shift and optimal alloying. The structural alterations reveal deeper traps and higher densities in the polymeric alloy XLPE‐PS, leading to significantly improved electrical properties, including reduced DC conductivity by up to 1.3 and 0.7 decades at 30 and 90°C, and increased DC breakdown strength by up to 40.34% and 16.17% at 30 and 90°C, respectively, compared with micropinned XLPE‐PS. This research offers insights into stable high‐voltage insulation development.

Modified Release Interpenetrating Polymeric Network Hydrogel Beads of Montelukast Sodium Via Box Behnken Design

Background: Interpenetrating Polymeric Networks (IPN) are cross-linked polymeric alloys developed when two or more cross-linked polymers inter-penetratingly entangle. Interpenetrating polymeric networks possess several benefits including stability, biocompatibility, biodegradability, high swelling ability, and modified release efficiency. Aim: The aim of this study is to design stable, control-released montelukast sodium-loaded IPN hydrogel beads as a promising approach toward drug delivery. Objective: The goal of the present work was to develop Chitosan (swellable polymer) and glutaraldehyde (cross-linker) based modified (controlled) released montelukast sodium IPN hydrogel beads. Methods: The montelukast sodium IPN hydrogel beads were prepared via the precipitation method, and the final batch of IPN hydrogel beads was based on particle size, percent entrapment efficiency, area of swelling, and cumulative percent drug release using an overlay plot in Box-Behnken design. Compatibility studies (DSC, FT-IR) and microscopical observation (SEM) confirmed the compatibility and sphericity of the formulations. Results: The optimized (comprising 2.01% chitosan and 0.48% glutaraldehyde) IPN hydrogel beads having satisfactory particle size (817.76±54.49 μm), good entrapment efficiency (71.36±3.04%), and area of swelling (27.00±1.68 mm2) showed swelling and pH-dependent controlled montelukast release (92.96±1.05%) after 12 h with longer duration of action. Conclusion: The prepared montelukast sodium IPN hydrogel beads could be a potent control-released drug delivery vehicle.

Freeze-thaw impacts on geocell-stabilized bases considering effects of water supply and compaction

Although Novel Polymeric Alloy (NPA) geocells have been applied to stabilize road bases against the freeze-thaw (F-T) damage in practice, the relevant research lags the application. A scarcity of research has been reported to comprehensively evaluate the benefits of geocell stabilization in enhancing the F-T performance of bases. This study aims to investigate quantitatively the F-T performance of geocell-stabilized bases, focusing on two influencing factors-i.e., water supply and degree of compaction in the bases. A series of model-scale experimental tests (19 tests) was conducted using an upgraded customized apparatus. The results showed that the inclusion of geocells was beneficial for reducing frost heave and thaw settlement as well as mechanical properties (i.e., stiffness and ultimate bearing capacity) of road bases. The benefit of geocells was more remarkable for the well compacted bases than for the poorly compacted bases. The benefit was more pronounced in the open system than in the closed system.

Research on ultrasonic-stationary shoulder assisted friction stir lap welding of thermoplastic polymer and aluminum alloy

Friction stir lap welding (FSLW) has advantages on obtaining dissimilar upper polymer and lower aluminum materials joint (polymer/Al joint), and how to heighten the bearing capacity of polymer/Al joint as much as possible is greatly meaningful for the manufacturing industries. In this study, choosing dissimilar polyamide 6 (PA 6) polymer and 6061-T6 aluminum alloy materials as research object, traditional FSLW, stationary shoulder assisted FSLW (SSFSLW) and ultrasonic-stationary shoulder assisted FSLW (U-SSFSLW) processes were compared to understand the mechanism of ultrasonic enhancement on the polymer/Al joint. Firstly, the surface morphologies were studied. Then the analyses of micro/macro-structures, mechanical properties and fracture features were carried out by optical microscopy, scanning electron microscopy, differential scanning calorimetry, X-ray diffraction and tensile tests. Results showed that the lap shear failure load of polymer/Al joint by U-SSFSLW reached 1502 N from 814 N by traditional FSLW, because the addition of ultrasonic avoided the bulged-nodule structures on top surface and the cavity defect in stir zone (SZ), broke the Al anchor in upper plate, enlarge the width of SZ in lower plate, and made the deeper micro-pits and larger dents at the interface between SZ bottom and lower plate. The U-SSFSLW process provides an effective way to fabricate the high-strength hybrid joint of dissimilar upper polymer and lower Al materials.

