Additives for Polyethylene (PE): The Complete Formulation Guide to 18 Additive Families

Polyethylene degrades in the opposite direction to polypropylene: instead of losing molecular weight it crosslinks and forms gels, so its additive package is built around a hindered phenol with a phosphite, an acid scavenger for catalyst residues and, in film and pipe, a surface and weathering package on top, across 18 additive families in total. That base package costs a few tenths of a percent, but a greenhouse film, a PE100 pipe compound and a halogen-free cable sheath look nothing alike, so which families does each grade need?

Polyethylene is a family of grades that split apart by density and branching: LDPE at about 0.924 g/cm3, LLDPE between 0.916 and 0.940 g/cm3, and HDPE at about 0.961 g/cm3, alongside the linear low-density, medium-density, ultra-high-molecular-weight and crosslinked (PEX) variants. This guide sits inside the wider reference on plastic additives; the package a formulator builds follows the application more than the density grade.

This guide covers why polyethylene needs additives, the 18 families with dosage in wt% and ppm, nine application formulations, let-down ratios, the processing window, the five confirming tests, the EU and US rules specific to polyethylene, recycled-PE restabilisation, and a seven-step build routine.

Table T1: the polyethylene package at a glance. Levels are the ranges stated family by family in Table T2 below; no single compound carries all 18 families.

Why Polyethylene Needs Additives: Crosslinking, Gels and Catalyst Residues#

Polyethylene needs additives for three reasons: it crosslinks and gels when it is melted, it oxidises slowly in service under heat, sunlight, chlorinated water or copper contact, and almost every end product asks for a property the raw polymer lacks, from a low coefficient of friction to a fire rating. Polyethylene is not plasticised in commercial practice, so despite the related search for polyethylene plasticizers, this guide holds no plasticizer dosage for it; that demand belongs with plastics that actually take a plasticizer.

How polyethylene degrades during processing#

Polyethylene loses melt flow rate when it is over-processed rather than gaining it: the chains recombine and branch instead of splitting, so the first symptom of an under-stabilised compound is a falling MFR and a rising gel count. LDPE already carries branching at about 2% of its carbon atoms from polymerisation, and every extra shear and thermal cycle adds free-radical recombination, the opposite failure mode from polypropylene's chain scission. MFR is read at 190°C with a 2.16 kg load under ISO 1133-1 and ASTM D1238.

The package answer is fixed first: a hindered phenol paired with a phosphite protects the melt, with a phosphonite of the PEPQ type added for gel control in LLDPE, and an acid scavenger, calcium stearate, zinc stearate or hydrotalcite, neutralises the chloride and chromium residues Ziegler-Natta and chromium catalysts leave behind. Untreated, those residues corrode equipment and consume the phenolic antioxidant faster than oxygen alone, which is why polymer degradation is treated as a distinct mechanism here.

How polyethylene degrades in service#

In service polyethylene is attacked from four directions: heat with residual oxygen, ultraviolet light, the disinfectant in potable water, and copper contact in cable insulation. Each direction forces a different family into the compound:

• Heat and residual oxygen slowly oxidise the backbone even without sunlight, which is why every pressure pipe compound carries an OIT of at least 20 minutes at 210°C as a service-life proxy.
• Ultraviolet light breaks C-H bonds at the surface, answered with a hindered amine light stabilizer, a UV absorber, or carbon black in black compounds.
• Chlorinated and chlorine-dioxide-treated water accelerates antioxidant consumption; in one comparison, 4 ppm chlorine dioxide at 90°C consumed it about four times faster than conventional chlorination, so pipe compounds carry a generous OIT margin.
• Copper contact in cable insulation catalyses oxidation faster than heat alone; a metal deactivator such as Irganox MD 1024 is added where the insulation touches the conductor.

What the density grade changes: LDPE, LLDPE, HDPE and mLLDPE#

Density is not cosmetic in a polyethylene formulation: the US food-contact rules, several antioxidant caps and the need for a processing aid all change at a density line, and 21 CFR 177.1520 writes the olefin-polymer specification in terms of density (0.85 to 1.00), n-hexane extractables (at most 5.5% at 50°C) and xylene solubles (at most 11.3% at 25°C), with a 0.3 wt% antioxidant ceiling at 0.94 g/cm3 or above.

