Plastic Additives: 43 Types, Functions and the Complete List of Polymer Additives

Plastic additives are substances intentionally added to a polymer to change how it processes or how the finished article performs, looks or lasts, and this reference sorts them into 43 families and 7 functional groups. Their content in a finished plastic runs from 0.001 wt% for a biocide to about 70 wt% for the plasticizer in very soft PVC, so what separates one family from another? Function separates them, and the same functional logic runs through the mapping exercise the European Chemicals Agency (ECHA) published for the additives used in the EU.

The 7 functional groups are property modifiers, fillers and reinforcements, flame retardants and other functional additives, stabilizers, colorants and masterbatch, processing modifiers, and surface and optical modifiers. Plasticizers lead the class by weight at 34 % of global additive consumption, followed by fillers at 28 % and flame retardants at 13 %.

This page defines a plastic additive in law and in practice, names all 43 types with their typical level, host polymers and example substances, collects them in one complete list, explains how additives act in the bulk, chemically and at the surface, matches additive packages to 8 polymers, converts phr, wt%, ppm and let-down ratio, sets out a 7-step selection procedure, describes the 4 routes by which additives reach the melt, summarises the regulations that control them, lists the standards that measure their effect, and names the companies that make them. Each family carries its own hub, and the substance database behind those hubs holds 435 individual additives with CAS numbers, dosages and regulatory status.

Table T1. The 7 functional groups of plastic additives at a glance

Share by weight of global additive consumption (Wikipedia, Plastic additive); heat stabilizers take 5 %, impact modifiers 5 %, light stabilizers 1 % and other families 4 %.

What Are Plastic Additives?#

A plastic additive is a substance intentionally added to plastics to achieve a physical or chemical effect during processing or in the final material or article, and intended to be present in that final material or article (Regulation (EU) No 10/2011, Article 3(7)). ECHA applies the same definition in its Plastic Additives Initiative mapping exercise and extends it to pigments, so its record of the high-volume additives used in the EU holds 127 pigments among 418 substance entries. Which substances inside a plastic are therefore not additives?

Monomers, curing reactants, impurities, non-intentionally added substances (NIAS) and contaminants fall outside the definition, because none of them is both intentionally added and intended to stay. Polymer production aids sit outside it as well: catalysts, emulsifiers and chain-transfer agents are used to make the polymer rather than to modify it, and Article 3(8) of the same regulation names them as a separate class. The abbreviation PPA is ambiguous for this reason, since a polymer processing aid is an additive while a polymer production aid is not.

Why are additives added to plastics?#

Additives are added to plastics for 5 reasons: to make processing possible, to reach a performance target, to set the appearance, to extend service life and to meet a fire, food-contact or electrical requirement. Each reason maps onto a different part of the additive package.

• Processing. PVC releases hydrogen chloride from 100 to 120 °C, below its processing temperature, so every PVC compound carries a heat stabilizer and a lubricant package before it can be extruded at all.
• Performance. Flexible PVC contains 5 to 65 wt% plasticizer, which turns a rigid material into cable sheathing, flooring or medical tubing.
• Appearance. Pigments, clarifiers and matting agents set colour, haze and gloss, three properties the base polymer does not deliver on its own.
• Durability. Antioxidants, UV stabilizers and metal deactivators extend service life from months to decades in outdoor, cable and pipe applications.
• Compliance. A UL 94 V-0 rating requires that each specimen stops burning within 10 seconds and that 5 specimens total no more than 50 seconds of afterflame, a result only a flame retardant package delivers.

How much of a plastic is additive?#

The additive content of a plastic ranges from under 0.01 wt% for a biocide to about 70 wt% for plasticizers in very soft PVC, and most stabilizers sit between 0.05 and 3 wt%. The ranges below come from the review by John Hahladakis and colleagues at the University of Leeds (Journal of Hazardous Materials, 2018), as tabulated by Chea and colleagues in 2025.

Table T2. Typical additive content of finished plastic products by function

Ranges describe finished products, not recommended dosages. Curing agents (0.1 to 2 wt%) and residual catalysts (0.1 to 0.3 wt%) appear in the source table but are not additives in the EU sense.

The spread from 0.001 to 70 wt% has a practical consequence: a change of 1 wt% is a rounding error in a filled compound and a gross overdose for a biocide dosed at 0.001 wt%. It also explains why a single additive can dominate a bill of materials. Soft PVC at the top of the plasticizer range sits closer to half plasticizer than to pure polymer, while a polypropylene stabilizer package of 0.3 wt% costs more per kilogram than the resin it protects.

Which plastic additives are most common?#

Plasticizers are the most common plastic additives by weight, at 34 % of global additive consumption, followed by fillers at 28 % and flame retardants at 13 %. The 10 largest families by share of consumption by weight are ranked below.

1. Plasticizers, 34 %
2. Fillers, 28 %
3. Flame retardants, 13 %
4. Antioxidants, 6 %
5. Heat stabilizers, 5 %
6. Impact modifiers, 5 %
7. Colorants, 2 %
8. Lubricants, 2 %
9. Light stabilizers, 1 %
10. All remaining families together, 4 %

Ceresana measured the same class by tonnage in 2023 and reported 36.7 million tonnes of plastic additives in total, with fillers above 19.5 million tonnes and plasticizers above 8 million tonnes, an order that places fillers first rather than second. Rankings differ because analysts count fillers and reinforcing minerals differently, so the two lists are best read as one picture under two accounting rules.

Are pigments, fillers and catalysts additives?#

Pigments and fillers count as plastic additives, while polymerization catalysts do not: the ECHA mapping holds 127 pigments among its 418 substance entries, but EU law classes catalysts separately. Pigments qualify because they are intentionally added and intended to remain in the article. Fillers qualify for the same reason, and both the Hahladakis and Chea composition table and the Ceresana tonnage study count them inside the additive class. A polymerization catalyst fails the second test, because it acts on the monomer and is classed under Article 3(8) of Regulation (EU) No 10/2011 as a polymer production aid, not an additive.

