Chemical Blowing Agents: 7 Types, Decomposition Temperatures and Selection

Chemical blowing agents are solid additives that decompose between about 120 °C and 210 °C and release nitrogen, carbon dioxide, carbon monoxide, ammonia or water vapour, which expand a polymer melt into a cellular structure. Because the gas appears only inside a narrow temperature window, the whole selection problem is a matching problem: which agent decomposes where the polymer is already molten but not yet degraded?

Blowing agents make up 0.05 to 20 wt% of a finished plastic product, one of the widest dosage ranges of any group of plastic additives, according to Hahladakis et al. (2018) in the Journal of Hazardous Materials, as adapted by Chea et al. (2025).

This page separates chemical blowing agents from the physical route, sets out the exothermic and endothermic chemistries, profiles the 7 types used in plastics with their decomposition points and gas yields, matches each decomposition window to a process and a polymer, gives the verified dosage range and let-down arithmetic, explains how a decomposition point is measured, and states which agents are cleared for food-contact plastics in the EU and the United States.

Key figures

• 7 chemical blowing agent types are used in plastics: azodicarbonamide, activated ADC, sulfonyl hydrazides, sulfonyl semicarbazides, tetrazoles, endothermic bicarbonate systems, and water with isocyanate.
• Azodicarbonamide decomposes at about 210 °C pure and at 140 to 165 °C when activated with a kicker.
• Gas yields across the 7 classes range from about 95 mL/g (endothermic bicarbonate) to 231 cm3/g (azodicarbonamide, review value).
• Azodicarbonamide has been on the REACH Candidate List since 19 December 2012.

What Is a Chemical Blowing Agent?#

A chemical blowing agent is a substance that decomposes or reacts on heating and releases a gas that forms a cellular structure in a polymer, which is why the industry also calls it a chemical foaming agent (CFA). The main organic chemical blowing agents used in plastics are azodicarbonamide (ADC), the sulfonyl hydrazides, the sulfonyl semicarbazides, the tetrazoles and the water-isocyanate reaction, and together they release a gas mixture of nitrogen, carbon dioxide, carbon monoxide, ammonia or water. This page uses "chemical blowing agent" as the page-wide term and "CFA" only where the trade itself uses it, in masterbatch and injection moulding contexts.

The parent overview of blowing agents covers the physical and particle-form types alongside the chemical ones, and the distinction between the two routes is the subject of the next section.

How does a chemical blowing agent foam a polymer melt?#

A chemical blowing agent foams a melt in 5 steps: dispersion, decomposition, gas dissolution, nucleation and stabilisation. The foaming sequence runs in this order every time, whatever the chemistry:

1. Dispersion of the solid agent as fine particles throughout the polymer melt.
2. Thermal decomposition once the melt passes the agent's decomposition point.
3. Gas dissolution and supersaturation of the gas inside the melt.
4. Nucleation and cell growth as the pressure drops and the gas comes out of solution.
5. Stabilisation of the cell walls as the melt cools and the polymer regains its strength.

Azodicarbonamide illustrates the sequence: its azo group decomposes above the decomposition point and releases nitrogen together with carbon monoxide, carbon dioxide and ammonia, and the gas nucleates into cells as the pressure inside the mould or die falls. An endothermic system follows the same 5 steps through a different reaction: 2 NaHCO3 breaks down into Na2CO3, water and carbon dioxide, absorbing heat as it goes. Gas volumes, decomposition points and residues for each of the 7 types are covered in the type-by-type section below, not here.

What is the difference between a foaming agent and a blowing agent?#

In plastics processing the two words mean the same thing: a blowing agent and a foaming agent both describe the additive that creates the gas, and the choice of word follows the industry rather than the chemistry. Producers such as Avient, Ampacet and Reedy Chemical Foam favour "foaming agent" in their commercial literature, while academic literature and standards bodies favour "blowing agent". Outside plastics, "foaming agent" can also mean a surfactant used in concrete, soap or food, a usage this site does not cover.

Chemical vs Physical Blowing Agents: What Each One Does#

Chemical blowing agents generate their gas by decomposing inside the melt, while physical blowing agents are gases or volatile liquids that are injected into the melt and expand when the pressure drops, which is why only the chemical route leaves a solid residue in the part. The physical route covers nitrogen, carbon dioxide, pentane, cyclopentane, isobutane, HFCs and the newer HFOs, all metered as a gas or volatile liquid rather than dosed as a powder or masterbatch.

