Structure Of Resin Research Articles

Comparative study on matrix resins in two low‐density polyethylene based cable insulation materials with different voltage grades

AbstractIn industry, crosslinked polyethylene (XLPE) cable insulation is usually produced from crosslinkable compounds consisting of low‐density polyethylene (LDPE) and additives, which known as “cable materials”. Considering that in addition to additives, the structure of matrix resin is a key factor in determining the property of XLPE, it is worthy to study the structure requirements of matrix resin for the development of cable materials with different voltage grades. In this work, the structure of matrix resins of a high voltage grade and an extra high voltage grade cable material were comparatively investigated. Interestingly, it was found that the matrix resins have no significant difference in chain structure parameters including molecular weight and its distribution and vinyl content between two samples, and their crystalline structure as well as the melt rheology and melting crystallization behavior are also very similar. These results suggest that these matrix resins may not substantially differ. Our work shows that cable materials with different voltage grades are not necessarily diverge in terms of matrix resin structure, and it could be possible to develop higher grade cable materials using the same matrix resin as lower grade counterparts.

Geometry-based cross-linking algorithm for modeling resorcinol resins through united-atom molecular dynamics simulations

The addition-condensation polymerization (ACP) of resorcinol with formaldehyde and the electrochemical polymerization (ECP) of resorcinol were desirable to improve the performances of resins. To achieve computational design, a new geometry-based cross-linking modeling algorithm for three-dimensional (3D) cross-linked network structures of resorcinol resins was developed for molecular dynamics (MD) simulations using a united-atom model. The ACP and ECP of resorcinol were successfully modeled using one algorithm by changing the parameters of the reaction rate constants of methylene, ether, and biphenyl bond formations. Furthermore, reaction judgment was performed under a reaction probability function comprising the Gaussian functions based on the interatomic distance of the reaction candidate atom pairs and interior angles regarding the spatial arrangement of two resorcinol rings. This geometry-based cross-linking algorithm successfully generated strainless 3D cross-linked network structures of the ACP and ECP resorcinol resins without the formation of highly bent unstable structures, such as U-shaped biphenyls. The MD simulation results indicated that the cross-linking of the ACP resin comprising methylene linkages proceeded with a network structure formation mechanism similar to that of phenolic resins, where the cross-linked network structure was determined at the gel point and the reactions after the gel point were to fix and freeze the network structure. For the ECP resins comprising ether and biphenyl linkages, the molar ratio of ether to biphenyl bonds affected the elastic property of the resins, and the incorporation of rigid biphenyl structures into ether-linkage networks increased the elastic modulus. Moreover, an increase in rigidity was observed as a decrease in the Poisson's ratio.

Structure and properties of resole resin crosslinked vulcanizates of natural rubber grafted with polymethylmethacrylate

Structure and properties of resole resin crosslinked vulcanizates of natural rubber grafted with polymethylmethacrylate

Model Simulation and Rheological Research on Crosslinking Behavior of Polyethylene Resin.

The crosslinking behavior of polyethylene (PE) determines its exceptional performance and application. In this study, we investigated the crosslinking behaviors of different PE resins through model simulation and rheological methods. Specifically, the mathematical equation of "S" model was established for PE resin. According to this equation, the optimal maximum gel content for high-density polyethylene (HDPE) was found to be around 85%. Moreover, the maximum crosslinking degrees for different PE resins depended largely on their density and molecular weight. The melt viscosities before crosslinking in PE resins were highly influenced by their melt index. The higher melt indexes resulted in the lower storage moduli, improving melt processability during processing. In addition, the crosslinking rates of PE resins were strongly influenced by peroxide concentration, independent of PE resin structures. For high molecular weight and low-density PE resins, they exhibited decreased ti values, increased A0 values, and decreased k6 values. However, there were no noticeable variations in the values of k2 and phi among different PE resins. All simulated modeling outcomes showed remarkable consistency with the experimental rheological data. These findings are of strong significance in the industrial manufacture of PE resin.

