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Polyetherimide/Montmorillonite Nanocomposites via in-situ Polymerization followed by Melt Processing

NASA Langley Research Center; Advanced Materials and Processing Branch, Hampton, VA 23681-2199, USAD.M.DELOZIER{at}LaRC.NASA.GOV

D. C. Working

NASA Langley Research Center; Advanced Materials and Processing Branch, Hampton, VA 23681-2199, USA

Montmorillonite clay modified with the dihydrochloride salt of 1,3-bis(3-aminophenoxy) ben-zene (APB) was used in the preparation of polyetherimide(PEI)/organoclay hybrid films, powders, fibers, and rods. An APB-based organoclay that was optimized for charge was prepared and examined for dispersion behavior in a PEI under various processing conditions. High molecular weight poly(etheramide acid) (PEAA) solutions were prepared separately and in the presence of the organoclay at a weight loading of 3%. The neat PEAA and hybrid mixtures were converted to the PEI via thermal curing without solvent and by chemical and thermal imidization in solution. The mixtures that were thermally cured in an oven yielded thin films that were characterized for dispersion as well as mechanical properties. The PEIs prepared in the latter two methods were obtained as powders after precipitation in water. The neat and hybrid powders prepared via thermal imidization in solvent were dried and processed by melt mixing and extrusion. Aliquots were collected at different points in the processing cycle and clay dispersion evaluated via x-ray diffraction and transmission electron microscopy. The clay dispersion of the PEI/organoclay powders was generally poor but was enhanced after melt mixing and extrusion. The mechanical properties of the fibers that had been prepared by melt mixing and extrusion were determined. The addition of clay increased the moduli in all of the samples whereas the strength and elongation decreased. The decrease on the strength and elongation was less pronounced after processing in the melt.

Key Words: Organoclay • polyimide • extrusion

High Performance Polymers, Vol. 16, No. 4, 597-609 (2004)
DOI: 10.1177/0954008304042276


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