Do Plastic Pellets have an Odor?

Paul Gage

Recently, we have received some questions regarding plastic pellets and odors from the chemicals used to produce the pellets.   There are many different types of plastic used in the world around us.   Each type uses different chemistry in order to produce the desired properties of the plastic and polymer.   The building blocks of plastics are what are known as "monomers".  These monomers are oftentimes volatile...in other words...they are able to exist in a gas phase in the air around us. When a polymer or plastic material is produced, these monomers are linked together in a chemical reaction which makes longer molecules from the individual monomer building blocks.  These longer polymer molecules are NOT volatile and as a result, they will not have an odor as a general rule.  What you can smell in some plastic pellets is the residual monomer or additives which have not reacted to form longer polymer molecules. These monomer levels are VERY low and are barely measureable in most cases.  Most plastics will have some residual monomer and as a result, we can often smell this monomer...especially right after the product is produced.  As the plastic ages, this monomer bleeds out and the odor is reduced in most cases.  In some cases, polymers can adsorb chemicals from the environment and pick up an odor.  For example...if you were to dampen a cotton ball with fabric softener and place it in a 5 gallon bucket of polyethylene or polypropylene pellets, the pellets would pick up the scent of the fabric softener for several days, weeks, or even months.   Also, recycled plastics can have an oxidized or slight "burnt" odor if they are processed without and antioxidant or at high temps.  We are very careful to minimize the odor coming from the plastic pellets we sell!  We do this by choosing polymers which have a minimal level of residual monomer and additives which are not "smelly"!   As always...if you have questions, don't hesitate to drop us a line or call!    And....HAVE FUN!!!

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