Tailoring flexible-segment-rich resin network structure by multi-step copolymerization for improved composite bipolar plate of proton exchange membrane fuel cell

Composite bipolar plates composed of conductivity fillers and resins are widely employed in stationary proton exchange membrane fuel cell (PEMFC) due to their high corrosion resistance in acidic environments. Phenol-formaldehyde resin is a commonly used adhesive in composite bipolar plates; while numerous benzene rings in phenol-formaldehyde resin result in the poor flexibility of composite bipolar plates. Embedding the flexible segment (–CHOH–CH2-O-) in the resin network structure of phenol-formaldehyde resin by copolymerization with epoxy resin is an effective method for improving the defects of phenol-formaldehyde resin. In this contribution, to tailor flexible-segment-rich (–CHOH–CH2-O-) resin network structure, the co-polymerization mechanism of phenol-formaldehyde resin and epoxy resin is investigated in detailed by in-situ Fourier Transform Infrared (FTIR), based on which an Alter-T strategy is proposed for flexible-segment-rich (–CHOH–CH2-O-) resin network structure during composite bipolar plates fabrication process. The obtained composite bipolar plates consisted of graphite and flexible-segment-rich resin network structure delivers improved flexural strength (86.97 MPa), electrical conductivity (203.22 S cm−1) and areal resistance (3.41 mΩ cm2) in comparison to previously reported composite bipolar plates with same components, which are also over the technical standard of the DOE. It is further demonstrated that enriching the flexible segment for improving the poor flexibility of resin network structure is of great importance to enhance the performance of the composite bipolar plates.

Particleboards with Recycled Material from Hemp-Based Panels.

This research addresses the current need for sustainable solutions in the construction and furniture industries, with a focus on environmentally friendly particleboard. Particleboards were made from a mixture of virgin wood chips and hemp shives, which were then mechanically recycled and used to make new lightweight particleboards. Phenol-formaldehyde resin with 25% w/w phenol replacement by soybean flour (PFS) was used as the binder for the lignocellulosic materials. Laboratory analyses determined the resin properties, and FTIR confirmed the structure of the experimental PFS resin. The thermal properties of all the resins were evaluated using thermogravimetric analysis (TGA). The panels were manufactured using industrial simulation and tested for mechanical and physical properties in accordance with European standards. The FTIR study confirmed good adhesion, and the TGA showed improved thermal stability for the recycled biomass panels compared to virgin biomass panels. The study concludes that lightweight particleboards can be successfully produced from recycled hemp shive-based panels, providing a sustainable alternative to traditional materials in the construction industry.

Reversible thermochromic properties of bisphenol A aromatic phenolic resin's composite natural rubber film

Based on open system and solution copolycondensation method, 2,6-monosubstituted bisphenol A aromatic phenolic resin with M‾n of 1.133 × 103 g·mol−1 and PDI of 1.005, was prepared by microwave, using bisphenol A (BPA), terephthalaldehyde (TPD) and isophthalaldehyde (IPD) as monomers. The number of BPA and phthalaldehyde (TPD or IPD) monomers participating in alternating copolymerization were 3 and 3, respectively. TPD and IPD had similar and low activities, therefore their competitive polymerization reactivity ratio was consistent with raw materials' practical molar ratio. The resin's structure was confirmed by 1H NMR, 13C NMR and FTIR. Reversible thermochromic composite natural rubber film was prepared by resin as chromogenic agent. When mass ratio of crystal violet lactone, resin, mixed alcohols (cetyl alcohol and octadecanol) and natural rubber is 1:3.0:30:20, i.e. 0.0075:0.023:0.23 (0.14:0.09):0.15 (g), the composite film was obtained by salivation method. The composite film's total color difference (ΔE) is about 85, and its absorption-scattering color depth difference (ΔKS) values are averagely 15 and 40 at visible light zone of 480–600 nm and 600–660 nm at 20–35 °C respectively. Composite film has good thermal stability and recyclability stability.

