Challenges to using recycled High-density polyethylene materials for pipe manufacturing

Abstract: Recycling has become increasingly relevant to solve environmental problems related to the enormous amount of plastic waste. Recycling plastic has many environmental benefits, but it is challenging to find applications where recycled plastic can provide the same functionality as virgin plastic. This thesis highlights the challenges of using recycled High-density polyethylene (HDPE) in pipe applications. Additionally, the thesis addresses how the addition of recycled content in a blend may affect product quality and how different sources of recycled HDPE may affect the characteristics and quality of pressure pipes. HDPE plays a crucial role in the pipe industry since it is one of the most demanded plastics for manufacturing non-pressure and pressure pipes. The method involves literature review in two phases, one focusing on LCA studies on HDPE and the one on pipes made from HDPE. The initial search was made to include the entire life cycle of high pressure pipes made from HDPE and the second to include additional types of pressure pipes to gather insight if the allowed recycled content in manufacturing differ depending on pipe application. The results suggest that the possibility of using recycled material in pipe manufacturing depends on several factors such as quantity of recycled content in the blend, pipe grade and designated application. It is challenging to incorporate recycled HDPE in plastic pipes since it may affect properties of the pipe. Additionally, the quality of the waste and the presence of contaminants and impurities can affect the quality of the pipe. However, using recycled material in pipe manufacturing can create environmental benefits such as reduced use of resources, less energy consumption and lower impact on acidification. This thesis provides insights into the role of recycled HDPE in the pipe industry and its potential to contribute to a more sustainable and circular economy.