Solid poly(amic acid) (PAA) precursor is used for foaming into microspheres or foams depending on whether the powder particles are free or confined inside a mold. Solid-state foaming of powder precursors is studied by examining concurrent and competitive phenomena that determine the morphology and physical properties of the foam unit cell. Simultaneous analysis through thermo gravimetric analysis (TGA) and modulated differential scanning calorimetry (MDSC) is proposed for the characterization of important transitions during the blowing process. Effects of particle size and shape on bubble growth will be addressed.
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