Electric‐field‐induced chain orientation in poly(L‐lactic acid)

The orientational order was studied for melt‐state poly( L ‐lactic acid) under an external direct‐current electric field. A birefringence as high as 1.1 × 10 −2 was recorded against an external field of 1.0 MV/m at 190 °C. The evidence proved that a field–dipole interaction transferred from a randomly coiled conformation to a uniaxially drawn conformation. The field‐induced birefringence was temporally resolved, and the chain orientation and relaxation processes on the order of 100 s were observed in a real timescale after the field was turned on and off. A mechanism of chain orientation was examined with respect to the orientation polarization and viscoelasticity.