Reza Farasat

The adoption of sustainable forms of energy is necessary to aid in reducing the global dependence on fossil fuels. As demands for various forms of renewable energy continue to increase, not only should the quantity of devices increase, but the quality of these resources should be considered as well. Materials play a crucial role in the construction and operation efficiency of renewable energy resources. Much of the literature that is currently available on this topic focuses on specialized thermoplastic or elastomeric components in renewable energy devices. While these studies are valuable, thermosetting polymers are largely left out of this discussion. Although thermoplastics may also be considered as the matrix material for polymer matrix composites (PMCs), the elevated processing temperatures, high melt viscosity levels, and lower stiffness of these materials is less attractive for the structural applications discussed in this work. Currently, reinforced thermose–matrix composites are used as wind turbine blades, hydroelectric turbines, solar panel base boards, and coatings or encapsulants on solar panel devices. An evaluation of these crucial engineering materials is essential to improve the performance of renewable energy devices to lower the worldwide reliance on fossil fuels. Throughout this report, the synthesis of thermosets and their corresponding monomers for application in renewable energy has been discussed. For this purpose, the study has been conducted in two major sections. The dividing line is based on the main polymerization methods: step growth and chain growth. For each category, a brief background has been provided. Then, some selective thermoset polymers with their synthetic methods and novel applications in renewable energy field have been discussed.

The solid-solid phase transitions in ammonium nitrate, ammonium perchlorate, and sodium nitrite confined to native and organically modified Silica nanopores are analyzed by differential scanning calorimetry. The study reveals, the effect of nano confinement on the transition temperature and links' it to the kinetic parameters of the process. It is suggested that the effect of nanoconfinement is primarily the surface interaction effect in the native pores and the size effect in organically modified pores. It has been found that in organically modified pores the transition temperature is always depressed relative to the bulk, whereas in the native pores its behavior is generally unpredictable. Kinetic analysis of the transitions in terms of a nucleation model indicates that the experimentally observed shifts in temperature can be explained by a combination of changes in the free energy of nucleation and preexponential factor of the respective processes.

Differential scanning calorimetry (DSC) is used to study the kinetics of the coil-to-globule transition in aqueous solutions of poly(N-isopropoylacrylamide) (PNIPAM) prepared in the bulk (3 and 10 wt%) and nanoconfined (10 wt% inside 30 nm silica pores) forms. It is demonstrated that the kinetics can be described in terms of the classical nucleation model. The proposed treatment affords estimating the free-energy barrier and pre-exponential factor of the transition. The application of the nucleation model to the DSC data collected for the three systems studied provides physical insights into the effect of increasing the transition temperature due to dilution and nanoconfinement. Dilution appears to raise the free-energy barrier, whereas nanoconfinement causes a decrease in the pre-exponential factor.

This paper describes a calorimetric (DSC) study of the high temperature (similar to 190 degrees C) solid-solid phase transition in ammonium chloride in silica nanopores (4-30 nm) and in bulk The study focuses on the values of the transition heat and temperature as well as on the transition kinetics. Because ammonium chloride is loaded from a solution, the pores are only filled partially. Thermogravimetric analysis is employed to evaluate the pore fullness, which is further used to estimate the height of ammonium chloride layer deposited inside the pores. With increasing the layer height, the heat of transition increases toward the bulk value. Relative to the bulk value, the transition temperature measured on heating and on cooling respectively increases and decreases with decreasing the layer height. In larger pores (15 and 30 nm), the transition has revealed a second DSC peak that appears above 210 degrees C on heating and below 100 degrees C on cooling. The temperature dependencies of the effective activation energy derived from isoconversional kinetic analysis of DSC data have been parametrized in terms of the Turnbull-Fisher model. It is found that the transition in the pores encounters a larger free energy barrier to nucleation.

A model has been derived to estimate the fullness of nanopores loaded with salts from their solutions. The fullness is defined as a fraction of the filled volume to the total available volume of the nanopores and expressed as a function of the solution concentration and the number of loadings. The model has been tested on silica samples of 6-30 nm pore diameters loaded with ammonium chloride and ammonium nitrate. An assumption of cylindrical pore shape allows the model to be used for estimating the height of the layer deposited on the pore walls. (C) 2013 Elsevier B.V. All rights reserved.