Thermoplastic polyetherimide

Scheme 1. Synthesis of BPADA/PDA PA capped thermoplastic polyetherimide by the acid-ester route...

Thermoplastic polyetherimide Ultem can be formulated with high temperature foaming agents such as 5-phenyldihydro-l,3,4-oxadiazinone to produce structural form products [99] by injection molding. PEI could be readily imbibed with various volatile organic compounds such as chlorinated hydrocarbons [100] and acetone [101]. 

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). 

N. C. Patel. Methods of forming conductive thermoplastic polyetherimide polyester compositions and articles formed thereby. US Patent 6 734 262, assigned to General Electric Company (Pittsfield, MA), May 11, 2004. 

Thermoplastic polyetherimides provide the strength, heat resistance, and flame retardancy of traditional polyimides with the ease of simple melt processing seen in standard injection-molding resins such as polycarbonate and ABS. 

Polyetherimides are amorphous polymers with excellent dimensional stabihty. They are transparent with useful optical properties [12], but aU thermoplastic polyetherimides are a yellow amber color (as are almost aU polyimides). The yellowness index (YI) of a 3.2-mm (0.130-in) BPADA-MPD PEI injection-molded part is usually > 50. 

TABLE 8.2 Typical Properties of Various Thermoplastic Polyetherimides... 

Combinations of the thermoplastic polyetherimides with 10 to 40 wt% fiberglass reinforcement are very effective for increasing strength and modulus, as shown in Table 8.3. Heat resistance is shghtly increased too. The increase in stiffness is shown in Fig. 8.3, which compares modulus versus temperature for an unfilled BPADA-MPD-based PEI resin and blends with 10 and 30% short-chopped fiberglass. 

Conventional BPA polycarbonates can be blended with polyestercar-bonate resins to create miscible blends with a single Tg, they can also be blended with polyetherimides to yield immiscible blends with a fine-particle morphology. (See Chap. 8 in this book on thermoplastic polyetherimides for more details.)... 

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. 

Figure 4.3 Influence of morphology on the showing the final morphologies of the cured rheological behavior of epoxy resins with differ- blends. Reproduced with permission from ent content of thermoplastics (polyetherimide). Ref. [49] 1999, American Chemical Society. Transmission electron microscopy images...

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. 

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