Polymer alloys with high thermal properties consisting of polyfunctional benzoxazine derived from an oligonuclear phenolic compound and bismaleimide

Polymer alloys with high thermal properties consisting of polyfunctional benzoxazine derived from an oligonuclear phenolic compound and bismaleimide

Poly(4-methyl-1-pentene)/ polypropylene alloy hollow fiber membrane with high rigidity for blood oxygenation

The oxygenator with hollow fiber membranes (HFMs) is the key component of the extracorporeal membrane oxygenation which allows the blood to be oxygenated and the carbon dioxide to be removed. The poly(4-methyl-1-pentene) (PMP) is recognized as the optimal oxygenated membrane material with high gas permeability coefficient, and the oxygenated membrane fabricated from it has an asymmetric structure that can resist plasma leakage for a long period of time. However, the relatively low rigidity of PMP oxygenated membrane makes it difficult to be processed in subsequent weaving and applications, during which deformation and fracture of HFMs often happen. In this work, the polymer alloy oxygenated membranes are fabricated by blending polypropylene (PP) as a high rigidity reinforcement agent with PMP via thermally induced phase separation (TIPS). Firstly, the effect of the PP content on phase separation structure and crystallization of alloy flat sheet membrane are investigated. When the PP content is 15 wt%, the rigidity of the alloy membrane reinforces dramatically. The elastic modulus and tensile strength of the PMP-PP-15 alloy membrane is 288.5 ± 12.4 MPa and 8.3 ± 0.4 MPa, respectively, which is 275.7 % and 96.7 % higher than that of the PMP membrane. Furthermore, PMP-PP-15 alloy HFM are fabricated under the optimum polymer composition. The elastic modulus of the PMP-PP-15 alloy HFM is 312.6 ± 16.0 MPa, which is 679.6 % higher than that of the PMP HFM and 40.1 % higher than that of the commercial PMP HFM. Meanwhile, the tensile strength and fracture stress are 15.4 ± 0.7 MPa and 186 ± 12.2 cN, respectively, which are both higher than those of the PMP and commercial PMP HFM. In addition, the PMP-PP-15 alloy HFM shows high gas permeability and oxygenation performance. This study might provide a convenient method to achieve rigidity reinforcement of PMP-based oxygenated membranes with great potential for application.

Achieves Both Mechanical Properties and Hydrogen Permeability through Polymer Alloy Blend Resin Modification Technology

Achieves Both Mechanical Properties and Hydrogen Permeability through Polymer Alloy Blend Resin Modification Technology

Magnetic-responsive triple shape memory polymer from bio-based benzoxazine/urethane polymer alloys with iron oxide nanoparticles

Novel magnetic-responsive triple shape memory polymers (SMPs) derived from bio-based benzoxazine-urethane (V-fa/PU) polymer alloys containing iron oxide nanoparticles (Fe3O4 NPs) were developed in this work. Shape memory effect and curing behavior of the alloys were investigated at various bio-based PU contents. The polymerization of V-fa/PU polymer alloys with a heterogeneous network generated a broad glass transition temperature, which is a crucial feature for the development of triple SMPs. The influence of Fe3O4 NPs incorporation into the polymer nanocomposites on the SMP performance triggered by magnetic fields was also investigated. It was found that the addition of Fe3O4 NPs can enhance the dynamic mechanical properties and magnetic characteristics of the V-fa/PU polymer alloys thanks to the superparamagnetic property of Fe3O4 NPs. Moreover, the performance of the SMPs based on V-fa/PU polymer nanocomposites filled with Fe3O4 NPs showed high shape fixity of up to 98%, a shape recovery of 98%, and a recovering time of 8 s. Furthermore, bio-based V-fa/PU polymer alloys containing Fe3O4 NPs were developed as magnetic responsive triple SMPs with shape fixity in the range of 95–97% and shape recovery in the range of 85–95%. The results suggested that magnetic responsive triple SMPs from bio-based V-fa/PU polymer alloys filled with Fe3O4 NPs are promising candidate for advanced applications.

Molecular packing regulation of dopant-free hole transport polymers for efficient perovskite solar cells

Spiro-OMeTAD is a primary hole transport material (HTM) employed in most state-of-the-art regular perovskite solar cells (PSCs). The essential reliance on hygroscopic ionic dopants to enhance the conductivity and mobility of Spiro-OMeTAD has dramatically compromised the stability of PSCs. Here, we demonstrated excellent photovoltaic performance of PSCs by developing two dopant-free polymers, namely L1 and L2, using thieno[3,2-b]thiophene as a building block. It is found that the n-hexyl-modified thiophene side chains endow the polymer L2 with favorable crystallinity, unique self-assembly behavior, and a preferable face-on stacking orientation. After the addition of a small amount (10 %) of PM6 to create a polymer alloy named LPA, the above properties were further improved, and the resulting film exhibited a distinct fibrous morphology, resulting in increased hole mobility and effective defect passivation. Consequently, PSCs employing LPA as a dopant-free HTM afforded a high efficiency of 23.81 %. Importantly, LPA-based PSCs exhibit significantly enhanced operational stability with a T80 lifetime of 1572 h at 55 °C. This work provides a crucial guideline for the design of dopant-free polymers, thereby advancing the practical application of PSCs.

