FRACTURE IN COLUMNAR PHASES

Columnar phases are composed of a regular array of columns characteriz ed by either short-range, long-range, or quasi-long-range internal pos itional order. We discuss the Griffith problem of such systems where a thin cavity parallel or perpendicular to the columnar axis is extende d by a tensile stress sigma(alpha beta). The shape of the cavity is ch aracteristic of the type of order present inside the columns. This sim ple test could be used to clarify the nature of the still ambiguous H phase of hexa(hexylthio)triphenylene. This fracture mode would be obse rvable in polymerized samples.