Polyether-Imide PEI

PEI is a high-temperature engineering polymer with the structural formula 

Polyether-imides are noncrystalline polymers made up of alternating aromatic ether and imide imits. The molecular structure has rigidity, strength, and impact resistance in fabricated parts over a wide range of temperatures. PEI is one of the strongest thermoplasts even without reinforcement. 

PEI has a better chemical resistance than most noncrystalline polymers. It is resistant to acetic and hydrochloric acids, weak nitric and sulfuric acids, and alcohol. The unfilled polymer complies with FDA regulations and can be used in food and medical applications. Table 2.21 lists the compatibility of PEI with selected corrodents. Reference [1] provides a more comprehensive listing. 

PEI is useful in applications where high heat and flame resistance low NBS smoke evolution, high tensile and flexural strength, stable electrical properties, over a wide range of temperatures, and frequencies, chemical resistance, and superior finishing characteristics are required. One such application is under the hood of automobiles for connecters and MAP sensors. 

Ammonium hydroxide, 25% Ammonium Hydroxide, sat. Benzoic acid Carbon tetrachloride Chloroform Citric acid, 10% 

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Polyether Imides. Polyether imides (PEIs) are amorphous, high performance thermoplastic polymers that have been in use since 1982. The first commercial polyether imides were the Ultem series developed by the General Electric Co. The first, Ultem 1000 [61128-24-3] is prepared from phthahc anhydride, bisphenol A, and meta-phenylenediamine and has the following stmcture ... 

Different TPs have been used to modify thermosets, such as poly(ether sulfone) (PES), polysulfone (PSF), poly(ether ketone) (PEK), polyether imide (PEI), poly(phenylene oxide) (PPO), linear polyimides, polyhydan-toin, etc. (Stenzenberger et al., 1988 Pascal et al., 1990, 1995 Pascault and Williams, 2000). 

Boric acid in conjunction with APP was reported in epoxy intumescent coating.30-31 Boric acid and its derivatives were used in phenolics to impart thermal stability and tire retardancy. For example, Nisshin steel claims the use of boric acid and aluminum trihydroxide (ATH) in phenolics for sandwich panel.32 It was also reported that the small amounts of boric acid (around 0.25% by weight) in polyether imide (PEI) and glass-filled and PEI can reduce peak HRR by almost 50% in the OSU Heat Release test for the aircraft industry.33 In applications where high modulus and high strengths are needed, boric acid can be added without the softening effects of other additives such as siloxanes. 

Copolyester of p-hydroxybenzoic acid with ethylene terephthalate (PHB-PET, 60/40) was supplied by Tennessee Eastman Kodak Co., whereas polyether imide (PEI) was provided by General Electric. Co. (Ultem 1000). These polymers were dissolved together in a mixed solvent of phenol and tetrachloroethane in the ratio of 60/40 by weight at 80°C for about a week. The polymer concentration of the solution was 2 wt7.. Various PHB-PET/PEI films were cast on glass slides at ambient temperature, then dried in a vacuum oven at 60°C for two weeks. Thicker films were prepared in Petri dishes for differential scanning calorimetric (DSC) studies. 

An engineering plastic core was found preferable examples included polyetherether ketone (PEEK), polyphenylene sulfide (PPS), and polyether imide (PEI). Polytetrafluoroethylene bearers were placed in the mold to keep the core material away from the walls of the mold. No special cavity modifications were required. Any hot-melt fluoroplastic could be molded surrounding the insert examples include PVDF, FEP, ETFE, PFA, ECTFE, and PCTFE. 

Polyimides (PI) were introduced in 1962 as thermally non-processable Kapton . To improve processability, the main-chain flexibility was enhanced by incorporating segments with higher mobility, viz. polyamide-imide (PAl), polyether-imide (PEI), polyimide-sulfone (PISO), etc. These polymers are characterized by high T = 150-420°C and thermal resistance. They are blended with PPS to enhance its moldability, thermal stability and mechanical performance. 