• LDPE (about 0.924 g/cm3, roughly 2% branched carbon atoms), least stiff and most film-oriented, needs the lightest antioxidant load.
• LLDPE (0.916 to 0.940 g/cm3), most often blended with LDPE in film, is where a phosphonite is added for gel control.
• HDPE (about 0.961 g/cm3) crosses the line triggering the higher FDA caps and is used in pipe, geomembrane and blow moulding.
• mLLDPE, the metallocene grade, uses fluoropolymer processing aids most, since its narrow distribution is more prone to melt fracture.

The Polyethylene Additive Package: 18 Families and Their Dosage#

The polyethylene additive package has 18 families in 4 groups: stabilizers, surface and film additives, colorants and fillers with their delivery forms, and the structural and functional additives that crosslink, flame-retard, foam, nucleate or compatibilise the polymer. Most property modifiers, reinforcements and optical modifiers, three of the seven functional groups used across plastics generally, play no meaningful role in a standard polyethylene compound and are absent from the table below.

Every value above equals the fact stated in the family sections that follow; see the plastic additives database for the full CAS, EC and regulatory record of each named substance.

Stabilizers for polyethylene (4 families)#

Stabilizers are the families that keep polyethylene from oxidising during extrusion and in service: antioxidants, acid scavengers, metal deactivators and UV stabilizers, and only the first of the four is in every polyethylene compound.

Antioxidants#

Antioxidants are the one family every polyethylene compound carries: a hindered phenol such as Irganox 1010 at 0.05 to 0.4 wt% protects the polymer in service, and a phosphite such as Irgafos 168 at 0.05 to 0.2 wt% protects the melt, blended at a phosphite to phenol ratio between 1:1 and 4:1. Under 21 CFR 178.2010, Irganox 1010 is capped at 0.5 wt% and Irgafos 168 at 0.2% in ethylene polymers, with LDPE films above 0.051 mm limited to 0.062 mg/in2 or FDA conditions E through G; these are legal maxima, not recommended dosages. Vitamin E melt-stabilises PE and PP at 100 to 300 ppm and, in one study, 200 ppm in HDPE retained melt flow index over three passes where 200 ppm of Irganox 1010 did not, though it yellows, so a phosphite is still added for colour. See antioxidants for polyethylene for grade selection.

Acid scavengers#

Acid scavengers neutralise the chloride and chromium residues that Ziegler-Natta and chromium catalysts leave in polyethylene, which would otherwise corrode the die and consume the phenolic antioxidant. Calcium stearate, zinc stearate and hydrotalcite are the three substances used for this job, at levels that supplier guidance puts as high as 1,000 ppm of calcium stearate in a typical polyolefin compound; the choice between them depends on whether the compound also needs an acid scavenger that doubles as an FDA-cleared lubricant.

Metal deactivators#

Metal deactivators are chelating antioxidants that bind the copper ions diffusing from a conductor into the insulation, where they would otherwise catalyse oxidation far faster than heat alone. Irganox MD 1024 (CAS 32687-78-8), a hindered phenol hydrazide, acts as both a primary antioxidant and a copper deactivator in PE and PP cable insulation in direct copper contact; in one study, a PP and recycled-XLPE blend from end-of-life cables retained its mechanical properties over 6,000 hours at 105°C.

UV stabilizers#

UV stabilizers are the second stabilizer family most polyethylene carries outdoors: hindered amine light stabilizers such as Chimassorb 944 run at 0.05 to 1.0 wt% in thick sections and 0.1 to 1.0 wt% in film, with a UV absorber added in unpigmented articles. Cyasorb UV-3346 (EU FCM No 790, SML 5 mg/kg) can exceed that limit from LDPE above 0.3% w/w against fatty food, and the FDA caps it at 0.3 wt% in PE at density 0.94 g/cm3 or above. UV-531 runs at 0.15 to 0.5 wt% in agricultural film above 100 µm and 0.10 to 0.5 wt% in thick sections with a HALS; carbon black is the other route, family 10. See UV stabilizers for polyethylene for grade selection.

Surface and film additives (5 families)#

Surface and film additives are the families that act at the boundary of the polyethylene rather than inside it: slip agents, antiblock additives, polymer processing aids, antistatic agents and antifog additives, and they are the reason a blown film can be unwound, printed and sealed at all.

