Robust poly(p-phenylene oxide) anion exchange membranes reinforced with pore-filling technique for water electrolysis

\ua9 2024 The Authors. Journal of Applied Polymer Science published by Wiley Periodicals LLC. Mechanical robustness and durability are crucial for anion exchange membranes to guarantee the longevity and consistent performance of AEM water electrolysis (AEMWE) systems. In this study, a composite membrane based on the quaternized poly(p-phenylene oxide) (QPPO)/polytetrafluoroethylene (PTFE) was developed. This membrane was fabricated by enhancing the QPPO-based AEM through a pore-filling technique within a porous PTFE structure. The tensile strength of the composite membrane was increased significantly from 16.5 to 31 MPa. The conductivity of the composite membrane was 6.25 mScm−1 lower than 30 mScm−1 of the QPPO-based membrane at 20\ub0C, resulting from the low volume fraction of QPPO in the composite membrane. At 40% RH, the net change mass of the composite membrane is 1.59%, much lower than that of QPPO-based membrane (10.98%) at 40\ub0C. The composite membrane demonstrated a significantly increased lifetime in the working electrolyzer (>200 h) compared with an otherwise identical electrolyzer assembled with a QPPO-based membrane (50 h)

Degradation of QPPO-based anion polymer electrolyte membrane at neutral pH

\ua9 2023 The Royal Society of ChemistryThe chemical stability of anion polymer electrolyte membranes (AEMs) determines the durability of an AEM water electrolyzer (AEMWE). The alkaline stability of AEMs has been widely investigated in the literature. However, the degradation of AEM at neutral pH closer to the practical AEMWE operating condition is neglected, and the degradation mechanism remains unclear. This paper investigated the stability of quaternized poly(p-phenylene oxide) (QPPO)-based AEMs under different conditions, including Fenton solution, H2O2 solution and DI water. The pristine PPO and chloromethylated PPO (ClPPO) showed good chemical stability in the Fenton solution, and only limited weight loss was observed, 2.8% and 1.6%, respectively. QPPO suffered a high mass loss (29%). Besides, QPPO with higher IEC showed a higher mass loss. QPPO-1 (1.7 mmol g−1) lost nearly twice as much mass as QPPO-2 (1.3 mmol g−1). A strong correlation between the degradation rate of IEC and H2O2 concentration was obtained, which implied that the reaction order is above 1. A long-term oxidative stability test at pH neutral condition was also conducted by immersing the membrane in DI at 60 \ub0C water for 10 months. The membrane breaks into pieces after the degradation test. The possible degradation mechanism is that oxygen or OH˙ radicals attack the methyl group on the rearranged ylide, forming aldehyde or carboxyl attached to the CH2 group

Cost-effectiveness of rubber and polymer modified asphalt mixtures as related to sustainable fatigue performance

Load associated fatigue cracking is one of the major distress types occurring in flexible pavements. Flexural bending beam fatigue laboratory test has been used for several decades and is considered an integral part of the Superpave advanced characterization procedure. One of the most significant solutions to sustain the fatigue life for an asphaltic mixture is to add sustainable materials such as rubber or polymers to the asphalt mixture. A laboratory testing program was performed on three gap-graded mixtures: unmodified, Asphalt Rubber (AR) and polymer-modified. Strain controlled fatigue tests were conducted according to the AASHTO T321 procedure. The results from the beam fatigue tests indicated that the AR and polymer-modified gap graded mixtures would have much longer fatigue lives compared to the reference (unmodified) mixture. In addition, a mechanistic analysis using 3D-Move software coupled with a cost-effectiveness analysis study based on the fatigue performance on the three mixtures were performed. Overall, the analysis showed that the AR and polymer-modified asphalt mixtures exhibited significantly higher cost-effectiveness compared to unmodified HMA mixture. Although AR and polymer-modification increases the cost of the material, the analysis showed that they are more cost effective than the unmodified mixture

The influence of networks on consumer behavior: Understanding how social media networks impact online word of mouth and purchase behavior

