Additives for Recycled Plastics: 10 Additive Groups, Dosage and Formulation Guide

Additives for recycled plastics are the stabilizers, compatibilizers and functional additives added back to a recyclate to replace what recycling consumed and to correct what it introduced, and they fall into 10 groups, starting with a phenolic and phosphite restabilizer at 0.1 to 0.3 wt%. Post-consumer and post-industrial (PCR and PIR) polyolefins are generally not topped up with antioxidants at all before they reach a recycler, so what does a recyclate actually need once it does? It needs a package sized to the damage the process caused rather than to the resin's original specification, because every extrusion, moulding or use cycle a plastic already survived used up part of the protection it started with and left a measurable trace behind.

Recycled plastics draw on 10 groups of additives to close that gap: restabilizers replace the antioxidants the process consumed, light stabilizers protect parts destined for outdoor use, compatibilizers bind polymers that sorting failed to separate, chain extenders rebuild the viscosity hydrolysis destroyed, rheology modifiers reset a drifting melt flow rate, impact modifiers restore the toughness lost to chain scission and contamination, odour and VOC absorbers trap volatile compounds picked up from the original contents, desiccants remove residual moisture, colorants and sorting aids keep the next batch sortable, and fillers, lubricants and processing aids finish the compound. Each group belongs to one of the 43 families of plastic additives that this site catalogues, applied here to a feedstock condition rather than to a virgin resin.

This guide sets out what each of the 10 groups does, the package a compounder builds for rPP, rHDPE, rLLDPE, rPET, recycled PVC and recycled styrenics, how much of each additive a stream actually needs, how the package is compounded and tested, and what the PPWR, Regulation (EU) 2022/1616 and REACH Annex XVII require before a recyclate can be sold or used again. It closes with a 7-step method for building a package from a measured defect and a list of the suppliers that formulate for this market. The same package logic applied to virgin resins is set out in additives by polymer, the parent guide this page adapts.

The table below places all 10 groups side by side before the guide takes each one in turn.

Why Recycled Plastics Need a Different Additive Package#

A recyclate differs from virgin resin in four ways that additives have to correct: its stabilizers are partly consumed, its chains carry oxidised groups, it contains foreign polymers and contaminants, and it carries the additives of every product it was made from. Virgin resin arrives at the compounder stabilized to a known specification, made of a single declared polymer, with no processing history beyond its own production run. A recyclate arrives instead as the sum of an unknown number of prior lives, whatever extrusion, moulding or use cycles happened before collection, plus whatever sorting, washing and reprocessing added on top. The additive package therefore starts from a measurement of what is missing and what has been added, not from a standard formulation sheet, and that measurement differs for every incoming lot.

What mechanical recycling takes out of the polymer#

Every pass through an extruder consumes part of the antioxidant package and leaves oxidised groups on the chains, so a recyclate starts its second life with less protection than the virgin resin it came from. Restabilization, the practice of replacing that consumed protection, was defined by Rudolf Pfaendner, first at Ciba and later at the Fraunhofer Institute LBF, who reviewed 30 years of the concept in a 2022 paper in Polymer Degradation and Stability. The depletion is measurable rather than assumed. In an open-loop study, Knoben and colleagues (2025) found that r-PP regranulate without any added antioxidant can still retain more than 150 ppm of intact Irgafos 168, enough for one to two further processing steps before the phosphite is exhausted; the figure describes that single study and should not be generalised to every stream. In a closed-loop trial that added 500 ppm of a primary antioxidant plus 1,000 ppm of a secondary antioxidant in every cycle, the oxidation induction temperature at cycle 5 reached only 198 °C without any added antioxidant, against 257 °C with it, while the residual Irgafos 168 level itself rose from about 650 ppm at cycle 1 to more than 1,200 ppm by cycle 5.

The stabilizer types, grades and multipass data behind these figures are set out in full on restabilization of recycled plastics, the antioxidant family's recycling page.

What mechanical recycling puts into the polymer#

Recycling also adds things: foreign polymers from imperfect sorting, odorous compounds from the products' original contents, moisture from washing, and the additives of the original articles. Each of these arrives with a measurable consequence.

