Additives for Wire and Cable Compounds: PVC, LSZH/HFFR and XLPE in 10 Additive Functions

A wire and cable compound is the plastic that is extruded onto a conductor as insulation, bedding or sheath, and it carries 10 additive functions, from the flame retardant that can make up more than half its weight down to the metal deactivator dosed at a fraction of a percent. The same conductor can be covered with flexible PVC, an LSZH polyolefin filled with 160 to 180 phr of mineral, or peroxide-crosslinked polyethylene, so which package belongs to which compound?

A wire and cable compound carries 10 additive functions in the order a compounder fixes them: flame retardants and smoke suppressants, plasticizers, heat stabilizers, lubricants and processing aids, fillers, antioxidants, metal deactivators, crosslinking agents and catalysts, coupling agents, and colorants and conductive additives.

This reference covers the 3 compound families side by side: flexible PVC insulation and sheath, LSZH and HFFR polyolefin-EVA compounds, and XLPE and silane-crosslinked polyethylene insulation, alongside the smaller compound families built on polypropylene, TPU and TPE. It publishes two sourced reference formulations in phr from J.M. Huber, explains the phr and wt% convention a cable compounder works in, maps the CPR Euroclasses to the additive route that reaches each one, and covers compounding, the EU regulations that restrict cable additives, the tests a compound has to pass, and who supplies it. Every substance named in the tables below carries its own record in the site's substance database. Cable is one of 27 end uses covered under plastic additives by application.

Table 1. phr = parts per hundred parts of polymer. The loadings are the sourced reference formulations in Table 4, not universal values.

What Is a Wire and Cable Compound?#

A wire and cable compound is a fully formulated, pelletised plastic, base polymer plus its complete additive package, that a cable maker extrudes onto a conductor or over a cable core. The compound has to do what the bare polymer cannot: insulate at a rated temperature class, resist ignition and flame spread, resist oxidation for decades in service, and survive extrusion at line speed without sticking to the die or degrading in the barrel.

A cable compound is one of the most additive-dense products made from plastic additives; the flame retardant alone can outweigh the base polymer in a halogen-free sheath. A cable compound is not one generic plastic either: a PVC insulation compound, a PVC sheath compound and an XLPE insulation compound are each formulated separately even on the same cable, because each layer carries its own property target. The conductor, the metallic screen and any armour wire are not compounds and carry no additive package; this reference covers only the polymer layers built onto them.

Insulation, bedding and sheath: which layer carries which compound#

A cable carries up to 3 polymer layers, and each one is a different compound: the insulation around each conductor, the bedding that fills the core, and the sheath that faces the fire, the sun and the installer.

• Insulation: covers each conductor directly; XLPE insulation operates continuously at 90 to 105°C, reaches 130 to 140°C under emergency overload, and survives 250°C for about 0.5 seconds under short circuit.
• Bedding: fills the space between cores in a multicore cable and cushions the sheath, carrying a lighter additive package than the sheath.
• Sheath: faces the fire test, ultraviolet exposure and installation damage, and carries most of the flame-retardant load; a PVC insulation compound is formulated to a minimum limiting oxygen index of 26 vol% O2.

Semiconductive screens around the insulation or the core, where fitted, are a further conductive layer, but our source library carries no volume-resistivity specification for them, so this reference names their function without a loading value.

Which polymers are used in cable insulation and jacketing?#

Cable compounds are built on 5 polymer families: flexible PVC, polyethylene and its crosslinked form XLPE, polyolefin and EVA blends for halogen-free compounds, polypropylene, and thermoplastic polyurethane and other elastomers for flexible jackets.

• Flexible PVC: covers 4 temperature classes, 70, 90, 100/105 and 125°C, set mainly by the plasticizer.
• Polyethylene and XLPE: crosslinked in the cable line to lift its rating for power cable insulation.
• Polyolefin and EVA blends: the base of halogen-free compounds; EVA in cable compounds carries 12 to 70% vinyl acetate, and above 40% VA the polymer behaves like a rubber and needs curing.
• Polypropylene: takes a higher mineral load than polyolefin-EVA blends to reach a comparable fire performance.
• TPU and TPE: used for flexible, abrasion-resistant jackets.

The full PVC package is on additives for PVC, including the plasticizer and stabilizer choices behind each temperature class. Crosslinked polyethylene and its non-cable relative PEX together make up about 5 to 10% of the polyethylene market, with 6 to 8% compound annual growth expected. Grades and stabilizer packages are on additives for polyethylene.