43 Types of Plastic Additives in 7 Functional Groups#

The 43 types of plastic additives fall into 7 functional groups: property modifiers, fillers and reinforcements, flame retardants and other functional additives, stabilizers, colorants and masterbatch, processing modifiers, and surface and optical modifiers. The order of the groups follows the share of global consumption held by the largest family in each, and the order of families inside a group follows the same rule.

1. Property modifiers (8 families)#

Property modifiers are additives that change the bulk mechanical and thermal behaviour of a polymer; the group has 8 families: plasticizers, impact modifiers, nucleating agents, clarifying agents, crosslinking agents, chain extenders, compatibilizers and coupling agents. They act on the polymer chains themselves, on the crystal structure those chains form, or on the interface between two phases.

Plasticizers#

Plasticizers are esters and other low-volatility liquids that soften a polymer by placing their own molecules between the chains, which lowers the glass transition temperature and turns a rigid material flexible. ASTM D883 defines a plasticizer as a substance incorporated into a material to increase its flexibility, workability or distensibility.

Flexible PVC contains 5 to 65 wt% plasticizer, the widest dosage range of any additive family. European Plasticisers reports consumption of 8.4 million tonnes a year and states that more than 85 % of European plasticizer demand goes into flexible PVC. DEHP, DINP, DOTP, DINCH and TOTM are the volume products, and DEHP, DBP, BBP and DIBP have been limited to 0.1 % in all EU articles under REACH Annex XVII entry 51 since 7 July 2020. All 56 plasticizer substances in this reference are compared on the plasticizers hub.

Impact modifiers#

Impact modifiers are rubbery polymers such as MBS, chlorinated polyethylene (CPE) and polyolefin elastomers that disperse as small particles in a brittle plastic and absorb impact energy, stopping a crack before it runs through the wall of the part.

CPE is used at 1 to 10 phr in PVC and CPVC, with 2.5 to 7.0 phr the preferred range, and MBS at 5 to 6 phr in CPVC. Analysts place the impact modifier market between USD 3.9 billion and USD 5.0 billion for 2025. Grades by polymer are compared on the impact modifiers hub.

Nucleating agents#

Nucleating agents are fine particles or dissolved compounds that give a semi-crystalline polymer such as polypropylene more crystal nuclei, so it crystallises faster and at a higher temperature, which shortens moulding cycle time and raises stiffness.

NA-11 is authorised for food contact in the EU as FCM substance 749 with a specific migration limit of 5 mg/kg, and the FDA clears it at up to 0.30 wt%. HPN-20E and HPN-68L are further commercial grades. Crystallization temperature data are collected on the nucleating agents hub.

Clarifying agents#

Clarifying agents are nucleators, mostly sorbitol derivatives such as DMDBS, that make polypropylene crystals smaller than the wavelength of visible light, so the moulding scatters less light and haze falls sharply.

DMDBS is effective at 0.2 to 1 wt%, and the FDA caps it at 0.4 wt% in food-contact polypropylene. Irgaclear XT 386, a non-sorbitol clarifier, works at 150 to 200 ppm. Haze against dosage curves are given on the clarifying agents hub.

Crosslinking agents#

Crosslinking agents are peroxides, silanes and coagents that join polymer chains into a three-dimensional network, converting polyethylene into PEX or XLPE for hot-water pipe and power cable, grades that no longer melt.

PEX-a is produced with about 2 % peroxide, while vinyltrimethoxysilane (VTMS) and triallyl isocyanurate (TAIC) serve the silane and coagent routes. Crosslinked polyolefins take about 5 to 10 % of the polyethylene market. Dicumyl peroxide has been on the REACH Candidate List since 27 June 2024, classified as toxic for reproduction category 1B. Peroxide half-lives are tabulated on the crosslinking agents hub.

Chain extenders#

Chain extenders are multifunctional reactive additives, such as epoxy-functional styrene-acrylic oligomers, that re-link degraded polyester chains and restore molecular weight and melt strength.

Joncryl ADR is used at 0.1 to 0.5 wt% in PLA, and the same chemistry rebuilds intrinsic viscosity in recycled PET so that bottle flake can be extruded into sheet or spun into fibre. Grades for rPET and PLA are listed on the chain extenders hub.

Compatibilizers#

Compatibilizers are block or graft copolymers, such as maleated polypropylene, that bind two immiscible polymers across their interface in a blend or a mixed recyclate, so the blend carries load as one material instead of separating.

A polyolefin elastomer at 2 to 5 %, typically 3 %, in a 70/30 HDPE and PP recyclate roughly triples both impact strength and elongation at break. POLYBOND at 5 % roughly triples Izod impact in recycled PP and nylon blends. Blend pairs are matched to chemistries on the compatibilizers hub.

Coupling agents#

Coupling agents are silanes, titanates and maleated polyolefins that bond an inorganic filler or a glass fibre chemically to the polymer matrix, so stress transfers across the interface instead of stopping at it.

In polypropylene composites, maleic anhydride grafted polypropylene (MAPP) gives its best flexural result at 1 wt%, an increase of 24.7 %, and its best tensile result at 3 wt%. Aminosilanes such as APTES treat glass fibre and mineral surfaces before compounding. Silane and MAPP selection is worked through on the coupling agents hub.

2. Fillers and reinforcements (2 families)#

Fillers and reinforcements are solid particles and fibres that replace polymer volume or carry mechanical load; together they make up 28 % of additive consumption by weight, the second largest share of any group and the largest by tonnage in the Ceresana count.

Fillers#

Fillers are mineral powders such as calcium carbonate, talc and barium sulfate that replace polymer volume, lower cost and raise stiffness and heat deflection temperature, at loadings up to 50 wt% of the product.

Calcium carbonate runs at 20 to 40 % in polypropylene, 15 to 20 % in unplasticised PVC drainpipe and up to 70 phr in PVC cable compound. Barium sulfate reaches 70 % in polypropylene and polystyrene where density or radiopacity matters, and talc and silica cover the stiffness and anti-blocking roles. Ceresana put filler consumption above 19.5 million tonnes in 2023, the largest single additive volume. The 13 mineral fillers in this reference are compared on the fillers hub.