Состав и строение нефтяных дисперсных систем

Physico-chemical properties and behavior in the processes of extraction, transportation, processing, storage and use of petroleum products depend on the chemical, component and dispersed composition of oils, gas conden-sates, oil-like systems. For qualified management of these processes, it is necessary to understand the role of the composition and structure of oil dispersed systems (VAT). The classical descriptions of the structural elements of VAT are considered, their main varieties and types are given. It is shown how the size of a dispersed phase or a complex structural unit can change when external conditions change. Models of the structure of asphaltenes and resins, their composition and structure are given. A variety of approaches to the description of their structure and interaction with each other is shown, ranging from classical Ian-Mullins concepts to modern interpretations based on data from spectral analyses of nuclear magnetic and electron paramagnetic resonances (NMR and EPR) micrographs of a scanning electron microscope, computational computer programs. A hypothetical model of a complex structural unit formed by various groups of organic compounds from the standpoint of paired exchange interactions based on the paramagnetism of resinous-asphaltene molecules and compounds with a high carbon/hydrogen ratio is considered. Examples of the structure of complex polyheterophase oil dispersed systems containing particles of mechanical impurities, globules of water, bubbles of dissolved gases, demonstrating the multilevel structure of VAT, are given. Oil dispersed systems are, due to the extreme variety of compounds and impurities included in them, very complex objects, the study of the composition and structure of which is necessary for the qualified management of the processes of extraction, processing, transportation and storage of oil and petroleum products. Knowledge of the composition and structure of VAT, its dependence on external influences, on changes in conditions affecting it, the possibility of intensification of technological processes. The polyheterogenic composition and multilevel structure of VAT must be taken into account when determining the optimal effects on VAT in the processes of extraction, transportation, processing, storage of oil and the use of petroleum products. The chemical and component composition of VAT can be analyzed by known methods, including column chromatography, and the dispersed composition of dark petroleum products is determined by spectrophotometric method.

Recyclable and shape‐memory hydantoin epoxy resins based on dynamic ester‐exchanged bonds

AbstractThe permanent crosslinked network imparts chemical and mechanical stability to crosslinked elastomers, making their recycling a serious environmental issue. The decomposition products of pentaaryl diazoxide in the structure of hydantoin epoxy resin are nitrogen and carbon dioxide, and it is an environmentally friendly resin material. Here, we demonstrate a reversible covalent bonding reaction catalyzed by Zn2+ between the ester bond formed by the hydantoin epoxy resin and the acid anhydride, and construct a reversible crosslinked network structure of the environmentally friendly acid anhydride/hydantoin epoxy resin material. The strength, hardness and toughness of the cured material are greatly improved by optimizing its ratio. The ester exchange bonding can be reversible with temperature, which leads to the shape memory capability of the synthesized cured material. The cured product of HMY1 was recovered with ethylene glycol and completely dissolved at 180°C for 11 h. Ethylene glycol was volatilized at 190°C to obtain decomposed epoxy oligomer (DEO), which was added to the HMY1 resin system (the amount of DEO was 30 wt% of the total mass of the resin), and the network structure was cross‐linked to enable it to be recovered and remanufactured. Thus, this work provides a new avenue for the environmentally friendly development of recyclable, reconfigurable, and thermally adaptable shape‐memory hydantoin epoxy materials.Highlights Hydantoin epoxy resin eventually breaks down into non‐toxic CO2 and N2. Hydantoin epoxy and methyl tetrahydrophthalic anhydride form a reversible dynamic chemical bond catalyzed by Zn2+. Ethylene glycol can recover and reuse the solidified product.