What are the main components of a cable?#

A cable is built from a metallic conductor, an insulation layer, optional screens and armour, and an outer sheath, and of these only the insulation, the bedding and the sheath are plastic compounds with an additive package. The conductor is copper or aluminium metal, not a compound, and its metallurgy sits outside this reference. Screens, where fitted, provide electrical or mechanical shielding and are usually a metallic tape or braid, sometimes with a semiconductive polymer layer; armour is a metal wire or tape wrap. This page covers only the additive chemistry of the polymer layers.

The 10 Additive Functions in a Wire and Cable Compound#

A wire and cable compound carries 10 additive functions: flame retardants and smoke suppressants, plasticizers, heat stabilizers, lubricants and processing aids, fillers, antioxidants, metal deactivators, crosslinking agents and catalysts, coupling agents, and colorants and conductive additives. Table 2 sets out what each function does, its typical level in a cable compound, example substances and which compound family relies on it most; the ten rows keep the order used throughout this page, from the fire-driven functions that fix the largest loadings to the appearance and electrical-surface functions that close out the recipe.

Every example substance in the table has its own entry in the plastic additives database.

1. Flame retardants and smoke suppressants#

Flame retardants are the largest additive layer in a cable compound: a halogen-free sheath carries 160 to 180 phr of aluminium trihydrate or magnesium hydroxide, more mineral than polymer. The mineral decomposes endothermically under fire heat, aluminium trihydrate releasing water from about 200°C at 1,051 J/g and magnesium hydroxide staying stable to about 320°C at 1,316 J/g, so a compounder can process an MDH-filled compound roughly 110°C hotter than an ATH-filled one before the filler decomposes in the barrel.

In flexible PVC cable, zinc borate at 3 to 6 phr cuts dripping and smoke, releasing its own water content above 290°C. Antimony trioxide works as a synergist with halogenated systems, not as a flame retardant on its own; it is classified Carc. 2 under CLP Annex VI index 051-005-00-X, never as a substance of very high concern.

2. Plasticizers#

Plasticizers make PVC flexible enough to bend around a drum, and cable compounds use 55 phr or more of a low-volatility ester such as DIDP or the trimellitate TOTM. The Huber reference PVC cable recipe uses diisodecyl phthalate at 55 phr as the sole plasticizer, reaching a limiting oxygen index of 26 to 27% and a UL 94 V-0 rating at 3 mm.

Kaya et al., Polymers, 2026, measured a decomposition onset at 50 phr of 262°C for TOTM against 236°C for DOA. DINP and DIDP are listed under EU Regulation (EU) No 10/2011 as FCM 728 and 729, group restriction 26, with a combined migration limit of 1.8 mg/kg that applies only to food-contact use, not to cable.

3. Heat stabilizers#

Heat stabilizers stop PVC releasing hydrogen chloride during extrusion and in service, and cable one-packs are now calcium-zinc or calcium-organic systems at about 2.7 phr, because lead is no longer permitted. The Huber reference recipe uses a lead-free stabilizer at 2.7 phr alongside hydrotalcite (CAS 12304-65-3) as a co-stabilizer and acid scavenger.

PVC cable compounds are formulated to 4 temperature classes, 70, 90, 100/105 and 125°C, and the stabilizer package has to hold for the compound's rated service life at its class temperature. Lead at or above 0.1% has been banned in PVC articles since 29 November 2024 under REACH Annex XVII entry 63.

4. Lubricants and processing aids#

Lubricants keep the melt moving and stop it sticking to the die at cable line speeds, using paraffin and polyethylene waxes on the outside of the melt and metal stearates inside it. A rigid-PVC reference lubricant 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, and cable compounders adapt the same internal-external balance to their own line speed and die design.

In polyolefin cable compounds, calcium stearate also functions as an acid scavenger at up to 1,000 ppm, neutralising catalyst residues before they attack the extruder metal or the conductor.

5. Fillers#

Fillers add bulk, stiffness and cost control to a cable compound, and PVC cable sheathing takes calcium carbonate at up to 70 phr. Chalk sits alongside the flame-retardant filler rather than replacing it: the Huber reference PVC recipe carries 10 phr of chalk on top of its aluminium trihydrate loading.

Fillers in cable compounds are chosen for particle size and surface treatment as much as for chemistry, because an untreated mineral filler pulls down the elongation needed to pass a bend or cold-impact test. Our source library carries no sourced comparison between insulation-grade and sheath-grade filler selection.

6. Antioxidants#

Antioxidants keep a polyolefin cable compound from oxidising during extrusion and through decades at its rated temperature, and the halogen-free reference formulation uses 1.0 phr of a phenol-plus-phosphite pair. The Huber HFFR recipe combines Ethanox 310 at 0.75 phr with Ethaphos 368 at 0.25 phr, a primary-secondary antioxidant system typical of a filled polyolefin compound.

