| abstract |
A technique for initiating the formation of pores in a polymeric material that contains a thermoplastic composition is provided. The thermoplastic composition contains microinclusion and nanoinclusion additives dispersed within a continuous phase that includes a matrix polymer. To initiate pore formation, the polymeric material is mechanically drawn (e.g., bending, stretching, twisting, etc.) to impart energy to the interface of the continuous phase and inclusion additives, which enables the inclusion additives to separate from the interface to create the porous network. The material is also drawn in a solid state in the sense that it is kept at a temperature below the melting temperature of the matrix polymer. |