Additives for Nylon (Polyamide): PA6, PA66 and High-Temperature PAs, 17 Families and Their Dosages

Additives for nylon fall into 17 families, and the one that defines polyamide formulation is the copper halide heat stabilizer: 0.001 to 0.03 wt% of dissolved copper with 0.1 to 5 wt% of an iodide or bromide keeps PA6 and PA66 usable for thousands of hours at 150 °C and above. Everything else in a nylon compound answers one of four weaknesses of the polyamide chain, so which additive answers which?

This guide covers additives compounded into polyamide resin before moulding or extrusion, not bonding additives or finishes applied to nylon fabric or webbing. Polyamide, the resin family the trade calls nylon, spans two large-volume grades, nylon 6 (PA6) and nylon 66 (PA66), plus a smaller group of high-temperature polyamides, and all of them draw on the same 43 families of plastic additives that serve every polymer, of which 17 are relevant to polyamide.

A nylon compound answers its four structural weaknesses with a matched set of jobs: it survives long-term heat with a copper halide, phenolic amide or polyhydric alcohol antioxidant system, it carries load with glass fibre bonded through an aminosilane coupling agent, it passes fire and electrical tests with a phosphinate or melamine salt flame retardant, it gains toughness and shorter cycles from impact modifiers and nucleating agents, and it meets limits that United States and European Union law write specifically for nylon. The same logic, matching additive family to polymer weakness, runs through every one of the additives by polymer guides on this site.

Levels are wt% of the finished compound unless stated; each figure is sourced in the family table below.

Why Nylon Needs Additives: Four Weaknesses of the Polyamide Chain#

Polyamides need additives for 4 reasons: the chain oxidises at the carbon next to the amide group, it hydrolyses in an equilibrium with water, it takes up moisture that changes both dimensions and stiffness, and it is processed 20 to 100 °C above its melting point. All four weaknesses trace back to the amide linkage that gives polyamide its name, and the general mechanisms behind them are set out under polymer degradation. The sections below cover each weakness and the processing consequence that follows from it.

Thermo-oxidation at the amide carbon#

The weak point of a polyamide is the methylene carbon next to the amide nitrogen, where oxygen abstracts hydrogen and starts the radical chain that yellows and embrittles PA6 and PA66 at service temperatures of 120 to 200 °C. DuPont's original copper stabilizer package targeted this same site: copper acetate with potassium iodide and phosphorous acid in PA66 gave about 2,000 hours of heat stability at 150 °C in air, the benchmark that still frames how the industry reports heat ageing. Our source library holds no unstabilized service lifetime at these temperatures, since every heat-ageing figure on this page describes a stabilized compound.

Water uptake and hydrolysis#

Polyamide chains are in equilibrium with water: the amide bond hydrolyses and re-forms, so wet granulate loses molecular weight in the extruder rather than in service. Compounders counter this in three ways: drying the granulate before melt processing, adding carbodiimides that react with the carboxylic acid end groups hydrolysis creates, and adding chain extenders that rebuild lost molecular weight. Moisture uptake in service also changes dimensions and lowers stiffness, but our source library holds no verified saturation percentage for PA6 or PA66, so this guide describes the effect without a number.

Light and weathering#

Sunlight attacks polyamide through the same radical route as heat, which is why the light stabilizers used in PA are chosen for one extra property: they must not fight the copper in the heat stabilizer. Ultraviolet radiation generates the same alkyl and peroxy radicals that thermo-oxidation produces at the amide carbon, so a light stabilizer that reacts with or precipitates the dissolved copper undoes the heat-stabilization package at the same time. That compatibility requirement narrows the polyamide light-stabilizer shortlist to a small number of chemical classes, covered later under colour, light and surface additives.

A processing window at 240 to 320 °C#

PA6 melts at 215 to 218 °C and PA66 at 264 °C, and both are compounded and moulded at roughly 240 to 320 °C, which excludes any additive that decomposes or volatilises below about 300 °C. That processing band rules out aluminium trihydroxide, which begins releasing water from about 200 °C, most ammonium polyphosphate flame retardant grades, and low-molecular-weight phenolic antioxidants. The narrow gap between melting point and processing temperature, 20 to just over 100 °C depending on grade, is itself one of the four weaknesses the additive package answers, and it is the direct answer to why an unmodified polyamide part performs poorly in service.