Slip agents#

Slip agents are fatty acid amides that bloom out of the polyethylene to its surface and drop the coefficient of friction, dosed at 500 to 1,200 ppm in LDPE and LLDPE film. Erucamide blooms slowly and oleamide blooms fast; Ampacet data shows erucamide reaching most of its friction reduction within 24 to 48 hours and its final value only after 7 to 10 days (ASTM D1894 or ISO 8295). In HDPE closures, 15.7 µg/cm2 of erucamide was needed to reduce application torque, against only 1.7 µg/cm2 for behenamide, per Dulal and colleagues, 2017. Erucamide (EU FCM No 271, no SML) is cleared under 21 CFR 178.3860; oleamide (FCM No 335, also no SML) is not. See slip agents for polyethylene film for grade selection.

Antiblock additives#

Antiblock additives are mineral particles that hold two film layers a fraction of a micrometre apart so they do not weld together on the roll, at 2,500 to 10,000 ppm for diatomaceous earth and talc, or 2,500 to 20,000 ppm for calcium carbonate. Ampacet trials show a diatomaceous earth top cut as coarse as 44 µm can be used against a 25 µm film, and its irregular shape works better than rounder calcium carbonate particles, though the mineral is abrasive and its iron content can accelerate degradation if the antioxidant package is not sized to compensate.

Polymer processing aids#

Polymer processing aids remove melt fracture by coating the die wall with an immiscible fluoropolymer that lets the melt slip, at ppm levels delivered from a 2 to 5% masterbatch. The FDA sets a maximum of 0.2 wt% for the 65 to 71% fluorine grade and 1.0 wt% for the grade with at least 87% vinylidene fluoride; the droplets need a conditioning, or time-to-clear, period before coating is established, described by Yang and colleagues, 2025, and in one study by Adesina, 2015, a fluoropolymer PPA did not eliminate stick-slip in HDPE entirely. These grades fall under the proposed EU universal PFAS restriction, and PFAS-free grades already exist. Processing aids for polyethylene, the PE-specific page, publishes later and is named here without a link.

Antistatic agents#

Antistatic agents drain the static charge that untreated polyethylene holds at a surface resistivity of 1e15 to 1e16 ohm, by migrating to the surface and binding a conductive layer of atmospheric moisture. ANSI/ESD S541 classifies a surface as conductive below 1.0e4 ohm, dissipative between 1.0e4 and below 1.0e11 ohm, and insulative above that, while Ampacet's own "antistatic" range sits between 1e9 and 1e13 ohm. FDA limits are set per article, from 0.1 wt% for a C12-C18 amine in food-contact film to 0.2 wt% for a C13-15 amine in HDPE and PP containers above pH 5; ethoxylated amines outperform glycerol monostearate in HDPE, per Ampacet. Antistatic agents for polyethylene, the PE-specific page, publishes later and is named here without a link.

Antifog additives#

Antifog additives spread condensed water into a continuous transparent layer instead of droplets, and polyethylene needs less of them than polypropylene: 0.2 to 0.6% against 0.5 to 2.0% for the same supplier grade family from Palsgaard. Antifog masterbatch is typically let down at 1 to 3%, and in a coextruded LDPE and EVA film, 3 wt% in the EVA layer combined with 1 wt% in the LDPE layer gave a permanency close to 3,000 hours; antifog is listed as an Association of Plastic Recyclers Design Preferred additive for PE film.

Colorants, fillers and delivery forms (4 families)#

Colorants, fillers and their delivery forms are the highest-volume part of a polyethylene formulation: carbon black and pigments, the masterbatch that carries them, mineral fillers, and the coupling agents that bond those fillers to the polymer.

Carbon black and colorants#

Carbon black does two jobs in polyethylene at once, colour and ultraviolet screening, and at 2.0 to 2.5 wt% in a pressure pipe it is the single largest additive in the compound. Grade selection follows exposure time: N550 (40 to 48 nm) is the standard pipe grade, while N330 (26 to 30 nm) or N110 (below 20 nm) are chosen for articles outdoors more than 3 to 5 years. Under EU food-contact rules (Regulation (EU) No 10/2011, FCM No 411) and the drinking-water positive list (entry 0348), carbon black is capped at 2.5% w/w in the polymer, with benzo[a]pyrene at most 0.25 mg/kg and primary particles between 10 and 300 nm.