Boiling points, climate rules and dosing equipment for physical blowing agents are compared separately, but one worked contrast shows how far the two routes diverge inside a single polymer. In EVA foam the two routes reach different densities: a chemically foamed EVA reaches 0.15 to 0.25 g/cm3 inside a narrow 170 to 190 °C window, while nitrogen at 15 MPa reaches 0.13 g/cm3 across a much wider 80 to 180 °C window, according to a 2024 study in Materials.

Regulatory pressure follows a different logic for each route. Chemical blowing agents are governed substance by substance, through SVHC listing and food-contact clearance, while physical fluorinated blowing agents are governed at the climate level, through the EU F-gas Regulation (EU) 2024/573 and the US AIM Act (40 CFR 84.54).

Exothermic vs Endothermic Chemical Blowing Agents#

Exothermic chemical blowing agents release heat while they decompose and deliver more gas per gram, while endothermic agents absorb heat, release carbon dioxide instead of nitrogen and give a finer, more controllable cell structure. The exothermic classes are the azo compounds, the sulfonyl hydrazides, the sulfonyl semicarbazides and the tetrazoles; the endothermic class is sodium bicarbonate paired with an acid activator such as citric or tartaric acid or a hydrogen phosphate. Thick sections should use an endothermic or blended system unless the exotherm can be removed from the centre of the part.

Decomposition points are representative grade values, not specifications. Trials decide the final grade.

Exothermic blowing agents: more gas, self-sustaining decomposition#

Exothermic blowing agents decompose in a reaction that produces more heat than it consumes, so once the decomposition starts it continues on its own and can raise the temperature at the centre of a thick part. Azodicarbonamide releases 1.36 kJ/g, measured by differential scanning calorimetry between 160 °C and 230 °C, and has an activation energy of 182 kJ/mol, about 2.3 times the 79 kJ/mol of rubber curing. That activation energy explains why ADC needs a clear temperature threshold before it decomposes, and why a kicker that lowers the threshold also changes how sharply the reaction sets in.

Endothermic blowing agents: finer cells and shorter cooling#

Endothermic blowing agents absorb heat as they decompose: 2 NaHCO3 breaks down into Na2CO3, water and carbon dioxide, and with citric acid the acid-base reaction releases the same gas at a lower temperature. Because the reaction consumes heat instead of adding it, endothermic systems give finer, more even cells and shorter cooling cycles than an equivalent exothermic load, and the same particles double as nucleants when a process uses physical gas foaming instead. Grades, citric-acid ratios and food-packaging uses are covered in detail on endothermic blowing agents; this page stays at the level of definition and consequence.

Endothermic and exothermic blends#

Blended systems combine an exothermic and an endothermic agent so that the endothermic part starts the reaction and the exothermic part supplies the gas volume: Eiwa's ADC/OBSH Spangcell grades decompose between 150 °C and 185 °C and yield 150 to 180 mL/g. Kmetty et al. (2018), in "Characterization of Different Chemical Blowing Agents and Their Applicability to Produce Poly(Lactic Acid) Foams by Extrusion," Applied Sciences, compared exothermic and endothermic agents side by side in PLA extrusion foaming, one of the few peer-reviewed studies to test both chemistries in a single polymer.

What Are the 7 Types of Chemical Blowing Agents?#

The 7 types of chemical blowing agents used in plastics are azodicarbonamide, activated azodicarbonamide, sulfonyl hydrazides, sulfonyl semicarbazides, tetrazoles, endothermic bicarbonate systems and the water-isocyanate reaction in polyurethane, with azodicarbonamide accounting for most of the tonnage. This order is fixed and repeats in the table below, in the page's structured data and in every later list on this page.

Empty cells and "not established" entries mean the value is not verified against a primary source and is deliberately not stated. Grade values are representative, not specifications.

Request quotes for chemical blowing agents: send chemistry or CAS, decomposition temperature, polymer, volume and country in one form through the plastic additive supplier finder. A companion Chemical Blowing Agent Decomposition Chart, covering all 7 classes with decomposition points, gas yields and polymer windows, is available as a download against an email, role and company.

