What Are Corn Starch Biocompostables aka PLA Plastics?

pla plastics, made from corn

Biocompostable plastics are made from renewable, biodegradable corn starch.

Traditional plastic is made from petroleum products. The production of petroleum-based plastics involves all kinds of chemicals, some of which have raised health concerns among consumers. The other problem is that these type of plastics do not biodegrade and they are made with a non-renewable resource: petroleum. There are just lots of environmental and health concerns associated with conventional plastics.

Thankfully, plastics technology has come a long way. There are now biocompostable plastics made from renewable, biodegradable corn starch. In fact, you’ve probably already seen them. Have you ever used a plastic cup and noticed the text made from corn? Then, you’ve used corn start biocompostables!

How Are Corn Starch Biocompostables Made?

As the name implies, corn starch biocompostables are made from corn starch. The starch is converted into a polymer, the main ingredient in materials that have a plastic-like feel. The plastics can be clear or opaque, soft or hard. A kind of acid called polylactic acid (PLA) is made from the corn starch. This is why corn starch biocompostables are sometimes called PLA plastics.

PLA plastics are molded the same way conventional plastic is. They can be molded, extruded, or shaped by heating and cooling (thermal shaping).

Biocompostable Means More than Biodegradable

Biocompostable plastics are called so because they are a step beyond just biodegradable. For a plastic to be considered biocompostable, it must meet certain criteria. For instance, it must decompose at the same rate as paper, and it must break down into harmless material such as water, carbon dioxide, or biomass (organic matter).

Biocompostable plastic must not produce any toxic substances as it decomposes. It must also break down to the point that it cannot be discerned or filtered out of the surrounding compost. PLA plastics cannot be recycled. They must be composted.

The Benefits of Corn Starch Biocompostables

  1. No toxic chemicals associated with conventional plastic (such as polyvinyl chloride or dioxin)
  2. Can be disposed of in your home compost pile
  3. Eco-friendly (made from a renewable resource and less wasteful)
  4. Durable
  5. Especially well-suited for cold applications, such as in the freezer (this is good news, since chemicals from conventional plastic tend to leach into food when frozen)
  6. Corn allergies are not an issue since the allergen, profilin, is destroyed in the manufacturing process.

The Disadvantages of Corn Starch Biocompostables

  1. May not be as heat resistant
  2. Not microwave safe
  3. Can’t be thrown in the garbage or recycled; must be composted at home or in a commercial facility
  4. Thicker, harder items such as cutlery can takes up to 180 days to break down

Common Types of Biocompostable Items Made from Corn Starch

There are all sorts of items that can be made with PLA plastic. Here are some of the most common biocompostable plastic items:

  • Flatware/cutlery
  • Bowls
  • Straws
  • Cups (hot and cold)
  • Water bottles
  • Trays
  • Lids
  • Food storage containers (including “clamshell” containers used by take-out restaurants)
  • Bags
  • Plates

Comments

  1. I wish people would write the whole truth. First of all, not all plastics are made from petroleum. Polyethylene and polypropylene are made from natural gas. PLA is not backyard compostable. It is ASTM 6400 which means it needs commercial or municipal composting to break down.There are about 100 in the US, so how does one get the PLA to these facilities?All those people throwing it in the garbage should know it will take 500 yrs like regular plastic to break down.According to the article, “How Green are Green Plastics”, PLA uses MORE fossil fuels than plastic in its manufacture.Most PLA uses genetically altered corn (GMOs). It has been written that PLA is damaging the ozone more than gasoline! Corn costs rose 50% last year alone. Why? the diversion of corn from feedstocks and foods to PLA and ethanol.We have over 1 Billion people in the world going hungry due to the use of corn, soy beans, and sugar cane for plastics rather than food. Does anyone see something wrong with this besides me? There are biodegradable plastics that break down in landfills . Why not use them and not take food out of people’s mouths or enable the higher cost with a corn plastic that is neither sustainable, nor good for the environment.

  2. Environmentally Conscious says:

    I agree with Leslie (above) on some of the points risen, it seems there are definite incorrections in this article. However I have read that PLA plastic does not take as much energy to produce than other plastics, therefore a better alternative in energy consumption. Another point: before PLA plastic, there was enough food to feed the world – it was simply not getting to some people, while others had too much. Take this point up with the governments of the world; it is not the fault of PLA plastic. Nor has its presence meant more people are without food as the maize used for PLA is fodder – cattle food.
    I cannot speak for other countries but here in Australia, food costs have risen dramatically over the past 10 years due to the severe drought, not because of maize being used for PLA. Even if maize prices have risen worldwide due to its new use, is it not a better alternative to use an environmentally responsible and renewable product rather than sticking to plastics that are full of poisonous chemicals and use up a non-renewable resource? When PLA is broken down by heat (yes, it does need to go through special compostable machinery to break down and be re-formed into its next use, and yes, we certainly need alot more of them, Australia has none at this stage), there is nothing ‘bad’ going back into our environment. It just breaks down into lactic acid; a naturally-occurring substance. The same certainly cannot be said about plastics like HDPE and PET.
    My thoughts: separate the important issues of hungry people that certainly need and deserve the world’s care, and the idea of using cattle fodder for a plastic that has the capacity of breaking down into nothing harmful. PLA is not going to be problem-free, however it has alot going for it.

  3. Here is the solution for plastic or bio-plastic utensils: Use renewable paper instead.
    At Natural Products Expo West last week, tens of thousands of these cute little, smooth, compostable EcoTasters were being used by hundreds of exhibitors.
    The EcoTensil booth had 4 canisters:
    –two filled to the brim with 300 plastic/bioplastic tasters,
    –one with 300 EcoTasters that took up only a small corner of the canister,
    –one canister with compost in the bottom and little plants growing in it, which was labeled 70% EcoTaster compost.
    Clearly this company has figured it out.

  4. Conscious Chemist says:

    PLA will compost in your home composter. It is also used for internal sutures in surgery. Your body breaks it down to lactic acid, which is of course the same thing that your body makes when you exert your muscles to the point where they feel sore the next day. Of course, all types of manufacturing uses energy, which inevitably uses fossil fuels. The manufacture of paper products is not environmentally friendly either, so pick your poison! Realistically, the vast majority of the corn grown is used to feed cattle. Only a very small fraction is used to make PLA (or ethanol). The most environmentally sound decision to decrease corn production and redirect crops to more environmentally friendly species is chose vegetarianism. No need to feed livestock means significant reduction in fossil fuels burned and arable land used up.

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