Browsing by Author "Gu, AJ"

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A novel preparation of polyimide/clay hybrid films with low coefficient of thermal expansion
(2001-01-10)
Gu, AJ
;
Chang, FC
;
應用化學系
;
Department of Applied Chemistry
A novel polyimide (PI)/clay hybrid nanocomposite, designated as PI (PAAS)/CM, has been developed from the poly(amic acid) salt of triethylamine and organomontmorillonite (CM) using a mixture solution of tetrahydrofuran (THF) and methanol (MeOH). For comparison, two other PI/clay hybrids derived from poly(amic acid) and CM in THF/MeOH solution and N,N'-dimethylacetamide (DMAc) solution, denoted as PI/CM (T/M) and PI/CM (DMAc), respectively, were also prepared. Dispersion of CM in polymer matrix, tensile properties, and thermal expansion properties of the three hybrids were investigated. Results show that PI (PAAS)/CM has the best dispersion of CM in polymer matrix, highest elongation, and lowest coefficient of thermal expansion values in all hybrids presented in this report. In addition, PI/CM (T/M) has better dispersion of CM and lower coefficient of thermal expansion value than PI/CM (DMAc). (C) 2000 John Wiley & Sons, Inc.
Syntheses and properties of PI/clay hybrids
(2001-03-07)
Gu, AJ
;
Kuo, SW
;
Chang, FC
;
應用化學系
;
Department of Applied Chemistry
A new organomontmorillonite (CM) for PI hybrids has been developed by ion-exchange reaction of cetyl pyridum chloride with Na+ montmorillonite (MMT). Polyimide/clay hybrids have been synthesized by employing two methods. Method I is by first blending a dimethylacetamide (DMAC) solution of 4,4'-oxydianiline diamine (ODA) with a DMAC dispersion of CM before adding pyromellitic dianhydride (PMDA). Method II is by blending a DMAC solution of poly(amic acid) with a DMAC dispersion of CM. Tensile, thermal, dielectric, and water-absorption properties of hybrids prepared by these two methods have been studied in detail. Results show that these properties depend on the clay type (organophilic or not), clay concentration, and the method to synthesis hybrids. The CM concentration of 3 wt% in the hybrid by Method II results in optimum properties in tensile strength, modulus, elongation, coefficient of thermal expansion (CTE), and water absorption. (C) 2001 John Wiley & Sons, Inc.