Is Polypropylene Bad For The Environment? Statistics, Trends, Facts & Quotes

Polypropylene, a versatile and cost-effective thermoplastic polymer, is extensively used across various industries. Despite its widespread use, the environmental impact of polypropylene has become a topic of concern.

As the world's second-largest plastic resin by production volume, trailing only behind polyethylene, polypropylene, a thermoplastic polymer, is often identified by its chemical formula (C3H6)n. With its applications spanning across packaging, automotive, consumer goods, and medical industries, polypropylene's environmental impact is a critical question for consumers and manufacturers alike. 

While polypropylene has certain environmental advantages, such as low production impact and potential for energy recovery, its end-of-life disposal and low recycling rates remain. The increasing global demand for polypropylene underscores the need for improved recycling processes and sustainable practices within the industry.

As society grows increasingly eco-conscious, it is essential to scrutinise the lifecycle of polypropylene and its impact on the planet.

Polypropylene, often known as PP, is a thermoplastic polymer that's become a daily staple due to its unique properties. It's a type of polyolefin and is slightly more complicated than polyethylene, with a chemical formula of (C3H6)n. 

Known for being inflexible, rigid, and crystalline, polypropylene is the lightest polymer among all commodity plastics, making it a versatile material used in various products and industries. 

It has a melting point range of 160 - 165°C for homopolymer and 135 - 159°C for copolymer. This makes it one of the lightest polymers with a density, making it a favourable choice for many applications. 

Polypropylene (PP) comes in several types with unique properties and applications. Understanding the differences between these types does help manufacturers and consumers choose the right type for their needs.

Here, we explore the three primary types of polypropylene: Homopolymer (PP-H), Block Copolymer (PP-B), and Random Copolymer (PP-R).

The choice between these types of polypropylene depends on the specific requirements of the application, such as the need for clarity, flexibility, or impact resistance. 

The global polypropylene market size was valued at approximately £103.5 billion in 2022 and is expected to grow at a compound annual growth rate (CAGR) of 7.27%, reaching about £157.7 billion by 2028. 

The global production volume of polypropylene was approximately 79.01 million metric tons in 2022. 

The demand for polypropylene in 2022 was 86.74 million tons, with a global production capacity of 97.86 million tons.

It's expected to reach almost 104.99 million metric tons by 2030, growing at a CAGR of 3.6%.

The global polypropylene market was estimated to be £62,061 million in 2022. 

Polypropylene is projected to reach £70,272 million by 2028, growing at a CAGR of 2.1%.

The packaging industry is the major consumer of polypropylene.

The recycled polypropylene market was valued at £6.3 billion in 2021 and is expected to reach £10.3 billion by 2029, growing at a CAGR of 6.34%.

This growth is driven by the diverse applications of the material and its demand across various industries.

Polypropylene is used to make a myriad of everyday items, including:

The manufacturing process of polypropylene has high impacts on global warming potential, fossil resource depletion, human toxicity, acidification, and petrochemical oxidant formation. 

For instance, the manufacturing process of propylene emits 1.722 kg Oil eq./kg-PP for fossil resource depletion and 0.0042 kg NMVOC/kg-PP for petrochemical oxidant formation. 

This means that the manufacturing process of PP is a significant contributor to greenhouse gas emissions, with the widespread use of polypropylene expected to contribute 1.3 billion tonnes of CO2 to the atmosphere. 

Furthermore, if thermoplastics like PP are burned, they can discharge toxins and vinyl chloride, posing a severe environmental threat. 

The following table provides a snapshot of the environmental impact of polypropylene production.

The environmental impact of polypropylene also extends to its usage. 

For instance, US single-family households generate over 2 billion pounds of PP annually. If just 30% of this material were recovered, it would reduce greenhouse gas emissions by 311,000 metric tons. 

The USA and China are major markets for polypropylene, with significant growth expected in the coming years. 

Countries like Saudi Arabia, UAE, Oman, and Israel account for most of the polypropylene production in the Middle East. 

The UK has traditionally used more polypropylene in Europe than other European countries. In 2022, other key European countries, such as Germany and the Netherlands, will join in the most used polypropylene production.