Masterbatch#

Almost no additive reaches a polyethylene line as a neat powder: it arrives as a masterbatch, a concentrate in a PE carrier the processor lets down at a fixed ratio. A 35% carbon black masterbatch let down at 5 to 6.5% gives about 1.75 to 2.3% carbon black in the compound, and masterbatches above 40% carbon black are avoided because dispersion suffers; coloured pipe masterbatch runs at 2 to 4%. The black masterbatch page covers carrier and let-down mathematics in full.

Fillers#

Fillers are used in polyethylene for a specific effect more often than for cost: a fine ground calcium carbonate is what makes a breathable hygiene film porous once stretched, since the mineral nucleates pores during biaxial stretching. In a study by Radebe and colleagues, 2022, a 60 wt% calcium carbonate masterbatch in LLDPE, with 1.0 wt% zinc stearate and 3 wt% wax, returned melt viscosity to just above the neat polymer. Wood-plastic composites from recycled HDPE, for example 34% resin with 60% sawdust plus a coupling wax, process at least 28°C below the unfilled resin's window and at most about 200°C, since cellulose degrades above that. Fillers for polyethylene, the PE-specific page, publishes later and is named here without a link.

Coupling agents#

Coupling agents give a mineral or wood filler a chemical bond to the polyethylene instead of a mechanical one, which is what turns a filled compound into a composite. Maleated polypropylene is used at 1 to 3 wt% in wood-plastic composites, and maleated polyethylene and silanes serve the same bonding function in mineral-filled polyethylene compounds.

Structural and functional additives (5 families)#

The last five families change what the polyethylene fundamentally is: crosslinking agents turn it into a thermoset, flame retardants give it a fire rating, blowing agents turn it into foam, nucleating agents change how it crystallises, and compatibilizers let it live in a blend.

Crosslinking agents#

Crosslinking agents convert polyethylene from a thermoplastic into a thermoset network, by peroxide, by a grafted silane that cures in water, or by an electron beam. PEX-a, by the Engel process, uses about 2% peroxide (commonly cited) at 200 to 250°C; DIN 16892 minimum crosslinking degrees, 75% PE-Xa, 65% PE-Xb, 60% PE-Xc and PE-Xd, are also commonly cited, while ASTM F876 requires 65 to 89% overall. The XLPE cable hot-set limit is 175% maximum elongation under IEC 60811-507. Dicumyl peroxide (CAS 80-43-3) has been an SVHC since 27 June 2024 (Repr. 1B), and a residue above 0.1% w/w triggers REACH Article 33 and SCIP disclosure; vinyltrimethoxysilane (EU FCM No 453) carries a 0.05 mg/kg SML. See XLPE, crosslinked polyethylene for the three routes compared.

Flame retardants#

Flame-retarding polyethylene is a mineral-loading exercise rather than a chemical one: a halogen-free cable compound carries about 160 parts of alumina trihydrate on 100 parts of resin, roughly 60% of the finished compound. The Huber reference formulation runs EVA 67, LLDPE 17, coupling agents 16, alumina trihydrate 160 and antioxidant 1.0 phr; alumina trihydrate absorbs 1,051 J/g and releases its water of hydration from about 200°C, with magnesium hydroxide substituted where processing runs hotter, and a silane-crosslinked XLPE variant carries 180 phr. The EU Construction Products Regulation sets fire classes under EN 50399, and Regulation (EU) 2024/3110 applies to cables, product family 31, from 8 January 2026. Flame retardants for polyethylene, the PE-specific page, publishes later and is named here without a link.

Blowing agents#

Blowing agents create the cell structure of polyethylene foam, either as a gas injected into the melt or as a solid that decomposes in it and releases gas at the processing temperature. Azodicarbonamide, the chemical route, is limited to at most 5 wt% of the finished foamed polyethylene under 21 CFR 178.3010, and it has been on the EU SVHC Candidate List since 19 December 2012; physical blowing agents are the alternative where that ceiling or the substance itself is a concern.

