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. Record keeping requirements apply: you need to keep evidence that your polymer meets PLC criteria. 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).

N.B.: If you currently hold a PLC certificate for a polymer, you do not need to do anything. The polymer will be listed on the Inventory when the 5 year non-listing period expires. You cannot cancel or change your certificate after it has been issued.

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

N.B.: There are no volume restrictions on introductions of PLCs exempt from notification. You only need to:

  • keep evidence that your polymer meets PLC criteria

Read our guidance on chemicals exempt from notification


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 10 February 2020