Polyvinyl alcohol is a common component in household products. It’s typically presented as a nonplastic solution to plastic bottles, boxes, and other containers. Because of that, it’s become a popular ingredient in eco-friendly brands and product lines. There are a lot of questions about whether or not it’s plastic or if it degrades in the environment though. This article is going to touch on the basic questions and more. Where there is scientific support, I’ll cite it. Where the science is scarce, I’ll mention it. Let’s dig in!
Table of Contents
What is polyvinyl alcohol?
Polyvinyl alcohol is a synthetic polymer. That just means it’s a material made in labs (not nature), and on a molecular level it looks like a long chain of molecules. If you can remember back to high school biology, a monomer (mono = one) is one molecule that can interact with other monomers to make a polymer. A polymer (poly = many/several) is just a specific amount of monomers attached to each other.
Polyvinyl alcohol is also written as PVA, PVOH, and PVAl. I have never seen PVAl before researching for this article so you might not see it often either. PVOH and PVA are much more common when it comes to household ingredients. It’s just important to know that they all refer to polyvinyl alcohol.
How is PVOH/PVA made?
PVOH is considered a chemical ingredient and it comes from a chemical reaction between ethylene, oxygen, and acetic acid. That reaction forms vinyl acetate which dissolves into alcohol and forms the polyvinyl alcohol. The methods for this reaction may vary per lab based on their own polyvinyl alcohol needs or proprietary formulas.
What does that mean in normal-person talk? It basically means that PVOH is made through a series of chemical reactions. And that different labs might do things slightly differently to get a unique polymer at the end. The specifics beyond that aren’t important for the scope of this article so I’m not going to cover those details today.
Reference: Honest
How does it work?
Why is polyvinyl alcohol soluble in water?
Polyvinyl alcohol dissolves in water with ease. It can do that because it’s created to have water-friendly parts. PVOH has oxygen molecules and those oxygen molecules interact strongly with water molecules. When water molecules and PVOH interact, they form bonds (hydrogen bonds) and that results in the PVOH dissolving.
Reference: PubMed Central
How fast does PVOH dissolve?
For household products like dishwasher tablets, PVOH can dissolve in under a minute. If you’re working with industrial solutions and manufacturing-sized quantities, then you’ll want to refer to the supplier for more details. Dissolving PVOH on a large scale can vary based on the temperature of the dissolving solution, type of mixer, and brand of PVOH.
The molecular weight and polarity of the PVOH polymer chain can affect how quickly it dissolves in water which is why the answer for this question is a little vague. Like I said before, each lab can do things their own way which could result in a slightly different molecule with its own unique properties.
What is polyvinyl alcohol used for?
PVOH can be used in any number of things. Common uses include eye drops, skincare, food packaging, and cleaner packaging. Brands like Grove Collaborative and Dropps use polyvinyl alcohol in their products so they can deliver a specific amount of a solid formula for cleaning. Polyvinyl alcohol has so many uses because of its significant strength, flexibility, and ability to hold lipids and fats without breaking down.
Is polyvinyl alcohol plastic?
Technically, PVOH can be considered a kind of plastic. But obviously, plastic doesn’t dissolve when you throw some water on it. Not all plastics are created equally either. Different plastics will have a different molecular structure. But PVOH does have similar components when compared to common plastics today.
Image 1 is PVOH and Image 2 is what a portion of polyethylene looks like. These images are meant to represent a small part of the long chain called the polymer. Imagine it keeps repeating to the left and right of where the image ends.
Polyethylene is a common plastic polymer. You might recognize it as PET or PETE plastic. The red parts in both images are identical between the 2 molecules. You could think of it as a link in a chain. Where PVOH might have 2 different kinds of links (the red and the black are different), polyethylene has mostly one. Each link in the chain represents a monomer and when you string a bunch of them together it makes a long chain, or a polymer. The polyethylene and PVOH share a common link in their chains.
Does PVOH break down and/or biodegrade?
Some people have concerns with PVOH not because it dissolves but because of how quickly it degrades. For our purposes, degrade and break down mean the same thing. But biodegrade is a different term. Biodegradable means something can be broken down by a living organism.
In my research for this article, I found that several scientific articles refer to PVOH as biodegradable in the presence of certain microorganisms. I wasn’t able to find anyone downright claiming it wasn’t biodegradable.
So what does that mean? Well, it means PVOH functions like a conditional. You might remember that as an “if/then” statement. If the proper organisms are present, then PVOH biodegrades. That statement also implies that the opposite is true, if the proper organisms are not present, then PVOH does not biodegrade.
There’s no question that PVOH dissolves. But when something dissolves, it doesn’t magically disappear. In the case of polyvinyl alcohol, there are pieces of the PVOH floating around in the water. That’s where most of the concern around PVOH’s biodegradability comes from. It’s not clear how long those pieces last, how long it takes for them to get broken down by microorganisms, and how they affect the environment.
References:
Is polyvinyl alcohol bad for the environment?
If PVOH is dissolving into organic compounds (because the right microorganisms are hanging around), then those compounds can get used up and repurposed by other organisms just like anything else. That would be no big deal.
If PVOH isn’t dissolving in the environment, then it may be causing harm. The trouble is that there’s not enough research to make definitive statements about the effects of PVOH in the long term. There isn’t a bunch of research on the topic, and some studies suggest PVOH doesn’t last as long as plastic but it can still last a long time in the wild. That leaves us with a lot of important questions going unanswered.
Is PVOH safe? The molecular makeup of PVOH is different from most plastics, as you saw in the images above. That makes it hard to say if it could have the same effect on us as, say, microplastics. Scientists are still working hard to understand plastic and microplastic. Generally, it’s understood that microplastics aren’t good for us and they may be causing us serious harm. To read more about that, read this article. But science isn’t sure if PVOH affects us like plastic so it’s hard to say if PVOH is neutral or if it’s bad.
For now, it looks like PVOH is a better choice than plastic, because even if it takes 40 years to completely biodegrade it still beats traditional plastics. It just might not be the perfect solution we were hoping for.
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If you’d like to learn more about microplastics and how they’re getting found in places like our brain, placentas, and even babies, read this article.
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