Social media has permeated the everyday life of consumers and with that, its influence on consumer behavior has only grown. To better understand this growth a look into the different networks of influence is needed. This research looked at how the influence of personal networks and that of the general community impact online word of mouth and purchase behavior on facebook. We proposed that the endorsement of a marketing page from a user's own network and general community would both have positive impact on a consumer’s intent to engage in online word of mouth activities and purchase related behaviors. Furthermore, we propose that this relationship would be further moderated by the level of cognitive load consumers are exposed to. However, findings in this study suggest that while social media networks do have an influence on purchase behaviour and online word of mouth, there are different combinations of behaviors associated with different product types. Personal networks more heavily influence some Facebook pages, while others are more influenced by the general community, or by both types of networks or even by neither of the networks. This suggests that consumers react differently to the influence of networks based on the page category type

The Proportionality in Corporation Law

comRésuméLa présente étude porte sur le principe de proportionnalité en droit des sociétés. Même si la proportionnalité trouve sa source en droit public, elle a envahi différentes branches du droit privé sans avoir pour autant fait l’objet d’une analyse détaillée en droit des sociétés.Cet article se focalise sur le droit tunisien avec une ouverture sur le droit français, qui constitue sa source matérielle. En droit des sociétés, la proportionnalité présente deux aspects: il s’agit d’une proportionnalité mathématique et d’une proportionnalité finalisée. La proportionnalité mathématique se traduit par la concordance des droits de l’associé avec sa participation dans le capital social. Une telle corrélation lui permet la protection de ses intérêts dans la société. La proportionnalité finalisée se manifeste par l’adéquation des moyens utilisés avec les objectifs visés ainsi que l’équilibre des intérêts en présence. Certains auteurs estiment que la proportionnalité mathématique a cédé la place à la proportionnalité finalisée. Cette opinion n’est pas partagée par l’auteure de cette étude qui tente de démontrer son caractère exagéré. Effectivement, malgré les exceptions qui lui sont apportées, la proportionnalité mathématique résiste encore et doit être maintenue puisqu’elle traduit l’esprit de collaboration de l’associé ou encore l’intention de s’associer (l’affectio societatis). Le présent article creuse la proportionnalité finalisée en défendant sa prévalence en raison de sa relation avec la bonne gouvernance de l’entreprise.comAbstractThis study deals with the principle of proportionality in corporation law. Even if the proportionality stems from public law, it has invaded different branches of private law, but without being analyzed in detail in corporation law. This study also focuses on Tunisian law with an openness to French law, its inspiration source. In corporation law, the proportionality has two aspects: it is mathematical and linked to a goal. The mathematical aspect of the proportionality is reflected in compliance with the shareholder’s prerogatives with his participation in the capital, so that he could protect his investment and thereby the interests of the company. The proportionality, which is linked to the purpose, is expressed by two ideas: the adequacy of the means used with the purposes in mind and the search of the balance of interests. Some authors think that the mathematical proportionality gave way to the proportionality linked to a purpose. We do not share this opinion and we have tried to show that it is exaggerated. In fact, despite the exceptions to the mathematical proportionality, it is still surviving and should be maintained, because it translates the shareholder’s spirit of cooperation (affectio societatis). This study has deepened the proportionality linked to the purpose, defending its enhancement, since it has a relation with the good corporate governance.يعالج البحث مسألة التناسب في قانون الشركات. عند ظهورها، اكتسحت فكرة التناسب في القانون العام فروع القانون الخاص دون تناولها بالتفصيل في مادة قانون الشركات. ارتكزت هذه الدراسة على القانون التونسي وانفتاحه على القانون الفرنسي، بوصفه المصدر المادي له. يتجلى التناسب في قانون الشركات في مظهرين؛ الأول "رياضي" أو "رقمي"، والثاني مرتبط بالغاية. بالنسبة للتناسب "الرياضي"، فإنّه يظهر من خلال الملاءمة بين حصة الشريك في رأس المال وصلاحياته المالية وغير المالية، وهي ملاءمة منطقية؛ إذ بقدر تعريض الشريك لأمواله للمخاطر يتسع نفوذه حتى يتسنى له الحد من هدرها والمساس بمصلحة الشركة. وفيما يتعلق بالتناسب المرتبط بالغاية، فهو يتجلى في الملاءمة بين الوسائل المستعملة والأهداف المنشودة، بالإضافة إلى البحث عن توازن المصالح. ويرى جانب من الفقه أن التناسب "الرياضي" قد تم تهميشه لفائدة التناسب المرتبط بالغاية، دون الاستدلال على ذلك بحجج مقنعة، وهو رأي لا نشاطره وحاولنا تنسيبه باتباع منهج تحليلي استدلالي نقدي أثبت صمود هذا التناسب رغم الاستثناءات التي طالته مع الدعوة إلى المحافظة عليه لكونه من مظاهر نية الاشتراك كأحد عناصر عقد الشركة. بقي التناسب المرتبط بالغاية، والذي عالجه الفقهاء ببعض الإشارات دون التعمق في أبرز تجلياته وتأليفها، وهو ما تضمنته هذه الدراسة التي دعمت تنامي أهمية هذا الوجه للتناسب مع المناداة بتعزيزه لارتباطه بالحوكمة الرشيدة للشركات

