Thermoplastic polyimide applications

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... 

Ying L, Edelman R (1986) A novel thermoplastic polyimide for composite matrix applications. 31st International SAMPE Symposium 1131... 

Confidence in the ability of certain synthetic resin-based adhesives to provide satisfactory structural bonds has developed during the past 40 years. The requirement that the adhesive be able to withstand loads over long periods of time means that most structural adhesives are based on thermosetting resins, whose crosslinked structure provides good creep-resistance. However, certain thefhioplastic resins (notably linear thermoplastic polyimides and cyanoacrylates) do appear to be useful for some structural bonding applications. 

Ultem 1000 26 (Fig. 13) marketed by General Electric is a poly(ether-imide) representative of a series of thermoplastic polyimides that can be used as adhesives or moulding materials for applications at moderate temperatures T = 220°C). 

Fig. 19.1 The plastics pyramid according to thermal literature data of common polymers preferred materials for HT-PEM applications are in the upper right region TPI thermoplastic polyimide, PES polyether sulfone, P P)SU poly(phenylene)sulfone, PE E)K polyether(ether) ketone, LCP liquid crystal polymer, e.g., Vectra, PPS polyphenylene sulfide, PTEE polytetrafluoroethylene.

Morita A. Thermoplastic polyimide. In Margolis J, editor. Engineering plastics handbook thermoplastics, properties, and applications. New York McGraw-Hill 2006. p. 221-38. Chapter 10. 

Fully imidized aromatic thermoplastic polyimides (TPI) are linear polymers with good thermomechanical performance, used in high-temperature (>230°C) applications. Pis based on aromatic diamines and dianhydrides exhibit excellent heat resistance. In addition to their outstanding high-temperature resistance (Sancaktar et al. 1984 Sancaktar and Schenck 1985 Sancaktar and Dembosky 1986), toughness and good dielectric properties, low flammability, and high radiation resistance are desirable characteristics for this class of adhesives. 

For die attachment, polyimide adhesives have reached a peak and now the market is progressively slowing down. However, for other applications, there is a trend in the direction of thermoplastic polyimide films that can be used as interlayer adhesives. Flexible circuits and MCMs seem to be the main... 

As can be deduced from plant purchases, the PRC is still at the formative stage where emphasis is on producing only the most basic petrochemicals. No plants were purchased for producing dibasic acids (phthalic and maleic anhydrides, etc.) and fluro-carbon or tetrafluoro ethylene or some of the advanced engineering plastics like ABS polyacetals, polycarbonates, polyimides or any other unsaturated polyesters. Another important area of low Chinese activity is thermoplastics for space and defense applications. ... 

As previously stated, the rigid polyimides meet many of the requirements for microelectronics applications however, the presence of an ordered morphology, coupled with the lack of a softening transition results in extremely poor self-adhesion. Alternatively, thermally stable thermoplastics exhibit excellent self-adhesion, but often lack sufficiently high temperature dimensional stability and/or solubility and processability from common organic solvents. For instance, po-ly(phenylquinoxaline) (PPQ) has a T in the 370 °C range, thereby overcoming... 

Addition poly(imide) oligomers are used as matrix resins for high performance composites based on glass-, carbon- and aramide fibers. The world wide market for advanced composites and adhesives was about 70 million in 1990. This amounted to approximately 30-40 million in resin sales. Currently, epoxy resins constitute over 90% of the matrix resin materials in advanced composites. The remaining 10% are unsaturated polyester and vinylester for the low temperature applications and cyanate esters and addition poly(imides) for high temperatures. More recently thermoplastics have become important and materials such as polyimides and poly(arylene ether) are becoming more competitive with addition polyimides. 

Polyimides. They were developed first by DuPont and Monsanto for ultra-high-temperature applications such as electrical insulation, machine bearings, and structural components in instrumentation and aerospace development. These are theoretically linear but not at all processable by thermoplastics techniques. 

Plastics. Almost all commercial plastics find some use both dry and lubricated for sliding at low speeds and light loads the most commonly used thermoplastics are nylon, acetal resins, and polytetrafluoroethylene (PTFE). Typical thermosetting resins for bearing applications are phenolics, polyesters, and polyimides. Table 8 compares the characteristics of plastic bearing materials with those of graphite, wood, and rubber which find use in somewhat similar applications. 

Burning may be considered another means of oxidation. Non-burning plastics are a must in commercial constructions according to building codes and are often required for automotive, electronic, and electrical applications. From the numerous thermoplastics, only the halogen-containing polymers, polyamides, polycarbonate, poly(phenylene oxide), polysulfone, and polyimides are self-extinguishing. Even these, such as poly (vinyl chloride), may become flammable when plasticized with a flammable plasticizer. Fire control can be the key to volume use of plastics. Polyester panels, urethane foam, and PVC tarpaulins account for nearly 90% of all fire retardants consumed. Consumption in 1967... 

The resin matrix can be either thermosetting or thermoplastic. Thermosetting resins such as epoxy, polyimide, polyester, and phenolic are used in applications where physical properties are important. Polyester and epoxy composites make up the bulk of the thermoset composite market. Of these two, polyesters dominate by far. Reinforced with glass fiber, these are known as fiberglass-reinforced plastics (FRPs). FRPs are molded by layup and spray-up methods or by compression molding either a preform or sheet molding compound (SMC). 

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