Synthesis, characterization, and properties of a novel propargyl ether naphthalene phenolic resin

AbstractIn this study, 1,5‐dihydroxynaphthalene moiety was introduced into a novolac resin structure, and propargyl ether naphthalene phenolic resin (PNPF) was synthesized by the Williamson etherification reaction, which improved the heat resistance of the resin and its processability. The structure of the PNPF resin was characterized using 1H NMR and FTIR analysis, and its processability, heat resistance, thermal expansion, and dielectric properties were evaluated. The results revealed that the addition of 1,5‐dihydroxylhine, increased the reaction activity of the PNPF resin, and decreased its initial curing temperature, with the resin exhibiting excellent processability. The cured resin also showed excellent heat resistance and thermomechanical properties. The 5% weight loss temperature (Td5) and glass transition temperature (Tg) of the resin increased to 437.61 and 362.04°C, respectively, while the coefficient of thermal expansion decreased from 60.17 to 44.52 ppm, with a reduction of 26.01%. Moreover, the dielectric constant and dielectric loss of the cured resin were 3.02 and 0.00239, respectively.

Ultrasound-enhanced adsorption of amino acids from aqueous solution onto macroporous resins for green separation: Mass transfer mechanism and acoustic cavitation properties

The utilization of green technology for the recovery of renewable components has garnered significant attention. In this study, efficient and rapid separation of amino acids from aqueous solutions was achieved through ultrasound-assisted macroporous resin adsorption. The numerical simulation revealed the underlying mechanism of mass transfer during ultrasound-assisted adsorption and clarified the impact of acoustic properties on the adsorption process. Low-frequency (LFUS, 20 kHz) caused the damage of resin structure and the increase of adsorption capacity whereas these were less influenced by high-frequency ultrasound (HFUS, 1056 kHz). The external mass transfer coefficient was increased by 161% and 45% during LFUS- and HFUS-assisted adsorption than agitation-assisted adsorption. In addition, both US modes contributed to an enhancement of surface diffusion coefficient by over 100%. The predominant factor governing the intraparticle diffusion for amino acid adsorption was found to be pore volume diffusion, accounting for more than 70% of the overall process. Both LFUS and HFUS were observed to augment the influence of surface diffusion within the overarching diffusion phenomenon, aligning with the concurrent elevation of the surface diffusion coefficient. Furthermore, the mechanism of ultrasound-assisted adsorption was illustrated from the aspect of physical and sonochemical effects generated by the acoustic cavitation. The accumulated acoustic pressure of LFUS exceeded that of HFUS by a factor of 105, reflecting its strong physical effects. The connection between the mass transfer behaviour and acoustic bubble properties during ultrasound-assisted adsorption can provide guidance for the industry to apply ultrasound as a green technology to separate and recover renewable biomaterials from wastewater.

Evaluating (p-Semidine-Guanidine-Formaldehyde) terpolymer resin efficiency as anti-corrosive agent for mild steel in 1 M H2SO4: An experimental and computational approach

Corrosion is a critical concern in various industrial applications, especially in acidic environments. In this study, for the first time, we investigate the efficient anti-corrosive effect of (p-Semidine-Guanidine-Formaldehyde) terpolymer resin on mild steel in a corrosive sulfuric acid (H2SO4) medium. The research employs a comprehensive approach, combining experimental and computational methods to gain deeper insights into the corrosion inhibition mechanism. Electrochemical and gravimetric measurements are performed to determine when the inhibitor is incorporated andor not, mild steel corrodes at similar rates. The inhibition efficiency (%) is calculated based on the obtained data, revealing the effectiveness of the terpolymer resin showing an inhibitory efficacy of 93.70 % at an ideal concentration of 1 × 10−3 M as a corrosion inhibitor. Moreover, the adsorption behavior of the inhibitor on the mild steel surface is examined, and a Langmuir adsorption isotherm model is applied to explain the adsorption process. The computational simulations including HOMO and LUMO analyses shed light on the electronic properties and chemical structure of the (p-Semidine-Guanidine-Formaldehyde) terpolymer resin, elucidating its anti-corrosive mechanism. These findings hold significant implications for designing effective and environmentally friendly corrosion inhibitors for various industrial applications, leading to improved material durability and safety.

