Poly(amic acid) (PAA) hybrids with organically modified montmorillonite (Cloisite 30B) were synthesized from N,N 0 -dimethylacetamide (DMAc) solution. These hybrids were heated at various temperatures, yielding 64-to 68lm thick films of polyimide (PI)/Cloisite 30B hybrids with various clay contents (0-1.5 wt%). The intercalation of PI chains among the organoclay particles was examined using wide-angle X-ray diffraction (XRD) and electron microscopy (TEM) techniques. The thermo-optical properties were measured by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and ultraviolet-visible (UV-vis) spectrometry. The optimum thermal and 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 presence of only 1.0 wt% Cloisite 30B in a PI hybrid film was found to result in an 83% reduction in the rate of O 2 permeability with respect to that of the pure PI film. 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.
A series of colorless and transparent polyimide (PI) nanocomposite films was synthesized from 4,4'-(hexafluoroisopropylidene) diphthalic anhydride (6FDA) and bis(3-aminophenyl) sulfone (APS) with various organoclay contents via solution intercalation polymerization to poly(amic acid)s, followed by thermal imidization. Varying the organoclay loading in the range of 0 to 1.00 wt% produced variations in the thermal properties, morphologies, and optical transparencies of the hybrids. The hybrid films exhibited high optical transparencies and almost no color, with cut-off wavelengths between 330 and 346 nm and very low yellow index (YI) values of 1.78-3.80. The hybrid PI films showed good thermal properties with glass transition temperatures of 236-245 degrees C. Most films did not show significant thermal decomposition below 450 degrees C. It was found that the addition of only a small amount of organoclay was sufficient to improve the thermal properties of the PI films, with maximum enhancements being observed at 0.50 wt% organoclay. Moreover, these PI hybrids also showed low coefficients of thermal expansion (CTE).
A series of transparent polyimide (PI) nanocomposite films was synthesized from bicyclo(2,2,2)oct-7ene-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 0-1.5 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 100-140% 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%. V C 2012 Wiley Periodicals, Inc. J Appl Polym Sci 126: E2-E11, 2012
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