Pyromellitic dianhydride (PMDA, CAS 89-32-7) is an aromatic monomer used to make polyimide films. For film producers, the incoming grade matters because monomer purity and the balance of reactive groups affect the precursor used for coating or casting. Free acid and moisture exposure are two separate points to track alongside assay.
How PMDA Fits into Polyimide Film Production
PMDA reacts with an aromatic diamine such as 4,4′-oxydianiline (ODA) to form a polyamic acid precursor. Film formation involves applying the precursor and converting it to polyimide through imidization. Monomer balance matters to precursor molecular weight and processing consistency. Polyimide film chemistry and processing.
Flexible printed circuits are one downstream use of polyimide films. The final film must meet the dimensional and mechanical requirements of the circuit design. Formulations may combine PMDA with other dianhydrides or diamines to reach the intended film properties. Flexible laminate and polyimide film patent publication.
Purity and Free Acid in the Incoming Grade
The grade listed on our Pyromellitic Dianhydride (PMDA), CAS 89-32-7 product page specifies white crystals, at least 99.5% purity, a free acid limit of 0.5 wt%, and a melting range of 286–288 °C. These figures describe the listed specification. Batch results are recorded separately against the applicable limits.
The free acid limit is a separate release criterion alongside purity. For film processes that rely on a narrow precursor viscosity range, lot comparisons are most useful when the assay and free acid results use consistent test methods and reporting bases.
Moisture Control Before Charging
PMDA reacts with water to form acid. Moisture exposure can change the balance of intact anhydride groups before the monomer enters the reaction. Dry storage, well-closed containers and controlled opening of the pack help limit that exposure during staging. ILO and WHO chemical safety card for PMDA.
The storage conditions for the supplied grade and its handling precautions belong in the applicable technical and safety documents. For film production, consistent handling between receipt and charging supports comparison of incoming lots on the same basis.
Commercial Packaging and Supply
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Post time: Nov-11-2026