The Nylon Additive Package: 17 Families and Typical Dosages#

A nylon compound draws on 17 of the 43 additive families: antioxidants, reinforcing fibres, coupling agents, flame retardants, impact modifiers, nucleating agents, lubricants, mould release agents, colorants, UV stabilizers, chain extenders, mineral fillers, laser marking additives, processing aids, antistatic agents, tribological additives and plasticizers.

The package is additive, not alternative: a single automotive PA66 GF30 grade can carry eight of these seventeen families at once, and matching the right combination to a grade follows the same logic set out under how to select plastic additives. Every example substance named in the table above has its own record with CAS number, dosage and regulatory status in the plastic additives database.

Heat Stabilizers for Nylon: Copper Halide, Phenolic and Polyol Systems#

Polyamides are heat-stabilized in 3 ways: a copper salt with a halide, a phenolic amide antioxidant, or a polyhydric alcohol, and the service temperature plus the electrical requirement decides which. In polyamide the industry term "heat stabilizer" covers this entire long-term thermal-oxidative package, unlike in PVC, where the same term means a hydrogen-chloride scavenger working against a different mechanism; the full comparison lives on the dedicated heat stabilizers for nylon page. The three systems are not always alternatives: an under-hood PA66 grade rated above 200 °C often runs a copper halide together with a polyol.

How copper halide stabilizers work#

A copper halide stabilizer works as a redox shuttle: Cu(I) and Cu(II) alternate as they decompose the hydroperoxides that form on the polyamide chain, and the iodide or bromide keeps regenerating Cu(I) so the copper stays dissolved instead of plating out. The window comes from DuPont's original polyamide stabilization patent, US 2,705,227, filed on 15 March 1954, which specifies 0.001 to 0.03 wt% of dissolved copper (preferred range 0.005 to 0.01 %) together with 0.1 to 5 wt% of a halide (preferred range 1 to 2 %) and optionally 0.1 to 1 % of a phosphorus compound. Copper(I) iodide, identified under CAS 7681-65-4 (the EU list uses CAS 1335-23-5) and EC 231-674-6, is the reference salt for this chemistry, and suppliers rate copper halide systems for continuous service up to about 180 °C.

The same chemistry also creates four main drawbacks: discolouration as the copper complex forms, metallic plate-out on tooling, halide migration to the part surface, and corrosion that can cause electrical failure in connectors. Compounders accept the discolouration and plate-out risk in structural and under-hood parts, and switch to the copper-free systems covered below wherever a part sits in a circuit.

Phenolic amide antioxidants in polyamide#

The phenolic antioxidant written for polyamide is an amide rather than an ester: Irganox 1098 carries two hindered phenols on a hexamethylene diamide backbone, which keeps it compatible with the amide matrix at 0.05 to 1.0 wt%, typically 0.05 to 0.2 wt%. Irganox 1098, CAS 23128-74-7, is listed in the European Union as FCM 631 with a specific migration limit of 45 mg/kg, and the United States permits it under 21 CFR 178.2010 at up to 1 % in nylon, 0.75 % in nylon 12 and 0.6 % in polyester coatings and gaskets. In a PA56T glass-filled study aged at 150 °C, Irganox 1098 and the phosphonite co-stabilizer S-9228 slowed the rate of ageing but did not change its pathway, and the yellowing that followed came from carbonyl formation rather than from the copper chemistry described above.

A related phosphonite, P-EPQ, appears in the ECHA plastic additives mapping at 0.1 to 0.25 % in polyamide, listed as FCM 760 with a specific migration limit of 18 mg/kg; it works alongside a phenolic antioxidant rather than replacing it, in the same role that phenolic antioxidants play as primary radical scavengers elsewhere. Phenolic amide systems suit parts where colour matters more than the last years of thermal life, since they avoid copper discolouration entirely.

Polyhydric alcohols for 210 to 230 °C#

Above about 200 °C a copper system alone is not enough, and the route used in ultra-high-heat grades is a polyhydric alcohol: 3 wt% of dipentaerythritol added to a PA66 GF30 that already contains 0.3 % copper stabilizer held 99.1 % of tensile strength after 500 hours at 210 °C, against 78.2 % for the copper-only control. This chemistry comes from DuPont patent application US 2010/0029819 A1 (priority date 30 July 2008), which claims pentaerythritol, dipentaerythritol and tripentaerythritol at 0.25 to 15 wt%, preferably 0.25 to 8 wt%, and covers PA66/6T, PA6T/DT and PA6T/66 alongside PA6 and PA66.

