Structure development and melt viscoelastic properties of PE/organoclay nanocomposite blown films

The effects of compatibilizer and the type of polyethylene (PE) matrix on structure development of PE/organoclay nanocomposite samples were investigated by means of X-ray diffraction technique and transmission electron microscopy in conjunction with melt viscoelastic measurements. It was shown that the presence of compatibilizer plays a key role in determining the extent of intercalation and resulting structure development in both linear low-density polyethylene (LLDPE) and low-density polyethylene (LDPE). The LLDPE/organoclay nanocomposite samples exhibited a pronounced low-frequency nonterminal storage modulus whose values were found to be greater than those of LDPE/organoclay nanocomposite samples. The percentage increase in storage modulus values for the compatibilized LLDPE/organoclay nanocomposite sample compared to the virgin LLDPE sample was 1080, while the percentage increase in storage modulus values for the compatibilized LDPE/organoclay nanocomposite sample compared to the virgin LDPE sample was 200, at frequency 0.1 s-1. The melt viscoelastic measurements performed on the nanocomposite blown film samples indicated that at higher draw-down ratio the organoclay platelets and/or tactoids were aligned in the flow direction. Comparing the melt viscoelastic results obtained for annealed and unannealed nanocomposite blown film samples, it was demonstrated that the reorientation of the induced organoclay alignment, which led to network structure formation in the amorphous phase of PE, is very slow, and the time required to complete the reorientation was found to be longer than 3 h at annealing temperature (100 degrees C). (C) 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012