Polymers of low concern criteria

Polymers of low concern are now exempt from notification

Amendments to the ICNA Act have now commenced. This enables earlier implementation of aspects of the Australian Government's reforms to NICNAS ahead of the main reforms which will commence on 1 July 2020.

Polymers that meet our expanded PLC criteria are now exempt from notification and you do not need a permit or certificate to import or manufacture. Reporting requirements apply. If you wish (such as if you wish your polymer to be listed on the Inventory), you can still make an application for a permit or certificate assessment (fees apply).

A 'polymer of low concern' (PLC) is a polymer that meets the requirements set out on this page.

You can also complete this online questionnaire to check if your polymer is a PLC


Is my polymer an eligible PLC?

To be eligible as a PLC, a polymer must:

OR


Other criteria that must be met

To be an eligible PLC a polymer must also meet the following criteria:

  • have a low charge density
  • contain approved elements only
  • not contain fully fluorinated carbon chains
  • be stable under the conditions in which it is used
  • not be a high molecular weight (≥10,000 g/mol) water absorbing polymer
  • not be a hazardous chemical

Read these criteria below


Low molecular weight species requirements

Except for polyesters manufactured solely from allowable reactants, a PLC must meet the percentage of low molecular weight species requirements. This is dependent on the number average molecular weight (NAMW) of the polymer.

For polymers with an NAMW greater than or equal to 1,000 g/mol and less than 10,000 g/mol, the allowable content of low molecular weight species is less than 10% below 500 g/mol and less than 25% below 1,000 g/mol.

For polymers with an NAMW greater than or equal to 10,000 g/mol, the allowable content of low molecular weight species is less than 2% below 500 g/mol and less than 5% below 1,000 g/mol.

Note: Residual monomers and other reactants are not included when determining the content of low molecular weight species. The low molecular weight species in a polymer refers only to the oligomer content with NAMW less than 1,000 g/mol, where oligomer is defined as the low molecular weight species derived from the polymerisation reaction. This definition is consistent with that used by the US EPA in its polymer exemption criteria.


Reactive functional groups requirements (RFG)

A RFG is defined as: 'an atom or an associated group of atoms in a chemical substance that is intended, or may reasonably be expected, to undergo further chemical reaction'.

For polymers with an NAMW greater than or equal to 10,000 g/mol, there is no restriction on reactive functional groups (RFGs).

For polymers with an NAMW greater than or equal to 1,000 g/mol and less than 10,000 g/mol, a PLC must meet the following RFG requirement.

Scenario 
If the polymer includes moderate concern RFGs, and does not include high concern RFGsIt must have a combined Functional Group Equivalent Weight (FGEW) of at least 1,000 g/mol, calculated based on all moderate concern RFGs present in the polymer.
If the polymer includes high concern RFGs

Regardless of whether or not moderate concern RFGs are present, then it must have a combined FGEW of at least 5,000 g/mol, calculated based on all moderate and high concern reactive functional groups present in the polymer.

RFG categories — low, moderate and high concern

RFGs are divided into 3 categories — low, moderate and high concern — to reflect the comparative reactivity of each functional group.

The criterion for determining the category of the RFG is more qualitative than quantitative. It is based on the presence of chemically or metabolically-reactive or toxic (including eco-toxic) functional groups within the polymer.

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  • Low concern RFGs

    Low concern category RFGs

    RFGs in the low concern category generally lack reactivity in biological and/or aquatic media, or have low reactivity that does not have adverse effects.

    There are no restrictions for low concern functional groups. These may be used without limit.

  • Moderate concern RFGs

    Moderate concern category RFGs

    RFGs in the moderate concern category have evidence of reactivity in biological and/or aquatic media but the effects are not severe enough to place the functional group in the high concern category.

  • High concern RFGs

    High concern category RFGs

    RFGs in the high concern category are the most reactive and are known to pose health and/or environmental concerns.

    Where there is no information or insufficient or contradictory information on a RFG it defaults to the high concern category until sufficient information becomes available for it to be moved to another category.

A number of functional groups are implicitly not considered to be RFGs. These include:

  • carboxylic esters
  • ethers
  • amides
  • urethanes
  • sulfones and
  • nitro groups.

This is provisional on the functional group not being modified to enhance its reactivity (for example, the dinitrophenyl ester of a carboxylic acid).