The term HT-thermoplastics is used for polymers, which in the absence of fillers, have a continuous-use temperature above approx. 200 °C. In contrast, standard plastics, such as PVC, polyethylene or polystyrene, have continuous-use temperatures of the order of 100 °C. In addition to their high temperature stability, HT-thermoplastics, in general, possess good resistance to chemicals and usually also low flammability. Among the most important HT-thermoplastics are polyphenylene sulfides (PPS), polysul-fones (PSU), polyether sulfones (PES), polyether imides (PEI), polyetherether ketones (PEEK) and polyarylates (PAR). 

Polyether-imide (PEI) is an amorphous thermoplastic, with an excellent balance of physical properties and dimensional stabilities. PEI can be nsed with the fnll spectrum of sterilisation methods. Surgical probes that are subjected to repeated cleaning and sterilisation are their typical preferred application as a medical plastic. 

Schulte [46,47] has demonstrated how different organic solvents, such as hydraulic fluid encountered in the aerospace stmctures, lead to a reduction in the secant modulus of 45° glass fibre laminate under flexural fatigue and the number of cycles to failure. The matrix in this case was a polyether imide (PEI) which is plasticised by ingress of the fluid. A reduction in the matrix modulus means that the shear strength of the matrix will also be reduced with the consequence that the failure mechanism in flexure will change from matrix-fracture to delamination. 

The engineering polymers that have already reached maturity consist of the Nylons (PA), polycarbonate (PC), acetal (POM), polyesters (PBT and PET) and Noryl (PPO). Their relative price is aroxmd 3. Including very novel polymers, a prestigious high priced group consists of the advanced engineering polymers (high performance) polysulfone (PSU), polyphenylene-sulfide (PPS), fluoroethylenes (PTFE and its derivatives), polyamide-imide (PAI), polyether-imide (PEI), polyethersulfone (PES), polyether-ether-ketone (PEEK), aromatic polyesters and polyamides, polyarylates and liquid-crystal-polymers (LCP). 

Polyether-imide (PEI) combines stmctural stiffness (aromatic imide) together with easy flow and workability, due to the existence of the etheric bonds. It appeared initially in 1982 under the commercial name Ultem (GE). 

It can be seen in Table 8.4 that several polymers such as polystyrene (PS), polyether ether ketone (PEEK) and polyether-imide (PEI) enjoy an excellent resistance to gamma rays, whilst a wide range of polymers have very good resistance to gamma rays. 

Miscibility of segmented rigid-rod polyimide (PI), viz., biphenyl dianhydride perfluoromethylbenzidine (BPDA-PFMB), and flexible polyether imide (PEI) molecular composites was established by differential scanning calorimetry. The composite films of BPDA-PFMB/PEI were drawn at elevated temperatures above their glass transitions. Tensile moduli of the films were evaluated as a function of composition and draw ratio. Molecular orientations of polyimide were determined by birefringence and wide-angle X-ray diffraction. The crystal orientation behavior of the 80/20 BPDA-PFMB/PEI was analyzed in the framework of the affine deformation model. 

High performance engineering thermoplastics have recently assumed increasing importance due to their exceptional properties at elevated temperatures. A number of such specialty polymers have been introduced into the market for high temperature applications and examples of some of the outstanding ones are polyphenylene oxide (PPO), polyphenylene sulfide (PPS), polyether sulfone (PES), polyaryl sulfone (PAS), polyether ketone (PEEK), polyether imide (PEI) and polyarylate (PAr). 

Polyether imide (PEI) is very resistant to thermal-oxidative degradation. 

Virgin and recycled polyethylene terephthalate (PET) was blended with polyether-imide (PEI) in proportions between 0 and 50 percent PEI content and samples were examined by differential scaiming calorimetry and Fourier transform infrared spectroscopy. All blends were completely miscible, as indicated by a single glass transition temperature which is dependent on blend composition. Crystallisation rates of PET were retarded strongly at 20 percent PEI content and above, but degree of crystallinity was easily determined from a linear correlation between a structural parameter measured spectroscopically and enthalpy of fusion. Trans conformer activation energy measurement confirmed the effects of PEI content on crystallisation of PET. 9 refs. 

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