Highly efficient thermal conductivity of polyarylene ether nitrile composites via the introduction of hybrid fillers and tailored cross-linked structure

Polymer dielectrics with high thermal conductivity (λ) and excellent insulating properties are of interest in miniaturized and integrated electronic devices. However, most polymers are unable to fulfill this need due to their inherent structure. In this work, a polymer alloy with balanced thermal conductive and dielectric properties was successfully prepared by polyarylene ether nitrile(PEN), bisphthalonitrile-microsphere@boron nitride nanosheets(Bm@BNNS), and silicon carbide whisker (SiCws) at different scales. Specifically, introduction of Bm@BNNS fillers with core-shell structure into PEN resins results in heterogeneous interfaces, which effectively reduces the agglomeration and dosage of BNNS and synergistically improves the λ and dielectric performance. Besides, it has high breakdown strength (Eb) and high energy storage density (242.26 kV/mm, 1.66J/cm3) when filled with only 4.37 vol% BNNS compared to pure PEN. Furthermore, effects of one-dimensional SiCws at different scales on formation of heat-conduction pathways and electrical insulation properties of PEN/Bm@BNNS composites were investigated. The findings display that PEN/Bm@BNNS/SiCws composites with large size SiCws (7.81 vol%) achieved a high λ of 2.376 W/m.K, which was 135.24 % and 87.09 % higher than pure PEN and PEN/Bm@BNNS composites, respectively. Thus, the thermal conductive pathways are constructed by line-plate structure (SiCws-BNNS), and insulating performance primarily on the core-shell structure (Bm@BNNS). Besides, the novel PEN/Bm@BNNS/SiCws hybrid materials are together with a low coefficient of thermal expansion of 38–89 ppm/°C and high Tg of 220 °C. Thus, it gives a promising insight to achieve highly λ polymer-based insulating film materials used for high-temperature-resistant fields.

A Novel Graph Convolutional Neural Network Method for Improving Phase Severance Formation Planning in Polymer Alloys

A Novel Graph Convolutional Neural Network Method for Improving Phase Severance Formation Planning in Polymer Alloys

Simulation and experimental research on longitudinal-torsional ultrasonic vibration drilling of CFRP/Ti laminates

Carbon fiber reinforced polymer (CFRP) and titanium alloy (Ti) laminated materials are extensively employed as primary load-bearing structures in aerospace engineering due to their exceptional characteristics. During the drilling process of CFRP/Ti laminates, issues like delamination and burr formation significantly impede the overall performance of these laminates. The finite element simulation was carried out to address above challenges using longitudinal-torsional ultrasonic vibration drilling (LT-UVD) of CFRP/Ti laminates. A three-dimensional solid model of CFRP/Ti laminates was developed using the ABAQUS custom VUMAT subroutine interface. A cohesive element was skillfully incorporated into the model to simulate delamination defects in the CFRP material effectively and to elucidate the material damage trends and stress distribution throughout the drilling process of laminated materials. The results obtained from the finite element simulation are meticulously compared with experimental data, revealing a consistent trend in the axial force curve. The simulated axial force’s peak value is 14.45% lower than the peak value obtained from experimental observations. The findings of this research substantiate the efficacy of the developed finite element model for LT-UVD of CFRP/Ti. The model successfully predicted the changing trend of axial force and layered defects during the drilling process. Moreover, it provides a visually intuitive instantaneous cutting state and stress distribution, imparting valuable insights into the intricate drilling mechanisms involved in CFRP/Ti laminates.

Most recently developed polyester polymer alloy dialyzer: A new medium cut-off membrane?

