Characterizations of transparent polyimide nanocomposite films with various equibiaxial stretching ratios: Optical transparency, morphology, and oxygen permeability

Abstract

A series of transparent polyimide (PI) nanocomposite films was synthesized from bicyclo(2,2,2)oct-7-ene-2,3,5,6-tetracarboxylic dianhydride and 1,3-bis(3-aminophenoxy) benzene with various organoclay contents via solution intercalation polymerization to poly(amic acid)s, followed by thermal imidization. Varying the organoclay loading in the range 01.5 wt % produced variations in the optical transparency, morphology, and oxygen barrier properties of the hybrids. The optimum oxygen barrier properties were observed for the hybrids containing 1.0 wt % Cloisite 30B; these properties were degraded gradually by further increases in the clay content. The PI hybrid films were found to exhibit excellent optical transparency and to be almost colorless. However, the transparency of the hybrid films decreased slightly with increasing organoclay content. Transparent PI hybrid films containing 1.0 wt % Cloisite 30B were stretched equibiaxially with various stretching ratios in the range 100140% to investigate their optical transparency and oxygen permeability in detail; the variations with equibiaxial stretching ratio of the clay dispersion and morphology were also determined. PI hybrid films with stretching of 120% or greater were found to contain homogeneously dispersed clay in the polymer matrix and exfoliated nanocomposites. The highest barrier to oxygen permeation was found to arise at an equibiaxial stretching ratio of 130%. (c) 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012