All mankind is concerned about the problem of saving the planet from the garbage that it produces. Starch packages are considered to be one of the ways to address the problem. After all, we already know how to sew clothes from soybeans, make cups from coffee grounds and weave furniture from seaweed. Perhaps a package of cornstarch will save our world from environmental disaster? But, unfortunately, not everything is so simple here. It turns out that fully biodegradable plastic and cornstarch packages do not have as much in common as it seems at first sight.
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Chemists have long agonized over invention of plastic, dreaming to create a very strong and durable material. And when they finally succeeded, it turned out that all these “wonderful” advantages of plastic are also its disadvantages. The material turned out to be a rare long-liver, which is “too tough” for most microorganisms. However what is good for geomaterials for road construction, is bad for potato bags. After all, we use them in hundreds, and they decompose for decades.
It became clear that it was necessary to create biodegradable polymers, by their features similar to plastic, but at the same time digestible for bacteria.
And such materials soon appeared. Manufacturers said that they started the production of biodegradable polymers from starch and began to make various goods out of them: dishes, seedling pots, diapers, compostable packages.
Still no victory over the collapse of the trash took place. When all aspects of the industrial “corn revolution” began to be considered, everything turned out to be not so good. The reason for this is not even the high cost of the material, but the energy resources spent on its manufacture and the harm to the environment of such an industry.
The cornstarch eco-package is not really a sensational know-how. The raw material for the production of bio-packages from polysaccharides is the well-known polylactide (polylactic acid), first synthesized more than half a century ago. Fibers and films can be made from its solution in solvents (chloroform, benzene, butyl acetate). Truth be told, these toxic solvents are far from flower nectar, and the problem of their utilization without harm to the environment has not yet been resolved. However, this is a big topic to be discussed separately, so let's get back to the polylactide itself.
Polylactide (PLA) is a lactic acid polymer, a thermoplastic, which is synthesized in industry mainly from starch hydrolysates. Corn is crushed, starch is obtained from it, which contains 57%. Then it is processed into dextrose, which is further fermented in the presence of protein catalysts to obtain lactic acid. Lactide is obtained from concentrated lactic acid during the oligomerization reaction, and then a lactic acid polymer.
But this technology has its own problems:
The thing is that the specific yield of lactic acid in industrial synthesis is only 0.2-0.4 g/l per hour (Smirnov V. A. Food acids. Moscow, “Light and Food Industry”). And in the production process, a huge amount of by-products is formed that go to waste. Their processing requires high energy costs and leads to environmental pollution.
Many alternative methods for the synthesis of lactic acid have been suggested (and patented): from the hydrolyzate of starch with sugar, D-glucose (dextrose) sodium lactate, etc., in particular, to maintain the temperature regime of the cultivation of producers and to obtain the final product).
Such technologies can be implemented when it comes to the synthesis of lactic acid for manufacture of, for example, biodegradable implants for surgical operations. But does it make sense to spend a huge amount of resources and produce tons of garbage to obtain biodegradable packages?
To get to the bottom, you first need to understand what biodegradable plastic packages and eco-packages are.
All materials invented by mankind are biodegradable. The only difference is in time: some need a year for this, others need decades.
Ideal bio-packages, in theory, should decompose to carbon and water. However, this is only possible if they are 100% made from plant materials without chemical additives. In fact, as studies show, this does not happen. For example, the Journal of Polymers and the Environment published an article by Feuilloley, P. et al. Degradation of Polyethylene Designed for Agricultural Purposes. Journal of Polymers and the Environment 13, 349-355 (2005). It says that not a single biodegradable mulch (3 different films were taken), even in ideal laboratory conditions, did not completely degrade to nature-safe mineral substances. Alas, but only about 15% of the plastic actually decomposed.
And polylactide packages decompose pretty quickly, that’s true. But this does not mean that they are more environmentally friendly – production of starch packages is much more harmful to the environment than production of plastic packages.
In fact, these are materials of different composition requiring certain conditions for disposal:
Mankind has not yet invented quickly and completely degradable plastics. The Guardian published an article entitled 'Biodegradable' plastic bags survive three years in soil and sea. It contains the results of a study of the degradation of compostable, biodegradable and conventional plastic bags under the influence of seawater, air and compost pit conditions. None of them fully met expectations. Truth be told, the compostable bag decomposed after 3 months in sea water, but withstood with honor 27 months of underground “burial” (although something completely different was expected from it).
In general, each solution has its own pros and cons. And the technology for the production of starch bags requires thorough revision.
However, you can already buy organic starch packages in Ukraine. You just need to understand that this is not an ideal biomass and paper that gets soaked in the first rain, but just one of the types of plastic. By the way, do not take paper as an alternative to polyethylene. The pulp and paper industry causes colossal harm to the environment, which ecologists have long and unsuccessfully trumpeted at every bend.