New versions of the polyester polymer alloy (PEPA) membrane have appeared over the years, with increases in both the pore size and the amount of polyvinylpyrrolidone (PVP) to optimize hydrophilicity performance. This study aimed to assess the efficacy of the most recently developed PEPA dialyzer, the FDY series, in hemodialysis (HD) modality in terms of uremic toxin removal and albumin loss and to compare it with that of several high-flux dialyzers currently used in HD and post-dilution hemodiafiltration (HDF) treatments. A prospective study was carried out in 21 patients. All patients underwent six dialysis sessions with the same routine dialysis parameters; only the dialyzer and/or the dialysis modality varied: FX80 in HD, FDY 180 in HD, Clearum HS17 in HDF, Elisio 19H in HDF, Vitapes 180 in HDF, and FX80 in post-dilution HDF. The reduction ratios (RR) of urea, creatinine, ß2 -microglobulin, myoglobin, κFLC, prolactin, α1 -microglobulin, α1 -acid glycoprotein, λFLC, and albumin were compared intraindividually. Dialysate albumin loss was also measured. Both membranes FDY and FX80 are high-flux dialyzers and are applied here in high-flux HD. The average RR of β2 -microglobulin was slightly lower in the two HD treatments than in the HDF treatments. Comparison of dialysis treatments revealed that the PEPA FDY dialyzer in the HD modality was more effective than the FX80 dialyzer in high-flux HD and was as effective as post-dilution HDF, especially in terms of myoglobin, κFLC, prolactin, α1 -microglobulin, and λFLC RRs. The FDY treatments obtained similar albumin RR in blood and slightly higher dialysate albumin loss, although the values were clinically acceptable. The most recently developed PEPA dialyzers in the HD modality were as effective as all treatments in the HDF modality and were clearly superior to high-flux helixone HD treatment. These results confirm that this dialyzer should be categorized within the medium cut-off (MCO) membrane classification.

Development of a deep-learning model for phase-separation structure of diblock copolymer based on self-consistent field analysis

Self-consistent field (SCF) analysis is an indispensable tool for predicting the microphase separation structures of polymer alloys. However, the computation of the phase-separated structures in the equilibrium state is computationally intensive, leading to high costs. To address this challenge, we propose a novel deep learning approach that leverages a generative adversarial network (GAN), a powerful deep generative model, to accelerate SCF analysis. Specifically, we trained the GAN using comprehensive data obtained from SCF analysis, enabling us to generate various images of feasible structures that are similar to the SCF analysis results. Our results demonstrate that the latent variables in the GAN are linked to the physical parameters and features of the phase-separation structures.

Influence of two-phase structure of PET/PPSU alloys and selective distribution of flame retardants on the flame retardancy of polymer alloys

Polymer alloys can obtain the excellent performance of a variety of polymers. The polymer blending system has been studied by many scholars, especially the multi-component system containing additives, which is receiving more and more attention from researchers. The flame retardancy behavior of polyethylene terephthalate (PET)/Polyphenylene sulfone (PPSU) blends containing A 9,10-dihydro-9-oxa-10 phosphophenanthrene-10-oxide based derivative tris-(3-dopo-propyl) -triazine trione (TAD) is explored. Flame retardancy of PET/PPSU composite was characterized by Limiting oxygen index (LOI), vertical combustion test (UL 94), and cone calorimeter test. PPSU is a less flammable material with an LOI value of 40.0 % when used alone. With a 5 % flame retardant TAD addition, the LOI value of the PPSU/TAD-5 composite can be increased to 42.6 %. Interestingly, the LOI of PET with 5 wt% of TAD was 30.2 %, whereas the LOI of PET/PPSU(70/30) composites with the same 5 wt% of TAD was reduced to 26.3 %. We investigated by SEM-EDS that the flame retardant TAD always preferred to be distributed in the PPSU phase in PET/PPSU composites with different ratios. When PPSU was wrapped by the PET phase, which is the sea structure, the flame tended to follow the sea structure combustion channel of the polymer alloys during combustion, and the island structure of PPSU had little effect on the overall flame retardancy of the polymer alloys. Similarly, when PPSU becomes a continuous matrix, even without flame retardant, it significantly reduces the combustibility of the blends. However, with the addition of flame retardants, most of the flame retardants are distributed in the PPSU matrix, which significantly increases the LOI value of the PET/PPSU(40/60)/TAD-5 composite. Therefore, we conclude that there is an uneven distribution of flame retardants in the two phases, so for polymer alloys, the distribution of flame retardant in the two phases, as well as the construction of the continuous phase and the dispersion phase, determine the overall flame retardant properties of the composites.

General Entropy Approach Toward Ultratough Sustainable Plastics.

