Engineered plastics polyimides

Resins for advanced composites can be classified according to their chemistry typical resins are polyaryletherketones, polysulfides, polysulfones, and a very broad class of polyimides containing one or more additional functional groups (Table 2) (see also Engineering plastics). 

Commonly accepted practice restricts the term to plastics that serve engineering purposes and can be processed and reprocessed by injection and extmsion methods. This excludes the so-called specialty plastics, eg, fluorocarbon polymers and infusible film products such as Kapton and Updex polyimide film, and thermosets including phenoHcs, epoxies, urea—formaldehydes, and sdicones, some of which have been termed engineering plastics by other authors (4) (see Elastol rs, synthetic-fluorocarbon elastol rs Eluorine compounds, organic-tdtrafluoroethylenecopolyt rs with ethylene Phenolic resins Epoxy resins Amino resins and plastics). 

As can be deduced from plant purchases, the PRC is still at the formative stage where emphasis is on producing only the most basic petrochemicals. No plants were purchased for producing dibasic acids (phthalic and maleic anhydrides, etc.) and fluro-carbon or tetrafluoro ethylene or some of the advanced engineering plastics like ABS polyacetals, polycarbonates, polyimides or any other unsaturated polyesters. Another important area of low Chinese activity is thermoplastics for space and defense applications. ... 

Polyimides are engineering plastics used only for specialized and technical applications. The applications are always high-tech. The price and the difficulty of transformation limit the use of polyimides to well-targeted applications taking advantage of the high performance of these materials. 

As aromatic compounds have been exhausted as building blocks for life science products, A-heterocyclic structures prevail nowadays. They are found in many natural products, such as chlorophyll hemoglobin and the vitamins biotin (H), folic acid, niacin (PP), pyridoxine HCl (Be), riboflavine (B2), and thiamine (Bi). In life sciences 9 of the top 10 proprietary drugs and 5 of the top 10 agrochemicals contain A-heterocycIic moieties (see Tables 11.4 and 11.7). Even modern pigments, such as diphenylpyrazolopyrazoles, quinacri-dones, and engineering plastics, such as polybenzimidazoles, polyimides, and triazine resins, exhibit an A-heterocydic structure. 

Nylon, polyacetal, polycarbonates, poly(2,6-dimethyl)phenylene oxide (PPO), polyimides, polyphenylene sulfide (PPS), polyphenylene sulfones, polyaryl sulfones, polyalkylene phthalates, and polyarylether ketones (PEEK) are stiff high-melting polymers which are classified as engineering plastics. The formulas for the repeating units of some of these engineering plastics are shown in Figure 1.15. 

Aromatic polyimides are most useful super engineering plastics which exhibit excellent thermal, electrical, and mechanical properties, and have been used widely in aerospace, electronics, and other industries over the past three decades [ 1 -4]. Aromatic polyimides are generally prepared through a two-step procedure by the ring-opening polyaddition of aromatic diamines to aromatic tet-racarboxylic dianhydrides in NMP (or DMAc) solution giving soluble polyamic acids, followed by thermal cyclodehydration (Eq. 1) [1-5]. 

Nevertheless, further detailed information was unavailable on the polyimide synthesis from nylon-salt-type monomers that is referred to as salt monomer method , and this method was not really recognized as a simple synthetic method of both aromatic and aliphatic polyimides. In addition, many polyimide investigations have mainly been concentrated on aromatic polyimides, and little information is available about aliphatic polyimides [13-18] that are also potential candidates for engineering plastics. 

Wholly aromatic polyimides are highly thermally stable engineering plastics, and have been widely used as the reliable insulating materials in microelectronics. Recent developments in this field toward higher integration of devices required ultra thin films of polyimides. Minimum thickness of polyimide films cast by spin coating was about 0.1 Urn. 

There are two main methods for synthesis of polyimides. In one, the dianhydride and diamine are separately dissolved in A,lV-dimethylacetamide or A-methylpyrrollidinone. The solutions are mixed for 24 h to afford poly(amic) acid. The mixture is then refluxed for a further 24 h, using an azeotroping solvent to distill off water. Alternatively, the diamine is mixed with the dianhydride as its ester-acid, and heated at 190 °C in the presence of o-dichlorobenzene as azeotroping solvent. There are reported improvements113. A useful intermediate used in the manufacture of polyamide and imide engineering plastics is 1,3-bis(3-aminophenoxybenzene). 

Performance Coatings and Polymers nylon, acetal, polyester, polyimide and EPDM engineering plastics and elastomers industrial and powder coatings and inks ... 

The Performance Coatings Polymers business is involved in the production of nylon, acetal, polyester, polyimide and EPDM engineering plastics and elastomers and industrial and powder coatings and inks. The Wuppertal sites are primarily involved in the production of automotive coatings and refinishes, electrical insulation and adhesives. 

In case of ultrafiltration membranes, resistance of membrane is owing to membrane material. Therefore, selection of membrane material is the most important. Figure 9 shows comparison of engineering plastics which have ever investigated for ultrafiltration membranes with solvent and high temperature resistance. It is the most difficult to find materials which satisfy both excellent resistivity and excellent processibility. Polyimide is an only material commercialized for a rather resistant ultrafiltration membrane. 

Chem. Descrip. N-Cyclohexyl pyrrolidone CAS 6837-24-7 EINECS/ELINCS 229-919-7 Uses Solvent tor plating engineering plastics, esp. EMS applies. dye penetrant tor aramid fibers photo resists gas separation elec, insulating coatings chem. synthesis absorp. of sulfur dioxide and nifric acid aromafic extraction high temp, polyimide processing aid Features Superior resist, to hydrolysis... 

Thermosetting polyimides are one of the highest performing engineering plastics, exhibiting superior performance in applications requiring low wear and long life in severe environments. Polyimide materials feature ... 

Many kinds of polymers are used in the electronics industries, from polyethylene to so-called super engineering plastics, such as polyethersulfone or polyimide. Almost all of them require additives. The reason for this is either to retain intrinsic characteristics or to extend those characteristics. In order to retain properties, polymers need process and heat stability, thermal stability or light stability. For the acquisition of new function, many kinds of functional additives can be added. Metal deactivators, antistatic agents and flame retardants are just some examples. 

Structural adhesives must have a glass transition temperature higher than the operating temperature to avoid a cohesively weak bond and possible creep problems. Modem engineering plastics, such as polyimide or polyphenylene sulfides, have very high glass transition temperatures. Most common adhesives have a relatively low glass transition temperature so that the weakest thermal link in the joint may often be the adhesive. 

Aromatic polyimides are an important class of high-performance polymers with interesting properties such as good chemical and solvent resistance, high thermal and mechanical properties, and high optical transparency. These excellent properties make them suitable for engineering plastics to be used in... 

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