نانوالیاف به دلیل ویژگی‌های نو و کاربرد گسترده‌ی خود به سرعت توسعه پیدا کردند. تولید مقیاس‌پذیر نانوالیاف برای کاربردهای آتی آن ها بسیار مهم است. این مقاله مروری مختصر پیرامون فعالیت‌های پژوهشی فعلی مربوط به سنتز نانوالیاف با روش‌های ریسندگی مبتنی بر محلول، ازجمله الکتروریسی، ریسندگی دمشی، ریسندگ مبتنی بر سانتریفیوژ و ریسندگی کششی ارائه می‌کند. در میان این روش‌ها، الکتروریسی به طور گسترده‌تری مورد مطالعه قرار ...
In polymer electrolyte fuel cells (PEFCs), protons from the anode are transferred to the cathode through the ionomer membrane. By impregnating the ionomer into the electrodes, proton pathways are extended and high proton transfer efficiency can be achieved. Because the impregnated ionomer mechanically binds the catalysts within the electrode, the ionomer is also called a binder. To yield good electrochemical performance, the binder should be homogeneously dispersed in the electrode and maintain stable interfaces with other catalyst components and the membrane. However, conventional binder materials do not have good dispersion properties. In this study, a facile approach based on using a supercritical fluid is introduced to prepare a homogeneous nanoscale ...
The applicability and service time of polymer details working in various media are limited by the degradation of their physical and mechanical properties. From the structural point of view the weakest places strongly affected by ageing are the surface and boundary regions of the crystallites. If a material is subjected to high-strain deformation, it deforms permanently (plastic deformation) and ultimately fails. For sufficiently low stresses and strains, the polymeric material behaves as a linear elastic solid. The point where the behaviour starts to be non-linear is called the proportional limit. The local maximum in the stress-strain curve is called the yield point and indicates the permanent deformation. The corresponding stress and elongation are called ...