Biopolymers from renewable natural resources are a fashionable global trend. What are they, where are they, or what can they be made of? There are various technologies, including those created with the help of genetic engineering. For example, bio-plastics can be obtained from soy protein or vegetable oils, produced using bacteria. But the most promising was production of biodegradable polymers (polylactides) from corn.
PLA in its pure form is transparent, water-resistant, with a beautiful gloss, but too fragile, hard and not heat-resistant material (it cannot withstand temperatures over 50-55°C and starts to deform). However, it can be modified with various plasticizers. For example, addition of Eastar Bio (manufactured by Novamont) increases its viscosity, elasticity and flexibility. This additive is used globally in the production of eco-packages.
Many companies introduce their own technologies and produce raw materials from which packaging, biodegradable packages, plastic containers can be made. For example, BaSF (Germany) created and patented the innovative plastic Ecovio, which is almost half of corn PLA. Truth be told, it also contains Ecoflex petrochemical product, another BaSF corporation know-how.
The world's leading manufacturer of bio-plastics from plant polymers, NatureWorks, manufactures INGEO PLA for biodegradable films and thermal packaging obtained by extrusion method.
American company Cargill Inc. manufactures polylactide and very durable Eco-Pla bio-plastic. Mitsui Toatsu (Japan) has introduced the technology of one-stage modification of polylactide and reduced its cost. Biotec GmbH offers a starch-based composite in a form of compostable biomass (granules, foams, injection molded bio-plastics) for the production of soft packaging, agricultural films, rigid containers and other products.
However, it is known that manufacturers of soft packaging from PLA play cunning a little bit. Due to insufficient thermal stability, low barrier characteristics with respect to oxygen (compared to PET, they are about 10 times lower) and high CO2 diffusion coefficient, it is impossible to make soft packaging from pure PLA, which also can contact moisture and is suitable for frozen products. PLA has to be modified and additionally added to the composition of the composite additives to increase heat, oxygen resistance.
For example, let’s consider the content of biomaterials in the Biotec GmbH products (information from the company’s official website):
Chinese businessman Francis Choi Chee-ming the owner of Early Light International, who made his fortune by making toys, is now obsessed with the idea of making organic plastic from corn and potatoes. According to Forbes magazine, the Chinese man, together with one of the American eco-plastics manufacturers, has created the NuPlastiQ bio-plastics empire, which should have begun its work by the end of 2020.
In an interview, Francis Choi said, “This will be a huge business for us. The NuPlastiQ material can be used to make soft packaging, and can be blended with conventional plastics to create environmentally friendly items such as children's toys. The world will need bio-plastics in the near future.”
We, too, are no worse than the Chinese, because the extruder actually processes any raw material in the same way and produces both plastics and bio-plastics from it. But bio-packages from natural raw materials in Ukraine face completely different problems that we have not yet been able to solve.
T-shirt bag made of corn starch
As you can see, there is quite a lot of problems. But this is not a dead end. We just need a paradigm shift, that is, you need to look for a way out from the other side.
LDPE and HDPE polyethylene with oxo-biodegradable additives – an affordable and cost-effective alternative
If we still cannot address the problems associated with energy consumption and the complexity of disposal of packaging from polysaccharides, then it is necessary to introduce additives into ordinary polyethylene to initiate and accelerate its decomposition. Such technologies reduce production cost, do not have a significant impact on the environment, preserve all desired properties of polymer and ensure its rapid biodegradation.
Biodegradable polymers are materials with service life that can be adjusted, they degrade spontaneously as a result of natural chemical and microbiological processes.
Composites with oxo-biodegradable additives show the best results in terms of combined cost and benefit. For example, d2w is introduced in an amount of 1-2%, does not require changing technological modes, does not affect properties of the finished product, and does not increase its toxicity. The d2w additive is manufactured by Symphony Environmental Technologies plc, UK.
Raw materials for the production of eco-packages are: HDPE or LDPE polyethylene, oxo-biodegradable additive d2w (in an amount of 1-2%), masterbatches for film coloring, as well as stabilizers.
Comparison of biological polymers of plant origin with polyethylene LDPE, HDPE using oxo-biodegradable additive
Parameters for comparison
Plant (corn) based polymers
Polyethylene with oxo-bio-additives
Production energy consumption
Higher (40 times)
Higher (3-10 times)
Dependence on petrochemical feedstocks
Harm of the finished product to the environment
Degradation (decomposition) time
From 6 months
About 2-3 years
The need to create special composting conditions
Fast biodegradation without special conditions (decomposition of a bag discarded in nature)
Content of biomaterials in the composite
From 30%, the rest is hydrocarbons, that is, the same oil hydrocarbons
Product durability during the period of operation and ability to control decomposition time
Durability not guaranteed (the product may become fragile, not durable), decomposition time cannot be controlled
Durability guaranteed, decomposition time can be controlled
As you can see, each option has its own pros and cons. A beautiful picture is easy to draw, but how much will it line up with reality?
Cornstarch bag with a cut handle
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