Flexible microcellular foam from polymethylpentene/cyclohexane

Rapid freezing of a polymethylpentene (PMP)/cyclohexane solution to −80°C gives a tough, flexible foam, in marked contrast to the weak, friable foams obtained by phase‐separation of PMP from other solvents. X‐ray diffraction and differential scanning calorimetry (DSC) data indicate that the isotactic PMP is in an amorphous state. The production of a flexible, robust foam tube from PMP/cyclohexane implies that this material could find applications as replacement parts for arteries and veins or as filter devices. In sheet form, this material seems ideally suited for use as light‐weight insulation for clothing because its open, microcellular structure permits moisture to escape as vapors, but retards air flow. This study demonstrates that process parameters, such as solvent composition, play an important role in determining the various microstructures and physical properties that can be obtained from a single polymer.