Polyetherimide polymer

Bulk polymerization Conversion of low-M monomers or prepolymers into high-M polymers Polyetherimides, melamine-formaldehydes, polymrethanes, polyamides, PBT, PET, PS, PMMA... 

The objectives of this chapter are to describe the fabrication of novel composite hydrophobic/hydrophilic membranes for DCMD using different surface-modifying macromolecules (SMMs) and a hydrophilic polymer polyetherimide (PEI). The membrane characteristics are related to the DCMD performance. 

Materials. As a matrix polymer, polyetherimide (PEI) Ultem KXX) of General Electric and polyphenylenesulfide (PPS) Ryton GR-02 of Phillips Petroleum were used. The reinforcing component was thermotropic liquid crystalline copolyester (LCP) Vectra B950 of Hoechst-Celanese. The chemical structures of PEI and LCP are presented in Figure 1. 

As a third component, polysulfone (PSF) Udel P-17(X) of Amoco was tested for PPS/LCP blend, and three kinds of newly designed imide polymers, polyetherimide (PEsI), PET/PEsI block copolymer (BHETI), and PBT/PEsI block copolymer (BHBTI), were tested for PEI/LCP blend. The three compatibilizing agents, PEsI, BHETI and... 

In the case of polymers like nylon, polyethylene terephthalate (PET) and polycarbonate (PC), the steady shear viscosity is near Newtonian up to even a shear rate of a little over 100 s as can be seen from Figures 6.23-6.25. As an example of a moderately shear-thinning polymer, polyetherimide (PEI) could be considered [136] as shown in Figure 6.26 while, for a predominantly shear-tiunning pol3mier, polypropylene (PP) is a reasonable example as shown in Figure 6.27. Note that in Figures 6.24 and 6.27, the plots are shown as shear stress vs. shear rate which is, of course, another method of representation of the same information. 

In this way an accurate ranking of relative stability of different polymers can be obtained. For example, the polymers polyetherimide (PEI), polycarbonate (PC), polyethylene terephthalate (PET) and polyvinyl chloride (PVC) differ in their thermal stabilities due to the chemical make-up of their backbones (in the order PEI > PC > PET > PVC) and the... 

I itro-DisplacementPolymerization. The facile nucleophilic displacement of a nitro group on a phthalimide by an oxyanion has been used to prepare polyetherimides by heating bisphenoxides with bisnitrophthalimides (91). For example with 4,4 -dinitro monomers, a polymer with the Ultem backbone is prepared as follows (92). Because of the high reactivity of the nitro phthalimides, the polymerkation can be carried out at temperatures below 75°C. Relative reactivities are nitro compounds over halogens, Ai-aryl imides over A/-alkyl imides, and 3-substituents over 4-substituents. Solvents are usually dipolar aprotic Hquids such as dimethyl sulfoxide, and sometimes an aromatic Hquid is used, in addition. 

A number of amorphous thermoplastics are presently employed as matrices in long fiber composites, including polyethersulfone (PES), polysulfone (PSU), and polyetherimide (PEI). AH offer superior resistance to impact loading and higher interlaminar fracture toughnesses than do most epoxies. However, the amorphous nature of such polymers results in a lower solvent resistance, clearly a limitation if composites based on such polymers are to be used in aggressive environments. 

Some of the common types of plastics that ate used ate thermoplastics, such as poly(phenylene sulfide) (PPS) (see Polymers containing sulfur), nylons, Hquid crystal polymer (LCP), the polyesters (qv) such as polyesters that ate 30% glass-fiber reinforced, and poly(ethylene terephthalate) (PET), and polyetherimide (PEI) and thermosets such as diaHyl phthalate and phenoHc resins (qv). Because of the wide variety of manufacturing processes and usage requirements, these materials ate available in several variations which have a range of physical properties. 

The polyetherimides are competitive not only with other high-performance polymers such as the polysulphones and polyketones but also with polyphenylene sulphides, polyarylates, polyamide-imides and the polycarbonates. 

