Bio-based polymers are defined as materials for which at least a portion of the polymer consists of material produced from renewable raw materials. Decreasing fossil-based plastic usage is an important aspect of sustainability. As an alternative to fossil-based plastics in the market, bio-based polymers are gaining in popularity.

Types of Bio-based Polymers

According to their synthesis and origin of source, bio-based polymers can be classified into three categories: (1) pristine natural polymers, or chemical or physical modifications of natural polymers; (2) synthesis of bio-based polymers via polymerization of bio-based monomers with tailored chemical structures; and (3) manufactured bio-based polymers from a mixture of bio-based molecules with similar functionalities that are converted from biomass feedstocks (figure 1).

Fig. 1 Types of bio-based polymers

Relationship between Bio-based and Biodegradable Polymers

The use of biomass feedstocks does not necessarily mean that the finished product will be biodegradable. Thus, the bio-based polymers are not always biodegradable and that biodegradable plastics (polymers) are not always bio-based. Some bio-based polymers may be biodegradable, others are not, as a result of their specific polymer structure (figure 2).

Fig. 2 Material coordinate system of bioplastics

As can be seen in Figure 2, plastics (polymers) can be divided into four characteristics groups. The horizontal axis shows the biodegradability of plastic, whereas the vertical axis shows whether the material is derived from petrochemical raw materials or renewable materials.

Impact of Bio-based Polymers on the Environment

Firstly, bio-based polymers are products for which at least a portion of the polymer consists of material produced from renewable raw materials, thus, they generally have a lower CO₂ footprint and are associated with the concept of sustainability. Secondly, they are generally degraded under anaerobic or aerobic conditions, and the end-product (residue) may be used for supporting plant growth. Chemical recycling techniques may also be used to reclaim the original material, which might be used for rebuilding the polymer or converted into another polymer product. A graphical representation of bio-based plastics processing is shown in figure 3 ^[1].

Fig. 3 Graphical representation of the production of bio-based plastics and their recycling

Challenges in the Processing of Bio-based Polymers

The bio-based polymer processing industry is currently facing multiple challenges in the collection of raw materials and their fabrication into desired polymers. Despite the availability of various raw materials, every material has its production and application limitations. The biggest challenge faced by this industry is to produce green raw materials without compromising the wastage of feedstock. The other major challenge is to reduce the cost of bio-based polymers for a fair comparison with conventional petroleum-based polymers. This emerging industry needs to spread its roots in society to replace conventional polymers, which is certainly not easy; however, clear strategies and implementation will make it indispensable in near future.

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Reference

Hatti-Kaul R, Nilsson LJ, Zhang B, Rehnberg N, Lundmark S. Designing bio-based recyclable polymers for plastics. Trends Biotechnol 2020, 38(1): 50–67.

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