Where the insulation touches the copper conductor, a thio-phenol such as Irganox 1035 resists copper-catalysed oxidation; it is listed under EU Regulation (EU) No 10/2011 as FCM 690 with a specific migration limit of 2.4 mg/kg. Residual antioxidant activity is measured as oxidative induction time under ISO 11357-6:2018 and ASTM D3895.

7. Metal deactivators#

Metal deactivators chelate the copper ions that diffuse out of the conductor into the insulation, where they would otherwise catalyse oxidation faster than any antioxidant can stop it. Titanium, aluminium and copper are the catalytic metals that concern a plastics compounder, and wire and cable is the case the industry treats as critical, because the conductor sits in direct, permanent contact with the polymer.

Irganox MD 1024 is the reference metal deactivator: FCM 675 under EU Regulation (EU) No 10/2011 with a specific migration limit of 15 mg/kg, molecular weight 553, melting range 221 to 232°C, and cleared under FDA 21 CFR 178.2010 at or below 0.1% in ABS and POM.

8. Crosslinking agents and catalysts#

Crosslinking agents turn thermoplastic polyethylene into XLPE, and a dicumyl peroxide level above 1.4 phr lifts gel content past the point where the insulation passes its hot-set test. Raising the dose from 1.4 to 2.0 phr lifts gel content from 74.3% to 81.6% and cuts hot-set elongation from 300% to 80%, against a maximum of 175% under IEC 60811-507.

The peroxide route cures above 180°C for about 5 minutes; the silane route grafts vinyltrimethoxysilane onto the polyethylene and cures it with a tin catalyst such as dibutyltin dilaurate under ambient moisture. Dicumyl peroxide (CAS 80-43-3) has been on the REACH Candidate List since 27 June 2024 as a reproductive toxicant.

9. Coupling agents#

Coupling agents bond mineral flame retardant to the polyolefin matrix, and the halogen-free reference formulation uses 16 phr of maleated and acrylate-functional polymers to carry 160 phr of aluminium trihydrate. The Huber HFFR recipe splits this coupling-agent layer between Fusabond 226D at 8 phr and Lotader 3210 at 8 phr.

Without a coupling agent, a mineral load this high pulls elongation below what a cable sheath needs to pass its bend test; the maleic-anhydride or acrylate group on the coupling polymer reacts with hydroxyl groups on the filler surface, wetting the mineral into the polyolefin matrix instead of leaving it unbonded.

10. Colorants, carbon black and conductive additives#

Colorants identify cable cores and protect the sheath, and carbon black does both jobs at once by absorbing the ultraviolet light that would otherwise break the polymer chains at the surface. Cable cores are colour-coded for circuit identification, while the outer sheath is typically pigmented black or another UV-stable colour for outdoor duty.

Carbon black is specified under EU Regulation (EU) No 10/2011 as FCM 411, with primary particles between 10 and 300 nm, toluene extractables at or below 0.1% and benzo[a]pyrene at or below 0.25 mg/kg. A conductive grade also serves the semiconductive screens around some cable cores, though our source library carries no resistivity specification for that duty.

Which Additive Package Does Each Cable Compound Need?#

Each cable compound needs an additive package set by two things: the weakness of its base polymer and the fire class the finished cable has to reach. PVC needs a plasticizer to become flexible and a stabilizer to survive its own decomposition chemistry; a halogen-free polyolefin needs a coupling agent to carry a mineral load heavy enough to replace the halogen route; polyethylene needs a crosslinking agent to lift its temperature rating past its own melting point. Table 3 sets out the package for each of the 4 compound families side by side, and Table 4 publishes two sourced reference formulations in phr so the loadings can be checked against a real recipe rather than a rule of thumb.

Download the Wire and Cable Compound Checklist (PDF): the 10 additive functions, the 2 reference formulations and the Euroclass limits on one page. (email, role and company required)

Flexible PVC insulation and sheath (70 to 125°C)#

Flexible PVC cable compounds combine a low-volatility plasticizer, a lead-free calcium-zinc stabilizer and a mineral flame retardant, and the temperature class of the finished cable, from 70°C to 125°C, is decided mainly by which plasticizer is used. The finished cable's 4 temperature classes, 70, 90, 100/105 and 125°C, track the plasticizer's thermal stability rather than the PVC resin itself. The J.M. Huber reference formulation runs PVC K70 at 100 phr, DIDP at 55 phr, a lead-free stabilizer at 2.7 phr, aluminium trihydrate at 45, 50 or 100 phr depending on the target fire class, zinc borate at 5 phr and chalk at 10 phr, reaching an LOI of 26 to 27% and a UL 94 V-0 rating at 3 mm (Table 4). Temperature classes are matched to plasticizers on plasticizers for wire and cable, the record dedicated to PVC cable-plasticizer selection.

