Syftet med projektet var att samla in återvunnen polyeten och omvandla den till återvinningsbara högstyrke-härdplaster genom att designa ett kovalent anpassningsbart nätverk för det. Återvunnen polyeten samlades in och ympades med maleinsyraanhydrid genom reaktiv extrudering och en friradikalmekanism, vilket sedan tvärbands med laboratoriesyntetiserad polyimid. Den resulterande tvärbundna blandningen bearbetades genom formsprutning, och tester visade att den förväntade reaktionen hade utförts framgångsrikt och de mekaniska egenskaperna förbättrades avsevärt. Materialet bearbetades också om för att testa dess återvinningsbarhet och denna process samt analysen av materialet efteråt visade också lovande resultat. / The aim of the project was to collect recycled polyethylene and transform it into recyclable high-strength thermosets by designing a covalent adaptable network. Recycled polyethylene was collected and grafted with maleic anhydride through reactive extrusion and free radical mechanism, which was then cross-linked with laboratory synthesized polyimide. The resulting cross-linked blend was processed using injection molding, and testing showed that the expected reaction had been carried out successfully and mechanical properties were significantly enhanced. The material was also reprocessed to test its recyclability and this process and analysis of material after it showed promising results as well.

Degradation of steel pipes in district heating systems is often a result of corrosion processes. To maintain the power in the systems the pipes gets replaced when they have been worn-out, resulting in high cost and long service time due to excavation. A more affordable and time- effective method is known to be relining which implies renovation and facing of the already existing pipes. This thesis covers an initial review of the applicability of a polyamide curing solvent-free epoxy based relining for lifetime extension of corroded pipes in Stockholm Exergi's pipeline network. The research study is comprised of a literature search focusing on the permeability properties of epoxy coatings, an experimental part where the actual coating was tested for defined parameters similar to the prevailing ones in the system of Stockholm Exergi and finally an evaluation of the usability of the coating. Critical parameters such as the adhesion between the coating and the steel substrate, the sorption of water within the coating and the emit of Bisphenol A were carefully investigated during the analysis. Analysis methods such as pull of test, TGA, DSC and GC-MS were utilized in order to investigate the critical parameters. The adhesion between the coating and the substrate was found to be inadequate for the purpose, the TGA and DSC analysis showed a time-dependent increasing water sorption when exposure to 120 °C. At a higher temperature of 190 °C the sorption decreased. It was concluded that the coating cured at higher exposure temperatures which implied higher degree of conversion and thus a more brittle epoxy matrix. Additionally, the hydrophobicity decreased during 28 days of exposure, at both 120 °C and 190 °C, which can be supposed to affect the flow in the pipeline system during service. It can be stated that a spray coating consisting a polyamide curing solvent-free epoxy will not answer to a total solution for a lifetime extension for the pipes in Stockholm Exergi's pipeline network. An extended investigation regarding the exterior isolation of the pipes is suggested in order to circumvent the most critical breakdowns due to corrosion.