1. Azodicarbonamide (ADC): the reference exothermic blowing agent#

Azodicarbonamide (ADC, CAS 123-77-3) is the most used chemical blowing agent in plastics: a yellow to orange powder that decomposes at about 210 °C and yields 200 to 220 mL of gas per gram, mostly nitrogen. Its EC number is 204-650-8, its formula is C2H4N4O2, its molecular weight is 116.08 g/mol, and it has a density of 1.65 g/cm3 at 20 °C. ADC is insoluble in water and most common solvents but dissolves in DMSO.

Identity, grades and the full regulatory matrix of azodicarbonamide (ADCA) sit on its substance page. In plastics ADC foams PVC cushion vinyl flooring, wallpaper and artificial leather, EVA and PE foam for footwear, mats and carpet underlay, crosslinked polyolefin foam sheet, injection-moulded structural foam and, in the United States, closure gaskets.

Which gases and residues does azodicarbonamide leave behind?#

Azodicarbonamide leaves both gas and solid behind: the gas is mainly nitrogen with carbon monoxide, carbon dioxide and ammonia, and the solid residue consists of biurea, urazole and cyanuric acid, with semicarbazide formed as a secondary product. That semicarbazide sentence is the factual bridge to the EU food-contact suspension, explained in the regulatory section below: no quantity of semicarbazide is stated here because none is verified in our source library for this page.

2. Activated ADC: how kickers such as zinc oxide lower the decomposition temperature#

Activated azodicarbonamide is ADC supplied with a kicker such as zinc oxide, zinc stearate or urea, which lowers the decomposition point from about 210 °C to between 140 °C and 165 °C and brings it inside the fusion range of PVC plastisol.

Kicker systems themselves, and how each one shifts the decomposition curve, are compared under blowing agent activators (kickers).

Zinc oxide is the most used kicker, and ECHA also holds a registered reaction mass of azodicarbonamide and zinc oxide (EC 907-545-1), confirming how closely the two substances are used together. Gas yield falls as the decomposition point falls: activated grades yield 135 to 210 mL/g against 200 to 220 mL/g for standard ADC, a trade-off rather than a formula.

3. Sulfonyl hydrazides: OBSH and TSH#

Sulfonyl hydrazides decompose at lower temperatures than azodicarbonamide and release nitrogen together with water: OBSH (CAS 80-51-3) decomposes at 160 to 165 °C and yields 120 to 125 mL/g, which suits PVC wallpaper, EVA and LDPE sheet. OBSH is a fine white odourless powder with an EC number of 201-286-1, a molecular weight of 358.4 g/mol and a density of 1.52 g/cm3; its onset near 165 °C is too low for typical PE extrusion, so it is used mainly in lower-temperature processes such as plastisol and epoxy foam.

The TSH blowing agent (p-toluenesulfonyl hydrazide, CAS 1576-35-8, EC 216-407-3, molecular weight 186.23 g/mol) is a white, nearly odourless powder with a melting point of 108 to 110 °C. Its decomposition temperature and gas yield are not established from a primary source on file, and the figure published by at least one competitor site is unsourced, so this page states only the identity and hazard profile that are verified.

4. Sulfonyl semicarbazides: TSSC#

p-Toluenesulfonyl semicarbazide (TSSC, CAS 10396-10-8) is the higher-temperature member of the sulfonyl family: it releases nitrogen, carbon dioxide and ammonia and is used where azodicarbonamide decomposes too early. Its EC number is 233-857-6 and its molecular weight is 229.26 g/mol. TSSC is reported for engineering thermoplastics and rigid PVC, a use this page states as reported rather than confirmed, and no active REACH registration was found on ECHA CHEM as of 2026-09-22. Its decomposition temperature and gas yield are not established.

5. Tetrazoles: 5-phenyltetrazole for high-temperature polymers#

5-Phenyltetrazole (5-PT, CAS 18039-42-4) foams engineering thermoplastics that are processed above the azodicarbonamide window: its tetrazole ring opens at high temperature and releases pure nitrogen. Its EC number is 241-950-8, its formula is C7H6N4 and its molecular weight is 146.15 g/mol. Jeong et al., in a 2020 Polymers study on low-density PBT foams, used 5-phenyltetrazole to foam PBT by extrusion, and the substance is registered under REACH as an intermediate only. Its decomposition temperature, gas yield and dosage are not established from a primary source and are not stated here.

