Polymer Engineering and Science · 1989 · 43 citations · 6 references
Natural SciencesMaterials EngineeringMaterials SciencePolymer ChemistryPolymer MaterialsThermal AnalysisPolymer CharacterizationPolymer Physical ChemistryPolymer PhysicsPolymer ProcessingPolymer StructurePolymer Thin FilmsChain MobilityDynamic Mechanical CharacterizationHigh-temperature PolymersMolecular PackingPacking ProcessesPolyimidesPolymer PlasticizationStorage Modulus
Abstract The imidization of films of the polyamic acid obtained from reaction of pyromellitic dianhydride (PMDA) with oxydianiline (ODA) was studied by dynamic mechanical thermal analysis (with the Polymer Labs DMTA), Two process regions are observed. The first process is characterized by decomplexation of the NMP/polyamic acid complex, plasticization, and imidization. The heating rate determines the character of the first process. At high temperatures (above 300°C) the second process becomes apparent. It is connected to the increase in chain mobility at these temperatures which allow molecular packing processes (densification, ordering) to occur. The ordering leads to an increase of the storage modulus. The particular transition temperature increases with annealing time.
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