Synthesis and Investigation of Thermal and Dynamic Mechanical Properties of Urethane-Containing Epoxy Resins

This study aims to improve the thermal and mechanical properties of epoxy-based materials. For this purpose, the structure of epoxy resins was changed by chemical modification and epoxy resin containing urethane was synthesized. The synthesized resin was blended with commercial epoxy resin at the ratios of 25%, 50%, 75% by weight and hardened by curing. The thermal and mechanical properties of urethane-containing epoxy materials prepared in different proportions were compared with those produced from commercial epoxy resin. The structural characterization of the prepared materials was investigated by Fourier Transform Infrared Spectroscopy (FTIR) analysis, their thermal behavior was investigated by Thermogravimetric Analysis (TGA), and their mechanical properties were investigated by Dynamic Mechanical Analysis (DMA). TGA and DMA analyses of the materials showed that the presence of urethane in the structure of epoxy resins significantly changed the mechanical and thermal properties. It was observed that the storage and loss modulus values of urethane-containing resins increased approximately 2.5 times compared to commercial epoxy resins, and a decrease of approximately 10% in thermal degradation temperatures was observed.

Using non-destructive evaluation to monitor the influence of processing parameters on the curing process of thermoset polymers

The processing parameters used to manufacture thermoset polymers highly impact their curing process and final properties. However, these parameters, including stoichiometry and temperature, are difficult to monitor and control. This work presents a novel method to non-destructively evaluate in real-time the curing kinetics, mechanical properties, and chemical structure of an epoxy resin due to variations in the processing parameters using ultrasonics and Fourier transform infrared spectroscopy (FTIR). Samples with a different curing agent to epoxy ratio and varying curing temperatures were manufactured and tested. Changes in chemical structure and longitudinal sound speeds were monitored during the resin’s curing process, showing variations in the cure kinetics and final mechanical properties as a function of the processing parameters. The influence of these parameters on the glass transition temperature and thermal decomposition of the epoxy was also determined. Using ultrasonics and FTIR has the potential to non-destructively aid in the tailoring of polymeric materials by performing in-situ monitoring during their curing process. This method can also be implemented as quality control in both an in-field and manufacturing setting.

Effect of Surface Modification on Corrosion Resistance, Mechanical and Electrical Properties of Epoxy Resin-Based Nanocomposites

The epoxy resin-based nanocomposites have been used to overcome the drawback of epoxy resin such as brittle, low impact resistance, poor stress cracking and poor corrosion resistance in the aggressive environment by incorporating inorganic nanoparticles into the high cross-linked structure of epoxy resin. However, the main problem of these composites is the agglomeration of nanoparticles which influences the worst dispersion in the epoxy matrix and leads to poor properties of the composite. Therefore, this work aims to study the effect of nanoparticle additions, i.e. ZrO2 nanoparticle and SiO2 nanoparticle including waste glass powder (WGP) which is an alternative inorganic filler, on properties of the epoxy resin-based nanocomposite. The particle surface of each filler was also modified with 3-glycidoxypropyltrimethoxysilane (GTPMS) in order to achieve better dispersion in the disk-shaped bulk composites. The chemical property of modified fillers was characterized by Fourier transform infrared spectroscopy (FT-IR). The physical properties, mechanical properties, water absorption and corrosion resistance of all composites are then investigated. The results revealed that the incorporations of ZrO2, SiO2, and WGP with GPTMS surface modification into epoxy resin-based nanocomposite exhibit better performance in mechanical properties, water absorption and corrosion resistance than the unmodified surface of ZrO2, SiO2, and WGP additions. Although, both modified- and unmodified surfaces of fillers for the epoxy resin-based nanocomposites show improvement in all properties compared to the neat epoxy resin but the electrical properties of epoxy resin-based nanocomposites with unmodified fillers and GPTMS-modified fillers do not show a significant effect on any electrical properties.

