Journal of Applied Polymer Science, Vol.51, No.2, 271-278, 1994
A Rheological and Morphological Explanation of the Inherent Blocking Force in LLDPE Blown Films
The inherent film blocking force in linear low-density polyethylene (LLDPE) blown films was studied using several LLDPEs with varying density, molecular weight, and molecular weight distribution (MWD). Melt elasticity, fabrication conditions, and film surface morphology were found to have a significant effect on the inherent film-blocking force in LLDPE blown films. A comprehensive mechanism for the film-blocking force based on molecular weight, rheology, and morphology studies is proposed. LLDPEs with higher density exhibited a lower blocking force. At a constant density, the LLDPEs with higher melt elasticities (slower relaxation rates) exhibited rougher film-surface morphology and produced blown films with lower blocking force. These LLDPEs with an inherent low blocking force are used in grocery sacks, trash bags, and merchandise bag markets where bag openability is a critical performance property.
Keywords:POLYETHYLENE