6. Endothermic systems: sodium bicarbonate and citric acid#

Endothermic systems pair sodium bicarbonate as a blowing agent (CAS 144-55-8) with an acid such as citric acid, decompose between 120 °C and 200 °C and release 95 to 160 mL of carbon dioxide per gram. Sodium bicarbonate has a molecular weight of 84.007 g/mol and decomposes by the reaction 2 NaHCO3 to Na2CO3, water and carbon dioxide; Eiwa's Cellborn grade decomposes at 150 °C with a gas volume of 95 to 160 mL/g, and its FE-512 grade decomposes at 196 °C with 190 mL/g. Beyond its role as a blowing agent, sodium bicarbonate also acts as a cell nucleant in physical foaming, and it is used in food-packaging foam sheet, injection moulding for sink-mark removal and weight reduction, and pipe and profile foaming.

7. Water and isocyanate: carbon dioxide generated in situ in polyurethane#

Polyurethane foams itself: water reacts with isocyanate and produces carbon dioxide inside the rising foam, which makes water the only chemical blowing agent that is also a reactant. A representative flexible PU formulation runs 6 pphp water, 0.2 pphp silicone surfactant, 0.2 pphp tin(II) 2-ethylhexanoate and 0.5 pphp pentamethyldiethylenetriamine at an index of 100, and foam accounted for 67 % of polyurethane use in 2016. Water, cyclopentane and the newer HFO generation are compared in detail under blowing agents for polyurethane foam; this page keeps the PU chemistry to the reaction and the reference formulation.

How Do You Match the Decomposition Temperature to the Process?#

A chemical blowing agent works only if its decomposition point sits above the melting range of the polymer and below the temperature at which the polymer degrades, which is why the same agent can be right for PVC plastisol and wrong for PE extrusion. The two variables that decide the match are the decomposition point, which sets when the gas appears, and the gas yield, which sets how much of it appears.

Decomposition temperature versus melt temperature#

The decomposition point decides which processes an agent fits: OBSH starts at about 165 °C, which is below the temperature of a typical PE extrusion line, so the gas is released before the melt reaches the die. A mismatched decomposition point fails in one of 3 ways:

• Decomposes too early: the gas escapes before the die or the mould fills, leaving voids or no expansion at the surface.
• Decomposes too late: the melt has already been shaped, so expansion cannot occur and unreacted agent stays in the part.
• Decomposes too violently: the exotherm scorches the centre of a thick section, a known risk with high-yield exothermic agents such as ADC.

Activating ADC with a kicker is the main way processors move the decomposition window down, and the EVA processing window of 170 to 190 °C shows how narrow that target can be in practice.

Gas yield: how much gas a foam actually needs#

Gas yield sets how much agent a given density reduction needs: azodicarbonamide delivers 200 to 220 mL/g at 0 °C and 1 atmosphere, roughly twice the 95 to 160 mL/g of a sodium bicarbonate grade. Sulfonyl hydrazides sit in between, with OBSH yielding 120 to 125 mL/g. Exothermic chemical blowing agents commonly have a higher gas yield than endothermic ones, and that gap is the main reason formulators reach for an endothermic or blended system when the priority is cell fineness rather than maximum expansion. No conversion factor from gas yield to density reduction is verified in our source library, so this page states the yield only and leaves the density outcome to the polymer-specific sections below.

Cell structure: nucleation, cell size and skin quality#

Cell structure follows nucleation: the more nucleation sites the agent creates, the smaller and more even the cells, which is why endothermic grades are also sold as nucleating agents for gas-injection foaming. The same particle chemistry that nucleates a chemical foam also nucleates crystallisation, and the mechanism behind that dual role is covered on nucleating agents. No verified cell-size figures exist in our source library for chemically foamed thermoplastics; the one available reference point comes from microcellular physical foaming, where gas counter-pressure cut the cell size of a polycarbonate part by 45 % to 20.9 µm, a supercritical-CO2 case discussed further in the alternatives section below.

Which Chemical Blowing Agent Suits Which Polymer?#

The right chemical blowing agent follows the processing temperature of the host polymer: activated azodicarbonamide for PVC plastisol at 140 to 165 °C, standard azodicarbonamide for crosslinked PE and EVA foam, endothermic grades for polystyrene and polypropylene sheet, and tetrazoles for engineering plastics.

