What role do\u00a0PLA<\/a>\u00a0and\u00a0PETG<\/a>\u00a0play in this matter? In this article, we\u2019ll go over how recyclable 3D printing filaments are, the possibility of composting, tips for reducing plastic waste, and more!<\/p>\n Plastic can be classified into two types: thermosets and thermoplastics.<\/p>\n Thermosets are materials that are molded and then cured into their final forms and include materials like polyurethane or silicone. You will most commonly find thermosets being used as the resin for\u00a0vat polymerization<\/a>\u00a03D printing. Typically, these are difficult to recycle, so this article will focus on the other type of plastic.<\/p>\n Thermoplastics don\u2019t have any curing step and become pliable or workable after being heated past their melting temperatures. As a result, pretty much all\u00a0FDM 3D printers<\/a>\u00a0use thermoplastic.<\/p>\n In theory, most types of thermoplastic can be melted down and recycled, with differing amounts of efficiency and material loss for each type. However, the types of plastics that are processed by recycling plants can vary significantly around the world, or even between different municipalities of the same city!<\/p>\n For example, almost every recycling center processes PET and HDPE, which are the materials that plastic bottles and food containers are usually made of. On the other hand, even though PVC is recycled extensively in\u00a0Europe<\/a>, it\u2019s much less common in North America.<\/p>\n The two classic types of 3D printer filament, ABS and PLA, aren\u2019t recycled by most curbside municipal recycling programs. Under the ASTM\u00a0International Resin Identifier Codes<\/a>, both are classified as Type 7, or \u201cOther\u201d, which is not typically processed by municipal programs. So, unfortunately, you can\u2019t just throw your failed prints into the recycling bin.<\/p>\n Even though PETG and PET are chemically very similar, PETG is also excluded from being recycled by most programs. In fact, the chemical similarity of PETG to other types of PET plastic, combined with its low melting point, makes PETG a pesky contaminant during the recycling of PET. That\u2019s because it\u2019s difficult to differentiate from PET and dangerously reduces the temperature stability of the final PET material if it\u2019s mixed in.<\/p>\n Polypropylene (PP) filament isn\u2019t commonly used for 3D printing as its semi-crystalline nature causes it to\u00a0warp<\/a>\u00a0significantly while cooling. For the brave few that do print with PP, it\u2019s recycled in some municipalities. Contact your local recycling center to find out whether they accept it or not.<\/p>\n Almost every other type of printer filament (including\u00a0nylon<\/a>\u00a0and\u00a0polycarbonate<\/a>) are also classified as Type 7, like ABS and PLA, so they aren\u2019t usually processed by normal plastic recycling plants either.<\/p>\n Even though most local recycling programs won\u2019t turn your failed 3D prints into recycled plastic, there are many independent plastic recycling and processing companies that recycle the materials that aren\u2019t processed by the local pickup service.<\/p>\n Try calling local recycling companies and asking whether they process your plastic of choice. You might need to try multiple places because even if a company processes a plastic type used by 3D printing, many companies might hesitate on accepting plastic waste from a non-verified source.<\/p>\n If, however, they\u2019re willing to accept your waste materials, try accumulating big batches of waste plastic that you can periodically drop off. If you\u2019re part of a\u00a0Makerspace<\/a>\u00a0or\u00a0FabLab<\/a>, you can also make a big communal waste box for failed prints and take it over when it\u2019s full. Just make sure to keep the different types of plastic separated, with the plastic types clearly marked!<\/p>\n If you can\u2019t turn PLA into recycled plastic through conventional means, there\u2019s another interesting way to deal with it without sending it to a landfill. One of the unique features of PLA is that it\u2019s a biodegradable plastic, which means it can be broken down over time by bacteria and fungi. You can take advantage of this fact by \u201ccomposting\u201d your PLA waste.<\/p>\n Composting PLA involves breaking it\u00a0into small pieces\u00a0and leaving it in a microbe-rich environment like a compost pile. Depending on your local conditions, it can take a very, very long time until the PLA is fully broken down. (Expect up to a year in wet climates, and even longer in dryer climates!)<\/p>\n Note:<\/strong>\u00a0PLA is not compostable in the formal sense of the word (see this\u00a0article on bioplastics<\/a>\u00a0for more details). So if you live in a place with a municipal composting program, do not mix your PLA waste into your normal food waste. The long degradation time of PLA, as well as its potential to produce trace heavy metal residues after it degrades, makes it incompatible with commercial composting facilities. If you mix PLA into your food waste, it will probably end up getting removed from the compost and sent to a landfill anyway, so just keep it in your personal compost heap!<\/p>\n A great feature of the thermoplastics that are used in 3D printing is their ability to be melted down and re-extruded without a significant loss of material. Making and using a filament extruder at home is a little more advanced than using a 3D printer, but it\u2019s definitely within the reach of a dedicated hobbyist, and a great way to practically recycle your waste plastic! It also allows you to make your own filament, which cuts down on filament costs. That is if you don\u2019t consider the cost of making your own extruder.<\/p>\n Recycling waste plastic into usable filament requires two steps: shredding the plastic into small pieces, then melting and extruding it with a filament extruder. There are many solutions to the latter step, with hobby-grade plastic extruders like the Filastruder or Filabot available for sale, as well as designs for DIY filament extruders (for one such design, check out our\u00a0article on how to make your own filament extruder<\/a>).<\/p>\n Unfortunately, the plastic shredding step remains a bit difficult for the average hobbyist. Grinding up large pieces of plastic puts a lot of strain on the types of motors found in most commercial appliances, and industrial shredders, which can handle the strain, are too expensive for most individuals to purchase themselves. That said, people have found success using a blender or meat grinder to break down small amounts of their plastic waste for filament extrusion.<\/p>\n Even though the suggestions above can help you cut down on waste plastic buildup, the easiest way to reduce your waste is to prevent it from happening in the first place! Failed prints and prototypes are an inevitable source of waste for any 3D printing hobbyist, but here are some quick tips for preventing waste buildup:<\/p>\n <\/p>\nWhat Types of Plastic Are Recyclable?<\/h3>\n
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Is 3D Printer Filament Recyclable?<\/h3>\n
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Non-Municipal Recycling Centers<\/h3>\n
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PLA Composting<\/h3>\n
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Re-Extruding Filament<\/h3>\n
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Tips for Reducing Plastic Waste<\/h3>\n
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