فصلنامه بسپارش
سال دهم شماره 4 (پیاپی 37، زمستان 1399)

E xhaustion of fossil fuels, their environmental pollution, and human dependence onthis type of fuel have made the production of clean and sustainable energy, one of thegreatest issues in providing human energy in the future. This has led many researchers toseek new clean and sustainable sources of energy. In addition to solar, wind, geothermaland biomass energy, fuel cell energy is also become very important. Fuel cells are a newtechnology for generating energy that produces high-efficiency electrical energy throughdirect reaction between fuel and oxidizer without creating environmental and noisepollution. Currently, the most popular fuel cell is the hydrogen type, which is producedwater, heat, and electricity by the reaction between hydrogen and oxygen. Fuel cells consistof three main parts: a cathode, an anode, and an electrolyte. Electrolytes play an importantrole in the fuel cell and allow ions to pass through the cell with the necessary selectivity. Inrecent years, polymers have been used as electrolytes in the manufacture of conventionalhydrogen fuel cells, known as polymer fuel cells. Given the advances made in the field ofpolymer fuel cells and the specific polymers used in them, this paper intends to address thegeneral structure of hydrogen fuel cells with emphasis on the polymer structure.

T his paper reviews current knowledge about the rheology of highly filled polymers,focusing on hard fillers. Understanding the rheological properties would help forassist the formulation and processing of such polymeric materials. When solid particles areincorporated in a fluid, they affect the rheological behavior of the system via changes in theflow field. Nowadays rheology of suspensions, especially concentrated suspensions, is ofgreat importance due to their wide uses in various fields such as composite, petrochemical,and food industries. The main factors affecting the rheological behavior of these compositessuch as maximum packing fraction, percolation threshold, and the size distribution of thefillers are discussed. The size distribution of the fillers facilitates higher filling levels anddecreases the melt mixture viscosity for a specified content of fillers. The limitations andflow instabilities of highly filled polymers often lead to non-linear rheological behaviorsuch as wall slip, polymer-filler separation, swelling and surface instabilities phenomena.Following, mathematical models predicting the maximum packing fraction, which is oneof the most important rheological parameters of highly filled composites, is presented.The viscosity-containing also discussed as a function of the filler content for monomodal,bimodal, and multimodal highly filled suspensions.

Synthetic micro/nanomotors are functionalized micro/nanoparticles with the ability ofself-propelling motion. Synthetic micro/nanomotors are the mimic of mobile organismslike bacteria in nature. Micro/nanomotors have different types such as fuel required micro/nanomotors and fuel-free ones and various applications. Fuel-free micro/nanomotors movethrough environmental changes like increasing in temperature by heating, magnetic andultrasonic fields, etc. Platinum-based micro/nanomotors are the most common types of micro/nanomotors. Hydrogen peroxide is the fuel utilized in platinum-based micro/nanomotors.The decomposition of hydrogen peroxide fuel on the platinum surface of synthetic micro/nanomotors, supplies the required energy for motion of motors. Platinum-based micro/nanomotors have different structures and geometrics include spherical, stomatocyte, rod,tubular, and shell that that creates various motion mechanisms and speeds. The motionspeed of micro/nanomotors has a wide range of amounts from one micrometer per secondto hundreds micrometers per second. In this review, platinum-based micro/nanomotors andtheir different types have been introduced. In addition, different mechanisms of motioninclude self-electrophoresis, self-diffusiophoresis and bubble-propulsion mechanismshave been discussed. Then, the comparison of velocities in different motion mechanisms,applications of micro-nanomotors and the challenge of using their platinum type in in vivoconditions were also mentioned.

N owadays, with population growth, the demand for fresh water is rising rapidly.Development of membrane based systems such as reverse osmosis, nanofilteration,ultrafilteration, and microfilteration is important strategy to reduce water scarcity.Improving performance, life time and other properties of membranes are always importantissues to reduce cost and energy consumption of membrane based-water treatment systemand should be considered to develop membrane technologies. Recently, graphene oxidehas attracted great attention to modify relevant membranes and manufacture novelnanocomposite membranes. Graphene oxide has unique structure and properties and can beproduce at commercial scale with low cost. Functional groups of graphene oxide includinghydroxyl, epoxy and carboxyl lead to strong interaction with polymeric matrix. Usinggraphene oxide in surface and matrix of polymer can improve mechanical strength, thermalstability, hydrophilicity and antifouling of polymeric membrane and subsequently improvemembrane flux and performance in desalination process. In this review, the processes formodifying of membrane surface and synthesizing of nanocomposite membrane usinggraphene oxide have been evaluated. The mechanism of graphene oxide influence onmembrane porosity, structure, characteristics and performance has been also discussed.

P olymeric solar cells are a relatively new generation of photovoltaics that havereceived much attention in recent years. Due to advantages such as the abundanceof raw materials, the ability to produce in different colors according to customer demand,flexibility, light weight and low production cost, this generation of solar cells has a greatpotential for commercialization and production on large scale. In order to commercializethe polymer solar cells, it is important to evaluate the costs and economic aspects of theirindustrial production, and so far few studies have been done in this regard. In this paper, thecosts of raw materials, production process and finally the installation and commissioningof electricity generating systems based on polymeric solar cells has been estimated. Theresults show that despite the lower efficiency of solar energy conversion into electricalenergy in these systems, due to the adaptability of their manufacturing process withroll-to-roll printing, the cost is very low. Polymer solar cells also compete not only withcommercial products in this field, such as silicon-based solar cells, but also with otherelectricity generating systems, such as wind and water-based systems.