We achieved the intercalation of different types of paraffins and their mixtures with triglycerides inside carbon nanotubes (CNTs) by means of self-sustained diffusion followed by a proper rinsing. The CNTs were investigated using TEM, which showed that they were intercalated inside and clean outside. For the mixtures melting can be realized in an interval of about 20 °C, which opens new opportunities for Phase Change Materials (PCM) attracting attention in relation to solar energy storage, cooling of power electronic devices and the energy-saving technologies.
This work reports a systematic study of drop impacts of polar and non-polar liquids onto different electrospun nanofiber membranes (of 8–10 μm thickness and pore sizes of 3–6 μm) with an increasing degree of hydrophobicity. The liquids studied were water, FC 7500 (Fluorinert fluid) and hexane. The nanofibers used were electrospun from polyacrylonitrile (PAN), nylon 6/6, polycaprolactone (PCL) and Teflon. It was found that for any liquid/fiber pair there exists a threshold impact velocity (∼1.5 to 3 m s−1) above which water penetrates membranes irrespective of their hydrophobicity. The other liquids (FC 7500 and hexane) penetrate the membranes even more easily. The low surface tension liquid, FC 7500, left the rear side of sufficiently thin membranes as a millipede-like system of tiny jets protruding through a number of pores. For such a high surface tension liquid as water, jets immediately merged into a single bigger jet, which formed secondary spherical drops due to capillary instability. No mechanical damage to the nanofiber mats after liquid perforation was observed. A theoretical estimate of the critical membrane thickness sufficient for complete viscous dissipation of the kinetic energy of penetrating liquid is given and corroborated by the experimental data.
1 April 2016 in International Journal of Heat and Mass Transfer