Properties of foam and the solid (neat resin) from which it was derived were compared experimentally for polymethacrylimide (PMI). Viscoelastic properties of the foam and neat resin differed significantly in the range 50 Hz to 5 kHz. No significant differences in thermal properties were observed in differential scanning calorimetry. However, it was observed that the stiffness of the solid material from which the foam was made was increased after heat treatments. It is therefore likely that the properties of the solid material in the foam are changed by the foaming process, which involves elevated temperature. The properties of the solid material in the foam were also inferred from the measured foam properties substituted into the given foam structure-property relations.
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