Towards sustainable outdoor textiles: The life cycle analysis of waterproof microporous membranes

Abstract

More often than not, there is public criticism of waterproof outdoor wear because they contain perfluorinated chemicals (PFCs) which are harmful for the environment and human beings. In an attempt to address these issues and shed light on this complex topic, this thesis reports on a life cycle analysis (LCA) comparing two different production procedures of a PFC-free waterproof breathable (WB) membrane and the use of different types of raw materials (e.g., thermoplastic polymers and solvents). The thesis was conducted in a collaboration with a startup company, dimpora AG.

A direct comparison of the production processes of dimpora’s two membrane products, solvent-free sane membrane™ (SM) and solvent-based dimpora eco pur™ membrane (EP), was performed at their pilot production stage including the production of the raw materials and the membranes. Several impact categories were assessed: Global warming potential (GWP), human toxicity potential (HTP), as well as terrestrial, marine aquatic, and freshwater aquatic ecotoxicity potential (TETP, MAETP, and FAETP).

The results show that the SM has a significantly lower (96%) environmental impact potential than EP. This can be attributed primarily to the vast consumption of thermal energy and electricity during wet coating. Additionally, the results show that for the SM, the main contributing substance to the environmental impact potential is the polymeric material (thermoplastic polyurethane, TPU), whereas for the EP it is the solvent (dimethyl acetamide). A comparison of alternative raw materials was performed on the two above-mentioned processes, separately, by evaluating the toxicity, durability, circularity as well as the mechanical properties of the materials. This LCA recommends changing the polymeric material TPU for example to polyethylene (PE), which would result in a lower environmental impact potential compared to TPU, and it is suitable for membrane applications due to its durability and flexibility. Moreover, the results obtained from a sensitivity analysis support previous studies (Cobbing et al. 2015; Joerss et al. 2022) about the harmfulness of fluorinated polymeric materials: If dimpora would use polytetrafluoroethylene (PTFE) as a membrane material, the environmental impact potential of the membranes would increase significantly: EP up to 1,530%, and SM up to 20,770%.

The data used in this study primarily stems from primary data sources such as communications with dimpora and its production line operators. However, wherever data gaps existed, the study relied on secondary resources or on estimations based on averages. Therefore, for more accurate numerical results, more primary data would be needed. Nevertheless, the results reliably identify the substances and production steps that have the highest environmental impact potential, which benefits the research and development of dimpora’s products.