A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
Rigid polyurethanes foaming with CO2 as physical blowing agent
There is significant industrial interest in the development of innovative and efficient materials for thermal insulation applications. Indeed, the energy issues are becoming more and more important because of possible energy shortage in the future compounded by global warming. Moreover, regulations on thermal insulation in the household sector, building trade, aeronautics and gas transport are becoming ever stricter. One of the solutions to these issues is to fabricate materials with very low thermal conductivity. Many cellular materials are used in thermal insulation to take advantage of the good insulation capacity of some gases, in particular rigid polyurethane foams. The thermal conductivity of these polymers can become lower than the relevant gas, because of the Knudsen effect that limits the heat conduction via a confined gaseous phase. Fabrication of low density material within which the gas mobility is restricted is a challenge in terms of obtaining a very low thermal conductivity material. In this dissertation, the foaming of rigid polyurethanes by using high pressure carbon dioxide (CO2) as physical blowing agent was investigated starting from the knowledge of the behavior of the whole system in the presence of CO2. The study of CO2 sorption in the polymeric precursors of rigid polyurethane foam (polyol and isocyanate), by using a coupled gravimetry-Axisymmetric Drop Shape Analysis, was conducted to design the process and the equipment and to optimize the foaming. In particular, to address the recent interest in combining the gas (physical) foaming with the classical (chemical) polyurethane foaming, a novel instrumented pressure vessel was designed for studying: i) gas sorption under high pressure on the different reactants, kept separate and ii) synthesis under high gas pressure, upon mixing, by spectroscopic investigation and iii) foaming upon release of the pressure. In the literature, no papers addressed the use of CO2 as a physical blowing agent in polyurethane foams (as well as in other ...
Rigid polyurethanes foaming with CO2 as physical blowing agent
There is significant industrial interest in the development of innovative and efficient materials for thermal insulation applications. Indeed, the energy issues are becoming more and more important because of possible energy shortage in the future compounded by global warming. Moreover, regulations on thermal insulation in the household sector, building trade, aeronautics and gas transport are becoming ever stricter. One of the solutions to these issues is to fabricate materials with very low thermal conductivity. Many cellular materials are used in thermal insulation to take advantage of the good insulation capacity of some gases, in particular rigid polyurethane foams. The thermal conductivity of these polymers can become lower than the relevant gas, because of the Knudsen effect that limits the heat conduction via a confined gaseous phase. Fabrication of low density material within which the gas mobility is restricted is a challenge in terms of obtaining a very low thermal conductivity material. In this dissertation, the foaming of rigid polyurethanes by using high pressure carbon dioxide (CO2) as physical blowing agent was investigated starting from the knowledge of the behavior of the whole system in the presence of CO2. The study of CO2 sorption in the polymeric precursors of rigid polyurethane foam (polyol and isocyanate), by using a coupled gravimetry-Axisymmetric Drop Shape Analysis, was conducted to design the process and the equipment and to optimize the foaming. In particular, to address the recent interest in combining the gas (physical) foaming with the classical (chemical) polyurethane foaming, a novel instrumented pressure vessel was designed for studying: i) gas sorption under high pressure on the different reactants, kept separate and ii) synthesis under high gas pressure, upon mixing, by spectroscopic investigation and iii) foaming upon release of the pressure. In the literature, no papers addressed the use of CO2 as a physical blowing agent in polyurethane foams (as well as in other ...
Rigid polyurethanes foaming with CO2 as physical blowing agent
Di Caprio, Maria Rosaria (author)
2017-12-10
Di Caprio, Maria Rosaria (2017) Rigid polyurethanes foaming with CO2 as physical blowing agent. [Tesi di dottorato]
Theses
Electronic Resource
Italian , English
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