Influence of network structure determined by Time-domain [formula omitted] Double Quantum NMR on the creep properties of non-stoichiometric epoxy-amine resins aimed for chemical anchoring applications

Chemical anchors, used to fasten structural components, are prone to creep under sustained loading, which significantly affects their long-term performance and service life. In this study, the molar ratio, that determines the ultimate network structure of an epoxy-amine resin system, is systematically modified to investigate the creep properties. The percentage of physical entanglement and defects (free and dangling chains) for each formulation is obtained by Time-Domain 1H Double Quantum (DQ) Nuclear Magnetic Resonance (NMR) measurements. The crosslink density values from the dynamic mechanical analysis (DMA) and the network parameter from the NMR measurements show a strong linear correlation. Tensile tests were performed to determine the influence on the mechanical properties and set the load levels for tensile creep measurements of the selected formulations. Epoxy-rich systems (Epoxy-Amine adduct) show the highest modulus and tensile strength but inferior creep properties compared to stoichiometric and amine-rich (Amine-Epoxy adduct) compositions. This can be attributed to the build-up of several network structures with higher content of free and dangling chains leading to lower deformation resistance. At high loads, the entanglement density has an increasing impact on the creep behavior compared to defect-rich systems. Modeling using the Findley approach was carried out to link the obtained creep parameter with the material properties. Therefore, this work aims to deepen the understanding of the molecular-scale structures of epoxy resins required for material and design optimization, by investigating the correlation between network structure and creep properties.

Volatile Compound Chemistry and Insect Herbivory: Pinus edulis Engelm. (Pinaceae) Seed Cone Resin

Pinus edulis Engelm. (pinyon pine) is a tree in the Pinaceae family with wide geographic distribution throughout dry forests of western North America. Pinyon pine seed cones, which mature over a 2-year period before shedding seed, are often resinous. Conifer resin, which is a liquid-soluble mixture of volatile and non-volatile secondary metabolites, typically demonstrates significant ecological functions. In the current study, seed cones (n = 240) were collected monthly for a 1-year period from pinyon pine trees (n = 20) and separated equally into two groups, resinous and non-resinous cones, for research on the volatile compound chemistry and insect herbivory. Upon distillation, resinous cones yielded 41× more volatile oil and contained more viable seeds, compared to non-resinous cones. Chemical profiles of volatile oils were seemingly consistent between seasons but differed between cone groups. In resinous cone samples, volatile oils were largely composed of α-pinene (avg. 75.6%) and δ-3-carene (avg. 7.4%). In contrast, in non-resinous cone samples, the volatile oil profiles were not dominated by any single prominent compound. Cone inquiline insect communities varied with regard to the resinous status of the cones, the month of collection, and with overall volatile oil yield. Typically, with larger oil yields we saw more diverse and more abundant inquiline communities. Findings from this study suggest that the volatile oils, in addition to other components of cone resin and physical structures, play a significant ecological role in pinyon pine seed preservation from insect herbivory.

Molecular dynamics simulation of epoxy resin properties at different C=N contents

