Fiber-particle morphological transition and its effect on impact strength of PS/HDPE blends

A morphological analysis was performed to study the effect of postextrusion conditions on the properties of polystyrene (PS)/high-density polyethylene (HDPE) blends. The results show that both draw ratio (DR) and water contact distance (X) have a definite influence on the morphology and mean failure energy (MFE) of 3, 6, and 9% PS in HDPE. In general, the MFE of the blends increases with DR up to a critical value, being function of the water contact distance, where substantial decreases are observed. It was found that deformation of the dispersed phase increases with DR, but decreases with water contact distance. However, morphological analysis of the dispersed phase shows that particle-fiber transition occurs at critical values of DR and X up to a point where fiber break-up occurs. These morphological transitions can easily explain the impact strength behavior of the samples. Using normalized data, a master curve is proposed relating the postex-trusion conditions to the MFE. � 2008 Society of Plastics Engineers