Influence of LLDPE Blends and Coextrusions on HMW-HDPE Film Properties, 1990 Polymers, Laminations & Coatings Conference Proceedings

The interest of optimizing properties of HDPE film for particular applications has lead to combinations of HMW-HDPE with LLDPE. This study describes screening work directed at identifying trends in mechanical properties as a function of HDPE/LLDPE blends and coextrusion structures. Included are blends prepared from HMW-HDPE and hexene-1 LLDPE copolymers with LLDPE content ranging from 0 wt% up to 60 wt%. Coextrusions of HMW-HDPE with hexene-1 comonomer LLDPE were prepared using ABA structures of HD/LL/HD and LL/HD/LL. As in the case of the blends, the LLDPE content of the coextruded films ranged from 0 wt% up to 60 wt%. For both blends and coextrusions it was found that modulus and tensile properties were primarily additive properties based on the weighted characteristics of the two resins. The major differences between blends and coextrusion were found in impact and tear properties. Whereas impact was found to be an average of the components in coextrusions, blend products had much lower impact performance. Also, although neither coextrusions nor blends significantly increased machine direction tear, it was found that the degree of orientation for coextruded films was significantly less than the blend products.