Material Insights

Which Plastics Are Recyclable?


Which plastic materials can and cannot be recycled? How can different types of plastics be recognized? We are far too familiar with these and many other related questions. Luckily for you, we have the answers to your questions! 

In our previous blog post, we introduced you to our recycling journey and the mini-series we created for you on our YouTube channel. If you missed it, we recommend you checking it out first before continuing on with this blog. 

As you probably know, there are different types of plastic materials and not all can be recycled. In this blog post we are going to dive deeper into the different types that are out there and how you can recognize them. 


Types of Plastics 

There are 7 types of plastic materials; PETE or PET, HDPE, V or PVC, LDPE, PP, PS and Other / Miscellaneous Plastics. For most plastic consumables, you can recognize the type of plastic used by an indented icon of each plastic code stated below. 



PETE or  PET – Polyethylene Terephthalate
PET is the most common plastic material name nowadays. It’s used in mostly beverage bottles, oven – tray detergent and cleaning product bottles. It is also used for the finishing of objects such as liquid crystals, displays, carpets, clothes, guitars and pianos. Therefore, this material is suitable for recycling into filament, however, it absorbs odors and flavors from foods and liquids stored in it, which can prevent you from being able to recycle PET into filament. Furthermore, the plastic is designed for blow-molding, not extrusion (it does not flow easily inside an extruder). 

HDPE – High Density Polyethylene
Another common plastic material is HDPE, it is known for having a low risk of leaching into foods and or liquids. This material is mostly used in the making of children toys, yogurt cups, milk jugs, shampoo bottles and other similar products. Recycled HDPE is mostly turned into pens, plastic lumber, plastic fencing, picnic tables, and bottles. This material is suitable for recycling into filament, however, it is not easy to turn into filament; it flows easily but requires special cooling.

V or PVC – Polyvinyl Chloride
PVC plastics contain very harmful chemicals that have been linked to various diseases. This material is usually used for the making of plumbing pipes, tiles, windows and medical equipment. Due to the fact that this material has harmful chemicals it is not recommended to recycle it yourself. PVC only gets recycled by specialized programs that recycle it into flooring, paneling and roadside gutters. 

LDPE – Low-Density Polyethylene
This material is a very safe and clean plastic. It is recognized by its flexible and thin texture. It is commonly found in household items like grocery bags, plastic wraps, frozen food containers and food holding bottles. LDPE is recyclable but not recommended to recycle into filament, due to its behavior in molten state and the shape of the items it usually comes in (grocery bags being a good example of something painful to shred). Recycled LDPE is usually found back in garbage cans, paneling, furniture, flooring and bubble wrap.

PP – Polypropylene
Another known safe plastic is PP. This material has a sturdy texture and it commonly found back in tupperware, syrup bottles, medicine bottles and yogurt containers. It is also heat resistant as it is also used in making microwavable food containers. PP is suitable for recycling into filament (depending on the item you want to recycle), and it is usually recycled into heavy-duty items like pallets, ice scrapers, rakes and battery cables. 

PS – Polystyrene
This material is your everyday plastic, it is found in beverage cups, plastic utensils, insulation, packing materials, egg cartons, and disposable dinnerware. Although, some would say that it is notorious for leaching and poor recyclability, we actually managed to recycle it into filament. PolyStyrene is the material we used in our recycling video’s and therefore, we can recommend you to recycle your PS objects into filament. However, it is a possibility that random PS items could react differently and therefore, work differently as well, 

Other / Miscellaneous Plastics
SPI 7 is seen as all kinds of plastic that does not fall in the 1 to 6 category. Miscellaneous plastics are usually found back in nylon, baby milk bottles, sunglasses, computer casings, and compact discs. This is actually the most important category since it contains all of the interesting plastics. All of the cool engineering and high-performance ones would correspond to 7. It consists of an immense variety (Nylon6 and other types of nylon, PEEK, PEKK, PEI, TPU, PC, many more). This category is a lot harder to define, but there is a lot of potential.

No matter what plastic you choose (PEEK, PET,….), they each come in dozens of grades (versions). We might be able to extrude and print one LDPE, but not another one. The challenge with all commodity plastics (1 to 6, + a few in 7) is that the parts were originally injected. Injection-molding grades do not work well with extrusion. Moreover, despite which material, the recycling challenges are almost always the same, so is the methodology (purity of the batch, shredding to an even size, finding good settings,….). In other words, we can’t always predict how the recycling will go, but if it is doable, we will manage.

Now that you know how to recognize the different types of plastic, we can move on to the next step, which is how to shred the plastic correctly to be able to extrude it. That step will be explained in the next video and blog post so keep a lookout for that. 

If you are still left with some unanswered questions, we recommend you to visit our webpage that is dedicated to the polymer pyramid. You can also download all material guides in just one PDF file on that same webpage. It is also always possible to contact us and to speak with one of our material experts

We hope to see you back next week. In the meantime, sort out your collected plastic so we can move on to the next step together!