Formulating Epoxies with Dianhydrides

Dianhydrides are able to cure epoxy resins to extremely high degrees of crosslinking. This results in enhanced performance, for example, resistance to chemicals,  high temperature and electrical voltage.

However, the formulator must be careful of certain points to derive the advantages from such resin systems.

The rapid buildup of a densely crosslinked polymer network easily results in vitrification, trapping  unreacted anhydride groups.  Likely transformed to acid, these sites may create sensitivity to chemicals and water exposure. 

When a complete cure is achieved, for example, via post-cure at elevated temperature, the finally realized crosslink density could be too high. This can result in brittleness and generally non-optimum physical characteristics.

So, dianhydrides are best utilized at far below stoichiometric levels vs the epoxy resin. The table below shows a comparison with mono-anhydrides. This method brings the target crosslink density slightly lower and helps optimize the resulting physical properties.

This also helps to avoid residual anhydride (or acid) groups in the cured product, which results in many excess epoxide groups in the formulation. Via the side-reaction of epoxy homopolymerization, they will react within the cured network.

This etherification reaction decreases brittleness and lowers the crosslink density in the network when compared with a resin system which is fully crosslinked via just esterification with a dianhydride.

Many epoxy formulators do not usually want this epoxide side reaction, yet, users of dianhydrides frequently benefit from it, deliberately designing it into their formulations.

Table 1. Suggested Anhydride/Epoxide ratios (A/E) for different anhydride curatives, with standard liquid epoxy resin (DGEBA with EEW 190 g/eq). Fully stoichiometry would mean A/E =1.00. Source: CABB Group GmbH

Curative Suggested A/E ratios for
optimum performance
BTDA (Benzophenone tetracarboxylic dianhydride), a dianhydride 0.50 - 0.60
NMA (Nadic methyl anhydride), a mono-anhydride 0.90 - 0.95
MTHPA (Methyl tetrahydrophthalic anhydride), a mono-anhydride 0.93 - 0.97

This information has been sourced, reviewed and adapted from materials provided by JAYHAWK Thermoset Additives.

For more information on this source, please visit JAYHAWK.



Please use one of the following formats to cite this article in your essay, paper or report:

  • APA

    JAYHAWK Thermoset Additives. (2022, January 06). Formulating Epoxies with Dianhydrides. AZoM. Retrieved on February 23, 2024 from

  • MLA

    JAYHAWK Thermoset Additives. "Formulating Epoxies with Dianhydrides". AZoM. 23 February 2024. <>.

  • Chicago

    JAYHAWK Thermoset Additives. "Formulating Epoxies with Dianhydrides". AZoM. (accessed February 23, 2024).

  • Harvard

    JAYHAWK Thermoset Additives. 2022. Formulating Epoxies with Dianhydrides. AZoM, viewed 23 February 2024,

Tell Us What You Think

Do you have a review, update or anything you would like to add to this article?

Leave your feedback
Your comment type
Azthena logo powered by Azthena AI

Your AI Assistant finding answers from trusted AZoM content

Azthena logo with the word Azthena

Your AI Powered Scientific Assistant

Hi, I'm Azthena, you can trust me to find commercial scientific answers from

A few things you need to know before we start. Please read and accept to continue.

  • Use of “Azthena” is subject to the terms and conditions of use as set out by OpenAI.
  • Content provided on any AZoNetwork sites are subject to the site Terms & Conditions and Privacy Policy.
  • Large Language Models can make mistakes. Consider checking important information.

Great. Ask your question.

While we only use edited and approved content for Azthena answers, it may on occasions provide incorrect responses. Please confirm any data provided with the related suppliers or authors. We do not provide medical advice, if you search for medical information you must always consult a medical professional before acting on any information provided.

Your questions, but not your email details will be shared with OpenAI and retained for 30 days in accordance with their privacy principles.

Please do not ask questions that use sensitive or confidential information.

Read the full Terms & Conditions.