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What Is Plastic Anyway?

What Is Plastic Anyway?

Sep 17th 2019

It may seem like a silly question, but before we can go into detail about plastic-free packaging, it’s important that we answer the question, what is plastic? With conscious companies and individuals narrowing their focus on marine plastic pollution, we’re getting this question a lot: Is this packaging plastic-free? 

Depending on the packaging, this question opens up quite a can of worms! For example:

If a product has rubber in it, does it contain plastic?

What about silicone?

Is packaging made with plant-derived polymers considered plastic?

Does an acrylic emulsion adhesive contain plastic?

In trying to answer this question for our customers, we want to be accurate and thorough; we also realized there is no perfect, agreed upon industry standard for the question, "What is plastic?"

Unfortunately, this meant there is not always a clear cut way to say something is or is not plastic-free (leaving the door open for misguided information to be dispersed).

Here, we share the different definitions of plastic and put forth our own standard for plastic and what we mean by plastic-free.

Plastic Definitions

Since plastic can mean so many things, there isn’t really a single “plastic definition.” That said, here are a few different definitions of plastic; with a lot of similarities but also some important differences.

Types of Plastic

  • Broadest plastic definitionPlastics describe all polymers - including naturally occurring polymers such as shellac, tortoiseshell, cellulose, amber, and latex from tree sap. A polymer is a substance made of many repeating units.
  • Broad definitionPlastic is a material consisting of any of a wide range of synthetic or semi-synthetic organic compounds that are malleable and can be molded into solid objects. Plasticity is the general property of all materials which can deform irreversibly without breaking but, in the class of moldable polymers, this occurs to such a degree that their actual name derives from this specific ability.
  • Narrow definition: Plastic is a term used to describe any synthetic polymer, whose primary backbone is carbon (regardless of the raw materials being used to generate that carbon).
  • Narrowest definition: Plastic is a term used to describe any synthetic polymer generated from fossil fuels.

At first glance, the definitions don’t appear to vary much at all. But when analyzing specific materials, their differences become clear, and help us better understand- what is plastic?

  • Polyethylene terephthalate (PET), Low density polyethylene (LDPE) and High-density polyethylene (HDPE) are all examples of petroleum derived, carbon-based polymers. These are clearly plastics and fit all definitions of plastic.
  • Polylactic acid or polylactide (PLA) and bio-PET are all examples of plant-derived, carbon-based polymers. These would qualify as plastic based on all of the official, scientific definitions above. But we know that some people who aren’t as steeped in the science only consider the narrowest definition - and therefore may see these to be non-plastics because the carbon is derived from a renewable resource (EcoEnclose considers these materials to be plastic).
  • Cellophane is a semi-synthetic material made from a naturally occurring polymer - cellulose. The first two definitions would consider it plastic, but the second two would not. Cellophane has some plastic-like properties (though it is not 100% waterproof) but is derived from wood, and behaves a lot more like paper than like plastic. If you burned it (don’t!) it will light up the way paper does. If you fold it, it will stay folded (plastic wrap, on the other hand, would go back into its original shape).
  • Latex or rubber are naturally occuring polymers. However, today, most rubber is vulcanized (a process by which plasticizers and other chemicals are combined in the manufacturing process) Some natural rubbers will biodegrade (though they do so very slowly so do not throw them in your compost pile - rubber and latex belongs in the trash). Unlike plastics, however, natural and synthetic rubber is typically elastic - meaning that it can be stretched to a point and then will return to its original shape - so it does not necessarily have the plasticity many feel are required for a material to be called plastic.
  • Silicone is often described as a plastic alternative, but based on the first two definitions above, it should be considered plastic. Instead of being derived from petroleum-based carbon, it is derived from silica (i.e. basically sand). Sand is a non-renewable resource and the process of creating silicone requires the addition of similiar plasticizers that people worry about with more traditional plastics.

Phew! As with many things related to eco-friendly materials - answering a question as seemingly simple as “what is plastic?” can make your head hurt.

Which is why we’re here to educate our customers- making it a lot simpler than leaving them to dig through the deep dark trenches of the internet to figure out what plastic is for themselves.

How We Answer the Question "Is this Plastic-Free"

Now that we know what plastic is, and some different types of plastic, it becomes easier to answer the question “is this packaging plastic-free?” When we talk to those asking if something is “plastic-free”, what it seems like they are really asking is some combination of the following:

  • Is it a material that will not biodegrade? Will it cause lasting harm to the oceans and lands if left as litter? We believe this is the most important characteristic a person is asking about with the question, “Does it contain plastic?”
  • Is it a polymer that is synthetically or artificially made (even if it is derived from renewable resources) with chemicals or toxins that could leach and cause harm to people or to the environment.
  • Is it made with petroleum?

