**1. Introduction**

Recycling has been placed on the political agenda in the early 1990s with the rapid increase in the production and consumption of plastics and the increasing concerns over limited resources and plastics waste. As a result, a new industry, the plastics recycling industry, emerged. The main concerns behind the emergence of this industry were the environmental impact of plastics production, its waste management and the fact that almost all synthetic polymers are non-degradable. In many countries, used plastics end up in landfills and the landfill space, as well known, is limited. Two approaches, as a solution to these challenges were discussed to achieve the goal of sustainable development for material consumption [1]: dematerialisation and transmaterialisation.

Dematerilization, increasing the rate of recycling, is highligted as one of the three solutions in a recent report published by Ellen Mac Arthur Foundation [2]. Global Commitment Report stated these three solutions as: to eliminate the plastic items we do not need; innovate so all plastics we do need are designed to be safely reused, recycled, or composted; and circulate everything we use to keep it in the economy and out of the environment. Transmaterilization, a shift to bio-based raw materials, on the other hand, have attracted much attention due to the public concerns over limited fossil fuels and climate change recently [3, 4]. Global bioplastics production capacity is set to increase from around 2.1 million tonnes in 2020 to 2.8 million tonnes in 2025 [5].

Denim industry has started to vastly use recycled polymeric materials in the last 5 years. Recycled PET and recycled elastane as an example of synthetic polmers and recycled modified cellulose as a bio-based polymer are the main materials in use. Many novel bio-based plastics, such as PLA and stratch plastics are still at their early stage in use for denim fabrics.

A research gap exists on the environmental impact of denim fabrics from recycled polymeric fibers using the LCA methodology in the context of Turkey. For this reason, this chapter was conducted such that it firstly addresses sources of polymeric recycled materials as well as their chemical and biological recycling process. Finally, Life Cycle Assessment (LCA) methodology is adopted to quantify and compare the environmental impact of denim fabrics from recycled synthetic/man-made fibers.
