Polyamide — nylon — is the engineering polymer most commonly traded as surplus, and the one where a vague description costs the most money. "Nylon regrind" could be unfilled natural PA6 worth one thing and 30 per cent glass-filled black PA66 worth quite another. Three variables carry the specification: which polyamide, how much filler, and what viscosity. This is a plain-English reference for buying and selling nylon in any condition.
What is the difference between PA6 and PA66?
They are different polymers with genuinely different behaviour, not grades of one material:
- PA6 (polyamide 6) — melts around 220°C. Tougher, easier to process, better surface finish, absorbs more moisture, and cheaper to buy. Widely used in film, fibre, and general engineering mouldings.
- PA66 (polyamide 66) — melts around 260°C. Stiffer, harder, better creep and heat resistance, more demanding to process. Automotive under-bonnet parts, electrical connectors, gears. Historically priced above PA6.
PA66 supply has a specific fragility worth knowing: it depends on adiponitrile, which is made at a small number of plants worldwide, so an outage at one of them can move the PA66 price sharply while PA6 barely reacts. If you are quoted a nylon price that seems out of line with the market, establishing which polyamide is being discussed often explains it.
How does glass fill change the material?
Most engineering nylon in circulation is filled. The convention GF30 means 30 per cent glass fibre by weight; GF15, GF35 and GF50 are also common, along with mineral-filled and impact-modified compounds. Glass raises stiffness, strength, dimensional stability and heat distortion temperature substantially, and reduces toughness and surface finish.
Commercially, filler content is not a detail — it is the product. Unfilled natural PA6 and GF30 black PA6 sell to different buyers at different prices, and a load described only as "PA6 regrind" cannot be valued. Glass content is measurable by ash test, which is the usual way a dispute is settled. Note also that glass fibre length degrades each time filled nylon is reprocessed, so filled regrind performs below virgin at the same nominal fill.
What else belongs on a nylon offer?
- Viscosity — relative or solution viscosity, or viscosity number. It stands in for molecular weight and indicates whether the material suits extrusion, moulding or fibre.
- Colour — natural, black, or mixed. Natural commands a premium because it can be coloured downstream.
- Moisture — polyamide is strongly hygroscopic and will absorb water from the air. It must be dried before processing, and moisture in an as-received lot is both a weight and a quality question.
- Heat stabilisation and additive package, particularly for automotive and electrical grades.
- Source stream for recycled material — post-industrial regrind, automotive parts, carpet fibre, or reclaimed fishing net, each with a different consistency and a different buyer.
What drives the price of nylon?
- Which polyamide — PA66 typically above PA6, and the gap widens on feedstock disruption.
- Glass or mineral content, and whether it is declared and verifiable.
- Colour — natural above black above mixed.
- Condition and reprocessing history, since fibre length and viscosity both fall with each heat cycle.
- Moisture content and how the material has been stored and packed.
- Source consistency — single-source post-industrial regrind above mixed post-consumer.
- Quantity, location and incoterm.
These move independently, so no fixed list holds for long. Nylon is best priced against live offers of the same polyamide, fill level and colour.
How does Prime Polymers handle nylon?
Nylon listings state the polyamide type, grade, condition, colour, quantity, location, incoterm and the seller's own asking price per tonne, and sellers can attach a datasheet or certificate of analysis so fill level and viscosity travel with the offer rather than being asked for later. Prices are shown exactly as sellers enter them — never computed, adjusted or benchmarked by us. Browsing is free and open without an account. If nothing on the board fits, a Wanted post puts your specification in front of sellers. Prime Polymers is operated by ARC Polymers Ltd, a UK polymer trading company.
Frequently asked questions
- Which is better, PA6 or PA66?
- Neither, in general — they suit different jobs. PA66 melts around 260°C and is stiffer with better creep and heat resistance, favouring under-bonnet and electrical parts. PA6 melts around 220°C, is tougher and easier to process with a better surface finish, and costs less. The right one depends on the application.
- What does GF30 mean on a nylon grade?
- Thirty per cent glass fibre by weight. Glass raises stiffness, strength and heat distortion temperature and reduces toughness and surface finish. GF15, GF35 and GF50 are also common. Fill level is measurable by ash test and should always be declared, because it changes the material's value substantially.
- Why does moisture matter in nylon?
- Polyamide is strongly hygroscopic and absorbs water from the air. It must be dried before processing or it will degrade and give poor parts. Moisture in an as-received lot is therefore both a quality issue and a weight issue, and storage and packing are fair questions to ask.
- Is recycled glass-filled nylon as good as virgin?
- Not at the same nominal fill. Glass fibre length shortens each time the material is reprocessed, so mechanical performance falls even when the ash content is identical. Good recycled filled nylon is still very usable — it just needs to be specified and priced as what it is.
- How can I see what nylon is trading at?
- Compare live offers of the same polyamide, fill level and colour rather than a dated figure. On Prime Polymers each nylon listing shows the seller's asking price per tonne next to grade, condition, quantity, location and incoterm. If nothing matches, post a Wanted requirement and let sellers come to you.