• Foreign polymers. As little as 5 % polypropylene in recycled HDPE can cut slow-crack-growth resistance by up to 40 %, and polyethylene in recycled PP can cut it by up to 70 %; up to 7 wt% PP in recycled LDPE has been found to cause considerable brittleness.
• Odour and VOCs. Researchers have detected 169 odorous compounds in post-consumer plastic packaging, most of them absorbed from the products the packaging once held.
• Moisture. Washed film and flake streams carry residual water that causes voids and hydrolysis if it is not removed before melt processing.
• Legacy additives. A recyclate carries whatever stabilizers, flame retardants, plasticizers or pigments the original articles contained, which is why legacy additives in recycled plastic have to be screened before a new formulation starts.

Wiesinger and colleagues at ETH Zurich, sampling 151 Swiss PVC floorings in 2024, found that 16 % contained regulated chemicals above 0.1 wt%, mainly lead and DEHP, a result that describes that national sample rather than every recyclate stream.

How much recyclate is actually in the market#

Mechanical recycling supplies 14.5 % of European plastics production, against 0.2 % from chemical recycling, which is why almost every additive question about recyclate is a question about the mechanical route. European plastics production stands at just under 55 Mt, of which 14.5 % is mechanically recycled, 1.1 % is bio-based and 0.2 % is chemically recycled (Plastics Europe, 2025). Globally, 9 % of plastic was recycled in 2015 and about 1 % was recycled more than once. In PVC specifically, VinylPlus recorded 568,695 t of recycled PVC in 2016, rising to 739,525 t in 2018 and settling at 731,461 t in 2020.

The 10 Additive Groups Used in Recycled Plastics#

Recycled plastics use 10 groups of additives: restabilizers, light stabilizers, compatibilizers, chain extenders, rheology modifiers, impact modifiers, odour and VOC absorbers, desiccants, colorants and sorting aids, and the fillers, lubricants and processing aids that finish the compound.

1. Restabilizers: phenolic antioxidants, phosphites and acid scavengers#

Restabilizers are antioxidants, the stabilizer family of the root taxonomy, added back to a recyclate to replace consumed protection, and a binary phenolic and phosphite blend at 0.1 to 0.3 wt% is the standard starting point for recycled polypropylene and recycled HDPE. Songwon's SONGNOX 11B and SONGNOX 21B binary blends of Irganox 1010 and Irgafos 168 were tested at 0.1, 0.2 and 0.3 wt% in multipass extrusion at 250 °C for PP and 220 °C for HDPE, the supplier method used as the reference screen for this stream. Songwon XP 2121 at 0.15 to 0.4 wt% raised the days to embrittlement of r-PP at 150 °C from about 25 days unstabilized to about 37 to 42 days, and is supplied in granular form to allow easy dosing and minimise dust. SONGNOX PQ (P-EPQ) at 0.05 to 0.1 wt% is used in recycled LLDPE for processing stability and gel reduction, with the 0.1 % level cutting the gel count from about 210 to about 150 per 1,525 cm². Recyclobyk 4371 from ALTANA/BYK, dosed at 0.75 wt%, has kept the properties of recycled PP stable to 20 reprocessing cycles, and Songwon's SONGXTEND 2721 is offered as a dedicated top-up stabilization system for recycled PP. Phosphites and phosphonites combined with phenolics are, according to the Fraunhofer Institute LBF, the main post-stabilization chemistry for recyclate generally.

The mechanism of primary and secondary antioxidants for plastics is explained in full on the family hub, along with dosage in virgin resin for comparison.

2. Light stabilizers for recyclate used outdoors#

Light stabilizers are the UV-stabilizer family added to any recyclate destined for an outdoor part, because a stream that already carries oxidised groups photo-oxidises faster than virgin resin. A restabilization package for outdoor use includes HALS and UV absorbers alongside the phenolic and phosphite antioxidants, following the same logic Pfaendner set out for the antioxidant system. Our source library does not yet hold a recyclate-specific HALS dosage study; the dosing ranges used in practice are the general polyolefin ranges established for virgin resin, applied here with that qualification rather than as a recyclate-specific figure.