Nucleating agents#

Nucleating agents are a minority family in polyethylene, used mainly in HDPE closures and thin-wall mouldings where balanced shrinkage and a shorter cycle matter more than the clarity a polypropylene formulator would be buying. Hyperform HPN-20E, described by Sowinski, 2015, as roughly two-thirds calcium cis-1,2-cyclohexanedicarboxylate and one-third zinc stearate, is FDA-cleared at 0.25 wt% under FCN 608 and carries EU FCM No 816 (SML 5 mg/kg). HPN-68L (FCM No 817, SML 5 mg/kg) is not permitted with polyethylene in contact with acidic foods. Nucleating agents for polyethylene, the PE-specific page, publishes later and is named here without a link.

Compatibilizers#

Compatibilizers matter in polyethylene almost entirely because of recyclate: a mixed polyolefin stream is an immiscible blend, and 5% polypropylene contamination in recycled HDPE can cut slow crack growth resistance by up to 40%. In one study, Kraton's CirKular+ C1010 at 5% in a recycled HDPE and PET blend raised notched Izod impact strength by 70% and yield strength by 40%; EPDM rubber compatibilises PP and PE blends generally, and EPDM grafted with maleic anhydride is used specifically for HDPE/PP and LDPE/PP blends.

Polyethylene Formulations by Application#

A polyethylene compound is defined by its end product rather than by its resin grade: the same LLDPE goes into a stretch film with two additives and into a greenhouse film with six. The same 18 families reassemble into nine distinct packages once the application, rather than the density grade, sets the requirement.

Table T3: the nine application formulations at a glance.

LDPE and LLDPE blown film#

A blown film package is short and almost entirely about the surface: a hindered phenol with a phosphite, a slip agent at 500 to 1,200 ppm, an antiblock at 2,500 to 10,000 ppm for diatomaceous earth or talc (2,500 to 20,000 ppm for calcium carbonate), and a processing aid to remove melt fracture at the die. A PEPQ-type phosphonite is added where LLDPE is blended in, for gel control, and the fluoropolymer PPA is dosed from a 2 to 5% masterbatch rather than added neat. See additives for packaging film for the converting-line detail.

Greenhouse and agricultural film#

Agricultural film is the most heavily stabilised polyethylene there is, because it survives several growing seasons of sunlight while being sprayed with agrochemicals that destroy conventional HALS. NOR-HALS chemistry, dosed at 0.2 to 1.6% in greenhouse film, resists that attack better; 1,000 to 2,000 ppm of sulfur in pesticide residue cuts HALS film life by 20 to 25%. Mulch film (12 to 80 µm, about 700,000 t/yr) lasts 2 to 4 months; greenhouse film (80 to 220 µm) lasts 6 to 45 months; silage wrap (25 µm, 4 to 6 layers) adds an antifog layer, with 3 wt% in the EVA layer and 1 wt% in the LDPE layer giving a permanency close to 3,000 hours. Additives for agricultural film, the dedicated hub, publishes later and is named here without a link.

HDPE pressure pipe: PE80, PE100 and PE100-RC#

A pressure pipe compound is the most tightly specified polyethylene formulation in the standards: carbon black at 2.0 to 2.5 wt% with a primary particle size of 10 to 25 nanometres, and an OIT of at least 20 minutes at 210°C, both set by EN 12201-1 and ISO 4427-1. Carbon black masterbatch runs at 35%, let down at 5 to 6.5%, and N330 or N110 replace the standard N550 once the pipe sits outdoors more than 3 to 5 years; dispersion is rated under ISO 18553. Antioxidant consumption runs about four times faster in 4 ppm chlorine dioxide at 90°C than in conventional chlorination, so pipe compounds carry margin above the floor. Additives for plastic pipes, the dedicated hub, publishes later and is named here without a link.

HDPE geomembrane#

A geomembrane carries the same two additives as a pressure pipe at higher levels and with far longer retention requirements: carbon black at 2.0 to 3.0% and a stabiliser package that survives 90 days of oven ageing at 85°C. GRI-GM13 Rev. 16 (17 March 2021) requires a standard OIT of at least 100 minutes or a high-pressure OIT of at least 400 minutes, stress crack resistance of at least 500 hours, and density of at least 0.940 g/ml; 90 days at 85°C must retain at least 55% of standard OIT or 80% of high-pressure OIT. In the US market, HDPE holds about 35% of geomembranes, against 25% LLDPE, 25% PVC and 10% flexible PP. Additives for geomembranes, the dedicated hub, publishes later and is named here without a link.