Reinforcing fibres#

Reinforcing fibres are glass, carbon and natural fibres that carry mechanical load inside the polymer, usually at 15 to 30 wt%, and they raise tensile strength and modulus rather than stiffness alone.

Flame-retardant polyamides carry 10 to 50 % glass fibre, the highest routine loading of any thermoplastic family. Fibres enter a twin-screw compounder through a side feeder downstream of the melting zone, which keeps the shear that would break them short. Loadings by polymer are listed on the reinforcing fibres hub.

3. Flame retardants and other functional additives (12 families)#

Functional additives give a plastic a property it does not have on its own, such as fire resistance, a foam structure, antimicrobial or barrier action; flame retardants are the largest of these 12 families at 13 % of additive consumption. The other 11 families are small by tonnage and decisive for the application they serve.

Flame retardants#

Flame retardants are mineral, phosphorus, nitrogen and halogen compounds that delay ignition, slow flame spread and cut the rate of heat release, at 2 to 28 wt% of the plastic, acting in the gas phase, in the condensed phase or by endothermic decomposition.

An intumescent ammonium polyphosphate system needs 22 to 30 wt% to reach UL 94 V-0 in polypropylene, while halogen-free cable compounds carry 160 to 180 phr of aluminium trihydroxide (ATH) or magnesium dihydroxide. ATH releases its water of hydration from about 200 °C and absorbs 1,051 J/g in doing so, which both cools the substrate and dilutes the fuel gases. Analysts value the flame retardant market between USD 8.1 billion and USD 9.3 billion for 2025. The UL 94 routes available in each polymer are set out on the flame retardants hub.

Blowing agents#

Blowing agents are gases or gas-releasing chemicals that create a cellular foam structure in the melt, cutting part weight and adding thermal insulation.

They are used at 0.05 to 20 wt% of the product. Azodicarbonamide, the classic chemical blowing agent, is cleared by the FDA at up to 5 wt% in foamed polyethylene under 21 CFR 178.3010 and has been on the REACH Candidate List since 19 December 2012. Physical blowing agents such as hydrofluoroolefins (HFOs) are injected into the melt as liquids or gases instead of decomposing in it. Decomposition temperatures are tabulated on the blowing agents hub.

Antimicrobials#

Antimicrobial additives are biocides such as silver-zinc zeolite and zinc pyrithione that stop bacteria or fungi growing on a plastic surface, at 0.001 to 1 wt%, and they protect the article rather than the user.

Silver zinc zeolite is approved under the EU Biocidal Products Regulation for product types 2, 7 and 9 from 1 March 2026 to 29 February 2036. DCOIT is a second common active substance. The treated-article rules that apply to the finished plastic are explained on the antimicrobial additives hub.

Oxygen scavengers#

Oxygen scavengers are active packaging additives, typically an oxidisable polymer with a metal catalyst, that bind the oxygen passing through PET bottles and trays, extending the shelf life of beer, juice and sauces.

The common system pairs MXD6 polyamide with cobalt stearate (CAS 13586-84-0) as catalyst. EFSA could not conclude on the safety of a polyester-cyclohexene-oxide system with cobalt stearate in 2022, and cobalt carries a specific migration limit of 0.05 mg/kg in the EU. Competing systems are compared on the oxygen scavengers hub.

Barrier additives#

Barrier additives are platelet fillers such as nanoclay and barrier polymers such as MXD6 that lengthen the path a gas molecule must travel through a packaging wall, cutting oxygen or carbon dioxide transmission without a second layer.

The European PET Bottle Platform allows up to 5 % MXD6 in clear PET and 6 % in coloured PET before recyclability is affected. An organoclay authorised as FCM 1030 is limited to 12 % w/w in polyolefins. Passive and active barrier routes are compared on the barrier additives hub.

Odour control additives#

Odour control additives are adsorbents such as zeolites and reactive zinc salts that trap volatile odorants, and they matter most in recycled plastics, where residues of the previous contents remain in the polymer.

A zeolite at 4 wt% cut the measured odour intensity of a recyclate by 45 %. Zinc ricinoleate is the common reactive type, binding sulfur and amine odorants chemically. Adsorbent and reactive chemistries are compared on the odour control additives hub.

Laser marking additives#

Laser marking additives are laser-absorbing pigments such as bismuth oxide that turn an unmarkable plastic into one that takes a sharp permanent mark from a laser beam, replacing ink printing on cables, medical devices and electrical parts.

Graphene at 50 ppm produced dark laser marks in polypropylene. Nd:YAG lasers at 1,064 nm are the usual energy source, and contrast depends on the pigment absorbing at that wavelength. Contrast data by polymer are given on the laser marking additives hub.

IR absorbers and reheat additives#

IR absorbers are near-infrared-absorbing particles such as titanium nitride and lanthanum hexaboride that speed preform heating in PET stretch blow moulding or block solar heat in glazing.

A reheat additive is dosed at about 5 ppm in carbonated soft drink PET, where it cuts oven time without visible haze. Titanium nitride is authorised as FCM 807 for PET only, up to 20 mg/kg. Cesium tungsten oxide serves the solar-control side of the family. Grades by application are listed on the IR absorbers hub.

Tracers#

Tracer additives are fluorescent or spectroscopic markers, dosed at about 100 ppm, that let a sorting line or a brand owner identify a plastic.

Tracer-based sorting reads the marker under near-infrared or fluorescent excitation and separates a food-grade stream from an identical-looking non-food one. The same chemistry serves anti-counterfeiting, where the marker proves origin. Sorting and marking systems are described on the tracer additives hub.

Repellents#

Repellent additives are insecticides and bittering agents such as bifenthrin and permethrin that protect cable jackets and buried pipes from rodents and termites.

