Documentation Status: Draft
|Constituent monomers||PET, HDPE, PVC, LDPE, PP, PS, PMMA, PC, PE, ABS, PLA|
|Similar materials||Soft plastic|
|Common Sources||Food packaging, bottles, construction, E-waste, Automotive parts|
|Processing Tools||Shredders, Plastic extruders, FDM 3D Printers, Ovens|
Hard plastics are defined most readily as plastics which return to their shape when bent or flexed, and/or can't be scrunched into a ball. They are a meta category of plastics, meaning that it is less a definition related to a difference in their chemistry, and more a way to distinguish how the material will behave in a recycling process. Depending on the locale, this definition can be crucial in helping someone decide whether or not the plastic product they have can or can't be recycled via government recycling programs, such as Australia's ubiquitous kerbside recycling bins. Most hard plastic products found in domestic environments today can also be identified by their Resin identification code, and many jurisdictions may state that they accept all hard plastics via their recycling services, but may not have a solution in place for each particular polymer or resin. Sustainability Victoria for example states that they cannot recycle hard polystyrene.
Recycling hard plastics is usually achieved by sorting them, washing labels, and contaminants off them, shredding them into small flakes, and then including those flakes in the manufacturing processes for new plastic products. Due to the imperfect nature of most of these processes, many products which include recycled flakes, also include virgin, or newly produced plastic pellets, to ensure the end product does not fail. The equipment required to recycle hard plastics used to largely be the domain of large industrial facilities, but in recent years many hobbyists, tinkerers, and most notably the open source community Precious Plastics have developed ways to reuse plastic with much lower barriers to entry.
Hard plastics generally cause a large amount of environmental problems, from the production of Micro-plastics as they are worn down, to the release of their constituent Monomers, or other contaminant such as fire retardants. Many plastics still being produced today contain contaminants that are banned in various jurisdictions due to their toxic health effects, which presents a major challenge for recycling operations, especially where the source material is of an unknown origin. Of further concern is the general breakdown of recycling systems across the Western world, in particular in Australia and the United States, where materials have not been processed at all, and have ended up in landfill, either wasting precious resources, or causing serious contamination of these sites as the materials breakdown. As a result, the first and best way to deal with plastic waste is to reduce the amount you utilise.
Many plastic products designed for single use applications are perfectly suitable for multiple or continued use. PET water bottles for example can be refilled many times before they degrade. They can also be used for other pursuits such as Home Brewing. A bottle brush can help with cleaning bottles for reuse. Many common types of takeaway food containers can be used to store various items until they break without risk of contamination.
Most hard plastics are what's known as Thermoplastics, which can be melted and repaired with heat. This means that it can be possible to repair them, rather than discard them, if the appropriate caution is taken regarding ventilation and the heat source. Some plastics such as ABS can be melted with solvents such as acetone, to make a slurry that can be applied in a similar manner to a thick paint. Most plastic products also bond well with common household glues such as Cyanoacrylate, most commonly known as Superglue. This can allow the user to keep them out of the waste stream as long as possible.
One large source of plastic is in discarded E-waste. Many common household appliances and electronics are discarded when they break down or appear to have become redundant. Many E-waste processing facilities focus largely on the discovery of expensive components and precious metals in these products when dismantling them, and as a result the plastic can end up in waste streams. Where possible, repairing electronics rather than replacing them will prevent this. IFIXIT is a parallel Open Source project to Recyclopaedia that exists to share methods of repair for various electronic devices.
Many plastic containers can be reused in ways they were not originally designed for. HDPE Milk jugs can be cut and turned into planters in the garden. PET water bottles can be used in irrigation systems. Food trays can catch water under pots, to improve efficiency. ABS as mentioned above can be reused in a slurry form, either as an adhesive, or as a paint.
The first step in recycling hard plastics is identifying the kind of plastic you have. Most categories of products utilise the same plastic over and over again, and most again have resin identifier codes, however many plastic products utilise two or more types of plastic. Lids for bottles are almost always a different plastic to the bottle.
At home or in your community
Processing it yourself
Many hard plastics are relatively easy to recycle into entirely new products without the use of many complex tools. The simplest way is to simply heat the plastic up and bend or stretch it into a new shape. This can allow you to repurpose the item in new ways not possible with their original form. It is important however to identify any potential hazards that might arise from working with that type of plastic, and to work in a well ventilated area. More complicated objects can be made by creating gravity molds in the oven. This method often involves simply placing enough plastic above your mold inside an oven heated to the plastics melting point, allowing the plastic to fall into the mold before cooling it. Compressing the plastic while it is still molten will often result in stronger parts.
More advanced processes still are available to those with access to power tools, hot wire cutters, shredders, and extrusion machines. Heavy duty paper shredders can break down some lighter plastic containers, and drills and saws can be used to shape molded parts. The more advanced tools available for community organisations are the open source Precious Plastics machines.
Hard plastics are valuable materials when sorted, cleaned and ready for use, often fetching as much as $3 per kg, depending on the resin.
Industrial / Government processes
Container Deposit Schemes
Often the most lucrative method for an individual who is recycling hard plastics are government managed container deposit schemes. These schemes work by requiring companies to charge a levy for products that use plastic containers, which the customer can then collect when they return the container to an eligble location. In Australia, the rules for this scheme vary from state to state. Planet Ark provides information on where to return containers within Australia here; https://recyclingnearyou.com.au/containerdeposit/
Kerbside Recycling bins
Jurisdictions with kerbside recycling collection either have separate bins for hard plastics, or a co-mingled bin you can place hard plastic in alongside other materials such as glass, paper and cardboard. Some jurisdictions require residents wash plastic containers, and/or remove lids and neck rings. Lids on their own are too small for most recycling services and should be stored in a closed container of the same material. More information about which plastics can be put into kerbside recycling, and in what condition can be found here; https://recyclingnearyou.com.au/plastic
After collection, usually by a contractor who is paid by the government, hard plastics are usually transported with the other contents of the neighbourhood bin, to a primary industrial site where the materials are compressed and bailed, then put on another vehicle for transport to a secondary site, where they are then sorted via various manual and automated methods. They are then cleaned, shredded and sometimes sorted again by colour, before ending up ready to sell as a material to companies manufacturing products out of that plastic.
The secondary facility historically was often in China or other developing countries, but due to the poor quality of Western waste, the developing world began to reject these materials in favour of locally sourced waste. At present, a variety of facilities have been opened in the West to process the cleanest and highest grades of plastics, but much of the waste that previously went to the developing world has just been building up in transfer stations (the primary facilities) in lieu of a solution. Various organisations have exploited these markets and simply dumped or burnt this waste, while collecting fees for disposing of it correctly.