HDPE blow moulding, injection moulding and closures#

Bottles, intermediate bulk containers, crates and closures run the base package plus whatever the mould demands: a nucleating agent for balanced shrinkage and a slip agent tuned to the closure removal torque. In a closure application, a surface concentration of 15.7 µg/cm2 of erucamide was needed to reduce application torque, against only 1.7 µg/cm2 for behenamide, per Dulal and colleagues, 2017, and Hyperform HPN-20E is the nucleating agent most often specified for isotropic shrinkage in this category.

Wire and cable: HFFR and XLPE#

A halogen-free cable compound is mostly mineral: the reference formulation is 160 parts of alumina trihydrate on a 100-part EVA and LLDPE base, with a coupling agent to keep the filled compound processable. A metal deactivator protects the insulation against the copper conductor it surrounds, and a silane-crosslinked XLPE variant carries 180 phr alumina trihydrate with a hot-set limit of 175% maximum elongation under IEC 60811-507. See additives for wire and cable compounds for the PVC, HFFR and XLPE packages compared.

PEX pipe#

PEX is polyethylene that has been crosslinked after shaping, and the three routes are named by letter: PEX-a by peroxide in the melt, PEX-b by a grafted silane cured in water, and PEX-c by electron beam. PEX-a by the Engel process uses about 2% peroxide (commonly cited) crosslinked at 200 to 250°C; the DIN 16892 minimum degrees of crosslinking, 75% for PE-Xa, 65% for PE-Xb, and 60% for PE-Xc and PE-Xd, are also commonly cited figures rather than independently verified against ISO 15875, while ASTM F876 requires 65 to 89% overall crosslinking. PEX-b pipe has been measured leaching ethyl tert-butyl ether at 23 to more than 100 µg/L, against an odour threshold of 5 µg/L.

Polyethylene foam#

Polyethylene foam is made either by a physical blowing agent injected into the melt or by a chemical blowing agent that decomposes in it, and the US food-contact rule sets the chemical route's ceiling at 5 wt% of the finished foam under 21 CFR 178.3010. Crosslinked polyethylene foam uses the same peroxide or silane chemistry described for PEX and XLPE, applied to a foamable formulation rather than a pipe or cable compound.

Rotational moulding#

Rotational moulding is a polyethylene process before it is anything else: more than 80% of the material rotomoulded is PE, and the powder sits in a 300°C oven long enough, at 1 to 2 cycles per hour with a peak internal air temperature of about 180°C, that the stabiliser package, not the resin, sets the process window. A rotomoulding powder needs a heavier antioxidant load than the same resin would need as pellets, because the long, high-temperature dwell inside the mould consumes the phenolic and phosphite stabilisers faster than a short extrusion pass does.

How Much Additive Does Polyethylene Carry? wt%, ppm and Let-Down Ratio#

A polyethylene compound carries between 0.1% and 60% additive by weight, and the unit changes with the level: ppm for slip and processing aids, wt% for stabilizers and carbon black, and phr once a mineral filler dominates. Three units cover the whole page:

• Parts per million (ppm) covers low-dose surface additives such as slip agents, at 500 to 1,200 ppm.
• Weight percent (wt%) covers stabilizers and carbon black, for example 2.0 to 2.5 wt% in pressure pipe.
• Parts per hundred resin (phr), counted on 100 parts of resin, applies once a mineral filler dominates, as in a cable compound where 160 phr alumina trihydrate is about 60% of the compound.

A 35% carbon black masterbatch let down at 5 to 6.5% is the clearest worked example: the processor buys a concentrate, and the actual carbon black content, 1.75 to 2.3%, only appears once the let-down ratio is applied. The phr and its conversion to wt% reference works through this for every unit combination on this page.

Convert your polyethylene recipe into masterbatch let-down ratios with the let-down ratio calculator.

Processing Window and Compounding of Polyethylene#

Polyethylene is processed in a wide window compared with PVC, which is why its compounding problems are usually dispersion and residence time rather than degradation. Over-processing still shows up predictably, as a falling melt flow rate and a rising gel count, measured at 190°C with a 2.16 kg load (also reported at 5 kg) under ISO 1133-1 and ASTM D1238.

