A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
A Circular Economy Approach to Multifunctional Sandwich Structures: Polymeric Foams for District Heating Pre-Insulated Pipes
District heating pre-insulated pipes are a sandwich structure of material layers. Polyurethane foam bonds the medium pipe with the casing, providing an insulating function as well as a load bearing function. The high toxicity of the di-isocyanates required for its manufacturing triggers the need for a replacement. In this work, alternatives have been researched and developed considering the requirements of the circular economy. Two technology readiness levels (TRL) were covered. The higher TRL involved the evaluation of commercially available polymeric foam alternatives. Polyethene terephthalate foam was selected, and its ageing behaviour concerning degradation sources inherent to the application was studied in detail to confirm the fulfilment of the required service life. No degradation of the mechanical properties was found after exposure to thermal cycles or hygrothermal conditions at temperatures below its glass transition, which would correspond to the scenario of groundwater ingress. The previously determined highest service temperature of 80ºC was found conservative, as annealing at 100ºC increases its strength, allowing this service temperature. All results suggest it is a suitable candidate for the insulation of steel medium pipes. The fast embrittlement upon exposure to hot moisture, as would occur due to permeation of the heat carrier through a plastic pipe, prevents its recommendation for this case.The lower TRL research involved the re-evaluation of the complete sandwich assembly, from a cradle-to-cradle perspective. The foamability of polybutene-1 was explored, with the ultimate target of allowing the manufacturing of the sandwich element out of a single material, as to facilitate its recycling. Favourable grades for foaming were identified, confirming its foamability. The relationships between process parameters and the foam’s microstructure were evaluated. Foams in the required size for mechanical and insulating properties characterization were successfully produced. Mechanical properties of PU ...
A Circular Economy Approach to Multifunctional Sandwich Structures: Polymeric Foams for District Heating Pre-Insulated Pipes
District heating pre-insulated pipes are a sandwich structure of material layers. Polyurethane foam bonds the medium pipe with the casing, providing an insulating function as well as a load bearing function. The high toxicity of the di-isocyanates required for its manufacturing triggers the need for a replacement. In this work, alternatives have been researched and developed considering the requirements of the circular economy. Two technology readiness levels (TRL) were covered. The higher TRL involved the evaluation of commercially available polymeric foam alternatives. Polyethene terephthalate foam was selected, and its ageing behaviour concerning degradation sources inherent to the application was studied in detail to confirm the fulfilment of the required service life. No degradation of the mechanical properties was found after exposure to thermal cycles or hygrothermal conditions at temperatures below its glass transition, which would correspond to the scenario of groundwater ingress. The previously determined highest service temperature of 80ºC was found conservative, as annealing at 100ºC increases its strength, allowing this service temperature. All results suggest it is a suitable candidate for the insulation of steel medium pipes. The fast embrittlement upon exposure to hot moisture, as would occur due to permeation of the heat carrier through a plastic pipe, prevents its recommendation for this case.The lower TRL research involved the re-evaluation of the complete sandwich assembly, from a cradle-to-cradle perspective. The foamability of polybutene-1 was explored, with the ultimate target of allowing the manufacturing of the sandwich element out of a single material, as to facilitate its recycling. Favourable grades for foaming were identified, confirming its foamability. The relationships between process parameters and the foam’s microstructure were evaluated. Foams in the required size for mechanical and insulating properties characterization were successfully produced. Mechanical properties of PU ...
A Circular Economy Approach to Multifunctional Sandwich Structures: Polymeric Foams for District Heating Pre-Insulated Pipes
Doyle Gutierrez, Lucia (author) / Weidlich, Ingo
2022-12-02
doi:10.34712/142.35
Theses
Electronic Resource
English
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