How to Read an rPET Flake COA: IV, Moisture, PVC & Contamination

Q: What is a good intrinsic viscosity (IV) for rPET flakes?

Recycled PET flake IV commonly sits around 0.70–0.80 dL/g. Low IV makes PET brittle and prone to fines; very high IV raises melt viscosity and can disturb moulding or spinning. Match the IV to your application.

Q: How much moisture should rPET flakes have?

Moisture is typically specified below 1.0%, and cleaner grades target well under that. Even trace moisture can lower IV during melting, so low moisture matters.

Q: Why is PVC contamination important in rPET?

PVC degrades PET during melt processing, causing discolouration and defects, so it is tightly limited — often single-digit to low-tens of ppm. It's one of the most important numbers on a PET flake COA.

Key takeaways

A TDS is the target spec; a COA is the actual measured result for the lot you're buying.
IV drives processability — recycled PET flake IV is commonly around 0.70–0.80 dL/g.
Moisture is usually specified below 1.0%; even trace water lowers IV in the melt.
PVC is the villain: it degrades PET, so it's held to very low ppm.
Always ask for a per-lot COA — not a one-time certificate.

What is the difference between a TDS and a COA?

A Technical Data Sheet (TDS) states the target specification for a grade — the range a supplier commits to. A Certificate of Analysis (COA) reports the actual measured values for one production lot. Reputable rPET suppliers issue a COA with every shipment so you can confirm the material matches what you ordered.

What do the key COA parameters mean?

Intrinsic viscosity (IV)

IV is a measure of PET's molecular weight and, in practice, how it will process. A typical recycled PET IV is around 0.67–0.80 dL/g. If IV is too low, PET becomes brittle and creates more fines when granulated; if it's too high, the melt viscosity can interfere with moulding or spinning. Match IV to your process rather than assuming "higher is better."

Moisture

Post-consumer PET flake moisture is generally specified below 1.0%, and cleaner grades target well under that. Moisture matters because PET is hygroscopic — even small amounts of water can break polymer chains at melt temperature, cutting IV and mechanical properties. Lower moisture means less pre-drying for you.

PVC and foreign-polymer contamination

PVC is the single most damaging contaminant in PET recycling: it degrades and discolours PET during melting. Specifications hold it very low — often single-digit to low-tens of ppm. PP/PE (from caps) is also limited because it doesn't melt with PET.

Total contamination, metal, glass and specks

Cleaner grades also report floatable/label content, metal, glass and black-speck counts. Indicative "good" targets seen in industry specs include floatables under ~15 ppm, metal under ~10 ppm and black-speck particles in the low tens of ppm — but always use the numbers on your supplier's TDS/COA.

What does a typical rPET flake COA look like?

Below are general industry-typical ranges for context only — not a specific product spec. Ask your supplier for their actual TDS and per-lot COA.

Parameter	Typical range (context only)
Intrinsic viscosity (IV)	~0.70–0.80 dL/g
Moisture	< 1.0%
PVC	Very low ppm (≈ <5–50 ppm)
Total contamination	Low tens of ppm

What should buyers ask for?

A TDS per grade and a COA per lot — not a single annual certificate.
The test methods used (e.g., ASTM references) so results are comparable.
A sample to run on your line before committing to volume.

Frequently asked questions

What is a good intrinsic viscosity (IV) for rPET flakes?