In response to the green development strategies of countries all over the world, research on degradable epoxy resins has attracted widespread attention. The introduction of reversible covalent bonds in the conventional cross-linked structure of epoxy resins is one of the methods to achieve degradation of epoxy resins, and most researchers use molecular dynamics simulations in their preliminary studies to investigate the feasibility of the introduction of reversible covalent bonding schemes. The purpose of this paper is to investigate the feasibility of introducing C=N into the cross-linked structure of epoxy resins. Four formulation schemes of vanillin-based monoepoxides with the curing agent 4,4′-methylenebis(cyclohexylamine) were designed, and the molecular dynamics simulation method was used to cross-link them. The changes in the cross-linking degree, structural parameters before and after cross-linking, free volume fraction, and C=N content before and after cross-linking were investigated. The effects of different C=N contents on the thermal properties such as glass transition temperature and thermal expansion coefficient, as well as the mechanical properties such as the elastic modulus and shear modulus of this epoxy resin, were investigated. The bond-breaking characteristics of C=N, C–N, and C–O were compared by density of states and differential charge density simulations. Then the degradation mechanism of epoxy resin after the introduction of C=N was illustrated. The results show that as the specific gravity of the curing agent molecule increases, the cross-linking degree tends to increase. The cross-linked model has reduced volume, increased density, decreased energy, and a more stable structure. After crosslinking, the gaps between the segments in the system become smaller, and the fraction of free volume decreases as the proportion of crosslinking agent molecules increases. The C=N content in epoxy resin shows an increasing trend first and then decreases with the increase in the proportion of the curing agent. The glass transition temperature of the material increases with the increase in C=N content, while the coefficient of thermal expansion decreases with the increase in C=N content. The elastic modulus and shear modulus of the material show an increasing trend with the increase in C=N content, with a relatively gradual change in magnitude. Compared with C–N and C–O bonds, the C=N bond is weaker in strength, has a greater polarity, and is more prone to cleavage and degradation.

Facile fabricated transparent anti-smudge coating with high hardness and excellent flexibility from MTQ and branched silicone resins

The demand for high-transparent functional coatings with glass-like hardness, polymer-like flexibility, and anti-smudge properties has increased significantly, especially for foldable touchscreens. However, it is challenging to achieve all the required properties in a coating because the realization of these properties may conflict with each other. In this study, we present a facile method for preparing a special organic-inorganic hybrid coating by utilizing epoxy MTQ silicone resins and amine-terminated hyperbranched polysiloxane (HPSi). The chemical structure of the MTQ resin was fine-tuned to obtain the optimal M/T/Q ratio, and a novel HPSi with rich crosslinking sites and excellent flexibility was prepared as the curing agent. The resulting hybrid network imparted the coating with exceptional hardness (pencil hardness, 7–9H) and excellent flexibility (<2 mm bend diameter). In addition, by modifying the MTQ resin with fluorosilane, the surface energy of the coating was reduced to 14.8 ± 0.4 mJ/m2 and its anti-smudge and self-cleaning properties were improved without sacrificing the transparency of the coating (99.4 % at 550 nm). Notablely, even after 1000 cycles of steel wool abrasion, these coatings still maintain their outstanding performance. This study provides a promising strategy for the development of hard, flexible, and anti-smudge coatings suitable for foldable displays and other related fields.

Tuning the performance of composite bipolar plate for proton exchange membrane fuel cell by modulating resin network structure

Composite bipolar plates (CBPs) are promising candidates in proton exchange membrane fuel cell (PEMFC) for achieving mechanical strength and electrical conductivity as well as chemical stability in acidic environments simultaneously. While widely-explored CBPs composed with Phenol-Formaldehyde (PF) resin as adhesive (donated as PF-CBP) deliver poor flexibility due to the numerous hard π-conjugation (benzene ring) in PF network structure, which is becoming the main bottleneck index and largely hindering the practical applications of CBP. Herein, we propose a co-polymerization method by introducing Epoxy (EP) into PF resin as adhesive for CBP (donated as PF-EP-CBP), by which abundant flexible segments (-CHOH-CH2-O-) from EP are demonstrated to be well embedded into the structure of PF resin for enhanced flexibility. The obtained PF-EP-CBP exhibits significantly improved flexural strength of 46.20 MPa, 1.57 times higher than pristine PF-CBP (29.58 MPa), which is also higher than the 2025 DOE targets (40 MPa). Moreover, the detailed areal specific resistance, thermal conductivity, H2 permeability and corrosion behaviors are conducted systematically to support the single cell of PEMFC. The results provide a novel insight and convenient method on the adhesive tailoring by incorporating flexible linkers into resin network structure, which is of significance to drive the practical development of the CBPs in PEMFC fields.