Enhancing the physicochemical properties of nickel cobaltite catalyst for oxygen evolution reaction in anion exchange membrane water electrolyzers

\ua9 The Author(s) 2024. Hierarchical hollow urchin-like nickel cobaltite (NiCo2O4) was synthesized using a two-step hydrothermal method. The effects of metal composition and surfactant addition on the morphology, structure, and electrochemical performance toward oxygen evolution reaction (OER) were investigated. The addition of cetyltrimethylammonium bromide (CTAB) reduced particle aggregation, resulting in a higher electrochemical active surface area and electrical conductivity. Lowering the Ni content from 1.0 to 0.25 did not alter the morphology and structure of the product to any extent. However, the crystallite size slightly increased. Among the spinels with different Ni and Co compositions, NiCo2O4 exhibited a superior OER electrocatalytic activity, achieving a 380 mV overpotential at 10 mA/cm2 current density. It also delivered a good performance in an anion exchange membrane water electrolyzer (AEMWE) using 1 M NaOH at 60 \ub0C, reaching a current density of about 420 mA/cm2 at a cell voltage of 1.95 V

Investigation of high temperature polymer electrolyte membrane fuel cells

PhD Thesisthe major issues limiting the introduction of polymer electrolyte membrane fuel cells (PEMFC) is the low temperature of operation which makes platinum-based anode catalysts susceptible to poisoning by trace amounts of CO, typically present in reformed fuel. In order to alleviate the problem of CO poisoning and improve the power density of the cell, operating at temperature above 100°C is preferred. Nafion® type perfluorosulphonated polymers have been typically used for PEMFC but cannot function at temperatures above 100°C. In addition, higher temperatures will enable more effective cooling of the cell stacks and provide a means for combined electrical and heat energy generation. The solution to improved PEMFCs technology is to develop a new polymer electrolyte membrane which exhibits stability and high conductivity in the absence of liquid water. A HighTemperature PEMFC based on a Phosphoric acid (H3P04) doped Polybenzimidazole poly[2,2- (m-phenylene)-5,5 bibenzimidazole] (PBI) membrane has been developed and demonstrated as an alternative to Nafion® for operation at temperatures up to 200°C. PBI membranes, when doped with phosphoric acid, do not rely on hydration for conductivity; a significantly lower water content of the membrane, compared to Nafion, is required for proton transport. The resulting system improvements include; high CO tolerance, simple thermal and water management, excellent oxidative and thermal stability, and good proton conductivity at elevated temperatures. Two issues associated with phosphoric acid in the PBI based fuel cell are the lower activity of the electrocatalysts and the potential loss of the acid into the fuel cell gas/vapour exhaust streams. The limited oxygen permeability and slow oxygen reduction kinetics in phosphoric acid is a major limitation for the performance ofPBI based PEMFCs. The kinetics of oxygen reduction in PBVH3P04 has been studied in electrochemical single electrode cells. Several Membrane Electrode Assemblies (MEAs) have been manufactured to allow optimisation of the electrode performance. Various electrochemical techniques such as chronoamperometry, polarisation curves and Frequency Response Analysis (FRA) were used to study and separate the effects of the various phenomena taking place at the electrode surface: IR losses, mass transport and kinetics. A new Electrode structure utilizing PTFE has been developed allowing higher oxygen permeability and therefore enhanced performance of 0.55 W cm-2 with oxygen and 0.27 W cm-2 with air (atm) at temperature as low as 120 ·C. The Platinum loading