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Bioplastics: a clean alternative?

Bio-based plastics: a brief history

Interview Richard Robert, Journalist and Author
On February 2nd, 2021 |
3 mins reading time
Bio-based plastics: a brief history
Jean-Luc Dubois
Jean-Luc Dubois
Scientific director at Arkema
Key takeaways
  • Although plastics have traditionally been made from petrochemicals, manufacturers have been producing bioplastics since the early 20th century as well.
  • Polyamide-11, or “Nylon 11”, is made from castor oil and has been sold in France since 1945. However, it is still more expensive than fossil fuel-based polyamide-6.
  • The chemical processes used to make biological, oil-based polymers are well known. Nowadays, castor and soybean oil can be used to make bioplastics.
  • However, all aspects must be taken into account, especially issues related to biodegradability (which is not always a given) and recycling.

Whether you are think­ing about bio­plas­tics from a biodegrad­able or bio-based per­spec­tive, these mate­ri­als are still a long way from the ‘main­stream’, which uses petro­chem­i­cals. Although, they do have a long his­to­ry, which could help pave the way for the future.

When we talk about bio­plas­tics, we often assume that their name derives from the fact that they are biodegrad­able. But they are also named after the raw mate­ri­als used to make them. In fact, “bio-based” plas­tics (which are not nec­es­sar­i­ly biodegrad­able) have been around for a while. After Bake­lite (1907) and PVC (1912) were cre­at­ed, com­pa­nies start­ed to devel­op plas­tics from plant-based mate­ri­als, before Plex­i­glass (1924) and poly­eth­yl­ene (1933) came onto the scene.

Jean-Luc Dubois is sci­en­tif­ic direc­tor at Arke­ma, a spe­cial­ty chem­i­cals com­pa­ny. He shares his knowl­edge of the his­to­ry of bio­plas­tics, and Arkema’s vision of these materials.

Bio­plas­tics are cur­rent­ly expe­ri­enc­ing a renais­sance. How has this knowl­edge been car­ried on and passed down at Arkema?

Jean-Luc Dubois: It’s true that petro­chem­i­cals have long dom­i­nat­ed the indus­try, but some plas­tics, which have been around for a long time and are still being pro­duced today, found their own niche. Such is the case for polyamide-11, also known as “Nylon 11”, which is made from cas­tor oil.

What’s inter­est­ing is that bio-sourced plas­tics are expand­ing today due to polit­i­cal and reg­u­la­to­ry devel­op­ments, in the same way that the Nylon 11 sec­tor was green-light­ed at the high­est lev­el of the French gov­ern­ment. After 1945, they want­ed to sup­port the tex­tile indus­try and inte­grate the econ­o­my of the French colonies. So cas­tor beans brought to Mar­seille  were processed there, before the indus­try spread to the region of Lyon. Why Lyon? Because it was a tex­tile cen­tre. From that point on, a sig­nif­i­cant chem­i­cal hub start­ed to grow there. Around the same time, the Sovi­ets were try­ing to devel­op some­thing sim­i­lar with ethylene.

Polyamide-11 is still being made today. It is a spe­cial­ty poly­mer, more expen­sive than the fos­sil fuel-based polyamide‑6, but with a com­bi­na­tion of prop­er­ties that has won over many clients. For exam­ple, it is resis­tant to sol­vent, UV and cold weath­er. In this case, the val­ue clear­ly resides in the tech­ni­cal aspects, rather than it being bio-based.

Are cas­tor oil and petrol processed differently?

No. They are both chem­i­cal­ly, rather than bio­log­i­cal­ly, processed. All oils con­tain a long-chain acid, which is a good raw mate­r­i­al that already has an impor­tant chem­i­cal func­tion. In the Unit­ed States, they make sec­ondary plas­ti­ciz­ers from veg­etable oil (lin­seed and soybean).

For this pur­pose, palm oil would be a per­fect raw mate­r­i­al if it weren’t for the fact that plan­ta­tions com­pete with food crops and dam­age bio­di­ver­si­ty. Fur­ther­more, ris­ing qual­i­ty of life in devel­op­ing coun­tries means that the demand for this prod­uct is grow­ing. For that rea­son, it is no longer in the run­ning to replace petrol.

The fact remains that big com­pa­nies in our indus­try are close­ly mon­i­tor­ing shifts in Euro­pean reg­u­la­tions, and active­ly look­ing for alter­na­tive sources to petrol that could pre­vent a total over­haul of indus­tri­al factories.

Arke­ma had been devel­op­ing a bio-based acrylic acid. There is a mar­ket there for man­u­fac­tur­ing paint and nap­pies. From a tech­no­log­i­cal stand­point, it works; glyc­erol made using biodiesel and oleo­chem­istry would be a good option. But the fluc­tu­a­tions in the bio­fu­el mar­ket led us to aban­don the project.

Anoth­er strat­e­gy involves explor­ing entire­ly new approach­es, such as poly­hy­drox­yalka­noate (PHA), a poly­ester made from bac­te­r­i­al fer­men­ta­tion. But these process­es are very for­eign to our industry.

On the oth­er hand, can biodegrad­abil­i­ty be inte­grat­ed more eas­i­ly to your products?

Yes. It takes some R&D work but in terms of the indus­tri­al foun­da­tions it is less com­pli­cat­ed. That being said, we are care­ful to think about all aspects, par­tic­u­lar­ly the impor­tance of recy­cling. Biodegrad­abil­i­ty has to be defined accord­ing to the envi­ron­ment where the prod­uct will break down – in soil, home com­post, indus­tri­al com­post, the ocean and so on. What you need to remem­ber is that biodegrad­able plas­tic will often suc­cess­ful­ly break down in the con­di­tions of indus­tri­al com­post facil­i­ties, at 50–70°C, but not in your every­day gar­den. And even in indus­tri­al com­post, biodegrad­able plas­tics slow down the decom­po­si­tion process. As a result, the indus­try tends to avoid it. Only a small num­ber of plas­tics will break down in the ocean. 

It is best to choose biodegrad­able plas­tics for prod­uct fam­i­lies where that prop­er­ty will be tru­ly use­ful. Such as the pro­tec­tive mesh used to wrap the trunks of young trees, for instance, which breaks down over four or five years.

Anoth­er exam­ple is a 100% biodegrad­able ver­sion of the water-sol­u­ble film used to hold dish­wash­ing liq­uid, which was pro­duced by Lac­tips. It is a tru­ly use­ful prod­uct, in that the com­po­nents will all end up in wastewater.