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  • Table of reactive functional group categories
    Low, moderate and high concern categories of chemicals

    Low concern

    Moderate concern

    High concern

    Aliphatic hydroxyls

    Acid anhydrides

    Alkoxysilanes (with alkoxy of C1-or C2- alkoxysilane)

    Blocked isocyanates (including ketoxime-blocked isocyanates)

    Acid halides

    Alpha lactones

      Amines#

    Butenedioic acid groups

    Aldehydes

    Aziridines

    Carboxylic acids

    Alkoxysilanes (with alkoxy greater than C2-alkoxysilane)

    Azo groups#

    Conjugated olefinic groups contained in naturally occurring fats, oils and carboxylic acids

    Allyl ethers

    Beta lactones

    Halogens (except reactive halogen-containing groups such as benzylic or allylic halides)

    Conjugated olefinic groups not contained in naturally occurring fats, oils and carboxylic acids

    Carbodi-imides

    Imidazolidinone groups#

    Cyanates

    Disulfides#

    Imides#

    Epoxides

    Halosilanes

    Organic phosphate esters#^

    Hemiacetals

    Hydrazines

    Thiols Imines (ketimines and aldimines)

    Hydrosilanes

    Unconjugated nitriles

    Methylol-amides

    Isocyanates

    Unconjugated olefinic groups considered “ordinary”* Methylol-amines

    Isothiocyanates

      Methylol-ureas

    Partially-hydrolysed acrylamides

     

    Unsubstituted positions ortho or para to phenolic hydroxyl

    Pendant acrylates

      

    Pendant methacrylates

      

    Trithiocarbonates#

      

    Vinyl sulfones or analogous compounds

      

    Any other reactive functional group that is not a low concern reactive functional group or a moderate concern reactive functional group

    #Additional RFGs not listed in the regulations but have been determined to be in the low or high concern category

    *Not specially activated either by being part of a larger functional group, such as a vinyl ether, or by other activation influences, for example, a strongly electron-withdrawing sulfone group with which the olefinic groups interact.

    ^Must still meet the approved elements criterion to be eligible as a PLC.

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Polyesters

A polyester is defined as a chemical substance meeting the definition of polymer in the ICNA Act with polymer molecules containing at least two carboxylic acid ester linkages, at least one of which links internal monomer units.

Polyesters manufactured solely from allowable reactants, including any reactants at less than 2%, are eligible for notification as PLCs. This provision is independent of the NAMW and low molecular weight species criterion; however, all other PLC criteria must be met. Thus certain polyesters will not be eligible as PLCs, including biodegradable polyesters and highly water-absorbing polyesters with NAMW greater than or equal to 10,000 g/mol.

A number of allowable reactants are not on the Australian Inventory of Chemical Substances (the Inventory). Therefore the manufacture of polyesters from these reactants cannot be carried out in Australia without notification to and assessment of the reactants by us.

On the other hand, polyesters manufactured from these reactants overseas could be imported, as the reactant itself would not be introduced.

Note: In addition the methyl and ethyl ester derivatives, and anhydride derivatives, of a listed substance in the table are allowed. However no pendant anhydrides should remain in the final polyester polymer.

List of allowable reactants

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  • List of allowable monomers and other reactants
    Includes CAS numbers
    List of allowable reactants