was reduced to 0.4 mgpt cm-2 at the cathode and 0.2 mgpt cm-2 at the anode. Further reduction of cathode platinum loading to 0.2 mgPI cm-2 was achieved without dramatic drop in the performance by utilising Pt based binary alloy catalyst (Pt-Co/C). A simplified thin film steady-state, isothermal, one dimensional model of a proton exchange membrane fuel cell (PEMFC), with a polybenzimidazole (PBD membrane, was developed. The electrode kinetics were represented by the Butler-Volmer equation, mass transport was described by the multi-component Stefan Maxwell equations and Fick's law, and the ionic and electronic resistances described by Ohm's law. The model incorporated the effects of temperature and pressure on the open circuit potential, the exchange current density and diffusion coefficients, together with the effect of water on the acid concentration and ionic conductivity. The polarisation curves predicted by the model were validated against experimental data for a PEMFC which included the effect of temperature and oxygen/air pressure on cell performance. An additional problem which faces the introduction ofPEMFC technology is that of supplying or storing hydrogen for cell operation, especially for vehicular applications. Consequently the use of alternative fuels such as methanol and ethanol is of interest, especially if this can be used directly in the fuel cell, without reformation to hydrogen. A limitation of the direct use of alcohol is the lower activity of oxidation in comparison to hydrogen, and hence to improve activity and power output higher temperatures of operation are preferable. The performance of a high temperature direct methanol fuel cell (DMFC) using PBI based electrode assemblies was investigated. The performance of the system was limited by poor methanol oxidation kinetics in a phosphoric acid environment and consequently power performance was inferior to that achieved with low temperature DMFCs based on Nafion membranes.European commission for their financial support through the FURIM project "Further Improvement and System Integration of High Temperature Polymer Electrolyte Fuel Cells" under frame work 6. FURIM partners: Technical University of Denmark, Volvo Technology Corporation, Norwegian University of Science and Technology, Danish Power Systems, Case Western Reserve University, University of Stuttgart, HyGear, Freudenber

Three dimensional model of a high temperature PEMFC using PBI doped phosphoric acid membranes. Study of the flow field effect on performance

A three-dimensional isothermal model of a high temperature polymer membrane fuel cell equipped with polybenzimidazole (PBI) membrane is described. All major transport phenomena were taken into account except the species cross-over thought the membrane. The cathode catalyst layer was treated as spherical catalyst agglomerates with porous inter-agglomerate spaces. The inter-agglomerate spaces were filled with a mixture of electrolyte (hot phosphoric acid) and polytetrafluoroethylene (PTFE). This approach proved to be an essential requirement for accurate simulation. In this particular paper the influence of different flow field designs and dimensions on performance was intensely study. Traditional configurations were tested (straight, serpentine, pin-in and interdigitated), and a new designs were proposed. With these new designs we tried to maximize performance by providing homogeneous reactants distribution over the active area keeping low pressure drop and relatively high velocity. The dimension and position of the inlet and outlet manifolds were also analysed. From the obtained results was observed a massive influence of the manifolds position and dimension on performance. This fact leaded to an optimization of the manifolds which can give important guidelines for future bipolar plates production