PVC foam: plastisol, calendered and extruded#

PVC foam is the historical home of azodicarbonamide: cushion vinyl flooring, wallpaper and artificial leather are foamed with activated ADC grades that decompose between 140 °C and 165 °C, inside the plastisol fusion range. OBSH covers the lower end of the same range, and Eiwa's Neocellborn N#1000M grade is a fine-grain type built for faster decomposition in PVC wallpaper specifically.

Plastisol, calendered and Celuka processes are covered in more depth under blowing agents for PVC foam. The SVHC listing of ADC triggers REACH Article 33 disclosure duties for articles above a residual threshold, a duty stated here in principle only, because no verified residual level for PVC flooring is available.

Crosslinked polyolefin foams: PE and EVA#

Crosslinked PE and EVA foams use azodicarbonamide together with a zinc oxide kicker and a crosslinking peroxide, because the gas has to be released while the polymer network is building. Sheet, midsole and underlay formulations for this route are compared on blowing agents for polyolefin foams.

One published EVA midsole formulation combines 1.35 phr ADC, 2 phr zinc oxide and 0.5 to 0.7 phr of a peroxide crosslinker, pressed between 165 °C and 190 °C, according to a 2024 study in Materials. This is a published laboratory formulation, not a supplier recommendation.

The organic peroxides used alongside ADC in this route, such as BIPB, are covered on their own family page, which lists the grades and dosage ranges used for EVA and PE crosslinking.

Polystyrene, ABS and engineering plastics#

Polystyrene and ABS sheet are foamed mainly with endothermic bicarbonate grades and with azodicarbonamide masterbatches, while engineering thermoplastics such as PBT need a tetrazole that survives the higher melt temperature. Eiwa's Cellborn SC-K grade covers PS, PE and PP extrusion, its inorganic Polythlene EE-series masterbatches decompose at 155 °C, and Polythlene EB106 is an ADC masterbatch built specifically for ABS.

Bead, sheet and board processes for foamed polystyrene are separated on blowing agents for polystyrene. Expandable and extruded polystyrene (EPS and XPS) are physical-blowing-agent products built on pentane or carbon dioxide, not on the chemical agents covered on this page.

How Much Chemical Blowing Agent Is Used? Dosage in phr and wt%#

Blowing agents account for 0.05 to 20 wt% of a finished plastic product, and the level inside that range is set by the target density, the polymer, the section thickness and whether the agent is added as powder or as masterbatch. That is one of the widest dosage ranges of any additive group tracked on this site, because a light density reduction and a near-foam structural part sit at opposite ends of the same additive class.

Four factors drive the dosage inside that range:

• Target density: a small density cut needs far less agent than a structural foam with a density near half that of the solid polymer.
• Polymer: PVC plastisol formulations are conventionally dosed in phr, while polyolefin and engineering-plastic formulations are dosed in wt%.
• Section thickness: thick parts need less agent per unit volume to reach a given density than thin, fast-cooling sections.
• Physical form: powder gives finer dosing control at the mixer, while masterbatch gives better dispersion and a cleaner hopper.

Foam formulations are written in PHR (parts per hundred resin) for PVC and rubber and in wt% for polyolefins, and the two units convert directly once the total formulation weight is known.

One worked example shows the arithmetic: a 20 wt% ADC masterbatch let down at 2.5 % gives 0.5 wt% ADC in the finished part (0.20 multiplied by 2.5 % equals 0.5 %). Avient states that its Hydrocerol chemical foaming agents can cut plastic use by 10 to 20 % and reduced the weight of one automotive dashboard by 20 %, a supplier claim attributed here to Avient rather than stated as an independent finding. Formulators should treat the 5 wt% ceiling in 21 CFR 178.3010 as a legal maximum for foamed PE, not as a starting dosage. No verified per-polymer dosage or let-down range beyond this arithmetic example and the EVA formulation above exists in our source library; suppliers set the working level by trial on each formulation.

Chemical blowing agent masterbatch and let-down ratio#

Most processors buy the agent as a masterbatch rather than as powder, because a free-flowing pellet disperses better and keeps the fine, dusty and self-reactive powder out of the hopper. Carrier resins and activation temperatures for this route are compared on foaming agent masterbatch.