Zinc borate contributes to dripping and smoke suppression, releasing its own water content above 290°C, and it carries no harmonised SVHC classification. Identity and regulatory status are on DIDP (diisodecyl phthalate), the plasticizer that carries the largest single loading in the recipe above.

The lead-free stabilizer in the reference recipe is a calcium-zinc system, the class that has replaced lead-based one-packs across the EU cable market since the REACH lead restriction took effect. Composition and performance are on calcium-zinc stabilizers.

Cable-specific one-packs, dosed for the temperature class and the extrusion line rather than for a generic PVC recipe, are covered separately under stabilizers for PVC cables. Cable sits beside film and flooring as one of the major end uses for flexible PVC formulations, which set out the same plasticizer, stabilizer and filler logic for every flexible-PVC application, not cable alone.

LSZH and HFFR polyolefin and EVA compounds#

A halogen-free cable compound is mostly mineral: the reference formulation carries 160 phr of aluminium trihydrate, about 61.5 wt% of the compound, in a blend of 67 phr EVA and 17 phr LLDPE. The same recipe carries 16 phr of coupling agents and 1.0 phr of antioxidants (Ethanox 310 and Ethaphos 368). Unfilled EVA/LLDPE without a mineral load reaches a peak heat release above 550 kW/m2 at 35 kW/m2 irradiance, and adding ATH or MDH delays ignition by 120 to 160 seconds by keeping the surface temperature down and diluting the fuel with the water the mineral releases.

Particle sizes and grades are compared on mineral flame retardants (ATH and MDH), the two fillers behind nearly every halogen-free cable sheath on the market. Magnesium hydroxide processes about 110°C hotter than aluminium trihydrate before it starts releasing water, which is why a compounder switches from ATH to MDH when the extrusion temperature has to run higher.

Decomposition data are on aluminum trihydrate (ATH), which releases water from about 200°C at 1,051 J/g. A coated grade of magnesium hydroxide loaded into polypropylene at 185.7 phr reaches a limiting oxygen index of 30.2%, against about 17.5% for unfilled polypropylene.

Natural brucite and synthetic grades are compared on magnesium hydroxide (MDH), stable to about 320°C at 1,316 J/g. Alsayed et al., Polymers, 2025, found that 10 wt% of a phosphate low-melting glass added to a PE-EVA/ATH cable sheath cut peak heat release to 142 kW/m2, a 52% reduction. Li et al., Polymers, 2022, reviewed about 240 works on halogen-free flame retardants for polyolefin cable sheath materials.

What is an LSZH compound, and are HFFR and LSZH the same?#

An LSZH compound is a polyolefin or polyolefin-EVA blend filled to about 60% with aluminium trihydrate or magnesium hydroxide, so that it releases water instead of halogen acid when it burns. Yes, in practice: HFFR is one of 9 names the industry uses for the same compound class, alongside LSF, LS0H, LSOH, LSFH, ZHFR, NHFR, OHLS and HFT.

The acidity of the combustion gas is what separates a halogen-free compound from a PVC one in EU fire testing: reaching acidity class a1 under EN 60754-2 requires a conductivity below 2.5 µS/mm and a pH above 4.3, a bar a mineral-filled, halogen-free compound clears because it has no halogen to release as acid gas in the first place.

XLPE and silane-crosslinked polyethylene insulation#

XLPE insulation is polyethylene that has been crosslinked in the cable line, which lifts its rating from the melting point of polyethylene to 90 to 105°C continuous and 250°C for about half a second under short circuit, with an emergency overload rating of 130 to 140°C. The peroxide route melts the compound at 120 to 140°C during triple extrusion, with no cure onset at that temperature, then vulcanises it above 180°C for about 5 minutes, and finishes with a degassing step.

The 3 crosslinking routes are compared on XLPE (crosslinked polyethylene) for cable: peroxide, silane and electron beam. Raising the dicumyl peroxide level from 1.4 to 2.0 phr lifts gel content from 74.3% to 81.6% and cuts hot-set elongation from 300% to 80%, against a maximum allowed 175% elongation under IEC 60811-507; a level above 1.4 phr is the minimum needed to pass.

Half-lives and handling are on organic peroxides for polymers. Degassing removes the by-products the peroxide route leaves behind in the insulation: water, methane, acetophenone, cumyl alcohol and alpha-methylstyrene.