    Reactant

    CAS Number

    Monobasic acids and natural oils

    Benzoic acid

    65-85-0

    Canola oil

    120962-03-0

    Castor oil

    8001-79-4

    Castor oil, dehydrated

    64147-40-6

    Castor oil, dehydrated, polymerised

    68038-02-8

    Coconut oil

    8001-31-8

    Coconut oil, hydrogenated

    84836-98-6

    Corn oil

    8001-30-7

    Corn-oil fatty acids

    68308-50-9

    Cottonseed oil

    8001-29-4

    Dodecanoic acid

    143-07-7

    Fats and glyceridic oils, anchovy

    128952-11-4

    Fats and glyceridic oils, babassu

    91078-92-1

    Fats and glyceridic oils, herring

    68153-06-0

    Fats and glyceridic oils, menhaden

    8002-50-4

    Fats and glyceridic oils, sardine

    93334-41-9

    Fats and glyceridic oils, oiticica

    8016-35-1

    Fatty acids, C8-10

    68937-75-7

    Fatty acids, C14-18 and C16-18-unsaturated

    67701-06-8

    Fatty acids, C16-18 and C18-unsaturated

    67701-08-0

    Fatty acids, castor-oil

    61789-44-4

    Fatty acids, coco

    61788-47-4

    Fatty acids, dehydrated castor-oil

    61789-45-5

    Fatty acids, linseed oil

    68424-45-3

    Fatty acids, olive-oil

    92044-96-7

    Fatty acids, safflower oil

    93165-34-5

    Fatty acids, soya

    68308-53-2

    Fatty acids, sunflower oil

    84625-38-7

    Fatty acids, sunflower-oil, conjugated

    68953-27-5

    Fatty acids, tall-oil

    61790-12-3

    Fatty acids, tall-oil, conjugated

     

    Fatty acids, vegetable oil

    61788-66-7

    Fish oil

    8016-13-5

    Glycerides, C16-18 and C18-unsaturated

    67701-30-8

    Heptanoic acid

    111-14-8

    Hexadecanoic acid

    57-10-3

    9-Hexadecenoic acid, (9Z)-

    373-49-9

    Hexanoic acid

    142-62-1

    Hexanoic acid, 3,3,5-trimethyl-

    23373-12-8

    Hexanoic acid, 3,5,5-trimethyl-

    3302-10-1

    Linseed oil

    8001-26-1

    Linseed oil, oxidized

    68649-95-6

    Linseed oil, polymerised

    67746-08-1

    Nonanoic acid

    112-05-0

    Octadecanoic acid

    57-11-4

    9 Octadecenoic acid (9Z)

    112-80-1

    9,12-Octadecadienoic acid (9Z,12Z)-

    60-33-3

    Oils, cannabis

     

    Oils, palm kernel

    8023-79-8

    Oils, perilla

    68132-21-8

    Oils, walnut

    8024-09-7

    Olive oil

    8001-25-0

    Safflower oil

    8001-23-8

    Soybean oil

    8001-22-7

    Sunflower oil

    8001-21-6

    Tung oil

    8001-20-5

    Di and tri basic acids

     

