Nanocomposites Derived From a Low-Color Aromatic Polyimide (CP2) and Amine-Functionalized Vapor-Grown Carbon Nanofibers: In Situ Polymerization and Characterization (Preprint)
Abstract
Vapor-grown carbon nanofibers (VGCNF) were functionalized with amine-containing pendants via a Friedel-Crafts acylation reaction with 4-(3-aminophenoxy)benzoic acid. The resulting H2N-VGCNF with ca. 5 atom% functionaliztion was in attendance during the polymerization of 2,2-bis(phtalic anhydride)-1,1,1,3,3,3-hexafluoroisopropane (6FDA) and 1,3-bis(3-aminophenoxy)benzene (APB) in N,N-dimethylacetamide (DMAc) to afford a series of polyimide (CP2)-based nanocomposite films, which contained 0.1 to 5.0 wt% of H2N-VGCNF. For comparison purposes, the pristine VGCNF (0.1-5.0 wt%) was also used in the in situ polymerization of 6FDA and ABP. These two series of CP2/VGCNF nanocomposite films were cast from the respective polyamic acid/VGCNF DMAC solutions, followed by thermal imidization at curing temperatures up to 250 ?C. The benefit and limitation of functionalized VGCNF on the length scale and the extent of CNF dispersion in a polyimide matrix were clear: (a) 0.1 wt% H2N-VGCNF film was visually transparent whereas similar (0.1 wt%) pristine VGCNF film showed the presence of large CNF aggregates throughout; (b) at 0.3 wt% H2N-VGCNF contents, the nanocomposite film had become translucent, and at 5 wt%, it was opaque. Since CP2 is very soluble in THF, the CP2-grafted VGCNF were simply separated from the free CP2 by solvent extraction. The molecular weights of the extracted CP2 were measured using gel-permeation chromatography (GPC). The effects of VGCNF on molecular weight (MW) and glass-transition (Tg) were discussed in terms of GPC and thermal analysis results, respectively. The dispersion of VGCNF in CP2 was evaluated using scanning electron microscopy (SEM). The tensile properties of the nanocomposite films were determined, showing up to 45% increase in modulus as the functionalized VGCNF content raised to 5 wt%.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 2007
- Accession Number
- ADA469979
Entities
People
- David H Wang
- Jong-beom Back
- Loon-Seng Tan
- Michael J. Arlen
- Richard A. Vaia
Organizations
- University of Dayton