Characterization of bio-based reinforced composite aerogels
Aerogels are highly porous materials that contain a large amount of air inside and have a very low density (approximately 0,1 g/cm3 ). Due to their properties of low density, large specific area and low thermal conductivity, they are used in many applications such as heat insulators, particle filter...
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| Tipo de recurso: | tesis de maestría |
| Fecha de publicación: | 2022 |
| País: | España |
| Institución: | Universitat Politècnica de Catalunya (UPC) |
| Repositorio: | UPCommons. Portal del coneixement obert de la UPC |
| Idioma: | inglés |
| OAI Identifier: | oai:upcommons.upc.edu:2117/376443 |
| Acceso en línea: | https://hdl.handle.net/2117/376443 |
| Access Level: | acceso abierto |
| Palabra clave: | Aerogels Àrees temàtiques de la UPC::Enginyeria dels materials |
| Sumario: | Aerogels are highly porous materials that contain a large amount of air inside and have a very low density (approximately 0,1 g/cm3 ). Due to their properties of low density, large specific area and low thermal conductivity, they are used in many applications such as heat insulators, particle filters, packing and catalyst supports. Inorganic aerogels tend to be brittle which has led to the generation of polymer-based aerogels with properties similar to polymeric foams. However, most of the raw materials of polymer-based aerogels are petrol-based which has stimulated a great research effort to find natural alternatives for these polymers. Polysaccharides and proteins are two families of biopolymers that have met with great success in research as natural precursors of aerogels for making viable alternatives to replace more pollutant petroleum-based materials such as expanded polystyrene or polyurethane foams, among others. Polysaccharides,such as cellulose, have been used in many applications requiring porous, nontoxic and biodegradable structures. Proteins can be either of animal origin, such as gelatine, or plant origin, such as egg white protein, soy protein or corn zein. The use of proteins as aerogel precursors is motivated by their biodegradability and biocompatibility characteristics. The use of polymers as aerogel precursors produces an increase in the flammability of the material and this is a limitation for applications requiring fire resistance. To increase the fire resistance of polymer aerogels, it is necessary to add fillers and/or flame retardants. In this project taking gelatine as bio-based polymer, different compositions will be made by mixing it with montmorillonite and tannic acid as crosslink agent with the final aim of finding a balance in properties that make them suitable for industrial applications. Therefore, the final composition must offer good mechanical, thermal and fire resistance properties at the same time. The characterisation of the material is done with various instruments: Ubbelhode viscometer, FTIR, thermal conductivity, compressive strength, moisture absorption, thermogravimetric analysis and cone calorimetry. The thermal conductivity of the aerogel containing tannic acid, clay and gelatine at the same time increased as compared to the pure gelatine aerogel, from 0.037 W/m∙K to 0.046 W/m∙K. Mechanical properties also increased, both in terms of Young’s modulus and yield strength, as compared to basic gelatine aerogel when tannic acid is present. The presence of tannic acid and clay improved the thermal stability of the material and decreased the rate of thermal degradation of the aereogel. Finally, due to the intumescent characteristic of these two materials, it was also possible to decrease the peak heat released, the flammability of the material and the ignition time. In conclusion, the addition of tannic acid as a crosslinker and clay as a filler made it possible to increase both thermal and mechanical properties and fire resistance simultaneously. |
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