When we read “biobased” somewhere, we tend to associate it with something sustainable and good for the planet. But is this always the case? This is usually a complex topic, especially when it comes to the textile industry.
What does the term “bio-based” mean?
The term bio-based refers to the feedstocks (starting materials) that are used to produce the material. Biobased products are composed in whole, or in considerable part, of biological products, renewable agricultural materials, or forestry materials.
It is NOT the same as biodegradable.
Not all bio-based polymers are biodegradable.
Not all biodegradable polymers are bio-based.
THEN, What does the term “biodegradable” mean?
Biodegradability describes how a plastic product behaves at the end of its life and does not take into account what raw materials are used to produce the polymeric material.
Biodegradable polymers can be converted to biomass, CO2, and water through a thermochemical process in a specified time frame and in specified disposal environments. However, the raw material feedstock utilized can be either fossil-based or bio-based.
BIO-BASED = 100% BIO-BASED?
That a product is bio-based doesn’t mean it’s 100% made of bio-based feedstock. Usually, they are mixed with oil-based products to meet the performance requirements of the material such as flexibility, strength, or waterproofness. In the textile industry, it is particularly difficult to find a bio-based membrane that meets high-performance standards and has a bio-based content higher than 30% [1].
Nowadays, most bio-based biopolymers are derived from the so-called first-generation feedstock, which includes edible biomass such as sugar, starch, and plant oils, and nonedible sources such as natural rubber. Other commonly used raw materials come from the fermentation of sugars derived from crops (sugarcane and beets) or the ethanol produced as a result of starch hydrolysis.
However, biopolymers obtained from edible materials are in direct competition with food and animal feed production. In particular, the production of biopolymers is claimed to have the same disadvantages/side effects associated with biofuels, i.e., raising food costs, and deforestation to create extra cultivation fields.
This led the biopolymers industry to seek alternative feedstocks that will not compete with food markets in the future. Two categories of feedstock dominate research, namely non-edible biomass, the so-called second-generation feedstock, and alternative sources.
Second-generation feedstocks include food waste (non-edible, nonfood supplies such as waste cooking oil or fat and waste potato skins) products and lignocellulose: short rotation coppices and lignocellulose by-products such as forestry and agricultural residues. The main components of these materials are cellulose, hemicellulose, and lignin.
WHAT ARE THE 3RD & 4TH GENERATION FEEDSTOCKS?
New technologies have enabled further investigation also in the field of 3rd and 4th generation feedstocks: algae & seaweed, and captured CO2, respectively.
Algae biomass and seaweed can be utilized in biopolymer blends together with other material components and additives. Besides, algae itself produces a variety of biopolymer building blocks such as carbohydrates and hydrocarbons, which can be extracted from the medium without harming the algae culture.
Utilization of captured CO2 in polymeric materials is currently a hot topic in the industry and research fields, and CO2-based polymers have diversified in the last few years [2]. Researchers have said that:
“all chemical products currently manufactured from fossil raw materials can be produced from CO2” [3].
This could be a great solution to tackle the continuously growing GHG (greenhouse gas) emissions, however, several technical challenges still need to be overcome before the utilization of captured CO2 on a widespread basis.
What are the general advantages brought by bio-based polymers then?
Renewable feedstock
Reduced carbon footprint
Supports circular economy when waste and side streams can be utilized as feedstocks
Can have similar material properties to the conventional oil-based ones
For example, fossil-based polyethylene vs. bio-based polyethylene → polymer properties are similar only the raw material feedstock is different
The material is recyclable in existing recycling streams that are set for similar oil-based materials
The membrane can be produced using existing thermoplastic manufacturing machinery
what about the disadvantages?
Bio-based polymers are usually more expensive than fossil-based ones
Not available as large quantities as fossil-based polymers
Producing larger quantities of bio-based materials requires more land to grow the crops (depending on which feedstock is used)
Sustainability and responsibility must be considered when food crops are used as a feedstock
At dimpora, we’re currently developing a highly bio-based membrane. If you want to know more, please get in touch with us: info@dimpora.com
[1] Niaounakis M. (2015). Biopolymers: Processing and Products. William Andrew Publishing. DOI: 10.1016/B978-0-323-26698-7.00001-5
[2] Renewable Carbon News. (2021). Carbon Dioxide (CO2) as Chemical Feedstock for Polymers – already nearly 1 million tonnes production capacity installed!
Available at: https://renewable-carbon.eu/news/carbon-dioxide-co2-as-chemical-feedstock-for-polymers-already-nearly-1-million-tonnes-production-capacity-installed/
[3] Lehtonen, J., Järnefelt, V., Alakurtti, S., Arasto, A., Hannula, I., Harlin, A., Koljonen, T., Lantto, R., Lienemann, M. and Onarheim, K.,Pitkänen J. & Tähtinen M. (2019). 2019: The Carbon Reuse Economy: Transforming CO2 from a pollutant into a resource. VTT Technical Research Centre of Finland (Ed.). Available: www.cris.vtt.fi/ws/portalfiles/portal/25089333/190620_FINAL_WEB_VTT_CE_Discussion_Paper_PAGES_display.pdf