The moisture-cure routes are on silane crosslinking (Sioplas and Monosil), where vinyltrimethoxysilane is grafted onto the polyethylene and cured with a tin catalyst such as dibutyltin dilaurate. This route is not suitable for high-voltage insulation, because the water introduced by moisture curing adds charge carriers that the peroxide route avoids. In a POE/LLDPE silane-grafting study, an optimum of 0.2 wt% benzoyl peroxide gave 79% gel content and a 40.4% compression set, and raising the antioxidant to 0.3 wt% cut cure time from 14 to 16 hours down to 8 hours.

Voltage stabilisers with polar groups scavenge high-energy electrons and inhibit water treeing and electrical treeing in XLPE insulation (Nazrin et al., Heliyon, 2024); nanofillers such as boron nitride, graphene oxide and silica add further electron-trap sites for the same protection (Yurov et al., Materials, 2025).

What type of insulation is used in XLPE cable?#

XLPE cable insulation is polyethylene crosslinked by one of 3 routes: a peroxide such as dicumyl peroxide, a grafted silane cured with moisture, or an electron beam. Around the crosslinker sits a supporting additive package: a phenolic antioxidant paired with a phosphite at about 1.0 phr total, and a metal deactivator such as Irganox MD 1024 wherever the insulation touches the copper conductor. The antioxidant protects the polyethylene through the vulcanisation heat and decades of service; the metal deactivator stops copper ions diffusing out of the conductor from catalysing oxidation faster than the antioxidant alone can control.

Polypropylene, TPU and TPE cable compounds#

Polypropylene halogen-free compounds take an even higher mineral load than polyolefin-EVA: 185.7 phr of coated magnesium hydroxide lifts polypropylene from a limiting oxygen index of about 17.5% to 30.2%. The higher load is needed because polypropylene, unlike EVA, contributes no polar groups of its own to help the mineral filler bond and disperse, so the coupling-agent and filler-loading logic follows the same mineral flame-retardant chemistry set out for LSZH and HFFR compounds above, just at a higher phr.

Thermoplastic polyurethane and other thermoplastic elastomers are used for flexible, abrasion-resistant jackets on portable, mining and offshore cable. Our source library carries no cable-specific dosage for TPU and TPE flame-retardant packages; their selection is covered separately under the flame retardants used in TPE compounds, and this reference names the polymer class without a loading figure.

Table 4. Two sourced reference formulations, phr

Both formulations are published by J.M. Huber for its Martinal and Magnifin grades. They are reference formulations for illustration, not specifications. Trade names appear because the source names them; this site sells nothing.

Request quotes for cable-grade ATH, MDH, plasticizers, calcium-zinc one-packs or peroxides: grade or CAS, compound family, volume, country.

How Are Cable Additive Levels Expressed? phr, wt% and Loading Limits#

Cable additive levels are given in 3 units: phr, parts per hundred parts of polymer, which is the working unit of a cable compounder; wt% of the finished compound; and ppm for trace additives.

• phr: used for the major components of a recipe, such as fillers, plasticizers and stabilizers, always expressed against 100 parts of base polymer.
• wt%: used to compare a finished compound against a competitor's recipe or against a regulatory limit expressed on the whole compound.
• ppm: used for trace additives such as acid scavengers, where calcium stearate typically runs up to 1,000 ppm and zinc borate typically runs 3 to 6 phr.

wt% of a component equals its phr divided by the total phr of the recipe, multiplied by 100. Because a phr recipe is built on 100 parts of polymer and then adds every other ingredient on top, the total can run well above 100: the Huber HFFR reference formulation sums to 261 phr (67 EVA plus 17 LLDPE plus 8 Fusabond 226D plus 8 Lotader 3210 plus 160 ATH plus 0.75 Ethanox 310 plus 0.25 Ethaphos 368), so its 160 phr of aluminium trihydrate works out to 61.3 wt%, and the source's own rounded figure of 61.5 wt% is the number this reference prints. A 160 phr filler loading is therefore 61.5% of the finished compound, not 160% of it, precisely because the recipe is expressed against 100 parts of resin, not against the finished compound weight.

The conversion rules are set out under PHR (parts per hundred resin). Check the 160 phr conversion in the PHR to weight percent calculator.

Which Fire Class Must a Cable Compound Reach? CPR Euroclasses#

In the EU, a cable installed in a building is classified into 7 reaction-to-fire classes from Aca down to Fca, and the class it reaches is decided largely by the flame retardant in its sheath compound. The classification runs Aca, B1ca, B2ca, Cca, Dca, Eca and Fca in descending order of fire performance, and each class below Aca is defined by a combination of flame spread, heat release and fire growth rate measured on the cable itself, not on a small laboratory sample. A cable's sheath compound sets nearly all of this performance, because the mineral or halogenated flame retardant in the sheath decides how much heat the compound releases and how far the flame travels along the run. The test set-ups themselves belong to a dedicated reference; this page states the limits and the additive route that reaches them.