They are compounded into the outer layer, where the attack starts, rather than through the whole wall, which keeps the loading and the cost down. Jacket and pipe formulations are described on the anti-rodent and anti-termite additives hub.

Biodegradation additives#

Biodegradation additives are pro-oxidant metal salts or enzymes that accelerate the breakdown of conventional plastics, and oxo-degradable products using them have been banned in the EU since 3 July 2021 under Article 5 of Directive (EU) 2019/904.

Pro-oxidant masterbatches based on iron, manganese and cobalt salts were used at about 2 % w/w in the published studies. EN 13432, the European compostability standard, requires at least 90 % biodegradation within 6 months, a threshold oxo-degradation does not reach, which is the basis of the ban. The evidence and the bans are set out on the biodegradation additives hub.

Tribological additives#

Tribological additives are solid lubricants such as PTFE, silicone, molybdenum disulfide and graphite that lower the coefficient of friction and the wear rate in plastic gears, bearings and slides.

They work by forming a transfer film on the mating surface rather than by changing the melt. PTFE falls within the scope of the universal PFAS restriction proposed in the EU, which is pending, so silicone and graphite alternatives are being qualified. Wear and friction data are collected on the tribological additives hub.

4. Stabilizers (6 families)#

Stabilizers are additives that protect a polymer against heat, oxygen, light, acids, metal ions and water; the group has 6 families, led by antioxidants at 6 % of additive consumption. Each family answers one degradation mechanism, and a real formulation normally carries two or three of them together.

Antioxidants#

Antioxidants are hindered phenols, phosphites and thioesters that interrupt the oxidation chain reaction during processing and in service, at 0.05 to 3 wt% of the plastic. Primary antioxidants donate hydrogen to peroxy radicals, while secondary antioxidants decompose the hydroperoxides those radicals leave behind.

Irganox 1010, a hindered phenol, is used at 0.05 to 0.4 wt% in polyolefins and Irgafos 168, a phosphite, at 0.05 to 0.2 wt%, almost always in combination. Mordor Intelligence valued the polymer antioxidant market at USD 5.41 billion in 2025. Grades and oxidative induction time data are compared on the antioxidants hub.

PVC heat stabilizers#

PVC heat stabilizers are calcium-zinc, organotin and other metal compounds that neutralise the hydrogen chloride PVC releases from 100 to 120 °C, at 1 to 5 % of the formulation, and they also replace the labile chlorine atoms where that loss begins.

Without one, PVC discolours and then degrades before it reaches processing temperature. Calcium-zinc and calcium-organic systems account for 83 % of EU stabilizer use according to VinylPlus (2023). Lead compounds have been limited to below 0.1 % in PVC articles since 29 November 2024 under REACH Annex XVII entry 63, introduced by Regulation (EU) 2023/923. Calcium-zinc, tin and legacy lead systems are compared on the PVC heat stabilizers hub.

UV stabilizers#

UV stabilizers are hindered amine light stabilizers (HALS), UV absorbers and screening pigments that protect plastics against sunlight, and about 70 % of all light stabilizers go into polyolefins.

HALS are used at 0.05 to 1.0 wt% in thick sections and trap the radicals formed under UV light in a regenerating cycle, so they are not consumed as quickly as a UV absorber that simply converts photons to heat. The benzotriazole UV-328 was listed under the Stockholm Convention in 2023. MarketsandMarkets valued the UV stabilizer market at USD 2.53 billion in 2024. HALS and UV absorber selection is worked through on the UV stabilizers hub.

Acid scavengers#

Acid scavengers are basic salts such as calcium stearate and hydrotalcite that neutralise the acidic catalyst residues left in polyolefins after polymerisation, protecting both the polymer and the steel of the extruder.

Calcium stearate is used at up to 1,000 ppm in polypropylene. Hydrotalcite (CAS 12304-65-3) and zinc oxide take over where a higher neutralisation capacity is needed. Capacities and dosages are compared on the acid scavengers hub.

Metal deactivators#

Metal deactivators are chelating compounds such as Irganox MD 1024 that bind copper and other metal ions, which otherwise catalyse hydroperoxide decomposition and accelerate oxidation from the inside of the insulation outwards.

Their main use is polyolefin insulation in direct contact with a copper conductor. Irganox MD 1024 is authorised in the EU as FCM 675 with a specific migration limit of 15 mg/kg, and Naugard XL-1 is a second commercial grade. Chelating chemistries are described on the metal deactivators hub.

Hydrolysis stabilizers#

Hydrolysis stabilizers are carbodiimides and similar acid scavengers that protect polyesters, polyurethanes and PLA against chain scission by water, by capping the carboxyl end groups that autocatalyse the reaction.

A monomeric carbodiimide (CAS 2162-74-5) is authorised as FCM 438 with a specific migration limit of 0.05 mg/kg. Rudolf Pfaendner and colleagues at Fraunhofer LBF held molecular weight loss to about 10 % after 850 hours using an aziridine system. Carbodiimide and aziridine routes are compared on the hydrolysis stabilizers hub.

5. Colorants and masterbatch (2 families)#

Colorants give a plastic its colour and opacity, and masterbatch is the concentrated pellet form in which colorants and most other additives reach the processor. The two belong together because the delivery form decides how accurately the colour is dosed.

Colorants#

Colorants are pigments and dyes, such as titanium dioxide, carbon black and phthalocyanines, used at 0.01 to 5 wt% to colour or opacify plastics; pigments stay as discrete particles in the melt while dyes dissolve in it.

The ECHA mapping records organic pigments mostly at 2 wt% and titanium dioxide and complex inorganic colour pigments at 5 wt%. Colorants sit outside the Union list of Regulation (EU) No 10/2011 except for named entries such as carbon black (FCM 411) and titanium dioxide (FCM 610). Titanium dioxide has no harmonised EU classification: the General Court annulled it on 23 November 2022 and the appeals against that judgment were dismissed on 1 August 2025. Pigment classes are compared on the colorants hub.

