New anhydrous proton exchange membranes based on fluoropolymers blend imidazolium poly (aromatic ether ketone)s for high temperature polymer electrolyte fuel cells

The blend polymer membranes were synthesized from the methylimidazolium poly (aromatic ether ketone) (MeIm-PAEK) and fluoropolymers (PVDF and PVDF-HFP) with excellent thermal stability and improved dimensional stabilities for high-temperature polymer electrolyte fuel cells. The MeIm-PAEK exhibited good compatibility with PVDF or PVDF-HFP without phase separation. High phosphoric acid doping contents of the blend membranes were achieved at elevated temperatures with acceptable swellings. The acid doped blend membranes displayed lower dimensional swellings and higher mechanical strength compared to the MeIm-PAEK membrane, which allowed the blend membranes to obtain higher acid doping contents and proton conductivities. The MeIm-PAEK/10%PVDF membrane with a phosphoric acid doping content of 700 wt% showed a proton conductivity as high as 0.192 S cm^?1 at 180 °C under the non-humidified condition and a tensile strength of 4.3 MPa at room temperature.     

Two-Step Processing Method for Blending High-Performance Polymers with Notable Thermal and Rheological Differences: PEI and PBT

Blends between high-performance polymers (HPP) are barely studied, especially those produced by melting processing. In this work, it is proposed a novel methodology to prepare blends between polymers with notable processing temperature differences: poly(ether imide) (PEI) and poly(butylene terephthalate) (PBT). Processing parameters are settled after thermal and rheological evaluation of pure materials, those results suggest these blends need to be produced by steps. It is found a synergistic effect such as lowering PEI processing temperature and reducing PBT hydrolysis at high temperatures. Propose methodology allows to produce blends between HPP in the whole composition range with the same processing conditions.     

Effect of thermal crosslinking process on membrane structure and PEM fuel cell applications performed with SPEEK-PVA blend membranes

One of the promising options in the pursuit of clean and sustainable energy is fuel cell technology. PEM fuel cell stands out among fuel cell technologies due to its high efficiency, compactness, and ability to be used in portable applications. SPEEK (with different sulfonation degrees) and PVA blend membranes, which are thought to create a good synergy for PEM fuel cell, were prepared by using the solution casting method. As a result of the weight loss experiments, it was understood that the membranes dissolve in water regardless of the degree of sulfonation. Thermal crosslinking was carried out to prevent the membrane dissolution in water, which is in continuous contact with water in the fuel cell. Dissolution was mostly prevented by means of the thermal crosslinking process. Changes in the physical, chemical, and mechanical structure of the membrane after thermal crosslinking were comparatively determined by fourier transform infrared (FTIR), thermogravimetric analysis – differential thermal analysis (TGA-DTA), differential scanning calorimetry (DSC), water uptake capacity, swelling property, ion exchange capacity (IEC), dynamic mechanical analysis (DMA), electrochemical impedance analysis and oxidative stability. In addition, single-cell performance tests were performed with the membrane that gave the best results in the characterization analyses. Analysis results showed that thermal crosslinking prevented the dissolution of membranes in water ingreat extent. In addition, it was determined that the thermally crosslinked membranes had a more stable structure.     

异质文化的交融与共生

通过建筑实例, 分析厦门近代教堂风格特征的成因, 揭示中西建筑文化交融与共生中所呈现的复杂交错的现象, 以及对现今建筑设计、建筑遗产保护的启示。     

空间布局与营造技术的结合同济大学教学科研综合楼设计

文章简要介绍了同济大学教学科研综合楼设计,指出设计充分考虑了高校教育交流、融合、开放的特点,塑造了建筑简约的外形和丰富的内部空间,将该建筑营造为促进学术交流、拓展教育资源的战略平台及应用创新工程技术的展示平台。     

A new model and a reformulation for the crude distillation unit charging problem with oil blends and sequence-dependent changeover costs

In this paper, we address the problem of planning the crude distillation unit charging process with oil blend. It is well known that blending and splitting operations can lead together to both non-linearities and concavities in mathematical programming models. As result, many proposed models for this problem use simplifying assumptions to keep the formulation computationally tractable. However, we show the existence of splitting operations that can lead to inconsistencies in the solutions obtained by the previous MILP models from the literature. Then, we propose a way to address this issue through an aggregated inventory capacity combined with a disaggregation algorithm. Furthermore, we develop a mathematical reformulation that improves the solving efficiency of the method. Then, we report experiments that show that the reformulated MILP model presents significant gains concerning linear relaxation gaps and run times, and the disaggregation algorithm leads to feasible solutions for all the tested instances.     