Euroclasses B1ca to Fca and the additive route to each#

The reaction-to-fire class of a cable is set by 4 measured quantities: flame spread, total heat release in 1,200 seconds, peak heat release rate, and the fire growth rate index FIGRA. Class B1ca, the most demanding class an organic compound can practically reach, requires flame spread at or below 1.75 m, total heat release (THR1200) at or below 10 MJ, peak heat release at or below 20 kW and FIGRA at or below 120 W/s under a 30 kW ignition source. Class B2ca relaxes those limits to 1.5 m flame spread, 15 MJ, 30 kW and 150 W/s under a smaller 20.5 kW source; Cca allows 2.0 m, 30 MJ and 60 kW at 300 W/s; Dca allows up to 70 MJ, 400 kW and 1,300 W/s. Class Eca is defined only by flame spread at or below 425 mm under EN 60332-1-2, without a heat-release limit, and class Aca requires a gross calorific value at or below 2 MJ/kg, a bar that is effectively out of reach for a filled organic compound. The test rigs behind these limits are described under cable fire tests and CPR classes, the page dedicated to the EN 50399 cable-ladder test and its sister standards.

Smoke (s), droplet (d) and acidity (a) classes#

The letters after a Euroclass carry the rest of the fire performance: s for smoke, d for flaming droplets and a for the acidity of the combustion gases. Smoke class s1 requires total smoke production (TSP1200) at or below 50 m2 and a peak smoke production rate at or below 0.25 m2/s; s1a adds a light-transmittance requirement of at least 80% under EN 61034-2, s1b allows 60 to 80%, and s2 relaxes the limits to a TSP at or below 400 m2 and a peak rate at or below 1.5 m2/s. Acidity class a1 under EN 60754-2 requires the combustion gas to show a conductivity below 2.5 µS/mm and a pH above 4.3; class a2 allows conductivity up to 10 µS/mm at the same pH floor.

A halogen-free compound reaches class a1 for a structural reason, not a formulation trick: it carries no halogen to release as acid gas when it burns, so the conductivity of its combustion gas stays low by default. A PVC compound, which does carry halogen, cannot reach a1 regardless of how it is filled. In flexible PVC cable, zinc borate at 3 to 6 phr reduces dripping and smoke without changing this underlying acidity outcome.

How Are Wire and Cable Compounds Compounded and Extruded?#

A cable compound is made in 4 steps: the additives are compounded into the polymer, the compound is pelletised, the pellets are extruded onto the conductor, and crosslinked compounds are then cured and degassed.

1. Compound the additives into the base polymer by feeding resin and additives into an extruder or internal mixer, where they are melted and dispersed through the barrel.
2. Pelletise the melt by forcing it through a die, cooling the strands in a water bath or spray, and cutting them into a delivery-form pellet, or, for a one-pack system, keeping resin and additive package separate until the cable line.
3. Extrude the compound onto the conductor at line speed, where processing-temperature limits matter directly: aluminium trihydrate should not be processed above about 200°C, where it starts releasing water, while magnesium hydroxide can run to about 320°C, a roughly 110°C advantage that shows up as a real difference in achievable line speed.
4. Cure and degas crosslinked compounds after extrusion: an XLPE line runs the melt at 120 to 140°C through a triple-extrusion head with no cure onset at that temperature, then vulcanises the insulation above 180°C for about 5 minutes, then degasses it to remove the water, methane, acetophenone, cumyl alcohol and alpha-methylstyrene the peroxide leaves behind.

Feeding, melting and pelletising are covered under plastic compounding, and a compound bought as separate resin and additive package is referred to in the industry as a one-pack system.

Which Regulations Apply to Additives in Wire and Cable?#

Additives in cable compounds are controlled by 4 kinds of rule: the Construction Products Regulation, which sets how a cable's fire performance is declared; REACH, which restricts lead and requires communication on substances of very high concern; the POPs Regulation, which bans persistent flame retardants and chlorinated paraffins; and RoHS, which caps the same substances in electrical equipment. Every instrument that touches an additive is tracked under plastic additive regulations, and Table 6 lists the 7 instruments most relevant to a cable compound, what each one controls, an example additive it affects, and the date it applies from.

The new Construction Products Regulation (EU) 2024/3110#

The new Construction Products Regulation, Regulation (EU) 2024/3110, has applied since 8 January 2026 and replaces Regulation (EU) No 305/2011, with power, control and communication cables kept as product family 31. Some provisions of the new regulation applied earlier, from 7 January 2025, and Article 92 does not apply until 8 January 2027, so the transition runs across three separate dates rather than one. The existing harmonised standards, including EN 50575, continue to apply until they are replaced under the new framework; no replacement date for EN 50575 is set in our source library at the time of writing. For a cable compounder, the practical effect of the new CPR is unchanged from the old one for now: the Euroclass a compound reaches under EN 13501-6 still has to be declared, and the flame retardant, smoke suppressant and mineral filler loadings in the sheath compound still decide which class it reaches.