With this in mind, we realize that rather than giving a YES or NO answer to the question “Does your product contain plastic”, the most helpful way we can respond is by being specific about what materials are included and whether or not (and why) we see them as plastic or non-plastic.

We know this approach may not always give companies the answer they want to hear. But we hope this level of transparency helps everyone make the right decisions for their packaging strategy and support their customers to properly dispose of their mailers and boxes.

So for example, we may get the question: Are your 100% Recycled Kraft Mailers plastic-free?

Our answer: The 100% Recycled Kraft Mailer is a paper mailer and, as such, is largely free of any plastic. We know that most people would consider this to be a plastic-free product.

It is important to note that the glue, adhesive and the release liners for this product do contain synthetic polymers. The adhesive release liner on the Kraft Mailer is a small strip of silicone lined paper. We consider silicone to be a type of plastic (though it is a polymer derived from silica - sand - rather than fossil fuels, so many people do not). The silicone release liners should be landfilled and are neither recyclable nor compostable.

Glue is also required to form and seal the Kraft Mailer. This glue is a thermoplastic hot melt adhesive, and therefore does contain plastic. Additionally, the adhesive seal of the mailer is an acrylic emulsion adhesive. Because there are such trace amounts of these polymer adhesives in the overall package, the mailer can still be composted at home or in facilities that accept paper, envelopes, pizza boxes and other corrugated. However, we strongly recommend that these mailers be recycled.

Virtually all mailers on the market utilize hot melt glues, resin adhesives, and silicone lined release liners. While it is nearly impossible today to find “plastic-free” adhesives and release liners, we are actively working on R&D to develop non-plastic alternatives.

How EcoEnclose Defines Plastic

Looking at specific materials, we have come to define:

  • Low density polyethylene (LDPE), High-density polyethylene (HDPE), Polyethylene terephthalate (PET), Vinyl, PP, Polystyrene to be plastics. These are the most common types of plastics.
  • Polylactic acid or polylactide (PLA), bio-PET and most other plant derived plastics to be PLASTIC because they are artificially produced (even if they utilize plant-based inputs) and behave like petroleum based plastics if left as litter
  • Silicone to be PLASTIC. It is a synthetically made material, that is produced by heating silica (i.e. sand) up to very high temperatures to produce silicon, which is then reacted with fossil-fuel based hydrocarbons. This creates siloxane monomers that are bonded together (along with plasticizers) to create a silicone resin polymer. Silicone is more stable than some petroleum-based plastics, and is therefore often a preferred safer choice in food ware over other plastics; however, it does exhibit the same end of life, non-biodegradability characteristics as other plastics.
  • We consider an acrylic emulsion based paint or adhesive to contain plastic (as acrylic is a form of plastic). We know many in the industry consider acrylic emulsion adhesives to be “plastic-free” but we want to be more transparent about what the material contains. Paper based packaging that uses these adhesives can typically still be composted because it represents such a tiny percentage of the overall material. If you choose to compost these materials, double check with your composting service first - do they accept things like cardboard or corrugated boxes and envelopes? If so, they would accept packaging that uses polymer adhesives as its sealant. 
  • We do not consider cellophane a form of plastic, as it does not exhibit many critical characteristics of a plastic, and biodegrades naturally.
  • We do not consider rubber a form of plastic given that it does not exhibit many critical characteristics of a plastic and many will biodegrade more rapidly than a plastic, though still quite slowly, in a natural environment.

Plastic-free Is NOT the Same As Ecologically Superior

While we attempt to create as many products as possible that are plastic-free, these statements are in no way intended to demonize any materials or promote others as more ecofriendly. For example, we believe LDPE and HDPE (plastics) are typically ecologically superior materials to cellophane (which we don’t consider a plastic), as they require less energy to produce, create less pollution in manufacturing, and are more readily recyclable.

When we get the question, “Is X packaging “Plastic Free”?” we may overwhelm you with the answer!

If you are asking a question like this, we know you care deeply about your company’s impact on the environment. We know it is our responsibility to answer you clearly and as accurately as we can, with the knowledge and framework we have. Have more questions about what it means to go plastic-free with your packaging? Give us a ring or send us an email - we’d love to answer any questions you have.