Morphology and mechanical properties of blown films of a low-density polyethylene/linear low-density polyethylene blend

The morphologies of films blown from a low-density polyethylene (LDPE), a linear low-density polyethylene (LLDPE), and their blend have been characterized and compared using transmission electron microscopy, small-angle X-ray scattering, infrared dichroism, and thermal shrinkage techniques. The blending has a significant effect on film morphology. Under similar processing conditions, the LLDPE film has a relatively random crystal orientation. The film made from the LDPE/LLDPE blend possesses the highest degree of crystal orientation. However, the LDPE film has the greatest amorphous phase orientation. A mechanism is proposed to account for this unusual phenomenon. Cocrystallization between LDPE and LLDPE occurs in the blowing process of the LDPE and LLDPE blend. The structure-property relationship is also discussed. (C) 2002 Wiley Periodicals, Inc.