Lead and phthalates in PVC cable#

Lead stabilizers are out of EU cable: since 29 November 2024, REACH Annex XVII entry 63 has banned PVC articles containing 0.1% lead or more, and the derogation for flexible recovered PVC ended on 28 May 2025. Recovered rigid PVC may still contain lead below 1.5% until 28 May 2033, a narrower and later-expiring exemption than the one flexible recyclate had. Entries 52 and 63 are set out under REACH Annex XVII restrictions, the same annex that carries the phthalate restrictions a cable compounder sometimes confuses with the lead entry.

Annex XVII entry 52 restricts DINP, DIDP and DNOP above 0.1% only in mouthable toys and childcare articles; it does not restrict DIDP as a cable plasticizer, and no EU rule currently caps DIDP loading in wire and cable compounds. The derogation dates are listed on lead in PVC, the record dedicated to entry 63 and its recycled-PVC exemptions.

Dicumyl peroxide, MCCP, PBDEs and RoHS#

Dicumyl peroxide, the standard crosslinker for XLPE insulation, has been on the REACH Candidate List since 27 June 2024 as a reproductive toxicant, which means every article containing more than 0.1% of it needs a SCIP notification and a communication down the supply chain. Identity, half-life and the SVHC entry are on dicumyl peroxide (CAS 80-43-3, EC 201-279-3), classified under REACH Article 57(c).

What a Candidate List entry obliges is explained under the SVHC Candidate List: a communication duty above 0.1% concentration in an article, and, for products placed on the EU market, an entry in the SCIP database.

Medium-chain chlorinated paraffins were listed in the Stockholm Convention's Annex A at COP-12 in 2025 (decision SC-12/10), and Commission Delegated Regulation C(2026) 6262 of 11 September 2026 adds MCCP to Annex I Part A of the EU POPs Regulation, applying from 16 December 2026, with OJ publication pending as of 22 September 2026. The general unintentional-trace concentration is 0.1% by weight, but PVC recovered from cable metal recycling gets a 2% limit for two years, flexible PVC in construction wires and cables gets a two-year specific exemption, and wires and cables in medical and in vitro diagnostic devices get up to five years. The MCCP and PBDE listings are tracked under POPs in plastics.

PBDEs carry their own unintentional-trace concentration under the EU POPs Regulation: 10 mg/kg for the sum of tetra- to decaBDE in mixtures and articles, rising to 500 mg/kg for recovered-material articles, falling to 350 mg/kg from 30 December 2025 and 200 mg/kg from 30 December 2027 under Delegated Regulation (EU) 2025/1482. RoHS caps PBDEs at 0.1% in a homogeneous material and excludes cables and spare parts for the repair, reuse or upgrade of electrical equipment placed on the market before 22 July 2019, extended to 22 July 2021 for medical and monitoring equipment. The cable exclusions are explained under RoHS and plastic additives.

How Are Cable Compounds Tested?#

A cable compound is signed off on 4 property groups: fire performance, degree of crosslinking, thermal stability and electrical behaviour.

• Fire performance: flame spread, heat release and smoke, measured under EN 50399 and its companion standards behind the Euroclasses.
• Degree of crosslinking: hot-set elongation and gel content, both specific to XLPE and silane-cured insulation.
• Thermal stability: the Congo red induction time for PVC and oxidative induction time for polyolefins.
• Electrical behaviour: verified under cable-specific dielectric and voltage-withstand tests that sit outside this additive-focused reference.

Every method in the table is described under testing plastic additives, and Table 7 lists 8 tests against their standard and a typical cable target where our source library has a sourced value. Fire performance covers the EN 50399 cable-ladder test behind the Euroclasses, the limiting oxygen index measured under ISO 4589-2 and ASTM D2863, and the small-flame UL 94 rating; the Huber reference PVC recipe reaches an LOI of 26 to 27% and a UL 94 V-0 rating at 3 mm, while the HFFR PP reference reaches an LOI of 30.2%. Degree of crosslinking is read from hot-set elongation under IEC 60811-507, capped at 175%, and from gel content, which the reference XLPE compound carries between 74.3 and 81.6% at a dicumyl peroxide dose of 1.4 to 2.0 phr. Thermal stability in PVC is read from the Congo red test under ISO 182-1:1990, and residual antioxidant activity from oxidative induction time under ISO 11357-6:2018 and ASTM D3895. The glow-wire test under IEC 60335-1 clause 30.2.3 checks ignition by a hot part, requiring a flammability index at or above 850°C and an ignition temperature at or above 775°C for connections above 0.2 A in unattended appliances.