    1,2-Benzenedicarboxylic acid

    88-99-3

    1,3-Benzenedicarboxylic acid

    121-91-5

    1,3-Benzenedicarboxylic acid, dimethyl ester

    1459-93-4

    1,4-Benzenedicarboxylic acid

    100-21-0

    1,4-Benzenedicarboxylic acid, diethyl ester

    636-09-9

    1,4-Benzenedicarboxylic acid, dimethyl ester

    120-61-6

    1,2,4-Benzenetricarboxylic acid

    528-44-9

    Butanedioic acid

    110-15-6

    Butanedioic acid, diethyl ester

    123-25-1

    Butanedioic acid, dimethyl ester

    106-65-0

    2-Butenedioic acid (E)-

    110-17-8

    1,4-Cyclohexanedicarboxylic acid

    1076-97-7

    Decanedioic acid

    111-20-6

    Decanedioic acid, diethyl ester

    110-40-7

    Decanedioic acid, dimethyl ester

    106-79-6

    Dodecanedioic acid

    693-23-2

    Fatty acids, C18-unsaturated, dimers

    61788-89-4

    2,5-Furandione, dihydro-

    108-30-5

    Heptanedioic acid

    111-16-0

    Heptanedioic acid, dimethyl ester

    1732-08-7

    Hexanedioic acid

    124-04-9

    Hexanedioic acid, diethyl ester

    141-28-6

    Hexanedioic acid, dimethyl ester

    627-93-0

    5-Isobenzofurancarboxylic acid, 1,3-dihydro-1,3-dioxo-

    552-30-7

    1,3-Isobenzofurandione

    85-44-9

    Nonanedioic acid

    123-99-9

    Nonanedioic acid, diethyl ester

    624-17-9

    Nonanedioic acid, dimethyl ester

    1732-10-1

    Octanedioic acid

    505-48-6

    Octanedioic acid, dimethyl ester

    1732-09-8

    Pentanedioic acid

    110-94-1

    Pentanedioic acid, diethyl ester

    818-38-2

    Pentanedioic acid, dimethyl ester

    1119-40-0

    Undecanedioic acid

    1852-04-6

    Unsaturated fatty acids, C18, dimers, hydrogenated

    68783-41-5

    Polyols

    1,3-Butanediol

    107-88-0

    1,4-Butanediol

    110-63-4

    1,4-Cyclohexanedimethanol

    105-08-8

    1,2-Ethanediol

    107-21-1

    Ethanol, 2,2´-oxybis-

    111-46-6

    1,6-Hexanediol

    629-11-8

    1,3-Pentanediol, 2,2,4-trimethyl-

    144-19-4

    1,2-Propanediol

    57-55-6

    1,3-Propanediol

    504-63-2

    1,3-Propanediol, 2,2-bis(hydroxymethyl)-

    115-77-5

    1,3-Propanediol, 2,2-dimethyl-

    126-30-7

    1,3-Propanediol, 2-ethyl-2-(hydroxymethyl)-

    77-99-6

    1,3-Propanediol, 2-(hydroxymethyl)-2-methyl-

    77-85-0

    1,3-Propanediol, 2-methyl-

    2163-42-0

    1,2,3-Propanetriol

    56-81-5

    1,2,3-Propanetriol, homopolymer

    25618-55-7

    2-Propen-1-ol, polymer with ethenylbenzene

    25119-62-4

    Modifiers

    Acetic acid, 2,2´-oxybis-

    110-99-6

    1-Butanol

    71-36-3*

    Cyclohexanol

    108-93-0

    Cyclohexanol, 4,4´-(1-methylethylidene)-bis-

    80-04-6

    Ethanol

    64-17-5

    Ethanol, 2-(2-butoxyethoxy)-

    112-34-5

    1-Hexanol

    111-27-3

    Methanol

    67-56-1

    Methanol, hydrolysis products with trichlorohexylsilane and trichlorophenylsilane

    72318-84-4

    1-Phenanthrenemethanol, tetradecahydro-1,4a-dimethyl-7-(1-methylethyl)-

    13393-93-6

    Phenol, 4,4´-(1-methylethylidene)bis-, polymer with 2,2´-[(1-methylethylidene)bis(4,1-phenyleneoxymethylene)]bis[oxirane]

    25036-25-3

    1-Propanol, 2-methyl-

    78-83-1

    Siloxanes and Silicones, dimethyl, diphenyl, polymers with phenyl silsesquioxanes, methoxy-terminated

    68440-65-3

    Siloxanes and Silicones, dimethyl, methoxy phenyl, polymers with phenyl silsesquioxanes, methoxy-terminated

    68957-04-0

    Siloxanes and Silicones, methyl phenyl, methoxy phenyl, polymers with phenyl silsesquioxanes, methoxy- and phenyl-terminated

    68957-06-2

    Silsesquioxanes, phenyl propyl

    68037-90-1

    *1-Butanol may not be used in a substance manufactured from fumaric or maleic acid because of potential risks associated with esters which may be formed by reaction of these reactants.

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Other criteria

To be an eligible PLC a polymer must also meet the following criteria:

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  • Low charge density

    Cationic polymers and polymers reasonably anticipated to become cationic in a natural aquatic environment are not eligible as PLCs. The main concern is their toxicity towards aquatic organisms such as fish and algae.

    For the purposes of legislation, and this guidance, these definitions apply:

    • A polymer is a low charge density polymer if it is:
      • not a cationic polymer or is not reasonably anticipated to become a cationic polymer in a natural aquatic environment (4<pH<9)
      • a solid material that is not soluble or dispersible in water and will only be used in the solid phase (for example ion exchange beads), or
      • cationic (or potentially cationic) and the combined (total) FGEW of cationic groups is at least 5,000 g/mol.
    • A cationic polymer is a polymer containing a net positively-charged atom/s or associated group/s of atoms covalently linked to its polymer molecule. Examples are the ammonium, phosphonium and sulfonium cations.
    • A potentially cationic polymer is a polymer containing groups reasonably anticipated to become cationic. Examples are all amines (primary, secondary, tertiary, aromatic, etc.) and all isocyanates (which hydrolyse to form carbamic acids, then decarboxylate to form amines).
    • Reasonably anticipated means a knowledgeable person would expect a given physical or chemical composition or characteristic to occur, based on factors such as the nature of the precursors used to manufacture the polymer, the type of reaction, the type of manufacturing process, the products produced in the polymerisation, the intended uses of the substance and associated use conditions.