Masterbatch#

Masterbatch is a concentrate of pigment or additive in a carrier resin, supplied as pellets and let down by the processor at a fixed ratio, so a converter doses a few per cent of pellets instead of handling powders at the machine.

A black pipe masterbatch carrying 35 % carbon black is let down at 5 to 6.5 %, a ratio of 19:1 to 14:1, which puts roughly 2 wt% carbon black into the pipe wall. Colour masterbatch for pipe runs at 2 to 4 %. Masterbatch types and let-down ratios are set out on the masterbatch hub.

6. Processing modifiers (7 families)#

Processing modifiers make a polymer easier to melt, shape, release and handle; the group has 7 families: lubricants, polymer processing aids, mold release agents, slip agents, antiblock additives, dispersing agents and desiccants. They are judged by what happens in the extruder and at the die rather than by a property of the finished part.

Lubricants#

Processing lubricants are waxes, metal stearates and fatty amides that lower friction inside the melt and between the melt and hot metal, at 0.1 to 3 wt%. Internal lubricants cut melt viscosity, while external lubricants form a film on the screw, the die and the calibration tooling.

A rigid PVC pipe package combines paraffin wax at 0.6 to 1.5 phr, calcium stearate at 0.6 to 1.5 phr and oxidised polyethylene wax at 0.1 to 0.2 phr. The internal and external balance is explained on the processing lubricants hub.

Polymer processing aids#

Polymer processing aids are fluoropolymers and acrylic polymers that remove melt fracture in film extrusion or speed fusion in PVC, by coating the die wall or by building melt strength in the compound.

Under 21 CFR 177.1520 a fluoropolymer processing aid is limited to 0.2 wt% for grades containing 65 to 71 % fluorine and to 1.0 wt% for grades containing at least 87 % vinylidene fluoride. The proposed universal PFAS restriction in the EU is pending, which is why PFAS-free acrylic alternatives are being qualified. Those alternatives are compared on the polymer processing aids hub.

Mold release agents#

Mold release agents are internal additives or external coatings, such as pentaerythritol tetrastearate, that stop a moulded part sticking to the tool, cutting cycle time and scrap rate.

Internal types migrate slowly to the part surface during cooling and act at the moment of ejection. Pentaerythritol tetrastearate is limited to 0.5 wt% as a mould release in food-contact polycarbonate under 21 CFR 177.1580. Internal and external routes are compared on the mold release agents hub.

Slip agents#

Slip agents are fatty acid amides such as erucamide and oleamide that bloom to a film surface and lower its coefficient of friction, at 500 to 1,200 ppm, so that bags open and film runs on packaging machines.

In LDPE and LLDPE film the dose is 0.05 to 0.12 wt%. Erucamide delivers most of its friction drop within 24 to 48 hours and reaches its final coefficient of friction after 7 to 10 days, measured by ASTM D1894. Erucamide is authorised in the EU as FCM 271. Erucamide against oleamide is compared on the slip additives hub.

Antiblock additives#

Antiblock additives are mineral particles such as diatomaceous earth, talc and synthetic silica that roughen a film surface on a micro scale so that two layers do not stick together.

Diatomaceous earth and talc are used at 2,500 to 10,000 ppm, calcium carbonate at 2,500 to 20,000 ppm and precipitated synthetic silica below 0.5 wt%. Nepheline syenite is chosen where optical clarity has to be preserved. The minerals are compared side by side on the antiblock additives hub.

Dispersing agents#

Dispersing agents are waxes and surfactant-type esters that wet pigment particles and break up agglomerates, so full colour strength is reached with less pigment.

Einar 103, a polyglycerol ester type, is used at 1 to 5 % in colour masterbatch according to its supplier. Wetting and grinding behaviour is described on the dispersing agents hub.

Desiccants#

Desiccants are moisture-binding minerals such as calcium oxide, supplied as a masterbatch, that remove water from wet or recycled resin during processing, preventing voids, streaks and surface defects.

They bind the water chemically rather than adsorbing it, which is why they work inside the melt instead of in a hopper dryer. Dosage follows the moisture content of the incoming resin. Grades and carriers are listed on the desiccant masterbatch hub.

7. Surface and optical modifiers (6 families)#

Surface and optical modifiers change what happens at the surface of a plastic or how light passes through it; the group has 6 families: antistatic agents, antifog additives, anti-scratch additives, matting agents, light diffusers and cling agents. Most of them work by migrating to the surface, so their effect builds over hours or days rather than at the die.

Antistatic agents#

Antistatic agents are migrating surfactants such as glycerol monostearate, permanent conductive polymers and conductive carbon black that drain static charge from a plastic surface, at 0.1 to 1 wt%.

ANSI/ESD S541 classes a surface as static dissipative between 1.0 x 10^4 and 1.0 x 10^11 ohm. Glycerol monostearate and ethoxylated amines together hold more than half the antistatic market, and the ethoxylated amines carry a group specific migration limit, group 7, of 1.2 mg/kg. Resistivity targets by application are listed on the antistatic agents hub.

Antifog additives#

Antifog additives are non-ionic surfactants such as polyglycerol and sorbitan esters that spread condensed water into a continuous clear layer instead of droplets, keeping packed food visible on the shelf.

Polypropylene film needs 0.5 to 2.0 % and polyethylene film 0.2 to 0.6 % of the Palsgaard grades. Grades are split into cold fog and hot fog types according to the temperature at which the condensation forms. Both are compared on the antifog additives hub.

Anti-scratch additives#

Anti-scratch additives are fatty amides and silicone masterbatches that lower surface friction so that talc-filled polypropylene and other interior plastics show fewer visible scratches.

They migrate to the surface and cut the force the scratching tip transmits into the polymer. Silicone types can conflict with paintability, so a part that will be painted normally takes the amide route. The trade-off is set out on the anti-scratch additives hub.

Matting agents#

Matting agents are particles and incompatible polymers that roughen a moulded surface on a micro scale to lower its gloss, giving a matt finish without a coating step.

