Molded polyetherimide

Studies were conducted on molding polyetherimide with different types and quantities of mold release agents. It was concluded that a too high concentration of mold release agent results in reduced heat deflection temperature and Izod impact properties. Figure 10.12 shows how concentration of polyolefin release agent affects ejection pressure. ... 

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 appHcations as an alternative to standard flat printed circuit boards. Only semiadditive or fully additive processing can be used with these devices. 

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. 

The PEEK resin is marketed as neat or filled pellets for injection molding, as powder for coatings, or as preimpregnated fiber sheet and tapes. Applications include parts that are exposed to high temperature, radiation, or aggressive chemical environments. Aerospace and military uses are prominent. At present, polyamideimide (PAI) resin and poly(arylene sulfides) are the main competitors for applications requiring service temperatures of 280°C. At lower temperatures, polyethersulfones, amorphous nylons, and polyetherimides (PEI) can be considered. 

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. 

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]. 

Results of some of these short-term tests are shown in Table II. A comparison is given between PPS and five other plastics nylon (Zytel 101), polycarbonate (Lexan 141), polysulfone (Bakelite Polysulfone), polyphenylene oxide (Noryl), and polyetherimide (Ultem 2300). The data presented are based upon retention of tensile strength for all plastics except the Ultem 2300, which is based upon retention of flexural strength. Unsuccessful attempts were made to injection mold ASTM Type IV tensile bars out of the Ultem compound, but flexural strength bars could be made. Experience has shown that chemical resistance tests monitored by flexural strength retention are comparable to those monitored by retention of tensile strength. 

Materials For Molding (5) -Polyarylate -Polysulfone -Polyarysulfone -Polyethersulfone -Polyetherimide -Polyphenylene Sulfide... 

Xytrex . [EGC] Polyetherimide, PES, polyketone, PEEK, or PPS, some carbon or glass filled for inj. molding, compr. molding, extrusion, coating, bearing applies. 

Polyetherimide (Ultem 1000, GEC) is a high performance engineering thermoplastic with high heat distortion temperature (> 200°C), high mechanical strength and inherent flame-retardancy characteristics. Recently blends of polyetherimide with polycarbonate have been commercially offered as thermoformable sheets and as molding compounds (Table 15.28). The primary reason for... 

Winchester discs are molded as blanks in engineering plastics, usually General Electric s Ultem polyetherimide, then coated with an epoxy-ferric oxide layer. The main requirement in manufacturing these discs is absolute flatness because the magnetic read/write head moves only 8-20 microinches above the disc surface and is spinning at a high speed of 3,600 rpm. Any microscopic bump can thus cause damage to both the disc and head. 

An aqueous chemical pretreatment for unfilled polyetherimide substrates is described. The process includes the use of a chemical impregnator to increase the mechanical adhesion component and avoid metal lymer delamination during the initial electroless metallization step. Excellent adhesion was achieved for copper or nickel to both injection-molded plaques and extruded films. The metalA>olymer bond was found to be durable in thermal environments (dry and moist) as well as in simulated solder tests. Failure occurred within the polymer substrate during 90° peel testing. The process was found to be applicable to filled substrates as welt. 

The use of high temperature thennoplastics for electronic applications is of considerable and growing interest because of the enhanced thermal and electrical properties of these materials. One such material is GE s Ultem polyetherimide which can be injection molded as well as extruded. This latter property is important for utilizations such as flexible circuits where a pliable film is required. The inherent physical properties of the polymer can be enhanced through the addition of fillers. A potential disadvantage, however, is that the nascent translucence of the polyetherimide is eliminated. Visual clarity may be desirable in certain applications such as automatic climate control systems wherein an LED must be read through a patterned circuit board. In addition, neat polymer material may be desirable because of its improved flow properties relative to filled polyetherimide. 

The plastic substrates employed in this study were injection-molded plaques (1.5 mm thick) or 125 )im thick extruded films prepared from unfilled Ultem polyetherimide (Ultem KXX)). In addition, plaques containing 10, 20, or 30 % glass-filler (Ultem 2112, Ultem 2212, or Ultem 2312, respectively) were used. All materials are available from GE Plastics. 

The substrates utilized in this study were 1.S mm thick, unfilled polyetherimide (Ultem 1000) injection-molded plaques and extmded films (12S pm thick). In addition, glass-filled plaques containing 10, 20,30,40, or SO % filler were employed. These latter materials are known commercially as Ultem 2112,2212,2312,2412, or 2512, respectively. All the materials are availabk from GE Plastics. 

The polymer should be dried before processing, and typical melt temperatures are 340 to 425°C. Polyetherimides can be processed by injection molding and extrusion. In addition, the high melt strength of the polymer allows it to be thermoformed and blow molded. Anneahng of the parts is not required. 

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