Loading levels by section thickness and polymer type are set out on UV stabilizers for plastics, the family hub this recyclate practice draws on.

3. Compatibilizers for mixed and contaminated streams#

Compatibilizers are the compatibilizer family used in recyclate to bind polymers that sorting failed to separate, and they matter because as little as 5 % polypropylene in recycled HDPE can cut slow-crack-growth resistance by up to 40 %. A polyolefin elastomer such as Dow ENGAGE, dosed at 2 to 5 % (typically 3 %) in a 70/30 HDPE/PP recyclate, has raised impact strength and elongation about threefold while modulus was maintained. SI Group's POLYBOND 3150 and 3002 maleated polypropylene grades, at 5 % in recycled PP/nylon blends, improved notched and reverse Izod impact strength more than threefold. Kraton's CirKular+ C1000, at 3 to 5 % in a 72/18 PCR PP/PET blend, raised notched Izod by 50 % and yield strength by 30 %, and the C1010 grade, at the same 3 to 5 % range in PCR HDPE/PET, raised notched Izod by 70 % and yield strength by 40 %. ExxonMobil's Vistamaxx propylene-based elastomer is typically started at a 5 % dosage in PE/PP recyclate blends.

Blend pairs and dosage for the full compatibilizer range are set out on compatibilizers for recycled plastics.

4. Chain extenders for rPET, rPA and rPLA#

Chain extenders are multifunctional reactive additives that re-link the shortened chains of a hydrolysed polyester, and in recycled PET the epoxy-functional styrene-acrylic oligomer Joncryl ADR-4400 is used at 0.5 to 1.5 wt%, keeping gel content at or below 2 %. Chain extension carries a penalty if overdosed: in a 280 °C mini-extruder trial, 3 wt% of the same additive produced about 32 % gel, so chain extension in rPET is not risk-free above its working range. BASF's Joncryl ADR-4368 grade has a molecular weight of about 6,800 g/mol, an epoxy equivalent weight of 285 g/mol and about 9 epoxy groups per molecule; the ADR-4368-S variant is used as a chain extender in recycled PA6/PP blends reinforced with carbon fibre. Pyromellitic dianhydride (PMDA), a tetrafunctional chain extender with low hydroxyl reactivity, is used at 0.2 to 0.3 wt% in PET and rPET extensional-rheology studies and is often combined with epoxide chain extenders.

Viscosity-recovery data across these grades are set out on chain extenders for PET and rPET.

5. Rheology modifiers: peroxide visbreaking and melt-strength rebuild#

Rheology modifiers are organic peroxides used in reactive extrusion to move a recyclate's melt flow rate to the value the process needs, upward by chain scission or downward by long-chain branching. Nouryon's Trigonox 101 is used for visbreaking, or controlled rheology, of polypropylene and as a recycling modifier; Trigonox 301 is used for controlled rheology of virgin and recycled PP and for MFI reduction of recycled PE; and Perkadox PM-60ST-GR lowers the MFI and raises the melt strength of recycled PP through a patented long-chain branching mechanism. Controlled-rheology PP visbreaking in reactive extrusion works across 0 to 600 ppm of dialkyl peroxide (DHBP), with 200 ppm typically used for staple fibre applications. A separate process, electron-beam crosslinking of recycled PE, is effective across 50 to 150 kGy, with 110 kGy judged the best balance for recycled PE and gel content rising from 46.7 % to 56.2 % between 95 and 125 kGy; this describes a process condition, not an additive dosage.

Half-lives and decomposition temperatures for these peroxide grades are set out on organic peroxides for polymers.

6. Impact modifiers for recycled blends#

Impact modifiers are the impact-modifier family used to restore the toughness a recyclate lost to chain scission and to foreign-polymer inclusions, and in glass-filled rPET, ethylene copolymers raised notched Izod impact strength from 5.2 to about 8.1 kJ/m², a gain of 55 %. Ethylene-methyl acrylate (E-MA) and its glycidyl-methacrylate-functional variant (E-MA-GMA) were compared in that study, with the GMA-functional grade performing best on unnotched impact. Kraton's CirKular+ C2000, dosed at 3 to 10 % in PCR PP (9 % in the supplier's worked example), is described specifically as an impact modifier rather than a compatibilizer, though the two roles overlap in recyclate: a grade that binds two immiscible phases usually also toughens the blend, so the same product often does both jobs rather than needing separate additions.

