Reinforced Polyimides

Homrighausen et al. [5] evaluated the gamma radiation performance of glass fiber-reinforced polyimide laminates. 

The polyimide resin formulations were based on combining various amounts of 3,4 oxydianiline and 4,4-(l,3-phenylenedioxy)dianaline with 4,4 bisphenol A dianhydride and 3,3, 4,4 -benzopehnone tetracarboxylic dianhydride and terminated in 4-phenylethynyl phthalate anhydride. 

These glass fiber-reinforced 4-phenylethynyl phthalic anhydride-terminated poly-imides were of interest as possible S-2 glass fiber-reinforced composites as superconducting magnetic mataial insulation intended for use in future nuclear fusion devices, such as the International Thermonuclear Experimental Reactor (ITER), Fusion Experimental Reactor (ITER), or Fusion Ignition Research Experiment (FIRE). 

The effects of three different cobalt 60 gamma irradiation doses between 267 and 641 rad L on cryogenic (77°K) mechanical and thermal properties were measured. 

With unreinforced RTM 65, flexural strength at 77 K falls from 1227 to 1005 MPa when the radiation doses is increased from 0 to 1000 kGy, while with the fiberglass-reinforced polyimide the flexural strength falls by a much smaller amount, 1019 to 908 MPa, upon increasing the radiation dose from 0 to 1000 kGy. 

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Tests of a graphite-reinforced polyimide composite (C6000/PMR15) did not show any effect of radiation exposure (1 MEV electrons 6x109 rad total dose) on the thermal expansion behavior (14). DMA curves for unirradiated and irradiated composites were essentially identical over the temperature range of the thermal expansion measurements. 

Z. Ounaies, C. Park, K.E. Wise, E.J. Siochi, and J.S. Harrison, Electrical properties of single wall carbon nanotube reinforced polyimide composites, Compos. Sci Technol., 63(11) 1637-1646, August 2003. 

Sliney, H.E. and Jacobson, T.P., Graphite-Fiber-Reinforced Polyimide Liners of Various Compositions in Plain Spherical Bearings, Proc. 2nd ASLE Inti. Conf. on Solid Lubrication, Denver, Colorado, (15-18 Aug. 1978) ASLE SP-6, p. 258. 

Kevlar fiber reinforced polyimide or epoxy CTE matched to ceramic, available from DuPont-Howe, dielectric constant = 3.6, moisture absorption reduced Relatively thick (over 4.5 mil), fiber anisotropy may produce non-uniform strains, microcracking problems... 

Graphite fiber reinforced polyimide or epoxy CTE matched to ceramic, patented Boeing process available, can be used as ground plane or heat sink Poor dielectric constant, anisotropy and microcracking problems, relatively thick, vias must be insulated... 

Figure 5. Bunsen burner burning test of graphite fiber reinforced polyimide composites. Key a, TSTR-XL-PI/GrF specimen before test b, TSTR-XL-PI/GrF specimen after test and c, PMR-15-PI/GrF specimen after test.

Printed Circuitry. Printed circuitry, which represents a most intricate structure of polymers and conductors, is frequently made by laminating copper foil onto glass-fiber-reinforced epoxy composites. For certain specialty applications, more expensive fiber-reinforced polyimides are used. 

Tribology of Fiber-Reinforced Polyimides Sliding Against Steel and Silicon Nitride... 

T. A. DeVilbiss, D. L. Messick, D. J. Progar, and J. P. Wightman, "SEM/XPS Analysis of Fractured Adhesively Bonded Graphite Fibre-Reinforced Polyimide Composites," Composites. 16. 207-219 (1985). 

Thus, reinforced polyimide (PI) upon exposure to gamma rays had a decay of short term shear strength for a zero dose value of 87.1 to 79.3 MPa after cohalt 60 irradiation to 1,000 kGy... 

A very important recent development is the production of plastics such as carbon fiber-reinforced polyimides. These have, for example, very distinct applications in aerospace jet engines, which retain their mechanical and other properties at temperatures of 350 C or higher. Developments such as this one are proceeding rapidly. 

Shaohua Jiang, Duan Gaigai, Schobel Judith, Agarwal Seema, and Greiner Andreas. Short electrospun polymeric nanofibers reinforced polyimide nanocomposites. Compos. Sci. 

GLASS REINFORCED POLYIMIDE POLYAMIDE-IMIDE 8i POLYIMIDE ALLYLS ACRYLIC... 

GLASS REINFORCED POLYIMIDE POLYIMIDE 8( POLY(AMIDE-IMIDE)... 

Ounaies, Z., Park, C., Wise, K. E., Siochi, E. J., Harrison, J. S. (2003), Electrical properties of single-wall carbon nanotube reinforced polyimide composites. Composites Science and Technology, 63,1637-46. 

Organosilicon nanophase-reinforced polyimides may have a reasonably good potential as low dielectric permittivity materials. 

Three carbon fibre-reinforced polyimides were exposed to UV radiation at 177C, at three different intensities for three different times, so that the product of intensity and time was a constant. Intensities of 1,2 and 3 suns, where one sun is the power in space at one earth-sun distance, were used, for a time periods of 500, 250 and 167 h. The samples were characterised by X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis, thermomechanical analysis and dynamic mechanical analysis. Measurement of bulk properties showed no difference between samples exposed to heat and UV radiation, and control samples. Surface analysis by XPS showed an apparent decrease in carbonyl concentration on the surface of some exposed samples. This was correlated to surface contamination by a silicone-containing material. 3 refs. 

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