PVDF-Based Micro Inorganic Fillers-Containing Polymer Electrolyte Membranes

Polymer electrolyte membranes based on poly （vinylidene fluoride-co-hexafluoropropylene） （PVDFHFP） with and without different types of micro inorganic fillers were prepared by phase-inversion process. Morphologies, porosities and electrochemical properties ＇of the as-prepared membranes were investigated by means of scanning electronic microscopy （SEM）, PC （propylene carbonate） uptake and alternating current （AC） impedance technique. Compared with other membranes, the membrane with micro SiO2 filler shows a dense morphology so that its PC uptake is the highest, namely, 339 %. The membrane filled with micro TiO2 exhibits good electrochemical performances： the ion conductivity is as high as 1.1 × 10^-3 S/cm at 18 ℃, which can meet the demand of lithium ion batteries. Moreover, its initial charge-discharge efficiency exceeds 89 %. The composite membranes with micro SiO2, TiO2 and Al2O3 are more suitable for the utilization in lithium ion batteries due to better cycle.ability, whereas the battery assembled with the blank membrane containing no inorganic fillers encounters a short circuit after the 5th cycle.

PHOTOINITIATED CROSSLINKING OF EPDM/INORGANIC FILLER BLENDS AND CHARACTERIZATION OF RELATED PROPERTIES

Photoinitiated crosslinking of ethylene-propylene-diene terpolymer （EPDM） blends filled with calcium carbonate, talc and calcined kaolin （CK） in the presence of benzil dimethyl ketal as photoinitiator and trimethylolpropane triacrylate as crosslinker and their related properties have been studied by different analytical methods, The results from gel content and heat extension determination show that the efficiency ofphotocrosslinking of EPDM increases with increasing the content of diene and its molecular weight. The EPDM blends with 100 phr different inorganic fillers can be photocrosslinked to gel content of above 60% by 5 s UV-irradiation under optimum conditions. Under the same conditions of irradiation, the orders of photocrosslinking rate and final gel content are EPDM/CaCO3 〉 EPDM/talc 〉 EPDM/CK. The data from thermogravimetric analysis, dynamic mechanical thermal analysis, electrical properties, mechanical tests and scanning electron microscopy show that UV irradiation crosslinking apparently enhances the thermal stability, mechanical properties and electrical properties of the photocrosslinked EPDM/inorganic filler samples. Although the attenuated total-reflection FTIR data show that inorganic fillers can promote the surface photo-oxidation of EPDM/inorganic filler samples with increasing the irradiation time, the above related properties of the photocrosslinked EPDM blends irradiated within 5 s are enough to satisfy many applications in the cable industry.

Recent developments in high-performance Nafion membranes for hydrogen fuel cells applications

As a promising alternative to petroleum fossil energy,polymer electrolyte membrane fuel cell has drawn considerable attention due to its low pollution emission,high energy density,portability,and long operation times.Proton exchange membrane(PEM)like Nafion plays an essential role as the core of fuel cell.A good PEM must have satisfactory performance such as high proton conductivity,excellent mechanical strength,electrochemical stability,and suitable for making membrane electrode assemblies(MEA).However,performance degradation and high permeability remain the main shortcomings of Nafion.Therefore,the development of a new PEM with better performance in some special conditions is greatly desired.In this review,we aim to summarize the latest achievements in improving the Nafion performance that works well under elevated temperature or methanol-fueled systems.The methods described in this article can be divided into some categories,utilizing hydrophilic inorganic material,metal-organic frameworks,nanocomposites,and ionic liquids.In addition,the mechanism of proton conduction in Nafion membranes is discussed.These composite membranes exhibit some desirable characteristics,but the development is still at an early stage.In the future,revolutionary approaches are needed to accelerate the application of fuel cells and promote the renewal of energy structure.

改性聚四氟乙烯陷阱控制电导分析(英文)

The reasonable conduction property is beneficial to release the deposited charges by conduction current in dielectric space charging environment,thus the level of the deep charging and the pulse discharge can effectively be weakened and inhibited.A traditional method for conductivity measuring under ground circumstance was used,and both the applied voltage and temperature were varied to determine the dependence of volume conductivity in PTFE modified by different filler contents.The results inferred the volume conductivity was significantly affected by the phenomenon of the percolation conduction,as well as the high-field conduction.The shallow and deep charge traps were considered to be a key factor in volume conductivity variation.In this theory,modified by inorganic semi-conductive filler,the distribution of trap density and depth in PTFE can be controlled to achieve the ideal temperature-dependent conduction property and high-field conduction property,which will finally lead to gentle release of the deposited charges while the electrostatic field reaches the conductivity-variation threshold.