Eiwa's Polythlene EE-series is an inorganic PE masterbatch that decomposes at 155 °C, its Panthlene H7351 grade carries 70 % ADC in a PE carrier and decomposes at 200 °C, and Polythlene EB106 is the equivalent ADC masterbatch built for ABS.

Check the arithmetic behind any let-down calculation in the let-down ratio calculator, which applies the same formula used in the worked example above to any masterbatch percentage and target dosage.

How Are Chemical Blowing Agents Tested and Characterised?#

Chemical blowing agents are characterised by thermal analysis: differential scanning calorimetry gives the decomposition point and the heat of decomposition, and azodicarbonamide's 1.36 kJ/g was measured by DSC between 160 °C and 230 °C. Four methods together describe a grade:

• Decomposition point and decomposition energy, measured by differential scanning calorimetry (DSC).
• Mass loss and solid residue, measured by thermogravimetric analysis (TGA).
• Gas volume in mL/g, measured volumetrically at a stated reference state, typically 0 °C and 1 atmosphere.
• Foam density and cell structure, measured on the finished moulded or extruded part.

Sadik, Pillon, Carrot and Reglero Ruiz (2018), in a Thermochimica Acta study, used DSC as the reference method for characterising citric-acid and bicarbonate endothermic blowing-agent systems, confirming DSC as the standard first step for any new grade. Residue identification in a finished foam, once the part is moulded, is part of additive analysis (TGA and FTIR). No standard number for gas-volume determination or for cellular-plastics density is verified in our source library, so this page names the methods generically rather than citing a specific ISO or ASTM clause.

Which Chemical Blowing Agents Are Allowed in Food-Contact Plastics?#

In the EU, food-contact foam may be blown only with agents on the Union list of Regulation (EU) No 10/2011, which includes carbonic acid salts (FCM 21), citric acid (FCM 139) and carbon dioxide (FCM 307) but not azodicarbonamide. In the United States, azodicarbonamide is cleared under 21 CFR 178.3010 for foamed polyethylene, subject to a legal ceiling rather than a blanket approval.

Why azodicarbonamide is not allowed in EU food-contact plastics#

Azodicarbonamide has been suspended as a blowing agent in EU plastic food-contact materials since 2 August 2005, when Commission Directive 2004/1/EC amended Directive 2002/72/EC after semicarbazide was found in the decomposition residue. ADC is not listed in the EU 10/2011 Union list, and that suspension applies specifically to its use as a blowing agent in materials that touch food. The suspension does not cover flooring, wallpaper or footwear, and azodicarbonamide continues to be used in those applications, so the substance is not banned in all EU plastics, only suspended from this one food-contact use.

What 21 CFR 178.3010 allows in the United States#

In the United States azodicarbonamide is cleared under 21 CFR 178.3010 for foamed polyethylene at up to 5 wt% of the finished foam, and under 21 CFR 177.1210 for closure-sealing gaskets at up to 2 % of the gasket composition, or 5 % in polyethylene gaskets. The same 178.3010 section clears HFC-152a, isopentane and n-pentane as polystyrene blowing agents, with tetrachloroethylene capped at 0.3 wt% and toluene at 0.35 wt% as blowing-agent adjuvants. Full food types and conditions of use behind these clearances are decoded on the FDA food contact rules (21 CFR) page. None of these entries is an "FDA approval" in the marketing sense; each is a conditional clearance defined by its own CFR section and use limits.

REACH and CLP status: SVHC listing and self-reactive hazard classes#

Azodicarbonamide has been on the REACH Candidate List since 19 December 2012 because it is a respiratory sensitiser under Article 57(f), and its harmonised classification is Resp. Sens. 1, H334. Every additive on the SVHC Candidate List is tracked on this site with its listing date. ADC is not on Annex XIV and does not currently need authorisation. OBSH and TSH carry a different hazard profile: both are harmonised self-reactive substances of type D (H242), which sets storage and transport limits rather than a food-contact restriction. TSSC and 5-phenyltetrazole are not on the Candidate List, and sodium bicarbonate is not on the Candidate List, statements that are correct as of the November 2025 update and were not re-checked against any 2026 update.