Grade families across the impact-modifier range are compared on impact modifiers.

7. Odour and VOC absorbers#

Odour absorbers are the odour-control family used in recyclate to trap the volatile compounds the original packaging absorbed, and adding 4 wt% zeolite to a mixed polyolefin recyclate has cut average odour intensity by 45 %. Zeolite 13X or the branded grade Z310 are the adsorbents used at that level, and researchers have detected 169 odorous compounds in post-consumer plastic packaging that a recycler may be trying to remove. A 4 wt% adsorbent loading is a filler-level dosage with its own cost and mechanical consequences, and in the same evidence base, simply excluding the highest-load sorting categories from the input stream cut post-consumer film VOC by 56 %, a bigger reduction than dosing achieved; sorting, not additive dosing, removed more VOC in that comparison.

Sensory data and adsorbent types are set out on odor absorbers for recycled plastics, the odour-control family's recycling page.

8. Desiccants and moisture scavengers#

Desiccants are calcium-oxide masterbatches added to washed recyclate to bind residual moisture that would otherwise cause voids and hydrolysis in the melt. Plastiblends' desiccant masterbatch for recycled PE and PP is used at a ratio of about 1 % masterbatch per 0.15 % moisture in the flake, and Mascom's equivalent product is dosed at 1 to 5 % masterbatch. The calcium oxide content of these commercial masterbatches is not disclosed by the suppliers, so this page states only the masterbatch let-down, never an active-substance weight percentage.

Let-down guidance for the full desiccant range is set out on desiccant masterbatch.

9. Colorants, NIR-sortable blacks and tracers#

Colorants decide whether a plastic can be sorted at all: carbon black absorbs the near-infrared light that sorting lines use, so black packaging coloured with conventional carbon black is not detected and is routed to reject. The APR Design Guide criterion SORT-S-01 fails black or dark colours with an L* value below 40 or a NIR reflectance at or below 10 %. Ampacet's REC-NIR-BLACK masterbatch is COTREP-certified for PP and HDPE rigid packaging specifically because it is detectable by near-infrared sorting equipment where conventional carbon black is not. Tracer-based sorting is a separate route that uses fluorescent or XRF markers added at about 100 ppm to enable automated identification of the polymer or brand owner. Diarylide pigment decomposition products have also been implicated in the yellowing of recycled PE, a colour-stability issue distinct from the sorting problem.

Carbon-black-free alternatives are set out on NIR-sortable black colorants, the colorant family's recycling page, and marker systems that enable tracer-based sorting are covered on the dedicated sorting page.

10. Fillers, reinforcements, lubricants and processing aids#

Fillers, lubricants and processing aids finish a recyclate compound: they restore stiffness, lower melt friction and let a dirty, wide-distribution melt run at a stable throughput. In a recycled-HDPE wood-plastic composite formulated at 34 % rHDPE and 60 % sawdust, a coupling package of maleated polypropylene (MAPP) at 1 to 3 wt%, a coupling wax and stearic acid let the composite process at least 28 °C below the temperature of the unfilled resin and at most about 200 °C. Kenrich's Ken-React CAPS KPR 12/LV coupling agent, at 1.5 to 1.75 % in a mixed post-industrial resin, gave 20 % faster processing at a 9 % lower melt temperature. In an optimised rotomoulded recycled-PE composite, 30 % rPE and 0.5 % pigment reached a peak internal air temperature of 195 °C. Kisuma's Setogem RD, dosed at 200 to 300 ppm in PP, acts as both a nucleator and an acid scavenger in a recycled stream.

Loading limits across the filler range are set out on fillers for plastics.

Additive Packages by Recyclate Stream#

The package changes with the stream: recycled polypropylene needs restabilization and a compatibilizer, recycled PET needs a chain extender, and recycled PVC needs a legacy check before any formulation work starts. Table T2 lines up the six streams this reference covers against their dominant defect, first additive and key test.