3D additive manufactured composite scaffolds with antibiotic-loaded lamellar fillers for bone infection prevention and tissue regeneration

Bone infections following open bone fracture or implant surgery remain a challenge in the orthopedics field.In order to avoid high doses of systemic drug administration,optimized local antibiotic release from scaffolds is required.3D additive manufactured(AM)scaffolds made with biodegradable polymers are ideal to support bone healing in non-union scenarios and can be given antimicrobial properties by the incorporation of antibiotics.In this study,ciprofloxacin and gentamicin intercalated in the interlamellar spaces of magnesium aluminum layered double hydroxides(MgAl)andα-zirconium phosphates(ZrP),respectively,are dispersed within a thermoplastic polymer by melt compounding and subsequently processed via high temperature melt extrusion AM(~190◦C)into 3D scaffolds.The inorganic fillers enable a sustained antibiotics release through the polymer matrix,controlled by antibiotics counterions exchange or pH conditions.Importantly,both antibiotics retain their functionality after the manufacturing process at high temperatures,as verified by their activity against both Gram+and Gram-bacterial strains.Moreover,scaffolds loaded with filler-antibiotic do not impair human mesenchymal stromal cells osteogenic differentiation,allowing matrix mineralization and the expression of relevant osteogenic markers.Overall,these results suggest the possibility of fabricating dual functionality 3D scaffolds via high temperature melt extrusion for bone regeneration and infection prevention.

Preparation and properties of silane coupling agent modified steel slag as functional filler for anti-corrosion coating

The chemical composition and high wear resistance of steel slag(SS)make it a potential alternative to traditional inorganic fillers.3-Aminopropyltriethoxysilane(KH550)modified steel slag(MSS)was successfully prepared,and its application in epoxy(EP)anti-corrosion coating was introduced.Due to the grafting of silane coupling agent functional groups onto the surface of SS,MSS exhibited improved solubility in xylene organic solvent and reduced agglomeration.When the MSS content was 15 wt.%,the contact angle of the MSS/EP composite coating was 101°,and the abrasion was only 0.07 g,compared with 56.2°and 0.13 g,respectively,for the pure EP coating.The corrosion resistance of coatings was investigated by performing the electrochemical test(impedance)after immersion in a 3.5 wt.%NaCl solution.The electrochemical test results showed that the impedance modulus of the 15 wt.%MSS/EP composite coating at low frequency(Z_(f)=0.01 Hz)was approximately 1.08×10^(7)Ωcm^(2),which was two orders of magnitude higher than that of the pure EP coating.

Exploring porous zeolitic imidazolate frame work-8(ZIF-8)as an efficient filler for high-performance poly(ethyleneoxide)-based solid polymer electrolytes

Nano Research volume 13,pages2259–2267(2020)Cite this article 277 Accesses 1 Altmetric Metrics details Abstract The incorporation of inorganic fillers into poly(ethyleneoxide)(PEO)-based solid polymer electrolytes(SPEs)is well known as a low-cost and effective method to improve their mechanical and electrochemical properties.Porous zeolitic imidazolate framework-8(ZIF-8)is firstly used as the filler for PEO-based SPEs in this work.Due to the introduction of ZIF-8,an ionic conductivity of 2.2×10^−5 S/cm(30℃)is achieved for the composite SPE,which is one order of magnitude higher than that of the pure PEO.ZIF-8 also accounts for the broader electrochemical stability window and lithium ion transference number(0.36 at 60℃)of the composite SPE.Moreover,the improved mechanism of ZIF-8 to the composite SPE is investigated by zeta potential and Fourier transform infrared spectrograph characterizations.The stability at the composite SPE/lithium interface is greatly enhanced.The LiFePO4||Li cells using the composite SPE exhibit high capacity and excellent cycling performance at 60℃,i.e.,85%capacity retention with 111 mA·h/g capacity retained after 350 cycles at 0.5 C.In comparison,the cells using the pure PEO show fast capacity decay to 74 mA·h/g maintaining only 68 capacity.These results indicate that the PEO-based SPEs with ZIF-8 are of great promise for the application in solid-state lithium metal batteries.