    Example low charge density

    Consider a polyamide with a NAMW 7,000 g/mol manufactured from equimolar amounts of ethylenediamine and isophthalic acid. On average, the polymer will have one unreacted amino group at one end of the polymer chain and an unreacted carboxylic acid group at the other end. As the amino group is potentially cationic it needs to be included in the calculation of the FGEW of cationic groups in this polymer. The FGEW for the amino group can be calculated by end-group analysis i.e. 7,000/1 g/mol. Therefore, the polymer meets the criteria for low charge density as the FGEW is above 5,000 g/mol. If the NAMW had been less than 5,000 g/mol, or if the polymer had two free amine groups, then the polymer would not be eligible as a PLC.

    Note: There is no high NAMW cut-off for charge density. Therefore even if a polymer has a NAMW of ≥10,000 g/mol, it still needs to have a FGEW of cationic groups of 5,000 g/mol or above, or it will not meet the PLC criteria.

  • Approved elements criteria

    A PLC must contain, as an integral part of its composition, at least two of the atomic elements carbon, hydrogen, nitrogen, oxygen, silicon and sulfur.

    Excluding impurities, a PLC must only contain the following:

    • carbon, hydrogen, nitrogen, oxygen, silicon and sulphur
    • sodium, magnesium, aluminium, potassium, calcium, chlorine, bromine and iodine as the monatomic counter-ions Na+, Mg2+, Al3+, K+, Ca2+, Cl-, Br- or I-
    • fluorine, chlorine, bromine or iodine covalently bound to carbon
    • less than 0.2% (by weight) of any combination of the atomic elements lithium, boron, phosphorus, titanium, manganese, iron, nickel, copper, zinc, tin and zirconium.

    No other elements are allowed, except as impurities. Specifically, the fluoride anion (F-) is not allowed as it has a high acute toxicity.

    This requirement refers to monatomic species only. For example, a polymer containing the ammonium counter ion (NH4+) may be a PLC provided it meets the other PLC criteria.

    With the binding of halogens to carbon, note that the perchlorate anion ClO4- would not be allowed because the chlorine is not covalently bound to carbon, but the trichloroacetate anion CCl3CO2- would be allowed.

  • Fully fluorinated carbon chains

    A polymer is not eligible to be a PLC if it contains as an integral part of its composition (except as an impurity) a chain (whether branched or linear) of fully fluorinated carbon atoms, at least one end of which is terminated by a perfluoromethyl (CF3) group.

    The primary concern for perfluoroalkyl containing polymers is degradation in the environment to release potentially persistent, bioaccumulative or toxic degradation products.

  • Stable polymer

    A PLC must be a polymer that is stable under the conditions in which it is used.

    A polymer is not eligible to be a PLC if it readily breaks down by any process under the conditions in which it is used throughout its lifecycle. This includes break down by any process where the polymeric substance readily breaks down into simpler, smaller weight substances as the result of, but not limited to, oxidation, hydrolysis, heat, sunlight, attack by solvents or microbial action.

    Examples of polymers that would not meet this criterion include those that:

    • are designed to be pyrolysed or burnt during normal use
    • are explosive
    • substantially biodegrade in the environment (for example, starch)
    • are hydrolytically unstable (t1/2 < 12 hours).

    Note: A polymer may still be eligible as a PLC despite its potential to readily break down in the environment if under the conditions in which it is used substantial degradation would not be expected to occur. For example, polymers used in cements, adhesives, hot melts, and extrusion molding would be eligible as a PLC as the polymer would be expected to be protected from environmental degradation.

  • Water absorbing polymers

    Polymers with NAMW greater than or equal to 10,000 g/mol that are water absorbing (meaning a polymer capable of absorbing its own weight in water) do not qualify as PLCs.

    This criterion is for water absorbing polymers in particulate form only and is directed towards polymers known as 'super absorbents', such as those used in disposable nappies and paper towels.

    The concerns for water absorbing polymers are based on data showing that cancer was observed in a two-year inhalation study in rats on a high molecular weight water-absorbing polyacrylate polymer.

    Water-soluble and water dispersible polymers are not considered to be water absorbing. This is because it is assumed that particles of these polymers are adequately cleared from the lungs by normal clearance mechanisms after inhalation.