Recycled polypropylene (rPP)#

Recycled polypropylene is the best-documented stream: a binary phenolic and phosphite blend at 0.1 to 0.3 wt% is the standard restabilization, verified by multipass extrusion at 250 °C. Beyond restabilization, Songwon XP 2121 at 0.15 to 0.4 wt% raised days to embrittlement at 150 °C from about 25 to about 37 to 42, Recyclobyk 4371 at 0.75 wt% has held properties to 20 cycles, and SONGXTEND 2721 is supplied as a dedicated top-up system. Where the stream carries polyethylene contamination, a polyolefin elastomer at 2 to 5 % restores impact strength. PP pipe compounds containing post-consumer recyclate have been tested at 10, 20 and 30 m% recyclate content, and EN 13476-3 Annex D lists the properties that must be agreed for PP recyclate used in multilayer pipe walls: oxidative induction time, ash content, foreign polymers, impurities, pigments and additives, volatiles, tensile properties and origin. Recyclate is not permitted in pressurised gas or drinking-water PP pipe systems.

The virgin-PP package this recyclate practice is compared against is on additives for polypropylene.

Recycled HDPE and LLDPE#

Recycled HDPE and LLDPE are restabilized in the same way as recycled PP but at a lower multipass temperature, 220 °C, and the LLDPE film route adds a phosphonite for gel control. The binary phenolic and phosphite blend runs at 0.1 to 0.3 wt% in r-HDPE, while SONGNOX PQ (P-EPQ) at 0.05 to 0.1 wt% is the LLDPE-specific addition, cutting gels from about 210 to about 150 per 1,525 cm² at the 0.1 % level. Contamination is the other defining variable: as little as 5 % polypropylene in recycled HDPE can cut slow-crack-growth resistance by up to 40 %, and up to 7 wt% PP in recycled LDPE has been found to cause considerable brittleness. The Association of Plastic Recyclers treats film density as a sorting threshold, flagging material for testing as density approaches 0.996 g/cm³ and rating anything above 1.00 g/cm³ non-recyclable.

The virgin film and pipe packages this stream is measured against are on additives for polyethylene.

Recycled PET (rPET)#

Recycled PET loses intrinsic viscosity to hydrolysis and chain scission, so its signature additive is a chain extender rather than a stabilizer. Joncryl ADR-4400 at 0.5 to 1.5 wt% keeps gel content at or below 2 %, PMDA at 0.2 to 0.3 wt% is the tetrafunctional alternative, and glass-filled rPET toughened with ethylene copolymers raised notched Izod from 5.2 to about 8.1 kJ/m². The bottle-to-bottle route carries its own compositional limits: the European PET Bottle Platform (EPBP) caps PA-MXD6 at 5 wt% in clear bottles and 6 wt% in coloured or opaque bottles, caps EVOH at 3 wt% in coloured bottles, and requires an oxygen scavenger used in clear PET to remain thermally stable across 5 reprocessing loops with less than 0.1 % non-PET content. The Association of Plastic Recyclers lists reheat additives as "requires testing" because they can turn recycled flake dark or yellow. Intrinsic viscosity, controlled by ASTM D4603 or ISO 1628-5, is the primary control test for this stream.

Bottle, fibre and film grades for the virgin resin are on additives for PET resin, the parent polymer page.

Recycled PVC#

Recycled PVC is the one stream where the legal check comes before the formulation: lead has been restricted to below 0.1 % by weight in PVC articles since 29 November 2024 under REACH Annex XVII entry 63, Regulation (EU) 2023/923. Recovered rigid PVC is allowed up to 1.5 % lead in listed uses until 28 May 2033, provided the article carries the marking "Contains ≥ 0,1 % lead". The derogation dates and the marking requirement are set out in full on lead in PVC, the dedicated regulation page. Wiesinger and colleagues at ETH Zurich, sampling 151 Swiss PVC floorings in 2024, found that 16 % contained regulated chemicals above 0.1 wt%, mainly lead and DEHP, underlining why the screen has to run before any restabilization work begins. VinylPlus recorded 731,461 t of recycled PVC in 2020, down slightly from 739,525 t in 2018.

The derogation, the marking rules and the restabilization route specific to this stream are on recycled PVC, the stream's own child page.

