[Show abstract][Hide abstract] ABSTRACT: A series of colorless polyimide (PI) nanocomposite films were synthesized from 2,2'-bis(3,4-dicarbox-yphenyl)hexafluoropropane dianhydride (6FDA) and 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFDB) with various organoclay contents by solution intercalation polymerization to poly(amic acid)s, followed by thermal imi-dization. The variation with the organoclay content of the thermomechanical properties, morphology, and optical transparency of the hybrids was examined at organoclay loadings ranging from 0 to 1.0 wt%. The hybrid films showed high optical transparency and almost no color, with cut-off wavelengths ranging from 352 and 356 nm and very low b* values of 1.19-1.77. The hybrid PI films showed good thermal properties with a glass transition tem-perature of 280-287 o C. Most films did not show any significant thermal decomposition below 490 o C. The addition of only a small amount of organoclay was sufficient to improve the tensile properties of the PI films with maximum enhancement being observed at 0.25 wt% organoclay. Moreover, these PI hybrids also had low coefficients of ther-mal expansion (CTE).
Preview · Article · Aug 2008 · Macromolecular Research
[Show abstract][Hide abstract] ABSTRACT: Organically modified montmorillonite (C8PPh-MMT) was obtained using the ion exchange reaction between Na+-montmorillonite (Na+-MMT) and 1-octenyltriphenyl phosphonium chloride (C8PPh-Cl−). Polystyrene nanocomposites were then prepared by in-situ free-radical polymerization of the styrene containing intercalated
C8PPh-MMT. The resulting polystyrene hybrids with various organoclay contents were investigated with FT-IR, which confirmed
that PS hybrids were successfully prepared via the reaction of styrene monomer in the interlayers of the clays. The variations
of the thermal behaviors of the hybrids with increases in the organoclay content from 0 to 8 wt% were determined. The glass
transition temperatures (Tg) and initial thermal degradation temperatures (TD
i) of the PS hybrids were found to increase linearly with increases in the organoclay loading. Regardless of the organoclay
content of the hybrids, the clay was found to be dispersed homogeneously in the matrix polymer. This is direct evidence that
the PS hybrids formed nanocomposites. This result was confirmed with XRD and TEM.
No preview · Article · Dec 2007 · Fibers and Polymers