The patent's own tensile-retention data at 210 °C show the trade-off between loading and ageing time:

• 3 % dipentaerythritol with 0.3 % copper stabilizer in PA66 GF30: 99.1 % retention after 500 hours, 94.8 % after 1,000 hours.
• 1.5 % dipentaerythritol in the same base formulation: 89.3 % retention after 500 hours.
• Copper-only control, no dipentaerythritol: 78.2 % retention after 500 hours.
• 3 % dipentaerythritol in PA6 (no glass): more than 100 % retention after 1,000 hours, against about 52 % for the copper-only control.

Dipentaerythritol is the polyol named across these examples, and our source library carries no verified brand mapping for a commercial grade built on this technology, so none is stated here.

Copper-free and halogen-free systems for electrical parts#

In connectors and control units the copper itself becomes the problem, because migrating halide corrodes contacts and plated-out copper lowers tracking resistance, so compounders move to copper complexes or to metal-free stabilizers. The figures below are Brüggemann's own supplier claims, stated with their test condition rather than as measured facts. Brüggemann markets copper complexes for natural, undiscoloured colour (H3386/H3387, H3350/H3351) and grades rated to a comparative tracking index of 600 V for electrical and electronic parts (H3376/H3377). Its halogen- and metal-free TP-H2062 and TP-H2217 are claimed to hold more than 50 % tensile retention after 2,500 hours at 150 °C, while the copper-containing TP-H1804 is claimed at more than 5,000 hours at 190 °C in PA66 GF30, and TP-H1805 at more than 50 % after 3,000 hours at 200 °C, rated to 230 °C for PA66. This route serves parts rated for additives for electrical and electronics, trading some heat performance for freedom from migration-driven tracking failure.

Glass Fibre and Mineral Reinforcement in Nylon#

Glass fibre is the single largest additive in a nylon compound by weight: flame-retarded polyamides typically carry 10 to 50 % of it, and reinforced grades are named after that number, as in PA66 GF30. Reinforcement brings four additive consequences with it: copper stabilizers become the default choice in automotive glass-filled PA because the parts already run hot, the glass itself nucleates crystallization so talc matters less than in unfilled grades, black grades lean on nigrosine or carbon black to cover the visible fibre pattern, and any flame retardant has to defeat the wick effect, where fibres draw molten polymer toward the flame front. The general mechanics of glass fiber reinforced plastics apply to polyamide as to every reinforced thermoplastic, with the amide-specific detail in the aminosilane interface below.

Reinforcement is not limited to continuous glass. Nylon 6 with 4.7 wt% montmorillonite nanoclay reaches a heat deflection temperature of 152 °C, 87 °C above neat PA6, in the work of Kojima and co-workers, published in 1993 in the Journal of Materials Research. Grade-by-grade mechanical properties of glass-filled nylon belong to the dedicated glass-filled nylon page; nanoclay and mineral-filled grades have their own coverage under mineral fillers for nylon.

Aminosilane sizing and the fibre to polyamide interface#

Glass does not bond to polyamide on its own: the fibre arrives sized with an aminosilane whose amine end is chosen to match the amide chemistry of the matrix, and the strength of that interphase decides how much of the fibre's stiffness reaches the part. The general chemistry of silane coupling agents covers how the silane's other end anchors into the glass surface while the amine end reacts with the polyamide during compounding. Our source library holds no sourced sizing level specific to polyamide glass, so this page gives the mechanism without a percentage.

Flame Retardants for Nylon: Phosphinates, Melamine Salts and Legacy Systems#

Nylon is flame-retarded in 2 ways, and the split follows the glass: unfilled PA6 and PA66 can reach UL 94 V-0 on a melamine salt alone, while glass-filled grades need a phosphinate with a nitrogen synergist because the fibres act as a candle wick. Neat PA6 has a limiting oxygen index of 21.0 vol% oxygen, barely above the 21 vol% oxygen content of air, so both branches start from a polymer that offers almost no inherent fire resistance. The full comparison of phosphinate, melamine and legacy systems, including formulations this page does not cover, sits on the dedicated flame retardants for nylon page.