Recycled styrenics and engineering plastics#

Recycled styrenics and engineering plastics are a smaller and far less documented group, and their formulation question is usually which legacy additives the stream carries rather than which new ones to add. Joncryl ADR-4368-S is used as a chain extender in recycled PA6/PP blends reinforced with carbon fibre, and SEBS-g-MAH grades are described as efficient impact modifiers for nylon and polyester blends generally. The specific brominated flame-retardant content of recycled styrenic streams, such as material recovered from waste electrical and electronic equipment, is not quantified in our source library; this guide describes the mechanism qualitatively rather than stating a figure that has not been verified.

The virgin polyamide package this stream is compared against is on additives for nylon.

How Much Additive Does Recyclate Need? Dosage by Stream#

Restabilization is a tenth-of-a-percent job at 0.1 to 0.3 wt%, while odour control and fillers are percent-level jobs, so the additive cost of a recyclate compound is set by the functional groups, not by the stabilizer. Table T3 collects every documented dosage on this page in one place, each traceable to the fact ledger behind this guide.

Every level above is expressed in the unit the source used, wt% for compound-level dosage, phr-style masterbatch let-down for desiccants, and ppm for reactive-extrusion and tracer additions; converting between wt%, ppm and let-down ratio is set out on PHR (parts per hundred resin).

How Recyclate Additives Are Dosed and Compounded#

Compounding in plastic recycling is the melt-mixing step that turns washed, sorted flake or regrind into a specified pellet by adding the stabilizers, compatibilizers and functional additives the stream needs. Four routes are used to get an additive into the melt.

1. Melt compounding blends the additive package with the flake or regrind directly in the extruder, the route used for the multipass screening data behind the restabilization figures on this page, with r-PP evaluated over 5 passes at 250 °C and r-HDPE at 220 °C.
2. Masterbatch let-down disperses the additive in a carrier resin first, the route used for desiccants and for masterbatch colorants, where the dosage is stated as a masterbatch percentage rather than an active-substance weight percentage.
3. Liquid or powder direct dosing feeds the additive into the extruder throat or a side feeder without a carrier; Songwon's XP 2121, for example, is supplied in granular form specifically to allow easy dosing and minimise dust at this stage.
4. Reactive extrusion uses the extruder itself as a reactor, the route for peroxide visbreaking and for the epoxy and anhydride chain extenders, where the additive reacts with the polymer chain rather than simply dispersing in it.

Equipment configuration and sequencing for a general compound are covered on plastic compounding; our source library does not extend to recyclate-specific screw configurations, side-feeder positions or residence times, so this page does not state them.

How to Test a Restabilized Recyclate#

A restabilized recyclate is verified on four axes: oxidative stability by oxidative induction time, melt stability by melt flow rate over multiple passes, colour by yellowness index, and odour by a VDA 270 sensory panel. Table T4 lists the standard behind each check and, where our source library holds one, a reference value.

What the Rules Require: Recycled Content, Food Contact and Legacy Limits#

Three layers of rules govern a recyclate compound: recycled-content targets that create the demand, food-contact rules that decide whether the recyclate may touch food, and restriction rules that limit what the stream may still contain. All three layers interact with additive choice, because a recycled-content mandate is only useful if the resulting compound also clears the food-contact and restriction rules. The three layers, and the wider set of instruments that touch a recyclate, are set out in full on recycled plastics regulations, the dedicated regulatory hub.

Recycled-content targets that drive additive demand#

The Packaging and Packaging Waste Regulation, Regulation (EU) 2025/40, sets the first binding recycled-content targets: from 1 January 2030, 30 % post-consumer recycled content in contact-sensitive PET packaging and 35 % in other plastic packaging. The same Article 7 sets a 10 % target for contact-sensitive packaging other than PET and a 30 % target for single-use plastic beverage bottles from that date, rising to 50 %, 25 %, 65 % and 65 % respectively from 1 January 2040. The Regulation itself applies from 12 August 2026, and the design-for-recycling delegated acts that will determine which packaging designs count toward these targets are due by 1 January 2028.

The heavy-metal and PFAS limits carried by the same regulation are set out on PPWR and additives.

