rPET i dzianiny z recyklingu — co marka odzieżowa powinna wiedzieć

How a PET bottle becomes a knitted fabric

Polyethylene terephthalate, better known as PET, is one of the most widely recycled plastics in the world. Beverage bottles, food containers, and cosmetics packaging can all become raw material for the textile industry. The journey from waste to finished knit fabric involves five distinct stages.

The process begins with selective collection and sorting of bottles by colour — clear and pale-blue bottles yield the purest fibres; brown and dark-green ones require additional bleaching or are directed into darker yarns. The bottles are washed, stripped of labels and caps, and shredded into flakes. The flakes are hot-washed, dried, and melted. The molten polymer is extruded through spinnerets (dies with very fine orifices) to form continuous filaments. The filaments are drawn, crimped, and cut into staple lengths — this produces the fibre. Fibre is spun into yarn; yarn is knitted into fabric.

The key technical distinction is that fibres produced by mechanical (physical) recycling have a slightly shorter polymer chain than virgin polyester. Each reprocessing cycle shortens the chains and reduces melt viscosity, which has implications for mechanical properties — but in practice, for apparel applications, the difference is small and is generally well compensated for.

rPET vs virgin polyester: mechanical properties

Comparisons between rPET and virgin polyester tend to be oversimplified by marketing on both sides — by rPET enthusiasts and by virgin-material suppliers alike. The table below offers an honest assessment of the key parameters.

Property	rPET (mechanical)	Virgin PES	Difference
Tensile strength	Similar, approx. 90–95% of virgin	Reference	Small
Pilling resistance	Slightly worse at low fabric weights	Higher	Noticeable below 150 g/m²
Dimensional stability after washing	Comparable	Comparable	No difference
Moisture absorption & wicking	Depends on finish, not raw material	Depends on finish	No difference
Sublimation print quality	Comparable ≥80% PES	Full	No difference
Colour consistency after dyeing	May be harder with mixed feedstock	High repeatability	Supplier-dependent
UV resistance (degradation)	Marginally lower after repeated recycling	Full	Marginally worse
CO₂ emissions in production	Approx. 30–50% less than virgin	Reference	In favour of rPET

In practice, for standard sportswear — T-shirts, leggings, sweatshirts — rPET from a reputable certified supplier delivers a functionally identical end product. Differences become significant only for high-performance products where extreme mechanical parameters matter (e.g. triathlon suits, compression garments), and for very lightweight fabrics below 130 g/m², where pilling may appear earlier.

Other recycled raw materials in sportswear

Recycled nylon — Econyl and others

Econyl is the registered trade name for regenerated nylon (PA6) manufactured by Italian company Aquafil. The feedstock comes from fishing nets recovered from the ocean, carpet waste, and industrial nylon off-cuts. A chemical process (depolymerisation) restores the nylon to properties identical to virgin material — unlike the mechanical recycling of PET, which marginally degrades the material.

Recycled nylon is considerably rarer and more expensive than rPET. Its use is most justified where nylon is technically warranted: swimwear, sports underwear, compression tights, and wind-resistant fabrics. Using it purely for an "eco label" on products where rPET would perform equally well is a misdirected business decision.

Recycled cotton

Recycled cotton comes from pre-consumer waste (production off-cuts, substandard lengths) or from post-consumer garments. Mechanical recycling shortens cotton fibres, which reduces yarn strength — hence fabrics made from recycled cotton typically contain 20–30% virgin cotton or polyester to maintain performance parameters.

In sportswear, recycled cotton is primarily used in sweatshirts, lifestyle T-shirts, and casual clothing. For intensive sporting use, its properties are inferior to rPET — higher water absorption, slower drying, lower tensile strength.

What GRS certifies — and what it means in practice

The Global Recycled Standard (GRS) is a verification standard administered by Textile Exchange. It certifies the recycled content in products and production conditions — social and environmental protections throughout the supply chain. GRS is the most commonly cited certification in the context of rPET, but its scope and limitations are worth understanding precisely.

Recycled content thresholds

GRS threshold	What it certifies	What may appear on the label
≥ 20% recycled	Minimum threshold for product certification	State % content with certificate number
≥ 50% recycled	Product may be described as "made from recycled content"	Quantitative claim + GRS logo
≥ 95% recycled	Product may be described as "made from recycled materials"	Full claim + GRS logo

Pre-consumer vs post-consumer waste

GRS distinguishes two types of waste and treats them hierarchically. Post-consumer waste (e.g. PET bottles from consumers, used clothing) is rated more highly because it represents genuine diversion of material from the waste stream. Pre-consumer waste (production off-cuts, substandard batches) also qualifies for certification but carries lower environmental value. A GRS certificate does not state the proportion of each type — it is worth asking your supplier for details if you are communicating directly with end customers.

Chain of custody is the key element of GRS certification. Every entity in the chain — from the recycler, through the spinning mill, weaving mill, and dye house, to the garment manufacturer — must be independently certified by an accredited certification body (e.g. Control Union, Bureau Veritas, IDFL). A break in this chain invalidates the claim.

How to verify that your supplier's rPET is genuine

Greenwashing at the fabric level is a real problem. Some suppliers declare rPET without formal certification, relying on their own assurances or internal documents. Here is a practical verification checklist.