Who Makes Chemical Blowing Agents? Manufacturers and Trade Names#

Chemical blowing agents come from a small group of specialists: Eiwa Chemical (Vinyfor, Neocellborn, Cellborn), Avient (Hydrocerol), Baerlocher (ADC 271) and Dongjin Semichem (Unicell), with masterbatch versions sold by compounders. Plants, grades and certifications by company are listed in the directory of blowing agent manufacturers and suppliers. Buyers should compare grades by CAS number, decomposition point and gas yield, not by trade name, since the same chemistry is frequently repackaged under several brand names.

Request quotes for chemical blowing agents: send chemistry or CAS, decomposition temperature, polymer, volume and country to several suppliers at once with the plastic additive supplier finder.

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What Are the Alternatives to Chemical Blowing Agents?#

Three routes replace chemical blowing agents where residues, exotherm or regulation get in the way: physical blowing agents, expandable microspheres and supercritical gas foaming. Each route trades a solid decomposition residue for either a gas, a physical capsule or a dissolved supercritical fluid, and each is covered in depth on its own page within the types of blowing agents family.

Azodicarbonamide alternatives after the SVHC listing#

Azodicarbonamide alternatives fall into 4 groups: endothermic bicarbonate systems, the sulfonyl hydrazides OBSH and TSH, tetrazoles for high-temperature polymers, and physical routes such as expandable microspheres or supercritical nitrogen. The SVHC listing of ADC is the main driver behind formulators evaluating these substitutes, even though the listing itself does not restrict ADC's use outside food contact. The substitution routes are compared in detail under azodicarbonamide alternatives.

Expandable microspheres and supercritical gas foaming#

Expandable microspheres replace the chemistry with a physical capsule: a thermoplastic shell around a hydrocarbon core that starts expanding at 121 to 131 °C and peaks at 168 to 178 °C for Expancel 920 DU 40. Shells built from a vinylidene chloride, methyl methacrylate and acrylonitrile terpolymer can expand more than 40 times in volume. Shell chemistry and grade ranges are set out on expandable microspheres.

Microcellular foaming dissolves supercritical nitrogen or carbon dioxide directly in the melt, a process invented in 1979 at MIT by J.E. Martini and F.A. Waldman under Nam P. Suh and trademarked by Trexel as MuCell since 2001; cells typically run 0.1 to 100 µm. In one polycarbonate case study, 2 % supercritical CO2 gave a 17 to 32 % weight reduction, and gas counter-pressure cut the cell size by 45 % to 20.9 µm. Supercritical nitrogen and carbon dioxide are covered in full under microcellular foaming (MuCell).

Is azodicarbonamide banned?#

No, azodicarbonamide is not banned as a plastic additive, and it is still used in PVC flooring, wallpaper and polyolefin foam, but its use as a blowing agent in EU plastic food-contact materials has been suspended since 2 August 2005. In the United States it remains cleared under 21 CFR 178.3010 for foamed polyethylene, and the FDA opened a post-market assessment of azodicarbonamide in food and food-contact uses on 19 August 2025, a review rather than a ban. The agency published its Request for Information on 13 May 2026 (91 FR 27060, docket FDA-2026-N-4126), the comment period closed on 13 July 2026 and was not reopened, and no outcome has been published.

Is baking soda a foaming agent?#

Yes, sodium bicarbonate, the chemical in baking soda, is the standard endothermic blowing agent in plastics, where it decomposes between 120 °C and 200 °C and releases carbon dioxide and water. Plastics-grade sodium bicarbonate is coated and sized for even dispersion in a hot melt, so kitchen baking soda is not a substitute for a processing machine.

What is the chemical name for a foaming agent?#

No single chemical name covers foaming agents, because the term names a function: the three most common chemical names in plastics are azodicarbonamide (diazene-1,2-dicarboxamide), 4,4'-oxybis(benzenesulfonyl hydrazide) and sodium hydrogen carbonate. Each name corresponds to one of the 7 types covered on this page, and none of the three is interchangeable with the others.

Are chemical blowing agents dangerous to handle?#

Two hazards dominate: azodicarbonamide is a harmonised respiratory sensitiser (H334), and the sulfonyl hydrazides OBSH and TSH are self-reactive substances of type D (H242), which sets storage and transport limits. No storage temperature is verified in our source library for these substances, unlike the SADT values published for crosslinking peroxides, so none is stated here.

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