Food contact: Regulation (EU) 2022/1616 and the FDA route#

In the EU, recycled plastic may only touch food if it comes from a recycling process authorised under Regulation (EU) 2022/1616, which recognises exactly two suitable technologies: post-consumer mechanical PET recycling and recycling from closed, controlled product loops. The mechanical PET route allows at most 5 % input from non-food applications and its output may not be used for microwave or conventional ovens. The Regulation was adopted on 15 September 2022, published in the Official Journal (L 243) on 20 September 2022, entered into force on 10 October 2022, and repeals the earlier Regulation (EC) No 282/2008; it also maintains a public register of authorised recyclers, installations and processes. EFSA's safety assessment for this route assumes a baseline misuse contamination of 3 mg per kg of PET, and 182 recycling-process applications were published or submitted between 2008 and November 2023, of which 26 covered non-PET polymers. In the United States, the FDA works from a negligible dietary concentration of 0.5 ppb and issues no-objection letters rather than approvals; it requires no individual evaluation for tertiary recycling of PET and PEN. Outside these two markets, South Korea's Ministry of Food and Drug Safety recognised mechanically recycled PP under Notification 2026-24 from 27 March 2026.

The Union list an authorised recyclate must still comply with is set out on EU 10/2011.

Legacy and restricted additives that travel with the stream#

A recyclate carries the regulatory history of everything it was made from, which is why the restricted-substance check comes before the formulation and not after it. REACH Annex XVII entry 63 restricts lead in PVC articles to below 0.1 % by weight since 29 November 2024, with a derogation allowing recovered rigid PVC up to 1.5 % lead in listed uses until 28 May 2033. Medium-chain chlorinated paraffins (MCCP) were added to the Stockholm Convention's Annex A at COP-12 in 2025, and the EU's implementing measure, Commission Delegated Regulation C(2026) 6262 of 11 September 2026, has been adopted and applies from 16 December 2026, setting a general unintentional-trace concentration of 0.1 % by weight with a 2 % limit for recovered PVC from cable recycling for two years. Oxo-degradable plastic products have been banned outright in the EU since 3 July 2021 under Article 5 of Directive (EU) 2019/904. Compatibilizers themselves become legacy additives in the next loop, and additives generally can be released during recycling and recovery and from products made from recyclates, as Hahladakis, Velis, Weber, Iacovidou and Purnell, all at the University of Leeds, documented in the Journal of Hazardous Materials in 2018.

Entry 63 and the other article-level restrictions are explained in full on REACH Annex XVII restrictions, and the wider POPs listings that affect recyclate are covered on POPs in plastics, the Stockholm Convention and EU POPs Regulation page.

How to Build an Additive Package for a Recyclate: 7 Steps#

Build an additive package for a recyclate in 7 steps: identify the stream, screen its restricted-substance history, measure the starting point, restabilize, compatibilize, add the functional additive the defect calls for, then confirm on multipass extrusion.

1. Identify the stream and its origin. Establish whether the material is post-consumer or post-industrial resin, and whether it is a single declared polymer or a mixed stream, before any additive decision is made.
2. Screen the restricted-substance history before formulating. A recyclate should be checked against REACH Annex XVII entry 63 (lead in PVC), the POPs Regulation and any other applicable restriction before compounding starts, not after.
3. Measure the starting point. Run oxidative induction time, melt flow rate, yellowness, odour, ash content and foreign-polymer content on the incoming lot so the package is sized to the actual defect rather than a generic assumption.
4. Restabilize first, then re-measure. A phenolic and phosphite blend at 0.1 to 0.3 wt% should go in before any other functional additive, because a package built on an unstable base will keep degrading under it.
5. Add a compatibilizer only if foreign polymer is present, and size it by the contamination level. A stream that tests clean of foreign polymer should skip this step; one that tests contaminated should size the compatibilizer dosage to the measured contamination level, following the dosage-response data in Table T3.
6. Add the functional group the defect calls for. A chain extender addresses lost viscosity, an odour absorber addresses sensory failure, a desiccant addresses moisture, and a colorant or NIR-detectable black addresses sortability; these should be added individually against the measured defect, not as a standard package.
7. Confirm on multipass extrusion, then on the finished part, and record the package against the target specification. The EN 13476-3 Annex D property list is a ready-made specification checklist for this final step even outside pipe applications.