Gloss is measured by ASTM D523 or ISO 2813 at a fixed angle, so every matting result is quoted together with that angle. Particulate and polymeric types are compared on the matting agents hub.

Light diffusers#

Light diffusers are particles with a refractive index different from the matrix that scatter light inside polycarbonate and PMMA covers, hiding LED point sources behind an even glow.

A material with haze above 30 % counts as diffusing and is measured by ASTM E2387 rather than by the ASTM D1003 haze method used for transparent plastics. Bead chemistries and loadings are listed on the light diffusers hub.

Cling agents#

Cling agents are tacky low-molecular-weight polymers, mainly polyisobutylene, that make stretch film stick to itself, so a wrapped pallet holds without tape.

Polyisobutylene is the standard cling polymer for polyethylene stretch film, and it migrates to the surface after extrusion. Film structures and dosages are described on the cling agents hub.

Complete List of Plastic Additives: All 43 Families in One Table#

The complete list of plastic additives below gives all 43 families with their group, main function, typical level, main host polymers and example substances. Row order follows the group order and the family order used throughout this page, and every value repeats a fact stated above.

Table T3. The complete list of plastic additives: all 43 families

Each example substance links onward from its family hub to 435 substance pages in the plastic additives database, where CAS number, dosage, food-contact status and restriction status are given per substance.

How Do Plastic Additives Work?#

Plastic additives work in 3 ways: physically inside the bulk, chemically by reacting with degradation products, or at the surface after migrating there. Plasticizers and fillers act physically, by sitting between the chains or by replacing polymer volume with mineral. Antioxidants, HALS and PVC heat stabilizers act chemically, by trapping radicals, decomposing hydroperoxides or neutralising the hydrogen chloride the polymer releases. Slip agents, antistatic agents and antifog additives act at the surface, and they only work once enough of the additive has reached it.

Additives that stay in the polymer and additives that migrate#

Some additives are designed to migrate, such as erucamide, which blooms to a film surface within 24 to 48 hours, while others, such as oligomeric HALS and polymeric plasticizers, are chosen because they stay in the polymer. Glycerol monostearate antistats sit in the first group and give a short-term effect measured in weeks rather than years, because the surfactant that has reached the surface is eventually wiped or washed away.

Unwanted migration is the same physics with the opposite sign. A low-molecular-weight plasticizer moves out of PVC into air, fatty food or a solvent, which softens the article less over time and puts the additive somewhere it was not intended to be. Migration and extraction are measured by ASTM D1203, ISO 177 and ASTM D1239, and for food contact the EU caps total migration from the article at an overall migration limit of 10 mg/dm2. Diffusion models and worked migration calculations are collected on additive migration.

Synergy and antagonism between additives#

Additives interact: a phosphite and a phenolic antioxidant protect polyolefins better together than either alone, while thioester antioxidants and acidic flame retardants weaken HALS. A formulation is therefore a package, not a sum of single decisions, and changing one component can undo the effect of another.

The pairs that reinforce each other are listed below.

• Primary phenolic and secondary phosphite antioxidants, at a phosphite to phenol ratio of 1:1 to 4:1
• HALS with a UV absorber, one trapping radicals and the other absorbing the photons
• Antimony trioxide with a halogenated flame retardant
• A nucleating agent with a clarifier in polypropylene
• PTFE anti-drip with a flame retardant in PC and ABS

The pairs that work against each other are listed below.

• HALS with thioester antioxidants
• HALS with acidic flame retardants, which deactivate the amine
• Slip agents with antistatic agents, which compete for the same surface
• Anti-scratch silicone with paintability, where the additive that lowers friction also lowers paint adhesion

A full interaction matrix covering all 43 families is being built as additive interactions.

Which Additives Does Each Polymer Need?#

Each polymer needs an additive package matched to its weakness: PVC needs heat stabilizers because it loses hydrogen chloride from 100 to 120 °C, polypropylene needs antioxidants and HALS because its tertiary carbons oxidise, and polyamides need copper-halide heat stabilizers for long-term heat ageing. The package is therefore predictable from the chemistry of the chain rather than chosen freely, and every polymer has a formulation guide under additives by polymer.

Table T4. Additive packages by polymer

How Are Additive Levels Expressed? phr, wt%, ppm and Let-Down Ratio#

Additive levels are expressed in 4 units: phr (parts per hundred resin) for PVC and rubber, wt% for most thermoplastics, ppm for trace additives, and let-down ratio for masterbatch. The 4 units describe the same quantity from different reference points, so a formulation is only unambiguous once the unit is named.

• phr. Parts by weight of the additive per 100 parts of resin. A PVC pipe formulation of 100 parts resin plus 8.03 parts of additives totals 108.03 phr.
• wt%. Parts by weight of the additive per 100 parts of the whole compound. The conversion is wt% = phr of the component divided by total phr, times 100.
• ppm. Parts per million by weight, used where a wt% figure would need leading zeros, as for slip agents at 500 to 1,200 ppm.
• Let-down ratio. The dilution at which a masterbatch is added, written as resin to masterbatch.

A worked example makes the first conversion concrete. In the PVC pressure pipe formulation published by the Plastics Pipe Institute in TR-2, the components total 108.03 phr, so the 100 phr of PVC resin becomes 92.57 wt% of the finished compound and every additive is correspondingly diluted. A tin stabilizer specified at 0.3 to 1.0 phr in US PVC pressure pipe therefore sits between 0.28 and 0.93 wt% of the pipe wall. The full set of conversion rules is on PHR (parts per hundred resin).

Masterbatch is the one case where the unit refers to a product rather than to the compound. A 35 % carbon black concentrate let down at 5 to 6.5 % corresponds to a let-down ratio of 19:1 to 14:1 and delivers about 2 wt% carbon black. Any masterbatch dose can be checked in both directions with the let-down ratio calculator.

How Do You Select Plastic Additives? 7 Steps#

Select plastic additives in 7 steps: define the property gap, identify the host polymer, check the processing temperature, define the end use, screen the regulations, check interactions, then set the dosage and test. The order matters, because each step removes candidates that the next step would otherwise have to evaluate.

