New results on the correlation molecular architecture-melt elasticity-blowing process-film properties for conventional and metallocene-catalyzed polyethylenes

Melt elasticity of a series of conventional and metallocene-catalyzed PEs is investigated. The samples show very noticeable differences in their molecular architecture, including a variable degree of LCB and MWD. Four parameters (De, RSI, recoverable shear and steady state compliance), determined through dynamic viscoelastic measurements, are correlated with molecular architecture and blown film properties. RSI parameter shows a particular capacity to discern the LCB effect from the MWD effect on PE melt elasticity. Enhancing melt elasticity improves bubble stability, but provokes more haze and poorer impact properties in the film.