Compounding decisions follow from that tolerance. A fluoropolymer processing aid needs a conditioning period before the die wall is fully coated, so output before and after that window is not directly comparable, and carbon black masterbatches above 40% are avoided because dispersion suffers. Wood-filled compounds are the exception: they process at least 28°C below the unfilled resin's window and at most about 200°C, since cellulose degrades above that. General plastic compounding principles apply without the tight thermal margin PVC requires.

How Are Polyethylene Additive Packages Tested?#

Five tests decide whether a polyethylene additive package works: oxidative induction time for the stabiliser, melt flow rate for processing damage, environmental stress crack resistance for long-term performance, coefficient of friction for film handling, and a dispersion rating for carbon black.

Table T4: the five tests that confirm a polyethylene package performs as designed.

Which Rules Apply to Additives in Polyethylene?#

Four rule sets reach an additive in polyethylene, and three of the four write at least one of their limits for polyethylene specifically rather than for the additive alone.

Table T5: limits written per polyethylene, not per additive alone.

EU food contact: Regulation (EU) No 10/2011#

Regulation (EU) No 10/2011 authorises an additive for all plastics rather than for polyethylene, but four of its polyethylene-relevant entries carry a condition that names the polymer or the food type. The regulation's EU 10/2011 food contact rules set a generic SML of 60 mg/kg and an OML of 10 mg/dm2 unless a substance-specific entry states otherwise; carbon black (FCM No 411) is capped at 2.5% w/w, Cyasorb UV-3346 (FCM No 790) carries its fatty-food note, and the two Hyperform grades (FCM No 816 and 817) each carry a 5 mg/kg SML, with HPN-68L excluded from acidic-food contact in polyethylene. Erucamide (FCM No 271) and oleamide (FCM No 335) have no SML, and vinyltrimethoxysilane (FCM No 453), a crosslinking monomer, carries its own 0.05 mg/kg SML.

US food contact: 21 CFR 177.1520 and 178.2010#

The US rules work the other way round from the EU: 21 CFR 177.1520 first specifies what counts as a food-contact olefin polymer, by density, n-hexane extractables and xylene solubles, and only then does 21 CFR 178.2010 cap each stabiliser. Irganox 1010 is capped at 0.5 wt%, Irgafos 168 at 0.2% in ethylene polymers, and an AO-80 type antioxidant at 0.3 wt% in HDPE at density 0.94 g/cm3 or above; fluoropolymer PPAs are capped at 0.2 or 1.0 wt% by fluorine content, and antistatic amines at 0.1 to 0.2 wt% by article and pH. Azodicarbonamide is capped at 5 wt% of finished foamed polyethylene, and erucamide, not oleamide, is cleared under 21 CFR 178.3860. Every figure is a legal maximum, never "FDA approved". See FDA food contact rules for plastic additives.

Drinking water, cables and PFAS#

Two more rule sets reach polyethylene where food contact does not: the drinking-water positive lists that govern pressure pipe, and the construction and cable rules that govern a jacket compound's fire performance. Carbon black appears on the EU drinking-water positive list at entry 0348, the same 2.5% w/w cap as the food-contact entry; see plastic additives in drinking-water contact. On the cable side, the EU Construction Products Regulation sets fire classes B1ca, B2ca, Cca and Dca under EN 50399, applying to cables, product family 31, from 8 January 2026 (Regulation (EU) 2024/3110). Fluoropolymer PPAs sit inside the proposed EU universal PFAS restriction, still at proposal stage, while dicumyl peroxide has carried its SVHC listing since 27 June 2024, with residue above 0.1% w/w triggering REACH Article 33; see PFAS restrictions and plastic additives.

Additives for Recycled Polyethylene#

Recycled polyethylene arrives with its first stabiliser package already spent and a second polymer mixed into it, so restabilisation and compatibilisation are done together. Restabilisation typically uses a binary blend of Irganox 1010 and Irgafos 168 at 0.1 to 0.3 wt%, tested across multiple passes at 220°C for recycled HDPE and 250°C for recycled PP, using lines such as Songwon's Songnox 11B and 21B; a P-EPQ phosphonite at 0.05 to 0.1 wt% is added to recycled LLDPE for gel reduction. This logic is shared across additives for recycled plastics.

