Development of Lightweight Organic Aerogels for Thermal Insulation Applications

Organic aerogels provide the solutions for many sectors, due to their extremely unique feature and their unique structure that are spread-out at different length scale. Organic aerogels are considered the next generation materials due to their high tunability and adaptability by the tailoring of their final properties. Tailoring of organic aerogels properties is the theme of many nanocellular and low-density materials research, however, such process experiences many challenges. The main two challenges of tailoring such materials are: (I) the synthesis of monolithic aerogels with strong mechanical properties while preserving their unique features, and (II) the deep understanding of the origin of such features and correlating each feature to a structural parameter. This work addressed both these challenges to have a deep understanding of organic aerogels and to integrate them into many sectors. The synthesis process focused mostly on pure organic aerogels without any composites, at first, to correlate the processing conditions to the micromorphological parameters. The micromorphological parameters were further studied to quantify each parameter that controlled the assembly of the aerogel three-dimensional network. Then, each parameter was correlated to the structural final property to better understand the uniqueness of the organic aerogels features. With the correlation build-up between the processing-structure-properties of organic aerogels, a heat transfer model was conducted on the structure. In such model, each heat transfer mode was identified and linked to a structural parameter which controlled it. The organic aerogels were further modified to enhance their mechanical properties by the addition of nanofibers and nanosheets into the structure. The composites assembled homogeneously into the organic aerogel structure to create a uniform network of the aerogels particles along with the composites. With a such network, the mechanical properties of the aerogels increased dramatically while preserving their unique features. Finally, the operational limitations that are inherent to the organic aerogel were surmounted thru the modification of the aerogels chemical composition. The new aerogels could operate at high temperature and have a high fire retardancy ability. Furthermore, such aerogels could resist moisture, which makes these materials ideal to be used in high temperature and humid environments.Ph.D

Kinetic Study on Thermal Degradation of Crosslinked Polyethylene Cable Waste

Abstract Kinetic study of the pyrolysis of waste plastic is crucial in the design of an efficient and predictable thermochemical conversion system amidst the huge amount of plastic waste being rejected daily. Here, the chemical kinetics of cross-linked polyethylene under pyrolysis condition is conducted. The thermal degradation of the cross-linked LDPE/Si-XLPE was investigated under two different conditions: dynamic and isothermal heating. Moreover, two popular models of Kissinger and Flynn–Wall–Ozawa were used to infer the activation energy and pre-exponential constant during the dynamic heating at different heating rates. The isothermal conditions were tested at four different temperatures and reaction times based on the Arrhenius kinetic parameters. Thermo-gravimetric results showed the main region of weight loss occurs between 450 and 480 °C which corresponds to the highest conversion rate. The computed activation energies were 290.26 kJ/mole and 287.56 kJ/mole for Kissinger and Flynn–Wall–Ozawa models, respectively. The dynamic heating produced slightly different values than the one obtained from isothermal heating. This is because the kinetic parameters are highly dependent on the reaction time. These results suggest that Si-XLPE, which is commonly used in the cable industry, follows a similar behavior to the LDPE. This was demonstrated by the detailed analysis of the composition, melting point, thermal stability and thermal degradation