The Influence of Sizings on the Durability of High-Temperature Polymer Composites

Abstract

To increase performance and durability of high-temperature composites for potential rocket engine components, it is necessary to optimize wetting and interfacial bonding between high-modulus carbon fibers and high-temperature polyimide resins. Sizings commercially supplied on most carbon fibers are not compatible with polyimides. In this study, the chemistry of sizings on two high-modulus carbon fibers (M40J and M60J, Toray) was characterized as was the chemistry of PMR-II-50 fluorinated polyimide resin. The carbon fibers were characterized using single filament wetting, scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopic measurements. The polyimide matrix resins were coated onto glass filaments for characterization by wetting measurements. Surface energy components were obtained by wetting with nondispersive (methylene iodide), acidic (ethylene glycol), and basic (formamide) probes. A continuous desizing system that uses an environmentally friendly chemical-mechanical process was developed for tow level fiber. Composites were fabricated with fibers containing the manufacturer's sizing, desized, and further treated with a reactive finish. Results of room temperature tests after thermal aging show that the reactive finish produces a higher strength and more durable interface compared to the manufacturer's sizing. When exposed to moisture blistering tests, however, the better-bonded composite displayed a tendency to delaminate, presumably due to trapping of volatiles.

Keywords

Sizing desizing carbon fibers reactive finish thermal aging mechanical properties wetting surface energy blistering interface

Get full access to this article

View all access options for this article.

References

[1] Allred R E , Shin E E , Inghram L , McCorkle L , Papadopoulos D , Wheeler D , and Sutter J K 2002 Soc. Adv. Matl. Proc. Eng. Series 47 1187

[2] Wesson S P and Jen J S 1984 Intl. SAMPE Tech. Conf. Serie, 16 375

[3] Wesson S P and Allred R E 1989 Inverse Gas Chromatography D R Lloyd , T C Ward and H P Schreiber , eds ( Washington DC: ACS ) ACS Symp. Ser. No. 391, p 204

[4] Allred R E and Harrah L A 1989 Soc. Adv. Matl. Proc. Eng. Series 34 2559

[5] Hinkley J A Bascom W D and Allred R E 1990 Interfaces in Composite Materials C G Pantano and E J H Chen , eds ( Pittsburgh, PA: Materials Research Society ) p 351

[6] Wesson S P and Allred R E 1990 J. Adhesion Sci. Technol. 4 277

[7] Allred R E and Sutter J K 1997 Soc. Adv. Matl. Proc. Eng. Series 42 1291

[8] Clark D T 1977 Characterization of Metal and Polymer Surfaces L-H Lee , ed ( New York: Academic Press ) Vol 2 p 5

[9] Shin E E et al. 2002 Soc. Adv. Matl. Proc. Eng. Series 47 356