Compatibilisation is the second half of the problem, since a recycled stream rarely arrives pure. Just 5% polypropylene contamination in recycled HDPE can cut slow crack growth resistance by up to 40%, and the Association of Plastic Recyclers guide for PE film recommends testing when density approaches 0.996 g/cm3 and treating anything above 1.00 g/cm3 as non-recyclable; EVOH is Design Preferred at up to 10 wt% with a tie layer, and 4 wt% zeolite has cut odour intensity by 45%. In one study, Kraton's CirKular+ C1010 at 5% in a recycled HDPE and PET blend raised notched Izod by 70%. The restabilization of recycled plastics page covers the antioxidant side across every recycled commodity polymer.

How to Build a Polyethylene Additive Package: 7 Steps#

Build a polyethylene additive package in seven steps, from the inside out: stabilise the polymer first, then protect it from the environment, then serve the converting line, then add the property the specification asks for.

1. Fix the base stabiliser package, phenol plus phosphite plus acid scavenger, before anything else.
2. Add the weathering package only where the article sees sunlight: carbon black or a HALS with a UV absorber.
3. Add the surface package the converting step demands: slip, antiblock, processing aid.
4. Add the functional family the specification demands: fire class, foam density, degree of crosslinking.
5. Check every level against the food-contact, drinking-water or cable rule for the polymer, not just the additive.
6. Check interactions: an acidic flame retardant weakens a basic HALS, an abrasive antiblock consumes stabiliser, a fluoropolymer PPA needs a conditioning run.
7. Convert the recipe into let-down ratios and confirm the test values: OIT, MFR, COF, dispersion.

A later step can undo an earlier one if not checked against it; the full methodology is set out in how to select plastic additives, which hosts the site's gated selection guide.

Find the additive families your polyethylene grade and application need with the additive finder by polymer and function, publishing shortly after this guide.

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Migration, Microplastics and What This Guide Does Not Cover#

Two questions come up on every polyethylene page that are not formulation questions: what leaves the polymer, and what the polymer does once it is waste. This guide is part of the wider reference on additives by polymer, and the same formulation logic applied to a different backbone separates it from additives for polypropylene, the sibling guide.

Which additives migrate out of polyethylene?#

Some polyethylene additives are chosen because they migrate: a slip agent that stayed in the bulk would do nothing, and an antistat works only at the surface. Erucamide is designed to migrate and reaches its final surface concentration 7 to 10 days after production, and migrating antistatic agents work by the same mechanism. Not every migrating substance is an intentional additive: 2,4-di-tert-butylphenol, a degradation product of Irgafos 168 and therefore a non-intentionally added substance, was measured at up to 45.568 ± 31.513 mg/kg in BOPP and LDPE food-contact products by Qian and colleagues, 2018. PEX-b pipe has separately been measured leaching ethyl tert-butyl ether at 23 to more than 100 µg/L, against a 5 µg/L odour threshold. This mechanism is covered in additive migration in plastics.

Does polyethylene give off microplastics?#

Polyethylene, like other thermoplastics, releases particles alongside the additives embedded in it, and the fraction released under different conditions is an active research question rather than a settled figure. A 2023 review by Maddela and colleagues, "Additives of plastics: entry into the environment and potential risks," and a 2021 inventory by Wiesinger, Wang and Hellweg at ETH Zurich both examine how additives move with these particles once polyethylene reaches the environment, but neither study, and no source used on this page, provides a basis for a health-risk conclusion. This reference does not assess health risk; readers looking for a risk assessment should consult a public-health or environmental-toxicology source rather than a formulation guide.

Polymer properties this guide does not cover#

This guide covers what is added to polyethylene, not polyethylene itself. Several adjacent topics are deliberately excluded:

• What polyethylene is and how it is polymerised.
• Melting point and density tables for material selection.
• HDPE versus LDPE material selection outside the additive package.
• Chemical and solvent resistance.
• Welding and adhesion behaviour ("what will stick to HDPE").
• Chemistries that share the word polyethylene but sit outside this site's scope: fibrillated HDPE used in asphalt and cementitious construction, polyethylene glycol used in cosmetics and pharmaceuticals, and polyethylene wax used in coatings and inks.

The nearest contrast case on this site is additives for PVC, a polymer that needs a plasticizer and a heat stabiliser where polyethylene needs neither.

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