What are fossil-based polymers?
Fossil-based polymers, the plastics most people simply call plastics, are synthetic materials made from petroleum, natural gas or coal. Monomers pulled out during refining and cracking are polymerized into the finished material. They account for over 98% of global plastic production and hold up most of modern packaging, construction, transport and manufacturing.
They also define bioplastics by contrast, which is why this page exists. Fossil-based polymers are not bio-based and, with a few exceptions, not biodegradable. They draw on finite carbon and last for centuries when they escape collection. They are also cheap, versatile and thoroughly proven, which is the real reason replacing them is so hard.
How they are produced
Production starts with crude oil or natural gas from underground reserves. Cracking then breaks long hydrocarbon chains at high temperature into smaller molecules, the monomers: ethylene, propylene, styrene, vinyl chloride. Addition or condensation polymerization joins those monomers into chains.
The whole route from wellhead to pellet is energy-intensive and carbon-heavy. The plastics industry accounts for roughly 3.4% of global greenhouse gas emissions, and that share is expected to grow with demand. Replacing the bio-based polymer feedstock is one of the few levers available against it.
The five commodity polymers
A handful of polymers make up most of the market: polyethylene, polypropylene, polyethylene terephthalate, polystyrene and polyvinyl chloride.
Polyethylene (PE)
Polyethylene (PE) is the most produced plastic in the world, at over 100 million tonnes a year. It is a simple polymer of ethylene monomers, sold in several density grades:
- HDPE (high-density polyethylene) — Rigid, strong, and chemical-resistant. Used for milk jugs, detergent bottles, piping, and crates. Recycling code 2.
- LDPE (low-density polyethylene) — Flexible, transparent, and moisture-resistant. Used for plastic bags, food wrap, squeeze bottles, and agricultural films. Recycling code 4.
- LLDPE (linear low-density polyethylene) — Combines the flexibility of LDPE with improved tensile strength. Dominant in stretch wrap and industrial packaging films.
PE does not biodegrade but recycles well mechanically. Its bio-based twin, bio-PE, is chemically identical and goes into the same recycling stream.
Polypropylene (PP)
Polypropylene (PP) is second by volume at roughly 75 million tonnes a year. It balances stiffness, fatigue resistance and heat tolerance well enough to cover food containers, automotive interior panels, medical devices, living hinges and woven bags.
PP melts higher than PE, around 160 °C against 130 °C, which is what makes microwave-safe containers and hot-fill packaging possible. It carries recycling code 5 and is collected in more curbside programs every year, though its recycling rate still trails PET and HDPE.
Polyethylene terephthalate (PET)
Polyethylene terephthalate (PET) is the polyester behind single-use water and soft drink bottles, at roughly 30 million tonnes a year. Its clarity, gas barrier and dimensional stability make it the default for beverage packaging, food trays and polyester textile fiber.
PET is also the most successfully recycled plastic, with bottle-to-bottle systems established across Europe, North America and parts of Asia. Recycling code 1. Enzymatic recycling, which uses engineered enzymes to depolymerize PET back to its monomers, is the emerging chemical route toward genuine circularity.
Polystyrene (PS)
Polystyrene (PS) comes in two main forms: general-purpose polystyrene (GPPS), which is rigid and transparent, and expanded polystyrene (EPS), a foam that is roughly 95% air. Between them they cover disposable food service items, protective packaging, insulation board, laboratory equipment and CD cases.
EPS, widely known as Styrofoam, has drawn the most regulatory attention, because it persists in the environment and is difficult to recycle. The EU and other jurisdictions have banned or restricted it in food packaging. Recycling code 6. Biodegradable alternatives are steadily replacing PS in single-use applications.
Polyvinyl chloride (PVC)
Polyvinyl chloride (PVC) is third by volume and unusual in its composition: roughly 57% of its mass is chlorine derived from salt rather than petroleum, so it carries less fossil carbon than a fully hydrocarbon polymer.
It exists as rigid PVC (uPVC) in pipes, window frames and siding, and as flexible PVC, plasticized with additives, in cable insulation, flooring, medical tubing and inflatables. PVC pipe can last over 100 years in the ground, which is a genuine sustainability argument. Against it sit chlorine-based additives, plasticizer migration and dioxin formation during incineration, which together make PVC the most contested commodity plastic. Recycling code 3.