1. Define the property gap. State the property the compound misses and the target value with its test method, for example UL 94 V-0 at 1.6 mm rather than better flame performance.
2. Identify the host polymer and grade. Solubility, polarity and crystallinity decide whether an additive stays where it is needed, so the polymer grade should be fixed before the additive is chosen.
3. Check the processing method and temperature. Engineering polymers process at 240 to 320 °C, which rules out aluminium trihydroxide, since it releases water from about 200 °C, and most ammonium polyphosphate grades.
4. Define the end-use environment. Outdoor exposure, food contact, fire performance and electrical requirements each pull in a different family, and they should be listed together before any candidate is priced.
5. Screen the regulatory status in every target market. An additive that is compliant in one market should be checked against the EU Union list and specific migration limits, the relevant 21 CFR sections and the restriction lists of every market the article is sold in.
6. Check interactions with the rest of the package. A thioester antioxidant should not be combined with HALS, and an acidic flame retardant weakens the same stabilizer.
7. Set the dosage, calculate cost in use and confirm by testing. Cost in use follows from the dosage and the density of the compound, not from the price per kilogram of the additive alone.

Each of the 7 steps is worked through with examples on how to select plastic additives. Families can also be filtered by polymer and function with the plastic additive selector.

How Are Additives Added to Plastics?#

Additives reach the polymer in 4 ways: melt compounding on a twin-screw extruder, masterbatch let down at the processing machine, dry blending, which is standard for PVC, and direct dosing of liquids or powders. The route decides how evenly the additive is distributed and how much handling the processor takes on.

• Melt compounding. A twin-screw extruder melts the polymer and disperses the additives into it, with fillers and fibres fed downstream through a side feeder so they are not broken by the full shear of the screw.
• Masterbatch. The additive is pre-dispersed in a carrier resin and supplied as pellets, so the converter meters pellets into pellets at a fixed let-down ratio instead of handling powder.
• Dry blending. PVC powder and its additives are mixed in a hot mixer and then cooled in a cold mixer, producing a free-flowing dry blend that feeds directly to pipe and profile extruders.
• Direct dosing. Liquids and powders are metered into the throat of the processing machine, which suits low-volume additives and colour changes but demands accurate gravimetric feeding.

Twin-screw set-ups, screw configurations and feeding positions are described on plastic compounding. The same additive is often sold in 5 physical forms, and powder, granules, pastilles, liquids and dust-free blends each suit a different one of the 4 routes above; those additive product forms are compared separately.

How Are Plastic Additives Regulated?#

Plastic additives are regulated in 4 layers: chemical registration and restriction, food-contact positive lists, persistent-pollutant bans, and product rules for toys, packaging and electronics. The EU works through REACH and CLP in the first layer, Regulation (EU) No 10/2011 in the second, the POPs Regulation in the third and sector regulations in the fourth; the United States works through TSCA, 21 CFR and state law such as California Proposition 65.

Table T5. The 8 instruments that control plastic additives

Every instrument in the table is summarised, with its entry numbers and dates, in plastic additive regulations.

Food-contact rules: EU 10/2011 and US FDA#

Food-contact plastics in the EU may contain only additives on the Union list of Regulation (EU) No 10/2011, within an overall migration limit of 10 mg/dm2 and each substance specific migration limit. The generic specific migration limit is 60 mg/kg where no substance-specific value is set, the overall migration limit is expressed as 60 mg/kg for food intended for infants, and a substance behind a functional barrier is capped at 0.01 mg/kg. Phthalate limits have applied since Regulation (EU) 2023/1442, which sets DEHP at 0.6 mg/kg. Union list entries, FCM numbers and the migration testing rules are set out on EU 10/2011.

The United States works from a different starting point. Additives are cleared for named uses in 21 CFR, with 178.2010 covering antioxidants and stabilizers and setting limits per polymer, and 178.3740 covering plasticizers. The FDA final rule of 20 May 2022 left 8 ortho-phthalates authorised as food-contact plasticizers. Substances migrating below the Threshold of Regulation of 0.5 parts per billion in the diet can be exempted from a food additive listing. No additive is ever FDA approved as a substance: it is cleared for a use, under conditions, and the 21 CFR sections are mapped family by family on FDA food contact rules.

Restricted additives: REACH, POPs, Prop 65 and TSCA#

The most restricted plastic additives are low-molecular-weight ortho-phthalates, lead stabilizers and persistent pollutants such as UV-328: DEHP, DBP, BBP and DIBP have been limited to 0.1 % in all EU articles since 7 July 2020. The 6 landmark restrictions that shape formulation practice today are listed below.

1. REACH Annex XVII entry 51. DEHP, DBP, BBP and DIBP at or below 0.1 % by weight in all articles since 7 July 2020.
2. REACH Annex XVII entry 52. DINP, DIDP and DNOP in mouthable toys and childcare articles only; DINP is not banned in the EU.
3. REACH Annex XVII entry 63. Lead in PVC below 0.1 % since 29 November 2024, introduced by Regulation (EU) 2023/923, with recovered rigid PVC allowed below 1.5 % until 28 May 2033.
4. Stockholm Convention listing of UV-328. Adopted as SC-11/11 in 2023, with EU limits of 100 mg/kg from 2025, 10 mg/kg from 2027 and 1 mg/kg from 2029.
5. Stockholm Convention listing of MCCP. Adopted at COP-12 in 2025; the EU delegated regulation C(2026) 6262 has been adopted by the Commission but is not yet in force.
6. US TSCA and California Proposition 65. Final TSCA risk evaluations for BBP, DBP, DCHP, DEHP and DIBP were noticed on 6 January 2026 (91 FR 373), and DEHP has been listed under Proposition 65 since 1 January 1988.

Entries 51, 52 and 63 are explained clause by clause on REACH Annex XVII restrictions. Candidate List status is the earlier warning signal, because a substance of very high concern triggers supply-chain communication duties before any restriction exists, and every listed additive is tracked on the SVHC Candidate List. The Stockholm listings and their EU implementation are covered under POPs in plastics, and the US programme under TSCA and plastic additives.

