Polyimide reinforced

The hybrid materials having silica content below 50 wt% were composed of polyimide matrix with finely dispersed silica particles, and their hardness values were very close to that of the matrix polyimide. On the other hand, the hybrid materials having a silica content over 50 wt% were very hard and tough, and their hardness values increased with increasing silica content. In the latter hybrid materials, the silica formed a continuous phase with polyimide as the minor phase that probably acts as binder. This is a new type of polyimide-based composite, and may be referred to as polyimide-reinforced silica glass , al-... 

Celazole Thermoplastic polyimides, reinforced or not Hoechst Celanese Corp. 

Bazzar, M., Ghaemy, M. 1,2,4-Triazole and quinoxaline based polyimide reinforced with neat and epoxide-end capped modified SiC nanoparticles Smdy thermal, mechanical and photophysical properties. Compos. Sci. Technol. 101-108 (2013)... 

Privalko V P, Shautalii T A and Privalko E G (2005) Polyimides reinforced by a sol-gel derived orgauosilicon uanophase synthesis and structure-property relationships, in Polymer composites from nano- to macro-scale (Eds. Friedrich K, Fakirov S and Zhang Z ) Springer, New York, pp. 63-76. 

Polyimides Reinforced by a Sol-Gel Derived Organosilicon Nanophase Synthesis and Structure-Property Relationships... 

Chapter 4 Polyimides Reinforced by Organosilicon Nanophase Table 3. Experimental and calculated dielectric permittivities of nanocomposites. 

T. A. Shantalii, I. L. Karpova, K. S. Dragan, E. G. Privalko, V. P. Privalko (2003) Synthesis and thermomechanical characterization of polyimides reinforced with the sol-gel derived nano-particles, Sci. Technol. Adv. Mater. 4,115. 

Poetschke P, Dudkin S M and Alig I (2003) Dielectric spectroscopy on melt processed polycarbonate-multiwalled carbon nanotube composites, Polymer 44 5023-5030. Kramarenko V Y, Shantalii T A, Karpova I L, Dragan K S, Privalko E G, Privalko V P, Pragiadakis D and Pissis P (2004) Polyimides reinforced with the sol-gel derived organosilicon nanophase as low dielectric permittivity materials, Polym Adv Technol 15 144-148. 

A continuing trend has been to polymeric retainers. Laminated phenoHc cages have often been used for high speeds at temperatures up to 130°C. Heat stabili2ed nylon-6,6 has come iato broad use ia small ball beariags, both with and without glass reinforcement (39). Polyimide and PTFE are used up to 250°C. 

Because of this continued emphasis on adhesive bonding technology development over the years, the airframes of modem front-line aircraft such as the B-2 bomber and the F-117 and F-22 fighters are largely structurally bonded advanced composites. They tend to be comprised of materials that are more advanced (expensive) than commercial aircraft such as carbon and boron fiber reinforcements with cyanate esters, bismaleimides, polyimides or other high-temperature resin matrices and adhesives. 

Recent work has focused on a variety of thermoplastic elastomers and modified thermoplastic polyimides based on the aminopropyl end functionality present in suitably equilibrated polydimethylsiloxanes. Characteristic of these are the urea linked materials described in references 22-25. The chemistry is summarized in Scheme 7. A characteristic stress-strain curve and dynamic mechanical behavior for the urea linked systems in provided in Figures 3 and 4. It was of interest to note that the ultimate properties of the soluble, processible, urea linked copolymers were equivalent to some of the best silica reinforced, chemically crosslinked, silicone rubber... 

Experimental results are presented that show that high doses of electron radiation combined with thermal cycling can significantly change the mechanical and physical properties of graphite fiber-reinforced polymer-matrix composites. Polymeric materials examined have included 121 °C and 177°C cure epoxies, polyimide, amorphous thermoplastic, and semicrystalline thermoplastics. Composite panels fabricated and tested included four-ply unidirectional, four-ply [0,90, 90,0] and eight-ply quasi-isotropic [0/ 45/90]s. Test specimens with fiber orientations of [10] and [45] were cut from the unidirectional panels to determine shear properties. Mechanical and physical property tests were conducted at cold (-157°C), room (24°C) and elevated (121°C) temperatures. 

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. 

The aeronautics sector is a significant composite consumer, particularly in terms of turnover, because of the high proportion of advanced composites used with matrices such as epoxies, polycyanates, polyimides, PEEK, and reinforcements such as carbon fibres. 

Creep behaviour is good even when the temperature rises. Neat polyimides have medium moduli that involve rather low strains for moderate loading. Consequently, creep moduli are also in a good range at room temperature but they decrease more slowly than the majority of other thermoplastics when the temperature rises. Reinforcement with fibres leads to high moduli and, consequently, high creep moduli. 

General chemical properties are subject to the compatibility of the fillers and reinforcements with the ambient conditions. If the fillers are well adapted, the chemical properties are the same as the polyimide matrix. 

Aerospace, top-of-the-range sports and leisure the core is generally made of honeycombs or high-performance foams and the skins can be made of carbon fibre reinforced thermoplastic polyimides. 

Fiber-reinforced composites contain strong fibers embedded in a continuous phase. They form the basis of many of the advanced and space-age products. They are important because they offer strength without weight and good resistance to weathering. Typical fibers are fiberous glass, carbon-based, aromatic nylons, and polyolefins. Typical resins are polyimides, polyesters, epoxys, PF, and many synthetic polymers. Applications include biomedical, boating, aerospace and outer space, sports, automotive, and industry. 

Poly[2,2 -(m-phenylene-5,5 -benzimidazole)] (PBI) is a very high glass transition temperature (Tg 430°C), commercially available material. It possesses excellent mechanical properties, but is difficult to process into large parts and has high moisture regain and poor thermo-oxidative stability at temperatures above approximately 260 °C. Polyimides, especially the thermoplastic polyimides, offer attractive thermo-oxidative stability and processibility, but often lack the thermal and mechanical characteristics necessary to perform in applications such as the matrix for high use-temperature (over 300 °C) structural composites (for example, carbon fiber reinforced) for aerospace use. The attempt to mitigate... 

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. 

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