Plastic 5, also known as polypropylene (PP), is a resin made of the monomer propylene which is an alkene hydrocarbon. The number 5 denotes the resin identification code for Polypropylene. Polypropylene is a widely used thermoplastic with an array of uses in our modern lives.
In this article, I will discuss whether Polypropylene (PP) is recyclable, what are the methods by which PP could be recycled, and how un-recycled PP in landfills affects the environment.
Is it possible to recycle Polypropylene?
Yes, Polypropylene is recyclable. However, there are many barriers to recycling this plastic. Globally, about 1% of PP is recycled each year. This is an abysmal number, it is one of the least recycled plastics in the world.
However, many recent technologies are paving the way for more polypropylene to be recycled. Better mechanical recycling methods as well chemical processes that convert PP back into its raw materials are slowly being implemented into the industry.
Some mail-in programs do take polypropylene waste for recycling. There are drop-off sites in some cities which accept only polypropylene for recycling.
Different cities have different services available but make sure that you check out what the rules are in your city.
However, if no such recycling programs exist in your area, the only thing you can do is to throw it in the trash. This is unfortunate but is currently the only option in most countries.
Polypropylene is a versatile plastic that is denoted by the number 5 of the resin identification numbers. It is an extremely useful plastic that is used to make a range of items, from food containers, plastic bags, automotive parts, textiles, stationery, cosmetic bottles, cleaning agent bottles, food packaging, and many more.
Polypropylene is extremely unreactive, it does not react with acids or bases under normal circumstances. This makes it an ideal candidate as a container for cleaning agents as well as certain industrial chemicals.
Polypropylene also is known to be very flexible and some can be bent almost 360 degrees without breaking. This makes it a great candidate for many applications that range from industrial to domestic. Shampoo bottles or any flip-top bottles are usually made of PP due to their rigidity, and fatigue resistance.
Compared to other plastics, PP is heat resistant. Which allows it to be used inside car engines or some other home appliances. It’s also a great insulator which is why most copper wire casings are made with it.
All in all, polypropylene has many advantages over other plastics leading to its wide use in multiple industries. This implores the plastic industry and governments to implement changes that will increase Polypropylene recycling rates to reduce waste build-up in landfills as well as reduce fossil fuel consumption and carbon emission.
How is Plastic number 5 or polypropylene recycled?
Currently, the main method by which most plastic 5 material is recycled is mechanical. This means the material is sorted, cleaned, shredded, melted, and finally, the molten plastic is cooled and cut into pellets.
The first three steps of PP recycling are the same as other plastics, the challenge is in the last two steps.
Due to PP being highly heat resistant, it needs to be heated at 2,400 °C, this requires special machinery most recycling centers do not have. This melted plastic is then solidified and cut into pellets.
There are chemical recycling methods that have been developed in recent years which can turn PP into an oil akin to the raw material it was made from. This oil can then be used to produce new plastic which is almost of virgin quality.
This chemical process is called pyrolysis since it helps break the plastic down to its more basic building blocks in the presence of heat.
Recently a scientist named John Layman working for Procter & Gamble developed a recycling system for PP which turns used plastic to almost virgin quality.
P&G has funded the development of a company called PureCycle technology, with John Layman at the helm. This company is dedicated to using the PP in our landfills to make recycled plastic which can be used to make plastic containers and other materials.
As things stand now, we still have a long way to go. A lot of plastic 5 materials end up in landfills taking up around 30% of the space.
PP takes around 20-30 years to decompose and often releases harmful chemicals into the soil when it does break down. Chemicals like lead and cadmium are two examples.
The main reason why most polypropylene is not recycled is that most municipalities and counties do not have the proper equipment to recycle polypropylene.
Curbside recycling systems rarely accept polypropylene and most PP items thrown into these bins end up in landfills.
There are two main reasons why PP recycling is so difficult, these are listed below.
- Most curbside recycling programs do not accept Polypropylene since special machinery is needed to process it.
- It is hard to clean the smell of certain food, cosmetics, or cleaning agents off of Polypropylene containers and this smell persists in recycled products.
This is a shame since PP is a plastic that retains its flexibility even after melting during the recycling process making it a high-quality thermoplastic.