How Are Additive Effects Tested?#

Each additive family has a standard test: UL 94 and the limiting oxygen index for flame retardants, oxidative induction time for antioxidants, xenon-arc weathering for UV stabilizers and the coefficient of friction for slip agents. A dosage claim is only meaningful with the method and the edition of the standard beside it, because editions change the specimen, the conditioning or the calculation.

Table T6. Test methods by additive family

All of these methods, with their typical values and the way each additive family shifts them, are indexed under testing plastic additives.

Who Makes Plastic Additives? Market Size and Suppliers#

The plastic additives market is worth between USD 43.5 billion (2023, MarketsandMarkets) and USD 63.71 billion (2025, Precedence Research), depending on how analysts define it, and totals about 36.7 million tonnes a year (Ceresana, 2023). The spread between the two value figures is a definition problem rather than a growth figure, because analysts differ on whether fillers, reinforcements and masterbatch belong inside the market. Asia-Pacific accounts for more than 50 % of volume according to Ceresana. Segment data by family and region are collected on the plastic additives market page.

Table T7. 10 producers of plastic additives, their headquarters and brand lines

Consolidation shaped this list: BASF completed its acquisition of Ciba on 9 April 2009, which brought the Irganox, Irgafos and Tinuvin lines into one portfolio. Company profiles, site lists and product ranges are held in the directory of plastic additive manufacturers and suppliers, and the producers are ranked by additive sales and by family on largest plastic additive companies.

Are Plastic Additives Harmful to Health and the Environment?#

Some plastic additives are harmful and restricted, such as the reproductive toxicant DEHP and the persistent pollutant UV-328, while many others, such as most antioxidants and fillers, carry no harmonised hazard classification. DEHP carries the harmonised classification H360FD under CLP, antimony trioxide is classified as Carc. 2, and UV-328 is listed under the Stockholm Convention. Titanium dioxide sits at the other end of the same scale, with no harmonised EU classification at all after the General Court annulment of 23 November 2022 and the dismissal of the appeals on 1 August 2025. Restriction is the control mechanism: the instruments listed above remove or cap the additives that fail assessment, family by family and use by use. A full list of the substances of concern is being compiled as toxic plastic additives.

How many chemicals are used in plastics?#

More than 16,000 chemicals are associated with plastics, and more than 4,200 of them are of concern, according to the PlastChem project led by Martin Wagner at NTNU in its report of 14 March 2024. Monclús, Wagner and colleagues put the count at 16,325 in Nature in 2025. UNEP reported more than 13,000 chemicals with more than 3,200 having one or more hazardous properties in 2023. Wiesinger, Wang and Hellweg at ETH Zürich identified more than 10,000 substances used in plastics in Environmental Science and Technology in 2021, of which more than 2,400 were of potential concern and 901 were approved for food-contact plastics in at least one jurisdiction. The ECHA mapping counts over 400 high-volume additives specifically in the EU, a much smaller number because it covers additives alone.

Which plastic additives are toxic or restricted?#

The additives most often restricted as toxic are low-molecular-weight ortho-phthalates, lead and organotin stabilizers, brominated flame retardants and a few benzotriazole UV absorbers. Ortho-phthalates such as DEHP, DBP, BBP and DIBP fall under REACH Annex XVII entry 51, lead stabilizers under entry 63 and organotin compounds under entry 20. HBCD and decaBDE are controlled as persistent organic pollutants, and UV-328 joined them in 2023. Bisphenols in food contact are regulated separately by Regulation (EU) 2024/3190, in force since 20 January 2025, although BPA is a monomer rather than an additive and so falls outside this reference. Exposure routes and the toxicological endpoints behind the phthalate restrictions are set out on phthalates: health effects.

Do plasticizers leach out of plastic over time?#

Yes: plasticizers are not chemically bound to PVC, so they migrate slowly to the surface and into fatty foods, oils and solvents, which is why the EU limits DEHP migration into food to 0.6 mg/kg. The rate depends on the molecular weight of the plasticizer, the temperature and the medium in contact with the article, and polymeric plasticizers are chosen where loss has to be minimised. Migration and extraction are measured by ISO 177 and ASTM D1239. The mechanisms, the tests and the prevention routes are covered in detail under plasticizer migration.

What are the four types of additives?#

No standard defines exactly four types of plastic additives: short summaries usually group them into functional additives, colorants, fillers and reinforcements, while this reference splits them into 7 functional groups and 43 families. The four-way split is a simplification used in overview articles; it has no basis in a standard or a regulation, and it hides the distinction between stabilizers and processing additives that matters most in formulation.

How do additives affect plastic recycling?#

Additives affect recycling in both directions: legacy additives such as lead and DEHP travel into recyclate, while restabilizing antioxidants at 0.1 to 0.3 wt% let recycled polyolefins be processed again. Wiesinger and colleagues found in 2024 that 16 % of Swiss floorings sampled contained regulated chemicals above 0.1 wt%, mainly lead and DEHP. Recovered rigid PVC may still contain below 1.5 % lead until 28 May 2033 under the transitional rule of Annex XVII entry 63. Oxo-degradable additives work the other way and make polypropylene packaging unrecyclable according to the Association of Plastic Recyclers. Which additive choices raise or lower recyclability is set out on design for recycling, and the substances carried over from earlier decades are tracked as legacy additives in recycled plastic.

A short history of plastic additives#

The history of plastic additives runs from plasticized cellulose to modern stabilizer chemistry, and it is traced step by step on the history page. Two dated milestones sit inside this reference: the radical-trapping cycle that explains how HALS work is named after E. T. Denisov, who described it in 1991, and BASF completed its acquisition of Ciba on 9 April 2009, which consolidated much of the stabilizer industry into one portfolio. The FDA issued its public health notification on DEHP in medical devices on 12 July 2002. The full chronology is collected under history of plastic additives.