  • Hazardous substance

    A polymer can only be a PLC if it is not classified as a hazardous chemical as defined in the regulations under the ICNA Act.

    A hazardous chemical is a chemical that satisfies the criteria for a hazard class under the GHS, but does not include a chemical that satisfies the criteria solely for one of the following hazard classes:

    (a) flammable gases, category 2
    (b) acute toxicity—oral, category 5
    (c) acute toxicity—dermal, category 5
    (d) acute toxicity—inhalation, category 5
    (e) skin corrosion/irritation, category 3
    (f) serious eye damage/eye irritation, category 2B
    (g) aspiration hazard, category 2
    (h) hazardous to the aquatic environment, category acute 1, 2 or 3
    (i) hazardous to the aquatic environment, category chronic 1, 2, 3 or 4
    (j) hazardous to the ozone layer.

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How to calculate functional group equivalent weight

The functional group equivalent weight (FGEW) is used to determine if the RFGs in a polymer are substantially diluted by polymeric material to allow the polymer to be a PLC.

The FGEW of a polymer is defined as the ratio of the NAMW to the number of functional groups in the polymer. It is the weight of a polymer that contains one formula weight of the functional group.

The level of low concern RFGs in the polymer is not restricted. Low concentrations of moderate and high concern RFGs are permissible in polymer molecules, but the quantity is restricted by the reactivity of the functional group/s in question.

Unless the FGEW can be determined empirically by recognised, scientific methodology (typically titration), a worst-case estimate must be made for the FGEW.

All moderate and high concern functional groups must be taken into account when calculating FGEW.

End-group analysis or percent charged method

The FGEW may be calculated by end-group analysis or by the percent charged method.

  • End-group analysis applies to polymers containing reactive functional groups at terminal positions.
  • The percent charged method applies to polymers with reactive functional groups distributed throughout the polymer.
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  • End group analysis - linear and branched polymers
    FGEW example equations 1 (linear) and 2 (branched)

    Linear polymers

    For linear polymers containing RFGs only at the terminal positions, the FGEW can be calculated using equation 1.

    Equation 1 linear polymers

    End group analysis equation

    For linear polymers, such as some condensation polymers (for example, polyesters and polyamides), the only RFGs are at the end of the chain because the others are used up in the condensation reaction. The number of end groups (n) may be equal to 1 or 2 depending on the molar ratio of the starting monomers.

    For example, for a polyamide with a NAMW 1,500 g/mol made from an excess of ethylenediamine and adipic acid, an amine group (high concern) would be expected at each end of the polymer chain. Therefore, the amine FGEW = 1,500/2 = 750 g/mol.

    On the other hand, if the polyamide was made from equimolar amounts of ethylenediamine and adipic acid, the polymer will on average have one unreacted amine group at one end of the polymer chain and an unreacted carboxylic acid group at the other end. In this case, the amine FGEW = 1,500/1 = 1,500 g/mol ( the carboxylic acid group is not considered in the calculation, as it is a low concern RFG).

    In both examples, the polymer would NOT be eligible as a PLC as the amine FGEW is below the required minimum equivalent weight threshold of 5,000 g/mol for polymers containing high concern (potentially cationic) groups.

    Branched polymers

    For simple branched polymers (having only one monomer possessing more than 2 reactive sites), the FGEW is calculated from an estimated degree of branching, which is derived by knowing the number of reactive groups in the polyfunctional monomer. It is assumed that the monomer responsible for the branching will be incorporated in its entirety to form the polymer. The FGEW can be calculated using equation 2.

    .

    Equation 2 branched polymers

    End group analysis equation for simple branched polymers

    Consider a branched polyurethane polymer containing isocyanate groups (high concern) at chain ends derived from the polymerisation of pentaerythritol (molecular weight (MW) 136 g/mol) with polypropylene glycol and an excess of isophorone diisocyanate. The polyfunctional branching monomer pentaerythritol (4 reactive sites) is added to the reaction at 10 weight %. The NAMW of the polymer is 2,720 g/mol.

    Chemical image example Branched polymer

    Example not a PLC as isocyanate FGEW is below required minimum, equivalent weight threshold

    In the above example, the polymer would NOT be eligible as a PLC as the isocyanate FGEW is below the required minimum equivalent weight threshold of 5000 g/mol for polymers containing high concern groups.