Glass-filled PA: aluminium diethylphosphinate plus a nitrogen synergist#

The standard halogen-free system for glass-filled polyamide is aluminium diethylphosphinate with a nitrogen synergist, and Clariant rates Exolit OP 1312 at 15 to 20 wt% in PA6 and PA66 glass-fibre compounds for UL 94 V-0 from 0.4 to 3.2 mm, according to its 2019 Exolit brochure, which also reports GWIT of 775 °C, GWFI of 960 °C, a comparative tracking index of 600 V, and EN 45545-2 hazard level R22 HL3 for rail interior parts. OP 1312, OP 1314 and OP 1400 are all aluminium diethylphosphinate blended with a nitrogen synergist, with OP 1400 formulated for hot, humid service; Clariant's own hazard information classifies OP 1312 and OP 1314 for reproductive toxicity and long-term aquatic hazard, a classification stated here from the brochure rather than generalised to the whole phosphinate class.

Semi-aromatic PA and PA46 use Exolit OP 1230, which Clariant reports at V-0 from 0.4 to 3.2 mm and passing JEDEC J-STD-020C moisture sensitivity level 2 with a 260 °C reflow peak; about 15 wt% is recorded for V-0 at 1.6 and 0.8 mm in PA6T/66. Fire performance always carries its test thickness. Published research corroborates the phosphinate route at other loadings: a glass-filled PA6 with 25 % glass reached V-0, an LOI of 32 % and a peak heat release rate of 103 kW/m2 with a 20 wt% system of expandable graphite, aluminium diethylphosphinate, melamine polyphosphate and montmorillonite, while a PA6 with 15 wt% of an ADP system (12 % ADP with a 3 % P/N/Zn synergist) reached an LOI of 30.7 % and V-0 at 3.2 mm, cutting peak heat release from 787.3 to 362.4 kW/m2 while CTI fell from 600 to 550 V. AlPi/MPP systems in PA66 can bloom to a white surface frost after ageing at 85 °C and 85 % relative humidity.

Unfilled PA: melamine cyanurate#

In unfilled PA6 and PA66, melamine cyanurate reaches UL 94 V-0 on its own: it decomposes endothermically above about 300 °C, releases inert gas and thins the melt so burning material drips away from the flame front. Melamine cyanurate, CAS 37640-57-6 and EC 253-575-7, is the nitrogen flame retardant of choice for unfilled polyamide electrical parts and connectors, sold as Melapur MC by BASF and as Melagard MC15, MC25 and MC50 by Italmatch; it is not a substance of very high concern. Our source library holds no verified loading figure for the V-0 result described above, so this page states that melamine cyanurate is the sole additive needed for that result, and that the loading depends on the specific PA grade, without stating a number.

Two legacy routes still appear where melamine cyanurate is not used: red phosphorus flame retardant, effective but limited by its dark colour and a risk of phosphine release, and brominated polystyrene combined with antimony trioxide as the synergist. Both predate the halogen-free systems described above and now serve mainly applications where colour and the halogen-free requirement are not decisive.

Fire and electrical targets a nylon part has to pass#

A nylon part in an appliance or a connector usually has to clear four separate tests: UL 94 for flammability, GWFI and GWIT for glow wire, CTI for tracking, and in rail applications EN 45545-2.

Toughening, Nucleation and Lubrication of Polyamide#

Three families decide whether a polyamide part survives a drop test and whether the mould can be opened on time: impact modifiers, nucleating agents and lubricants.

Impact modifiers: maleated elastomers and the 0.3 micrometre rule#

Toughening a polyamide is a geometry problem before it is a chemistry problem: Souheng Wu showed for PA66 and rubber blends that the blend turns tough once the ligament between rubber particles falls below a critical interparticle distance of 0.3 micrometres, whatever the particle size or rubber content, in research published in 1985. Reactive maleic-anhydride-grafted polyolefin elastomer and EPDM grades are the standard route to that ligament distance in polyamide, and Brüggemann's Compoline CO/PA range is marketed for toughening down to minus 40 °C. Compatibilizer-grade maleated polyolefins produce large gains outside virgin polyamide too: POLYBOND 3150 and 3002 at 5 % loading roughly tripled Izod impact strength in recycled polypropylene and nylon blends, and a PA6/PP/ABS blend compatibilized with 10 wt% of a maleated, styrene-grafted polyolefin elastomer plus 10 wt% of a similarly grafted SEBS raised impact strength by 823 %. Comparative grade performance sits under the dedicated impact modifiers for nylon coverage.