Recyclate Additive Package Worksheet (PDF). Download the worksheet to record stream, defect, test result, additive group, dosage and re-test result in one sheet. Requires email, role and company.

The general method behind these steps, extended to virgin resin, is set out on how to select plastic additives.

Who Supplies Additives for Recycled Plastics?#

No single supplier covers the whole recyclate package: the stabilizer blends come from Songwon, BASF, Clariant and Baerlocher, the compatibilizers and impact modifiers from Dow, Kraton, ExxonMobil and SI Group, and the chain extenders from BASF. Table T6 lists the supplier, headquarters and recycling-specific brand line for each company named on this page.

Company profiles beyond the recycling line are in the directory of plastic additive manufacturers and suppliers.

Compare quotes for a recyclate additive package. Send one request covering stream and volume to the matched suppliers at once with the plastic additive supplier finder.

What Additives Mean for Recycling and the Circular Economy#

Additives work in both directions in a circular system: restabilizers at 0.1 to 0.3 wt% are what make a second and third life possible, while legacy additives and non-detectable blacks are what keep material out of the loop. Additives can be released during recycling and recovery, and from products made from recyclates, as Hahladakis and colleagues at the University of Leeds documented in 2018, which means every additive decision made on this page also has a consequence for the next cycle. The wider picture of this dual role is set out on plastic additives in a circular economy, the environment section's overview page.

Which additives make a package non-recyclable?#

Three additive decisions can disqualify a package: a degradable additive, a filler load that pushes the density past the float-sink cut, and a black pigment that defeats near-infrared sorting.

• A degradable additive. Oxo-degradable plastic products have been banned in the EU since 3 July 2021 under Article 5 of Directive (EU) 2019/904, and the Association of Plastic Recyclers rates any degradable additive as making PP and PE packaging non-recyclable outright.
• A density-shifting filler load. APR rates PP rigid packaging below 0.970 g/cm³ as preferred, 0.970 to 1.0 g/cm³ as requiring testing, and anything at or above 1.0 g/cm³ as non-recyclable; PE film is tested as density approaches 0.996 g/cm³ and rated non-recyclable above 1.00 g/cm³.
• A NIR-opaque black pigment. Carbon black absorbs the near-infrared light sorting lines use, so conventional black packaging fails the sortability check covered above under NIR-sortable blacks.

By contrast, thermal stabilizers, UV stabilizers, nucleating agents, antistatic agents, lubricants, fillers, pigments, impact modifiers and chemical blowing agents are all rated Design Preferred workhorse additives by APR, meaning none of them disqualifies a package on its own.

The full APR and EPBP criteria behind these ratings are set out on design for recycling.

Do additives travel into the next loop?#

Yes: every additive added to a recyclate becomes part of the next stream, which is why closed-loop recycling with a full antioxidant top-up in each cycle builds the phosphite concentration up rather than holding it steady. In the closed-loop PP trial referenced earlier, residual Irgafos 168 rose from about 650 ppm at cycle 1 to more than 1,200 ppm by cycle 5 under a repeated top-up regime. Compatibilizers follow the same pattern: once added, they become legacy additives in the next recycling loop rather than disappearing from the stream, and additives can be released during recycling and recovery and from the finished products made from recyclates, as Hahladakis, Velis, Weber, Iacovidou and Purnell (University of Leeds, Journal of Hazardous Materials 344, 2018) documented. Wiesinger and colleagues at ETH Zurich found the same accumulation effect in practice, with 16 % of the 151 Swiss PVC floorings they sampled in 2024 carrying regulated legacy chemicals above 0.1 wt%.

Release from the polymer during use and at end of life is covered in full under additive migration.

What this guide does not cover#

This guide covers the additives used in mechanically recycled plastics; chemical and enzymatic recycling, sorting and washing equipment, and waste-collection policy are outside the scope of this reference. It also does not cover the health debate around recyclate in depth, which is handled separately on toxic plastic additives, the health section's chemicals-of-concern page.