**2.1 Sources of biologically recycled materials**

Due to the public interest in the environment, climate change and the limited resources of fossil fuel, bio-based plastics which could be divided into three principal groups, have been investigated for some time [49]:


**Table 1.**

*Samples of recycled polymer based commercial products [43, 36].*

*An Evaluation of Recycled Polymeric Materials Usage in Denim with Lifecycle Assesment… DOI: http://dx.doi.org/10.5772/intechopen.99446*


The actual development stage of emerging bio-based polymers is given in **Figure 2**. While the main application of bio-based plastics is in packaging, around 11% of global production (240.000 tones), are used in textiles, mainly polytrimethylene terephthalate (PTT) and PLA [20, 35, 50, 51].

Bio-based synthetic fibers are often mentioned as environmentally friendly alternatives to traditional, virgin fossil-based ones. Mostly bio-based synthetic fibers, such as bio-PET, are developed to have the same properties and therefore chemical composition as their fossil-based counterparts [35]. It is important to note


**Figure 2.** *Development stage of emerging bio-based polymers (adapted from [49]).*

that bio-based origin does not imply that the fibers are bio-degradable [13–15]. The key to bio-based synthetics lies in bio-based feedstocks, and the production of these feedstocks has some sustainability issues such as the use of land. This is due to the fact that the cultivation of biomass for bioplastic production can compete with food production for arable lands [35, 52].

As is well known, there are differences in terms of environmental impact between crop based-and waste-based feedstocks. Crop-based corresponds generally to commodity crops such as corn or sugar cane whereas biomass or waste-based raw materials employ agricultural residues and organic waste. There are commercially available bio-based fibers and yarns and some of them are given in **Table 2** [36]. Obviously, feedstocks from waste will most likely be more environmentally preferred and more efficient, as they generally do not require new production of crops and they reutilize residues that would otherwise end up discarded [52]. Additionally, although there is growing interest in textile and apparel industry for bio-based fibers, some barriers such as production cost and low process efficiencies, hinder their further commercialization. Also, some new bio-based fibers, having different structures and properties than conventional ones, cannot yet be handled in current textile manufacturing processes.

Addressing climate change is one of the most urgent action areas for the textile industry. If apparel industry continues on its current path, by 2050, it could use


**Table 2.** *Bio-based fibers and yarns (adapted from [36]).* *An Evaluation of Recycled Polymeric Materials Usage in Denim with Lifecycle Assesment… DOI: http://dx.doi.org/10.5772/intechopen.99446*

more than 26% of the carbon budget associated with a 2 °C pathway. Therefore, in addition to academic institutions several companies have been exploring innovative approaches to recycle carbon and directly use it as feedstock for textiles. Covestro is working with university partners and various textile manufacturers to develop the production process on an industrial scale and aim to make the innovative fibers ready for the market. The company announced in 2019 that they have succeeded in making elastic textile fibers based on CO2 and so partly replacing crude oil as a raw material [53]. Fairbrics, being another example, has developed a novel process to create the components of polyester from waste CO2, and with Airwear, became a Global Change Award winner in 2020 [36, 54]. The significant amount of textile waste generated is also a potential feedstock for bio-based products [55]. A detailed discussion for this very resource and its conversion to feedstock is given in Section 4.
