Orientational phase-separated domains in a polyolefin blend under a temperature gradient field

We investigate the effect of a temperature gradient on the orientation of phase-separated structures in a polyolefin blend system. Phase contrast optical microscopy (PCOM) has been used to measure the morphology of phase separation via spinodal decomposition as a function of phase separation time and temperature gradient. The bicontinuous and interconnected tubelike structure, the characteristic morphology of the spinodal decomposition process, exhibits a preferential alignment along the direction of temperature gradient after phase separation. The orientation of the bicontinuous and interconnected tubelike structures gradually increases with phase separation time and temperature gradients. Also the orientation of phase-separated domains can respond really quickly to the change in the direction of external temperature gradient field. The results suggest that “thermal force” induced by the temperature inhomogeneity might play an important role in aligning phase-separated domains preferentially along the temperature gradient direction.