Coextruded HMW HDPE Film Structures With Improved Bubble Stability, 2006 PLACE Conference

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Grocery bag and institutional can liner products have typically coextruded blown films with a large portion of high molecular weight, high density polyethylene (HMW-HDPE) and small percentage (less than 30 percent) of linear low density polyethylene (LLDPE). In addition to contributing some important physical properties, HMW-HDPE provides bubble stability during the “high stalk” blown film process. Previous research has shown that the addition of LLDPE to HMW-HDPE does not significantly improve physical properties, such as puncture and tear, at concentrations less than 30 percent. At higher LLDPE levels, however, the bubble stability is often reduced to the extent that it is not commercially viable. This work shows that higher ratios of LLDPE can be used by changing the molecular weight of the HMW-HDPE resin to improve bubble stability in coextruded films.