Entropy is a universal concept across the physics of mixtures. While the role of entropy in other multicomponent materials has been appreciated, its effects in polymers and plastics have not. In this work, it is demonstrated that the seemingly small mixing entropy contributes to the miscibility and performance of polymer alloys. Experimental and modeling studies on over 30 polymer pairs reveal a strong correlation between entropy, morphology, and mechanical properties, while elucidating the mechanism behind: in polymer blends with weak interactions, entropy leads to homogeneously dispersed nanosized domains stabilized by highly entangled chains. This unique microstructure promotes uniform plastic deformation at the interface, thus improving the toughness of conventional brittle polymers by 1-2 orders of magnitude without sacrificing other properties, analogous to high-entropy metallic alloys. The proposed strategy also applies to ternary polymer systems and copolymers, offering a new pathway toward the development of sustainable polymers.

Significant Enhancement in Dielectric Properties of Polyimide Alloys Through a Two‐Phase Interlocking Structure

AbstractHigh temperature dielectric polymers are the favored materials for energy storage devices under harsh‐environment, e.g., electronic devices and power systems. It is widely acknowledged that the energy storage capabilities of dielectric polymers are markedly deteriorated at elevated temperature because of the exponential increased leakage current. Herein, all‐organic dielectric polymer alloys with two‐phase continuous hard‐soft structure have been firstly investigated via blending high glass transition temperature (Tg) fluorinated polyimide (FPI) and high bandgap aliphatic polyimide (API). The large energy band difference between FPI and API is conducive to trap energy and greatly inhibits conduction loss. In addition, the hard and soft molecular chains with two‐phase interlocking structures are more closely arranged, bringing torturous pathways for charge carriers and reducing free volume, which enhances the breakdown strength. FPI/API alloy with high Tg (296 °C) and concurrent large bandgap delivers an ultrahigh discharge energy density of 6.6 J cm−3 at 150 °C and 3.02 J cm−3 at 200 °C with 90% discharge efficiency, significantly surpassing those reported dielectrics. Moreover, the FPI/API alloy exhibits remarkable cyclability and dielectric stability up to 10000 charge‐discharge cycles even at elevated temperatures. This work provides an unprecedented opportunity on structure design of dielectric polymers to achieve high‐temperature energy storage capacitors.

Research on joint strength and energy absorption of CFRP and Al sheets bonded-FDS hybrid joining

The application of a composite-metal alloy lightweight body structure is one of the ways to achieve lightweight in an automobile. Materials such as carbon fiber reinforced polymer (CFRP) and aluminum alloys are widely used in the automotive industry due to their excellent performance. However, the significant differences in performance parameters between CFRP and aluminum alloy materials make joining heterogeneous materials challenging. Therefore, a rational joining process is crucial for the development of CFRP–aluminum alloy structures. This study proposes a hybrid joining method that combines flow drill screw (FDS) and adhesive bonding to join commonly used aluminum alloy sheets with CFRP sheets in automotive body manufacturing. Finite element analysis simulations were used to compare and characterize the failure modes of the bonded-FDS hybrid joints in tensile tests. The results were verified for accuracy. Tensile tests were conducted to compare the mechanical performance and failure modes of bonded joints, FDS joints, and hybrid joints. By analyzing the load–displacement curve, it was found that the FDS process in the hybrid joining damages the internal structure of the adhesive layer. However, the joint strength is still higher than that of the single joint strength, and the energy absorption value is about 4.7 times that of the adhesive and 1.6 times that of the FDS. This study provides a new industrial solution and serves as a reference for failure performance in composite material structures in the automotive industry, especially in cases involving one-sided access joining points.

Progress in Friction Stir Welding of Polymer and Aluminum Alloys

Progress in Friction Stir Welding of Polymer and Aluminum Alloys

Rehabilitation of rail track facing cross-level issues using polymeric geocell

One of the issues with the existing rail network is the cross-level issue, where the two parallel tracks have unwanted elevation differences, risking train derailment. The speed of trains is typically reduced in those identified areas but still, the geometric irregularity causes train body vibrations reduces the riding comfort. Once that elevation difference exceeds a design limit operation ceases for safety. Conventional solutions to this are jacking up the track by re-filling material inside and injecting expandable foam. None of those temporary techniques have a significant contribution to eliminating the root cause; rather invite additional risks with unpredictable differential stiffness. An enduring solution is rebuilding the embankment with the use of strong geocell reinforcement. The threedimensional confinement along with the high tensile strength of reinforcing polymeric geocell introduces a stiffer layer. Through this paper, a design approach utilizing the tensile strength, stiffness, and geometric properties of the geocell has been established to provide a dependable solution. Three projects have been discussed where a high-strength novel polymeric alloy geocell with the established design method was successfully used. The effective theoretical reduction of bearing pressure was from 38% to 55%. Observation over a year indicated the effectiveness of the design methodology.