Nucleating agents and cycle time#

A nucleating agent shortens the injection-moulding cycle by giving the polyamide more crystal nuclei, so the part solidifies sooner and can be ejected earlier. BRUGGOLEN P22 is Brüggemann's nucleating agent sold specifically for injection-moulding cycle-time reduction in polyamide, distinct from the polyester-grade P252 in the same product family. Glass fibre itself nucleates polyamide as it cools, which is why talc matters less in reinforced grades than in unfilled ones, and nigrosine, covered later under colour additives, slows the crystallization rate of PA66 rather than speeding it. Our source library holds no verified dosage figure for a polyamide nucleant, so neither the nucleating agents for nylon coverage nor the general talc in plastics coverage states a loading level here.

Lubricants, mould release and die drool#

Polyamide compounds build deposits at the die and on the mould, and the additives that stop this are the lubricants and mould release agents, dosed low enough not to disturb the fibre to matrix bond. Struktol TR 063A, a process additive purpose-built for polyamide, is dosed at 0.2 to 2.0 % to reduce die bearding and drool at the die face. Montan esters, ethylene bis stearamide (EBS) and metal stearates are the general lubricant classes used in polyamide compounding, matched in Brüggemann's branded range by P14 and P130 as lubricants and by P1507, P1810 and P2201 as flow improvers for flame-retardant grades; montan wax is the raw material behind the ester-based systems.

Colour, Light and Surface Additives for Nylon#

The last three families give a nylon part its finish: colorants, UV and light stabilizers, and the surface additives that control marking, static and friction.

Nigrosine and carbon black in PA66#

Glass-filled PA66 is coloured black in two competing ways: nigrosine, an aniline black dye that covers the fibre and leaves a high-gloss surface, or carbon black, which also screens ultraviolet light. Nigrosine, listed by CAS 8005-02-5 and carried in the ECHA inventory under both "Nigrosine Base" (616-851-1) and "Solvent Black 7" (934-134-4), decreases the crystallization rate of PA66 and can cause discolouration, which is the same crystallization effect that makes it a slower-nucleating alternative to the fibre-driven nucleation described above. Its REACH tonnage band and food-contact status are not established in our source library, so this page states only its function and its effect on crystallization, and readers who need its regulatory status should consult the nigrosine (Solvent Black 7) record directly. Carbon black in plastics is the alternative black pigment and doubles as an ultraviolet screen where nigrosine's dye chemistry is not wanted.

UV and light stabilizers that tolerate copper#

A light stabilizer for polyamide has one extra requirement: it must not react with the copper in the heat stabilizer, which is why oxanilide UV absorbers and one piperidyl isophthalamide HALS dominate the PA light-stabilizer shortlist. Oxanilides are the UV absorber class typical for polyamides and polyurethanes, and the supplier of oxanilide UV-312 states that it does not interact with copper-based PA heat stabilizers, the compatibility property that matters more here than absorption strength alone. The one hindered amine light stabilizer listed for polyamide food-contact use in the European Union is N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)isophthalamide, CAS 42774-15-2, listed as FCM 1051 with a specific migration limit of 5 mg/kg and classified under the harmonised CLP entry 616-129-00-6 as Acute Tox. 4* (H302) and Eye Irrit. 2 (H319); it is sold under the trade name Nylostab S-EED. UV stabilizers for nylon covers the selection process across both chemistries, and the general mechanism of hindered amine light stabilizers (HALS) applies to the piperidyl isophthalamide grade as it does elsewhere.

Laser marking, antistatic and tribological additives#

The last three families are surface families: laser marking additives that let a moulded connector be coded without ink, antistatic agents that lower surface resistivity, and tribological additives that cut friction in polyamide gears and bearings. Anti-drip PTFE, usually SAN-encapsulated, is used at 0.1 to 0.5 wt% in polycarbonate, PC/ABS, PBT and PA, where it forms a fibrillar network that stops flaming drips and is often the difference between a V-2 and a V-0 rating. Tribological additives for polyamide and POM gears and bearings are PTFE, silicone, molybdenum disulfide and graphite, and PTFE itself falls within the scope of the pending, not-yet-adopted EU universal PFAS in plastics restriction, a status this page describes as pending rather than as a ban.