The packaging industry is a significant consumer of polypropylene, with other major applications in the automotive, building & construction, and medical sectors.

The global key manufacturers of polypropylene include LyondellBasell, SABIC, Exxonmobil, Dupont, INEOS, Total, Formosa, LG Chem, and Sumitomo Chemical.

The landfilling of polypropylene waste has significant environmental impacts. As polypropylene degrades, it may release cadmium, a carcinogen toxic to plants and animals. However, polypropylene is considered safer than many other plastics, as it doesn't generate toxic gases when burned.

While polypropylene is fully recyclable, recycling presents several challenges. The properties of recycled polypropylene may differ from those of virgin polypropylene, such as melt-flow rate, molecular weight, or thermal stability. This can limit the use of recycled polypropylene in applications where impact performance and part stability are required.

The recycling process of polypropylene involves several phases, including collection, sorting, cleaning, shredding, separation, and compounding. However, achieving high-quality recycled polypropylene, especially for food-grade applications, requires eliminating all contaminants from post-consumer waste that could harm human health.

Despite these challenges, recycling polypropylene has significant environmental benefits. For instance, recycling one ton of plastic saves 5,774 kilowatt-hours of energy, 16.3 barrels (685 gallons) of oil, and 30 cubic yards of landfill space. 

The post-consumer recycling rate of PP worldwide is about 1%, indicating a significant opportunity for improvement. 

Efforts to improve polypropylene recycling are underway. In the US, access to polypropylene recycling collection has increased to 65%, which has led to an estimated additional recovery of 25 million pounds annually. 

Companies like PureCycle are pioneering processes transforming polypropylene waste into ultra-pure recycled resin. Additionally, the green polypropylene market, which offers a more eco-friendly alternative to traditional polypropylene, is projected to grow at a CAGR of 5.6% from 2023 to 2031, reaching a market value of £51.8 million by 2031.

However, the inconsistency of post-consumer plastic waste remains a significant challenge for recyclers.

Given the environmental impact of polypropylene, there is a growing demand for more sustainable alternatives. Bio-based packaging is increasingly being used as a replacement for petroleum-based plastics. 

For instance, Cereplast has developed a range of sustainable resins, in which between 50 and 70 per cent of the traditional petroleum content of the plastic resins has been replaced. 

According to Dr Jane Goodall, a renowned environmentalist,

Polypropylene's environmental impact is thus twofold: it is both a product of and a contributor to the fossil fuel industry.

Polypropylene is not entirely sustainable, but it is considered more sustainable than many other types of plastic. It is more quickly biodegradable, has a lighter carbon footprint, and doesn't threaten our health.

Moreover, the carbon emissions of recycled PP macro-fibres were 50% less than that of virgin PP, and the water and fossil fuel consumption was reduced by 99%.

However, the production of polypropylene still emits greenhouse gases, and while it is recyclable, not all polypropylene products are recycled.

In the quest for more sustainable packaging solutions, several alternatives to polypropylene have emerged:

Polypropylene often has a better environmental profile than polyethene terephthalate (PET) or polystyrene. For instance, it has a lower density than PET, meaning less material is required to produce a product with the same volume. This can lead to a reduction in waste and resource use.

However, polypropylene has its challenges. It is less easily recycled than PET, which has a well-established recycling infrastructure. The complexity of polypropylene recycling means that much of it ends up in landfills or as environmental litter. 

As environmental consultant Dr Lucy Rogers explains,

Polypropylene competes with various alternative materials depending on the application. For instance, it competes with ABS and AES in the automotive industry. In applications requiring chemical resilience, it competes directly with HDPE and PVC.

Alternative materials to polypropylene include Cyclic Olefin Copolymer (COC), Acrylonitrile Styrene Acrylate (ASA), and Polycyclohexylenedimethylene.

The table below shows the comparative analysis of polypropylene with other materials regarding energy consumption during production, CO2 emissions, and recyclability.

Experts in the field of sustainability have weighed in on the use of polypropylene. Dr Markus Lambert, a materials scientist, states,

This sentiment is echoed by sustainability advocate Sarah Smith, who argues,

For instance, the Blue Shoe Guys states,

This highlights the material's lower environmental impact during the production phase.

