Thermoplastic polyetherimide applications

This review summarizes our work at the University of Bayreuth over the last few years on improving the electret performance of the commodity polymer isotactic polypropylene (Sect. 3) and the commodity polymer blend system polystyrene/polyphenylene ether (Sect. 4) to provide electret materials based on inexpensive and easily processable polymers. To open up polymer materials for electret applications at elevated temperatures we concentrated our research on commercially available high performance thermoplastic polyetherimide resins and synthesized several fluorinaled polyetherimides to identify structure-property relations and to improve further the performance at elevated temperatures (Sect. 5). 

Semi-IPNs were prepared by the sol-gel technique through in situ polymerization of BMI in thermoplastic polyetherimide (PEI) as well as in polysulfone (PSF) (Kurdi and Kumar 2006). Structure and properties of semi-IPN membranes could be varied by controlling the thermoset BMI microdomain size interpenetrating within a thermoplastic polymer network. The size of this microdomain depended on the polymerization time of BMI and on the degree of thermoset/thermoplastic phase separation. These semi-IPN membranes showed an improved Tg but a decrease in their thermal stability and could be used for Oj-emiched-air applications where high selectivity is not required. At ambient temperature, it was possible to increase the permeance of semi-IPN membranes. 

Gallucci R. Thermoplastic polyetherimide. In Margolis J, editor. Engineering plastics handbook thermoplastics, properties, and applications. New York McGraw-Hill 2006. p. 155-80. Chapter 8. 

Connectors, switches, electric distributors, fuse boxes and other electric fittings need a subtle balance of electrical and mechanical properties, durability, cost and aesthetics. This broad field creates fierce competition not only between engineering thermoplastics and SMC/BMC for the main applications but also with polypropylene and polyethylene or PVC for the lower performance parts and, at the opposite end of the scale, with high-tech plastics such as polyetherketone, polyetherimide, liquid crystal polymers. .. For example, without claiming to be exhaustive ... 

Mat and continuous glass fibre reinforcements theoretically all the thermoplastics are usable in these forms, but up to now developments have concentrated on polypropylenes (PP), polyamides (PA) and thermoplastic polyesters (PET) fibre-reinforced PEEK, polyetherimide (PEI) and polyphenylene sulfide (PPS) are used for high-performance applications. They are presented in a range of forms from stampable sheets to pellets, prepregs, ribbons, impregnated or coated continuous fibre rods. More rarely (as in the case of PA 12, for example), the thermoplastic is provided in liquid form. 

Newer resins include polysulfone, polyethersulfone, polyetherimide, and polyetherketone. Some of these newer materials are high temperature thermoplastic, not thermoset, resins. They are being promoted for the design of injection-molded printed circuit boards in three-dimensional shapes for functional applications as an alternative to standard flat printed circuit boards. Only semiadditive or fully additive processing can be used with these... 

Parts molded from polyetherimide can be assembled with all common thermoplastic assembly methods. Adhesives that are recommended include epoxy, urethane, and cyanoacrylate. However, service temperature must be taken into consideration in choosing an adhesive because PEI parts are generally used for high-temperature applications. Good adhesion can be effected by simple solvent wipe, but surface treatment by corona discharge, flame treatment, or chromic acid etch will provide the highest bond strengths. 

The effect of adverse environments on the fatigue behaviour of glass fibre reinforced pofymers will be discussed, taking polyetherimide (PEI) as an example [36], PEI is an amorphous thermoplastic, so a low resistance to solvents and similar harsh environments can be expected. Because of its potential applications in aircraft and railways, the hydraulic fluid (Skydrol) and the solvent methyl ethyl ketone (MEK) were chosen. 

Polypropylene is generally used as oriented polypropylene. Polyvinyl chloride film is commonly used in plasticized form. Polyvinylidene chloride is often known as Saran and is generally used in copolymer form with acrylonitrile. Polyethylene terephthalate is a thermoplastic polyester. Polystyrene is sometimes used in biaxially oriented form. Polycarbonates, polysulfones, polyether sulfones, poly-imides, polyetherimides, and several fluoropolymers are also used for specialty applications. 

Engineering thermoplastic resins (ETP) are those whose set of properties (mechanical, thermal, chemical) allows them to be used in engineering applications. They are more expensive than commodity thermoplastics and generally include polyamides (PA), polycarbonate (PC), linear polyesters such as polyethylene terephthalate (PET) or polybutylene terephthalate (PBT), polyphenylene ether (PPE) and polyoxymethylene (POM). Specialty resins show more specialized performance, often in terms of a continuous service temperature of 200°C or more and are significantly more expensive than engineering resins. This family include fluoropolymers, liquid crystal polymers (LCP), polyphenylene sulfide (PPS), aromatic polyamides (PARA), polysulfones (P ), polyimides and polyetherimides. 

Wilson et al. [3] showed that pultrusion is also applicable to other high-performance thermoplastics, in particular, amorphous polyetherimide (PEI). In this case, a wet-impregnation station for impregnating carbon fiber bundles with a PEI solution was put in line with a die system that was designed to consolidate multiple plies of prepreg tape by gradual reduction into rectangular profiles. 

In today s markets, the use of thermoplastic products is regulated from a standpoint of fire safety. Minimum performance in dozens of fire tests is spelled out by standards, regulations, and building codes that regulate over 90% of the products specified and used. In tests for transportation, electrical and construction applications, polyetherimides show excellent performance. 

High-performance engineering thermoplastics have recently assumed hicteas-ing importance due to their exceptional properties at elevated tenqioatures. A number of such spedalty polymers has been introduced into the market for higili-temperature applications and examples of some of the outstanding ones are poly phenylene oxide (PPO), poly fdienylene sulfide (PPS), polyetlier sulfone ES), polyaryl sulfone (PAS), polyether ether ketone (PEEIQ, polyetherimide (PEl, and polyarylate (PAr). 

The most widely used and least expensive polymer resins are the polyesters and vinyl esters. These matrix materials are used primarily for glass fiber-reinforced composites. A large number of resin formulations provide a wide range of properties for these polymers. The epoxies are more expensive and, in addition to commercial applications, are also used extensively in PMCs for aerospace applications they have better mechanical properties and resistance to moisture than the polyesters and vinyl resins. For high-temperature applications, polyimide resins are employed their continuous-use, upper-temperature limit is approximately 230°C (450 F). Finally, high-temperature thermoplastic resins offer the potential to be used in future aerospace applications such materials include polyetheretherketone (PEEK), poly(phenylene sulfide) (PPS), and polyetherimide (PEI). 

The combination of processability and performance provided by these polymers makes them natural candidates for applications such as microelectronics laminates as well as structural and dielectric composites (2). The versatility provided by the use of phenolic feedstocks has allowed the extension of this chemistry into polyesters (i), classical photoresist chemistry (4), and thermally crosslinkable thermoplastics (5). It has also provided a method for thermally processing low molecular weight imide-containing oligomers into high molecular weight polyetherimides (d) In addition, oligomers which are useful as fluorinated lubricant fluids have been prepared (7). 

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