Additive Packages by Nylon Grade and Application#

The same 17 families give very different packages: an under-hood PA66 GF30 is built around copper and glass, a connector is built around a phosphinate and a copper-free stabilizer, and a high-temperature part is built around a polyol.

This same automotive to electronics range is where the additives for automotive plastics under-hood requirement and the additives for wire and cable compounds connector requirement diverge most sharply from each other, even though both start from the same 17-family package described above.

How Nylon Additives Are Compounded and Dosed#

Additives reach a polyamide in 4 ways: melt compounding on a twin-screw extruder with the glass side-fed downstream, masterbatch let down at the moulding machine, direct dosing of liquids, and, before any of them, drying the granulate. Because polyamide degrades hydrolytically, drying comes before every other step: wet granulate loses molecular weight in the barrel before any additive can work. Glass and mineral fillers are side-fed downstream of the melting zone to protect fibre length.

• Melt compounding on a twin-screw extruder blends heat stabilizer, colorant and process additives at the throat, with glass fibre side-fed downstream.
• Masterbatch let-down carries pigment or a smaller package into the moulding machine at a fixed ratio, using a carrier resin compatible with polyamide, typically EVA or LDPE, or a universal wax carrier.
• Direct dosing of liquids adds a stabilizer or process aid straight into the feed throat or barrel.
• Drying the granulate, always the first step, removes the moisture that would otherwise hydrolyse the polymer.

The general principles of plastic compounding apply to each route, and masterbatch is treated here as a delivery form rather than an eighteenth family, since it carries other families rather than performing a function of its own. Dosage figures on this page are given in wt% of the compound; where a data sheet reports PHR (parts per hundred resin) instead, the two units convert directly.

Limits Written Specifically for Nylon#

Nylon is one of the few polymers that United States food-contact law names directly: 21 CFR 178.2010 sets separate maximum levels for antioxidants and stabilizers in nylon, and 21 CFR 177.1500 lists the nylon resins that may be used at all. The European Union writes its own nylon-specific entries into Regulation (EU) No 10/2011, covering both the substances listed in Annex I and the metal limits set in Annex II. The full set of plastic additive regulations that apply across every polymer forms the background these nylon-specific entries sit inside.

The dossier also records cupric acetate at 0.025 % with lithium iodide at 0.065 %, and potassium bromide with 0.005 % copper as acetate or carbonate, both permitted in nylon 66 under the same rule.

US food contact: 21 CFR 178.2010 and 177.1500#

The United States writes the copper stabilizer limits into the adjuvant rule itself: 21 CFR 178.2010 permits cuprous iodide at up to 0.01 wt% in nylon 66T for oven-baking use at a thickness of 0.001 inch or less, and it permits cuprous iodide with cuprous bromide at 0.0025 % and 0.0175 % respectively in nylon 66. Irganox 1098 is listed alongside these copper entries at up to 1 % in nylon and 0.75 % in nylon 12. 21 CFR 177.1500 lists the nylon resins usable in food-contact articles by designation. Nylon is never described here as "FDA approved"; the correct wording is that a substance is listed in, or permitted up to, a stated level under the FDA food contact rules.

EU food contact: copper, iodide and the polyamide HALS entry#

In the European Union the same copper system is controlled from two directions at once: the iodide falls under group restriction 6 of Regulation (EU) No 10/2011 with a total specific migration limit of 1 mg/kg expressed as iodine, and copper carries its own 5 mg/kg limit in Annex II. Our source library also records related iodide salts on the Union list: potassium iodide as FCM 512, sodium iodide as FCM 513 and lithium iodide as FCM 588, alongside the copper entry. The general frame both entries sit inside is the Union list principle of EU 10/2011, together with an overall migration limit of 10 mg/dm2, the ceiling that governs how much of any listed substance, tracked through additive migration, may pass from a food-contact article into food.

The polyamide light stabilizer named earlier, FCM 1051, carries its own 5 mg/kg specific migration limit under the same regulation. Neither copper(I) iodide nor melamine cyanurate appears on the SVHC Candidate List, the two negative statuses our source library records for the additives that define this page; the Candidate List's total entry count is not stated here.

