Polyimide powders

Polyimides Powder, solutions Excellent high temperature properties, 400 to about 700 F. Difficult to process. High-temperature cable shielding, conductive film. 

Crystalline polyimide powders, 304 Crystalline transition temperature. See Melting temperature (Tm) Crystallization rate, for processing semicrystalline polymers, 44 CTE. See Coefficient of thermal expansion (CTE)... 

Polyimide cyclization, 305 Polyimide powders, crystalline, 304 Polyimides, 265-319 AB, 304-307... 

Polyimide matrix materials, 26 763-764 Polyimide powders, 20 284 Polyimide synthesis, 20 264-276 using imide-containing monomers, 20 272... 

Amorphous polyimide powders prepared by dissolution/precipitation processes, can be used to toughen thermosetting polymers. Polyethylene powders are frequently used in low-shrink unsaturated polyester formulations. 

The polyimide powder of 6F + 3,3 -ODA was likewise tested for its solubility limit in DMAc. Uie imide powder was prepared by chemically imidizing the 6F + 3,3 -ODA polyamic acid with pyridine/acetic anhydride, precipitating in distilled water, thoroughly drying at 60°C and heating for 2 hours at 200 C. 

A polyimide/Cu FGM was prepared by stacking different compositions of Cu and thermosetting polyimide powders using a spark plasma system. The consolidation temperature was about 520 C for the Cu layer and 390°C for the polyimide layer. One graded layer or two graded layers resulted in cracks. There were no cracks in the FGM prepared by stacking three graded layers. The thermal conductivity of thin... 

Polyimides (PI) were among the eadiest candidates in the field of thermally stable polymers. In addition to high temperature property retention, these materials also exhibit chemical resistance and relative ease of synthesis and use. This has led to numerous innovations in the chemistry of synthesis and cure mechanisms, stmcture variations, and ultimately products and appHcations. Polyimides (qv) are available as films, fibers, enamels or varnishes, adhesives, matrix resins for composites, and mol ding powders. They are used in numerous commercial and military aircraft as stmctural composites, eg, over a ton of polyimide film is presently used on the NASA shuttle orbiter. Work continues on these materials, including the more recent electronic apphcations. 

Various melt-fusible polyimides whose T s range from 250 to 350°C are avadable as mol ding powders or pellets. LARC-TPI was developed by... 

Kapton resin (5) (113) and Upilex (6) resin (114) are sold as films, partially polymerized resin coating solutions, and sinterable powders. Allied Signal also offers Apical polyimide film. 

Thermoplastic Condensation Polyimides. These include General Electric s Ultem Resin and Amoco s Todon polyamideimide although the latter is no longer offered as injection moldable pellets, but as compression moldable powder and in solution. Another resin, P-84, originally developed by Upjohn but now made by Lenzing (Austria), is based on benzoquinone dianhydride and aromatic isocyanates. 

SUPreM, Plytron, Quadrax (Gurit Suprem) consolidated tapes or fabrics are made from continuous fibres impregnated with thermoplastic powder. The fibres can be glass, aramid, carbon, steel and the matrices are polyethylene, polypropylene, polyamide, PPS, polyetherimide, PEEK, thermoplastic polyimide, or fluorothermo-plastic. High levels of fibres can be obtained, 65% in volume, for example. 

X-ray powder diffraction was recorded using a conventional x-ray powder diffractometer with Cu-Ka radiation. Polyimide film on which sample particles are deposited is glued on a glass sample holder with vacuum grease. Figure 1.6.9 shows the recorded diffraction pattern. An analysis of the pattern is made by comparing the lattice parameters and diffraction intensities of the particles and those of known iron compounds, and shows that the particles are Fe304. 

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