Another contributing factor to excess PP in landfills is that most materials made with plastic 5 have short lifespans, i.e. shampoo bottles, cleaning agent bottles, yogurt cups, etc.
The impacts PP waste has on the environment are discussed further in the following section.
How plastic 5 affects the environment:
Plastic 5 or Polypropylene does decompose at an average rate of 20-30 years. This releases heavy metals into the soil like lead and Cadmium.
Cadmium, in particular, is very toxic to the environment and it percolates in several bio-systems. It is poisonous to the respiratory system, is known to be carcinogenic, and inhaling cadmium can lead to toxicity in the liver and kidneys.
Thus the cadmium that is released into the atmosphere enters several food chains and poisons animals. It moves up the food chain in most cases and eventually reaches the top where it is very likely to harm us, humans.
Although the level of toxicity PP poses is low compared to other plastics like PVC, it is toxic nevertheless.
A great portion of the landfills is taken up by PP plastic items.
Particularly in south and southeast Asia, plastic waste in landfills has been of huge environmental concern.
Due to the lack of proper disposal and recycling systems of local waste, plastic clogs waterways and covers large stretches of land.
After 2018, when China stopped importing most of the West’s plastic waste, Western Nations have redirected much of their trash to South and Southeast Asian countries.
These countries do not have the infrastructure to process this mammoth amount of plastic, resulting in landfills filled to the brim with plastic items.
A lot of this waste spills into the oceans and creates large garbage patches. It affects aquatic life with devastating consequences for the environment.
To create a sustainable future, we need to ensure these plastic items need to be processed to reduce the load on landfills and we need to clean up the oceans.
With new technologies emerging, PP recycling is becoming more commonplace. The best feature of PP is its durability and a lot of the PP in landfills can now be cleaned and entered into the recycling system.
This is the next big project for companies and governments that are invested in creating a sustainable future.
Companies like PureCycle technology and Nextek Ltd.- are currently attempting to clean up the landfills. This needs to be a concerted effort where we all need to do our part.
In this article, I discussed whether Polypropylene (PP) is recyclable, what are the methods by which PP could be recycled, and how un-recycled PP in landfills affects the environment
Frequently Asked Questions (FAQs): Is plastic 5 recyclable?
Is number 5 plastic recyclable?
Yes, however, there are special recycling programs where you have to drop off your number 5 plastics. Most cities don’t accept it in their curbside programs, so make sure what your city’s policy is.
What can I do with #5 plastic?
Make sure to check if the plastic is recyclable and if your city has a recycling program. Some companies have mail-in options for polypropylene, you can check online for any such option in your area. If recycling isn’t an option you can try and repurpose it, yogurt cups, for example, can be made into flower pots. Your last option is to simply throw it in the garbage.
Is polypropylene widely recycled?
Unfortunately, no. Only 1% of polypropylene is currently recycled.
Is polypropylene easy to recycle?
It depends. Polypropylene recycling requires additional expensive equipment. So whether it’s recycled or not relies on your government or local companies investing in this machinery.
How to dispose of polypropylene?
First, check if there are any recycling options. If there are none in your area you can try to repurpose the plastic containers. But if these are not an option then you’re left with the option to throw it in the garbage.
How long does it take for Polypropylene to break down?
Around 20-30 years. The rate of break-down of this plastic depends on the conditions it’s in. In a landfill, with the optimum moisture level, temperature, and pH it will take around 20 years. It may take longer in closed conditions.
Is polypropylene environmentally friendly?
No plastic is truly environmentally friendly, but, as far as plastics go, polypropylene is a better alternative than most. It does decompose in 20-30 years, this is better than polystyrene for example, which takes over 500 years. It’s recyclable which means we can eventually develop a zero-waste system using PP. It’s less toxic than plastics like PVC. It may not be the most environmentally friendly option but it’s better than its counterparts.
Is polypropylene biodegradable?
No, it is not. The term biodegradable has been vaguely defined by most sources, which is why it is easy to assume since PP breaks down it must be biodegradable. However, biodegradable items are required to be decomposed by microorganisms and the end-products of this process must then enter the food chain. For example, a fruit when it degrades provides water, sugar, and other vital nutrients to the microorganisms in the soil. Polypropylene does not provide vital molecules to any microorganism. Thus it is not considered biodegradable.
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