  • Per cent charged method

    Some condensation and addition reactions create polymers where not all RFGs along the backbone of the polymer are consumed during the reaction, so an accurate FGEW cannot be determined through a simple end-group analysis. For any of these polymers, FGEW can be calculated according to equation 3.

    Equation 3 per cent charged method

    FGEW calculation polymer of low concern

    For example, for an acrylic polymer containing 7.5 weight % acryloyl chloride monomer (MW 90.5 g/mol), the FGEW of acid chloride groups in the polymer is:

  • Combined FGEW calculation for multiple RFGs in a polymer

    If the various RFGs in a polymer arise from multiple monomers, the FGEW must be calculated for each monomer separately, and then the combined FGEW is calculated according to equation 4.

    Equation 4 combined FGEW calculation for multiple RFGs in a polymer

    FGEW polymer low concern calculation

  • FGEW calculation examples

    Example 1

    Consider the reaction between ethylenediamine (MW 60 g/mol) (charged at 30 weight %) and diglycidyl ether (MW 130 g/mol) (charged at 70 weight %) to give a polymer of NAMW of 5,000 g/mol. The epoxides in the backbone are reacted to give an aliphatic alcohol (low concern). The amine groups remain intact, with their FGEW proportional to the charged amount of ethylenediamine. As the diglycidyl ether is in excess, it can be assumed that the polymer is epoxide-terminated at both ends.

    Chemical image diagram polymer epoxide-terminated at both ends

    Using equation 3, the FGEW for the amine group (high concern) is (100 x 60)/(30 x 2) = 100 g/mol. The FGEW for the epoxide group (moderate concern) can be calculated using end group analysis (equation 1), that is, 5,000/2 = 2,500 g/mol.

    Then, using equation 4, FGEWcomb = inverse of [1/100 + 1/2500] = 96 g/mol.

    In this example, the polymer would NOT be eligible as a PLC.

    Example 2

    Consider a p-cresol-formaldehyde condensation polymer which is reacted with 1.5 weight % epichlorohydrin to give an epoxide-capped resin. As a worst-case scenario, it is assumed that the polymer is phenol-terminated. This would mean phenol groups with reactive ortho positions reside at the polymer backbone termini. The polymer also contains epoxy rings from the epichlorohydrin (MW 92.5 g/mol). Both reactive functional groups are moderate concern. A NAMW of 8,000 g/mol is assumed.

    chemical diagram example of a reactive functional group of low concern

    Using equation 3, the FGEW for the epoxide group is (100 × 92.5)/(1.5 × 1) = 6,167 g/mol. The FGEW for the phenol group can be calculated using end group analysis (equation 1), that is, 8,000/2 = 4,000 g/mol.

    Then, using equation 4, FGEWcomb = inverse of [1/6,167 + 1/4,000] = 2,426.

    With a combined FGEW of 2,426 g/mol, this polymer would be eligible as a PLC because the FGEWcomb is above the required minimum equivalent weight threshold of 1,000 g/mol for a polymer containing moderate concern functional groups.

    Example 3

    Consider the addition reaction involving the polymerisation of three acrylates, glycidyl methacrylate (10 weight %, MW 142 g/mol, 1 RFG), hydroxymethyl acrylamide (2 weight %, MW 101 g/mol, 1 RFG) and acrylic acid (88 weight %).

    In this case, it can be assumed that each monomer is completely incorporated into the polymer, with the RFGs of concern being the epoxide group (moderate concern) from glycidyl methacrylate and the hydroxymethyl amide group (moderate concern) from the acrylamide. The carboxylic acid moiety from acrylic acid is of low concern and need not be included in FGEW calculations.

    A chemical image showing an example of a PLC low concern

    Using equation 3, the FGEW for the epoxide group is (100 × 142)/(10 × 1) = 1,420 g/mol. Again using equation 3, the FGEW for the hydroxymethyl amide group is (100 × 101)/(2 × 1) = 5,050 g/mol.

    Then, using equation 4, FGEWcomb = inverse of [1/1,420 + 1/5,050] = 1,108 g/mol.

    With a combined FGEW of 1,108 g/mol, this polymer would be eligible as a PLC because the FGEWcomb is above the required minimum equivalent weight threshold of 1,000 g/mol for a polymer containing moderate concern functional groups.

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Last update 8 April 2019