How the Package Is Tested#

A nylon additive package is judged on 5 measurements: tensile retention after heat ageing, UL 94 rating at a stated thickness, glow-wire and tracking values, heat deflection temperature, and melt flow rate before and after compounding.

• Tensile retention after heat ageing is reported as a percentage after a stated time at a stated temperature, the format behind every Brüggemann and DuPont figure on this page, following oven-ageing practice under ASTM D3012, ISO 188 or UL 746B.
• UL 94 rating is read at a specific sample thickness, since a V-0 result at 3.2 mm does not guarantee V-0 at 0.4 mm.
• Glow-wire and tracking values (GWFI, GWIT and CTI) come from the IEC standards listed in Table T3.
• Heat deflection temperature is measured to ASTM D648 or ISO 75 at 0.455 or 1.82 MPa.
• Melt flow rate before and after compounding, measured to ISO 1133 or ASTM D1238, tracks the viscosity drift that signals hydrolytic or thermal damage, particularly in recycled polyamide.

These five measurements sit inside the broader practice of testing plastic additives, and melt flow rate (MFR) is the fastest to run, which is why compounders check it most often.

Who Supplies Nylon Additives?#

The polyamide additive business is unusually concentrated: one German specialist, Brüggemann in Heilbronn, sets the reference for heat stabilization with its BRUGGOLEN range, while the halogen-free flame retardants come mainly from Clariant, BASF and Italmatch.

Brüggemann acquired Auserpolimeri to extend its polyamide compounding reach, and Clariant announced a capacity expansion for Exolit OP at Daya Bay on 5 June 2026, a signal of demand growth in halogen-free flame retardants for glass-filled polyamide. Our source library carries no market-size figure specific to polyamide additives, so this section describes the structure of the supply base rather than its value; the wider plastic additives market and the ranking of largest plastic additive companies sit on their own dedicated pages. Brand names are given in each company's own capitalisation and without a trademark symbol.

What the Additives in Nylon Mean for Safety, Recycling and End of Life#

None of the additives that define a nylon compound is on the REACH Candidate List, but two of them carry hazard classifications that matter to anyone writing an eco-label or EcoDesign file. Melamine cyanurate and copper(I) iodide are the two substances checked against that list, and the piperidyl isophthalamide HALS carries the Acute Tox. 4* and Eye Irrit. 2 classification described earlier.

Are the additives in nylon harmful?#

The honest answer is that the risk sits in the flame retardant and not in the stabilizer: copper(I) iodide and melamine cyanurate are not substances of very high concern, while Clariant's own brochure classifies Exolit OP 1312 and OP 1314 for reproductive toxicity and long-term aquatic hazard. That classification belongs to those two specific grades and is never generalised here to every phosphinate flame retardant on the market. The EU and US food-contact frame described above is the mechanism that keeps permitted substances within stated migration limits regardless of their broader hazard classification.

Chain extenders and restabilization in recycled polyamide#

Recycled polyamide arrives with the wrong molecular weight in both directions, and the additive answer runs both ways too: chain extenders rebuild degraded PA6 and PA66, while a chain breaker shortens over-long chains from fibre and extrudate scrap. BRUGGOLEN M1251 and M1253 are Brüggemann's linear chain extenders for polyamide, while M1417 is described by the same maker as a chain breaker for upcycling high-viscosity polyamide scrap recovered from extrudate or fibre waste. The molecular-weight loss these additives correct is the same hydrolytic degradation described earlier under water uptake, carried forward from a first processing pass or a first service life into a recycled compound; the wider principles behind it sit under additives for recycled plastics and design for recycling.

Nylon topics this guide does not cover#

This guide covers substances compounded into polyamide resin, so it does not cover how nylon is made: monomers and curing reactants are excluded from the legal definition of an additive, and textile finishing sits outside this reference altogether. Also out of scope are solvents for nylon, 3D-printing filaments based on polyamide, and the consumer health debate about synthetic textiles, none of which involve a substance compounded into the resin before moulding or extrusion. Three neighbouring polymer families carry their own formulation guides: additives for polycarbonate and PC/ABS, additives for PBT, and additives for high-performance polymers, which covers PPS, PEEK, PEI, PSU and LCP. Flexible polyamide grades that use a plasticizer rather than an impact modifier are covered separately under plasticizers for polyamide (nylon).