The markets for polyetherimides arise to an extent from stricter regulations concerning flammability and smoke evolution coupled with such features as high strength, toughness and heat resistance. Application areas include car under-the-bonnet uses, microwave equipment, printed circuit boards and aerospace (including carbon-fibre-reinforced laminated materials). The polymer is also of interest in flim, fibre and wire insulation form. 

Good electrical insulation properties with exceptional tracking resistance for an engineering thermoplastic and, in particular, for an aromatic polymer. In tracking resistance most grades are generally superior to most grades of polycarbonates, modified PPOs, PPS and the polyetherimides. 

These materials are developed from the polyetherimides introduced by General Electric (see also Section 18.14.2). At the time of writing one grade, Ultem Siltem STM 1500, is being offered. It is of particular interest as a material for wire and cable insulation, as it not only has excellent flame resistance coupled with low smoke generation but also avoids possible toxic and corrosion hazards of halogenated polymers. This can be of importance where there are possible escape problems in the event of a fire, such as in tunnels, aircraft and marine (particularly submarine) vessels. 

Note Glass filler can considerably extend the performance of the above polymers. PEI = polyetherimide PES = polyether sulfone PPS = polyphenylene sulfide PSF = polysulfone PC = polycarbonate. 

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 ... 

Glassy polymers with much higher glass transition temperatures and more rigid polymer chains than rubbery polymers have been extensively used as the continuous polymer matrices in the zeolite/polymer mixed-matrix membranes. Typical glassy polymers in the mixed-matrix membranes include cellulose acetate, polysul-fone, polyethersulfone, polyimides, polyetherimides, polyvinyl alcohol, Nafion , poly(4-methyl-2-pentyne), etc. 

Mixed matrix hollow fiber membranes made with modified HSSZ-13 zeolite in polyetherimide polymer matrix for gas separation. /. Membr. Sd., 288, 195-207. 

The initial announcement for the commercial preparation of polyetherimides (PEIs) was made by General Electric in 1982 under the trade name Ultem. The final reaction involves the imidization of a diacid anhydride through reaction with a diamine, here w-phenylenedia-mine (structure 4.62). The ether portion of the polymer backbone results from the presence of ether linkages within the diacid anhydride. 

Polyetherimides (PEI) are polyimides containing sufficient ether as well as other flexibi-lizing structural units to impart melt processability by conventional techniques, such as injection molding and extrusion. The commercially available PEI (trade name Ultem) is the polymer synthesized by nucleophilic aromatic substitution between 1,3-bis(4-nitrophthalimido) benzene and the disodium salt of bisphenol A (Eq. 2-209) [Clagett, 1986]. This is the same reaction as that used to synthesize polyethersulfones and polyetherketones (Eq. 2-206) except that nitrite ion is displaced instead of halide. Polymerization is carried out at 80-130°C in a polar solvent (NMP, DMAC). It is also possible to synthesize the same polymer by using the diamine-dianhydride reaction. Everything being equal (cost and availability of pure reactants), the nucleophilic substitution reaction is probably the preferred route due to the more moderate reaction conditions. 

Not all polyetherimides are limited by their tractability, however. Certain aromatic polyetherimides are characterized by a combination of properties that makes them potential engineering thermoplastics (90). One of these polymers contains an isopropylidene unit in the backbone to enhance the solubility. It is a mol ding material introduced by General Electric in 1981 and sold as Ultem resin. Attractive features include high temperature stability, flame resistance without added halogen or phosphoms, high strength, solvent resistance, hydrolytic stability, and injection moldability. 

Condensation of Dianhydrides with Diamines. The preparation of polyetherimides by the reaction of a diamine with a dianhydride has advantages over nitro-displacement polymerization sodium nitrite is not a by-product and thus does not have to be removed from the polymer, and a dipolar aprotic solvent is not required, which makes solvent-free melt polymerization a possibility. Aromatic dianhydride monomers (8) can be prepared from IV-substituted nitrophthalimides by a three-step sequence that utilizes the nitro-displacement reaction in the first step, followed by hydrolysis and then ring closure. For the 4-nitro compounds, the procedure is as follows. 

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