Who Supplies Wire and Cable Compounds and Their Additives?#

A cable maker buys its compound in one of 2 ways: as a ready-made pelletised compound from a compounder, or as base polymer plus a one-pack, which it compounds in-house. Producers by family are listed in the plastic additive manufacturers and suppliers directory. Dow, AlphaGary, Teknor Apex, Westlake, Aurora and ATP compound cable materials directly, and distributors such as Nexeo supply base resin and additive packages to compounders who blend their own recipe; these names are market context, not a recommendation.

ATH and MDH producers are compared under flame retardant manufacturers and suppliers. J.M. Huber, the source of both reference formulations on this page through its Martinal aluminium trihydrate and Magnifin magnesium hydroxide lines, took over these product lines from Albemarle's Martinswerk business in 2016. Antimony trioxide consumption as a flame-retardant synergist runs to about 25,000 t/y in Europe and about 10,000 t/y in the US.

One-pack makers are listed under PVC stabilizer manufacturers and suppliers. Analyst estimates of the wire and cable compound market differ widely and are not reproduced here until a sourced figure enters our source library.

Request quotes for cable-grade ATH, MDH, plasticizers, calcium-zinc one-packs or peroxides: grade or CAS, compound family, volume, country. Send one request to several cable-grade suppliers with the plastic additive supplier finder.

What Happens to Cable Additives at End of Life?#

Cable is recycled for its copper, and the compound that comes off it carries the additives that were put in decades ago, which is why EU law gives PVC recovered from cable metal recycling its own limit for chlorinated paraffins. The MCCP delegated regulation's 2% limit for two years, applied specifically to PVC recovered from cable metal recycling, is the clearest statement in EU law that cable recyclate carries legacy additive chemistry that current compounds no longer contain. What survives into recyclate is covered under legacy additives in recycled plastic, which tracks lead, chlorinated paraffins and brominated flame retardants across the wider plastics recycling stream, not cable alone.

Legacy additives in cable recyclate#

Three legacy additives dominate cable recyclate: lead stabilizers, chlorinated paraffins and brominated flame retardants, and each now has a dated limit in EU law. Recovered flexible PVC lost its lead derogation on 28 May 2025, so cable recyclate processed after that date has to meet the same 0.1% lead limit as virgin compound, while recovered rigid PVC keeps a narrower allowance below 1.5% lead until 28 May 2033. PBDEs in articles made from recovered material fall to 200 mg/kg from 30 December 2027, tightening the ceiling on brominated flame retardant carryover from older cable stock. XLPE compound adds a mechanical complication recycling does not solve by chemistry alone: because it is crosslinked, it cannot be remelted without a de-crosslinking step first. Recyclable-by-design choices are set out under design for recycling.

Common questions about cable compounds#

Three questions come up repeatedly once the additive package and the regulation are settled: which insulation performs better, what XLPE gives up for its higher rating, and why most outdoor sheathing is black.

Which insulation is better, PVC or XLPE?#

Neither is better in general: crosslinked polyethylene carries a higher continuous rating, up to 105°C, and survives 250°C for about half a second under short circuit, while flexible PVC covers temperature classes from 70°C to 125°C depending on its plasticizer, and can be remelted, which XLPE cannot. The choice depends on the application: XLPE dominates power cable insulation, where the higher continuous rating and dielectric performance matter, while PVC remains standard for building wire, control and instrumentation cable, where lower processing temperature and remeltability matter more.

What are the downsides of XLPE cable?#

The drawbacks of XLPE are all consequences of the crosslink: the line needs a curing and a degassing stage, the peroxide leaves methane and acetophenone behind, and the finished insulation cannot be remelted. Dicumyl peroxide, the standard crosslinker, is on the REACH Candidate List as a reproductive toxicant, a compliance step a plain polyethylene compound does not carry. The alternative silane route avoids the peroxide by-products but is unsuitable for high-voltage insulation, because moisture curing adds charge carriers; once crosslinked, the network cannot be remelted without pan-milling or a supercritical-methanol step.

Why is outdoor cable sheathing black?#

Outdoor cable sheathing is black because carbon black absorbs the ultraviolet light that would otherwise break the polymer chains at the surface. Pigment, UV and conductive grades are separated on carbon black in plastics, the substance behind the black colour of most outdoor sheathing. Where black is not acceptable for identification or aesthetic reasons, the alternatives are on UV stabilizers for plastics, which protect a coloured or natural compound by absorbing or quenching ultraviolet energy instead of blocking it outright.

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