Red flags

• The supplier claims to "use rPET" but has no GRS certificate and cannot provide a certificate number.
• The certificate covers a different company or a different product category from what you are purchasing.
• No Transaction Certificate for the specific transaction — a scope certificate alone is not sufficient to confirm that this particular batch is rPET.
• Material price identical to virgin polyester — quality rPET typically costs slightly more (though the gap is narrowing) due to higher processing costs.
• Declared % rPET with no indication of whether it is pre- or post-consumer, and without a certificate.

EU Green Claims Directive 2024

The EU Directive on Green Claims (GCD), adopted in 2024 and being phased in through to 2026, fundamentally changes the rules governing environmental communications in the European market. For clothing brands, this means concrete restrictions on how rPET products may be described.

The Directive prohibits generic, unsubstantiated environmental claims. It is no longer permissible to write "eco", "green", "sustainable", "environmentally friendly", "natural", or "responsible" without specific, documented justification based on recognised scientific methodologies.

What this means in practice for rPET:

• The phrase "made from recycled plastic bottles" is permitted if it can be documented with GRS certification or equivalent.
• The phrase "sustainable collection" without further substantiation is not permitted.
• Claims about a "reduced environmental impact" require a Life Cycle Assessment (LCA) or another recognised comparative methodology.
• Labels and claims must be verifiable by an independent, accredited body prior to publication — not only after a complaint is received.

How to use rPET in brand communications

Below is a concrete overview of what is permissible and what risks being classified as greenwashing under the GCD.

The principle is straightforward: the more specific and documented the claim, the safer it is. A GRS certificate with a number, a Transaction Certificate for the batch, and an LCA analysis — these are the pillars of communications that will withstand both regulatory scrutiny and the demands of an informed B2B buyer.

rPET limitations: microplastics and end-of-life recycling

Microplastics

This is rPET's most significant current limitation — and honest brands should address it openly. Every wash of polyester clothing, whether made from rPET or virgin polyester, releases hundreds of thousands of synthetic microfibres into wastewater. A proportion of these pass through sewage treatment plants and enter the aquatic environment.

Research by the Fraunhofer Institute and the University of Plymouth indicates that polyester fleeces can shed between 100,000 and 700,000 microfibres per wash. rPET does not improve this situation — it merely changes the origin of the polymer, not the emission problem during use.

The problem of recycling garments themselves

The rPET paradox: a jacket or leggings made from rPET are very difficult or impossible to mechanically recycle at end of life. The reasons are:

• Fibre blends — most sportswear knits combine rPET with elastane (5–25%). Separating these fibres mechanically is not economically viable.
• Finishes and coatings — DWR (durable water repellent) treatments, anti-odour coatings, and laminates all disrupt the recycling process.
• Labels, zips, prints — every additional component complicates the recycling stream.
• Fibre degradation — every cycle of mechanical recycling shortens polymer chains, limiting the number of possible cycles.

This means rPET solves the problem of one waste stream (PET bottles), whilst itself becoming a difficult-to-process waste material. This is not an argument against using rPET — it is an argument for developing chemical recycling (see the future section) and for designing products with end of life in mind.

Does rPET make sense for your brand: a 5-step decision tree

Before deciding to switch to rPET, it is worth working through a few key questions. The decision tree below is not a simple pros-and-cons list — it highlights specific contexts in which rPET is a better or worse choice.

The future: chemical recycling and fibre-to-fibre

Mechanical recycling of PET — as described at the beginning of this article — is today's mainstream. But the industry is working intensively on methods that address its biggest limitations: polymer degradation and the inability to process fibre blends.

Chemical recycling

In chemical recycling, the polymer is broken down to the level of monomers or oligomers and then repolymerised. The result is a raw material identical to virgin PET or nylon — with no polymer chain degradation. This means a product can pass through the process repeatedly without any loss of quality.

The main chemical depolymerisation methods for PET are: glycolysis (breakdown with ethylene glycol), hydrolysis (breakdown with water under high pressure), and methanolysis. Companies such as Carbios (France), Loop Industries (Canada), and Eastman (USA) have operational demonstration plants. Scaling to industrial levels is still ongoing — by 2030, the capacity of chemical PET recycling is expected to multiply, though it will still fall short of mechanical recycling volumes.

Fibre-to-fibre recycling

Fibre-to-fibre (F2F) recycling takes old textiles — including blends — and converts them directly into new fibres. This addresses the end-of-life problem described above. Projects such as Syre (Sweden) and Worn Again Technologies (UK) are working on chemically separating polyester–cotton blends, recovering both fractions independently.

F2F matters because today the only realistic "recycling" of used polyester garments is downcycling — conversion into building insulation, floor matting, or padding fillers. F2F would close the loop: a T-shirt from an old T-shirt, leggings from old leggings.

Where we are now

In 2026, mechanically recycled rPET from PET bottles is a mature, accessible, and certifiable option. Chemical recycling and fibre-to-fibre are technologically ready but not yet commercially scalable for mass garment production. That will change within 3–5 years. Brands that are building processes and supplier relationships around recycled materials today will be better placed to transition to these new streams — and to meet the tightening EU regulatory requirements under the Sustainable Products Regulation.

rPET is not the end of the story — it is the current sentence. Honest brands communicate where they are now, and in which direction they are heading.