Polypropylene is generally considered safe for use. The FDA approves it as a food container material, and no known cancer-causing effects are associated with polypropylene. 

It is also considered the safest of all plastics due to its heat-resistant nature. 

However, like any material, polypropylene has limitations and potential safety concerns. For instance, some studies have shown that certain polypropylene chemicals, such as additives and stabilisers, may leach into the food if the packaging is exposed to high temperatures or acidic foods. 

According to the Environmental Protection Agency (EPA), polypropylene is safer than other plastics. It has an EPA Safer Chemical Ingredients classification.

However, as stated by MedicineNet,

Research indicates that polypropylene is not biodegradable. It is a type of plastic that can take hundreds, if not thousands, of years to decompose in the environment. In general, polypropylene is not readily biodegradable. Exposure to the environment can take 20 to 30 years to decompose fully.

This is because polypropylene is a synthetic material that microorganisms do not recognise as food, so they do not have the enzymes needed to break it down.

Furthermore, polypropylene is resistant to weathering and chemical rotting, reducing biodegradability. 

However, it's important to note that as polypropylene degrades, it may release harmful substances such as cadmium, a known carcinogen toxic to plants and animals.

Estimates suggest that polypropylene products can take between 20 to 500 years to decompose in a landfill, depending on the product and environmental conditions. However, in marine environments, where much of the discarded plastic ends up, polypropylene items can take much longer to degrade due to the cooler temperatures and lack of light.

Despite its ubiquity, many people may need to be aware of the current trends in polypropylene products. Here are the trends on these products:

A significant trend in the polypropylene industry is the shift towards sustainability. Manufacturers are increasingly focusing on producing recyclable PP products and developing new methods to enhance the recyclability of PP. Companies are also exploring bio-based polypropylene as an alternative to fossil fuel-based plastics, which could significantly reduce the carbon footprint of PP products.

The adoption of advanced manufacturing techniques, such as 3D printing, is rising. Polypropylene is becoming a more popular material for 3D printing due to its strength and chemical resistance. This trend is opening up new possibilities for custom and on-demand manufacturing of PP products, which could revolutionise supply chains and reduce inventory costs.

The automotive industry is another sector where polypropylene is rising. Polypropylene is lightweight, which can help to improve fuel efficiency, and it is also durable and resistant to chemicals, making it suitable for various automotive applications.

According to the Plastic Trade Association, in 2020, among the different types of plastics used in the manufacturing of automobiles, PP accounted for a leading share of 32%.

There's an increasing demand for high-performance PP in various sectors, including automotive, medical, and packaging. Innovations in polypropylene composites are enabling the creation of lighter, stronger, and more heat-resistant products. For example, using PP in-vehicle components in the automotive industry helps reduce weight, improve fuel efficiency, and lower emissions.

The future of polypropylene (PP) is promising, with the market projected to grow significantly in the coming years. This growth is driven by increasing demand from various end-use industries such as packaging, automotive, building & construction, and healthcare. 

The global polypropylene market is projected to grow at a compound annual growth rate (CAGR) of 4.5% from 2022 to 2030, reaching a value of £136.415 billion by 2030. 

Regarding environmental trends, the focus on sustainability and recyclability is expected to continue. Companies are increasingly exploring innovative recycling techniques, such as advanced mechanical recycling and innovative depolymerisation, to improve the efficiency and effectiveness of polypropylene recycling. 

Developing biodegradable polypropylene and using agricultural residues and waste fish in polypropylene composites are also being explored. 

This statement encapsulates the current state of polypropylene recycling and the industry's commitment to improving it.

In response to these environmental concerns, there is growing interest in recycled polypropylene. Recycling polypropylene waste is generally considered environmentally preferable compared to other options.

However, it is important to note that its production and disposal do not solely determine the environmental footprint of a material. The entire material lifecycle, including its use and potential for recycling, should be considered when evaluating its environmental impact.

As the industry continues to innovate and adapt to changing environmental and market trends, polypropylene is set to remain a vital material in various sectors.