Cellular structures from anisotropic semi-crystalline polymer templates

This paper presents a method to prepare kinetically trapped composite foams using anisotropic semicrystalline media as a template. The semi-crystalline polymer templates used were films (Polyethylene Terephthalate) and filaments (Polyamide-12) which are biaxially and uniaxially oriented respectively. Supercritical carbon dioxide was used as a solvent to transport styrene monomer mixed with a radical initiator into the template. This phase was allowed to polymerize and foam to create a microcellular structure. Even though template anisotropy did not dictate the final morphology of the cells, interesting cell structures such as radial gradient and biaxial were observed due to the processing conditions. Initial mechanical tests showed an improvement in specific modulus and specific strength. This approach might be useful to create composite foams with tunable macroscopic and microscopic features that could be potentially used as a replacement for Balsa wood.