Properties compared
| Polymer | Global Production (Mt/yr) | Density (g/cm³) | Melting Point (°C) | Key Properties | Recycling Code |
|---|---|---|---|---|---|
| PE (HDPE) | ~50 | 0.94 – 0.97 | 125 – 135 | Chemical resistance, rigidity | 2 |
| PE (LDPE) | ~25 | 0.91 – 0.94 | 105 – 115 | Flexibility, transparency | 4 |
| PP | ~75 | 0.89 – 0.91 | 155 – 165 | Stiffness, fatigue resistance, heat tolerance | 5 |
| PET | ~30 | 1.33 – 1.40 | 250 – 260 | Clarity, gas barrier, recyclability | 1 |
| PS | ~15 | 1.04 – 1.06 | ~240 (softens ~100) | Rigidity, optical clarity (GPPS), insulation (EPS) | 6 |
| PVC | ~45 | 1.30 – 1.45 | ~160 (decomposes) | Durability, flame resistance, versatility | 3 |
Environmental problems
The environmental record of these materials is well documented, and it is bad in three specific ways.
Climate impact
The OECD put the plastics value chain, from extraction through production to incineration, at an estimated 1.8 billion tonnes of CO₂-equivalent emissions in 2019. On business-as-usual projections that figure nearly triples by 2060. Swapping fossil feedstocks for renewable ones addresses part of it.
Plastic pollution
The world generated around 353 million tonnes of plastic waste in 2019. Of that, 9% was recycled, 19% incinerated and 50% sent to controlled landfill. The remaining 22% was mismanaged: dumped, burned in open pits or leaked into the environment. An estimated 11 million tonnes reach the oceans each year, a figure projected to triple by 2040 unless the system changes.
Microplastics
Fossil-based polymers fragment into microplastics, particles under 5 mm, which have been detected in oceans, freshwater, soil, air, food and human blood. Because the polymers do not biodegrade, those fragments keep breaking down into smaller particles without ever disappearing, and they accumulate.
Recycling and end-of-life
Four end-of-life pathways are available:
- Mechanical recycling — The dominant recycling method. Plastics are sorted, shredded, washed, and re-extruded into pellets. Most effective for PET and HDPE; more challenging for mixed or contaminated streams.
- Chemical recycling — Includes pyrolysis, gasification, and depolymerization, which break polymers back to monomers or hydrocarbon feedstock. Emerging at industrial scale for PS, PE, PP, and PET.
- Energy recovery — Incineration with energy capture. Common in Europe and Japan, controversial due to CO₂ and pollutant emissions.
- Landfill — Still the most common fate for plastic waste globally. Fossil-based polymers persist in landfill for centuries.
Better recycling and bioplastic substitution work on different parts of the same problem, and neither closes it alone. The waste already in circulation needs recycling capacity; the waste not yet made needs different materials.
Regulation
Rules on fossil-based plastics are tightening on four fronts:
- The EU Packaging and Packaging Waste Regulation (PPWR), adopted in 2024, sets mandatory recycled content targets, design-for-recycling requirements, and single-use plastic restrictions.
- The UN Global Plastics Treaty, under negotiation through the Intergovernmental Negotiating Committee (INC), aims to establish a legally binding international instrument covering the full lifecycle of plastics.
- National bans on specific single-use fossil-based plastic products — bags, straws, cutlery, EPS containers — have been enacted in over 120 countries.
- Extended Producer Responsibility (EPR) schemes are making plastic producers financially responsible for end-of-life collection and recycling, incentivizing shifts toward more sustainable materials.
All four push buyers toward bio-based and biodegradable alternatives. Our standards and certifications page covers how compliance is actually demonstrated.
Where fossil polymers sit in the bioplastics picture
Not every fossil-based polymer is non-biodegradable. A small group of biodegradable fossil-based polymers, including PBAT, PCL and PBS, shows that biodegradability follows from chemical structure rather than from where the carbon was mined. That single fact undoes the neat split between conventional and sustainable plastics.
In the classification system, fossil-based polymers sit opposite bio-based polymers on the feedstock axis. The knowledge zone maps all four quadrants: bio-based biodegradable, bio-based non-biodegradable, fossil-based biodegradable and fossil-based non-biodegradable.
These materials will stay in the global mix for decades. The realistic aim is not to remove them but to cut their impact through better recycling, lower consumption and substitution with non-biodegradable bioplastics or biodegradable materials wherever the application and the local infrastructure actually support it.