Structural and optical characterization of ZnO doped PC/PS blend nanocomposites

PC50%/PS50% polymer blend nanocomposites, undoped and doped with different concentration of ZnO nanoparticles (1, 2, 3 wt%), have been prepared using solution casting method. Structural and optical studies have been performed using X-ray Diffraction (XRD), Scanning Electron Microscope (SEM) and Ultraviolet–Visible spectroscopy (UV–Vis). ZnO nanoparticles have been synthesized by chemical route method. The nanostructure of the ZnO nanoparticles has been ascertained through X-ray Diffraction (XRD) and Transmission Electron Microscopy (TEM). Optical Absorption Spectra has been used to study optical constants of prepared blend nanocomposites. Energy band gap of PC/PS – ZnO blend nanocomposites have been calculated by using Tauc relation. The band gap of the nanocomposites decreases as ZnO wt% increases. Extinction coefficient, refractive index and real & imaginary part of dielectric constants increase with increase in ZnO nanoparticles wt%.     

Improving the wear resistance of UHMWPE implants by in situ precipitation of hyaluronic acid using supercritical fluid technology

Recently, the increase in the number of patients who require a hip or knee implant, combined with the reduction of age at which this implant is demanded, emphasizes the urgent need for the development of new materials with enhanced mechanical and tribological properties. In this work, a new technique called supercritical in situ precipitation (SCisP) has been employed to manufacture a blend made of ultra-high molecular weight polyethylene with added vitamin E (UHMWPE_vit) plus a hyaluronic acid (HA) derivative. The precipitation of the HA derivative within the pores of a porous UHMWPE_vit preform allows getting a blend after the post-processing of the SCisP product. Blend characterization results report the reduction of friction coefficient and wear rate in comparison to reference UHMWPE_vit, probably due to the improvement in the wettability that hyaluronic derivative produces. Manufacturing times and raw material consumption have been drastically reduced by SCisP in comparison to processes reported up to now. Moreover, preliminary studies varying the conditions of the process, i.e. the type of hyaluronic acid derivative, solvent and number of injections, establish the basis of this technique for further development and open an interesting route in the manufacture of medical devices.     

Inverted organic photovoltaic device with a new electron transport layer

We demonstrate that there is a new solution-processed electron transport layer, lithium-doped zinc oxide (LZO), with high-performance inverted organic photovoltaic device. The device exhibits a fill factor of 68.58%, an open circuit voltage of 0.86 V, a short-circuit current density of −9.35 cm/mA² along with 5.49% power conversion efficiency. In addition, we studied the performance of blend ratio dependence on inverted organic photovoltaics. Our device also demonstrates a long stability shelf life over 4 weeks in air.     

Experimental investigation on the influence of different grades of wood chips on screw feeding performance

Although basic investigations on wood chip material properties haven been carried out, only few studies deal with transport of wood chips, despite the fact that significant problems are commonly observed when feeding biomass in industrial applications. Within the work presented, basic bulk material properties were measured and experiments carried out with a system consisting of a hopper, agitator and a screw conveyor. The aim of this study was to investigate how three different wood chip grades and two blends of wood chips influence typical design parameters, such as mass flow and driving torque, of a biomass feeding system. The measured basic bulk properties are in good overall agreement with the literature. However, discrepancies were discovered between two standardized methods for determination of the bulk density. The results for the driving torque, mass flow and mass-related energy consumption showed that different grades of wood chips can alter these values considerably. Between two wood chip grades, a twice as high torque was recorded, while a third grade could not be fed due to jamming. One of the major findings of this study is that mixing a rather small amount of a high-fine content grade with the non-feedable grade of wood chips resulted in a blend which inhibited jamming during the screw feeding process.