Polyamide-imide chemical resistance

Polyamide-imide chemical resistance to solvents is high. Polyamide-imide is resistant to aliphatic and aromatic hydrocarbons, solvents, acids, and exhibits limited resistance to weak bases. Table A.30 Appendix. 

Polyamide-imides are appreciated for good mechanical and electrical properties high service temperatures (up to 220°C with possible long service times at 260°C) rigidity good creep behaviour fatigue endurance low shrinkage and moisture uptake inherent flame retardancy chemical resistance usability down to -196°C. 

Polyamide-imide represents another group of high-temperature engineering polymers, with good dimensional stability, impact and chemical resistance. 

The Torlon materials produced by Amoco Chemicals are polyamide-imides of the type shown in Figure 4.20a. Torlon has high strength, stiflEness, and creep resistance, shows good performance at moderately high temperatures, and has excellent resistance to radiation. The polymers are unaffected by all types of hydrocarbons (including chlorinated and fluorinated products), aldehydes, ketones, ethers, esters, and dilute acids, but resistance to alkalis is poor. 

Most polyamide-imides are not as heat resistant as are the polyimides discussed in the next section. They are, however, easier to process. The polyester-imides might be considered as upgraded polyesters, though properties vary, depending upon chemical structure. ... 

Fibre choices for thermal protective clothing include inherently flame resistant (FR) fibres such as the meta- and para-aramids, polyamide-imide, polybenzimidazole, modacrylic and chemically modified fibres such as viscose and modal, polyester, and nylon, as well as FR treated or finished cotton and wooP"" (see also Chapter 8). The... 

Methyl-2-pyrrolidinone (NMP) n, (CH3) NCH2CH2CH2C = O. A solvent with a low order of inhalation toxicity, good thermal and chemical stability, and a high flash point. It is capable of dissolving resistant resins such as polyamide-imides, epoxies, urethanes, nylon, and PVC. It is a solvent of choice for spinning PVC fibers from solution. Previously known an N-methyl-2-pyrrolidone. 

Polyimides are a group of extremely strong polymers that are also highly heat and chemical resistant. These polymers contain the imide functionality. We have seen Uiat the amide functionality [—C(0)NH—] is present in synthetic polyamides like nylon-6,6 as well as in natural polyamides like proteins. The imide functional group is created when nitrogen is at-... 

Polyamide-imides are thermoplastic amorphous polymers that possess exceptional mechanical, thermal, and chemical- and wear-resistant properties. They are inherently nonflammable, have outstanding electrical properties, and possess enormous temperature stability from cryogenic to 300°C. These properties place polyamide-imides at the top of the price and performance pyramid with polyketones and polyimides. 

The endurance benefits and performance characteristics of polyamide-imides qualify them to be an excellent replacement for metal in aerospace components. Inherent nonflammability, chemical resistance, and superb strength at elevated temperatures allow polyamide-imide compounds to be used in metal applications once unheard of for plastic materials. Neat resin, friction and wear, along with glass- and carbon-reinforced polyamide-imide compounds are incorporated in a variety of parts and locations in aerospace vehicles. 

Polyamide-imides have a remarkable range of resistance against harsh chemicals. Polyamide-imides are virtually untouched by hydrocarbons, including the entire family of aromatic, aliphatic, chlorinated, and flu-orinated solvents. Most acids have little effect on polyamide-imides. The material s weakness lies in its relatively poor resistance against strong bases such as concentrated hydroxides and strongly basic amines. 

Many high-performance polymer fibres are used in filter media to meet various specific requirements in diverse filtration applications. Filters made from fluoropol-ymer (Polytetrafluoroethylene (PTFE), Polyvinylidene fluoride (PVDF), and Per-fluoroalkoxy alkane (PFA)) fibres, and membranes have inherent, chemical-resistant, and flame-retardant properties, and they are widely employed to filter aggressive chemicals and acids in the manufacture of wafers and microchips in the microelectronics industry. Ethylene ChloroTriFluoroEthylene (E-CTFE) melt blown fabrics have a unique ability to coalesce difficult liquids and can withstand the piranha effect in filtering ozone enriched ultrapure water. Polyphenylene sulfide (PPS) fibres are also chemical resistant, stand high temperature, and are suitable for making baghouse filters. Eilter media made from other high-performance polymer fibres, such as polyamide-imide, polyetherimide (PEI), Polyimide P84 fibre,polyetheretherke-tone, and liquid crystal polymers also appear in the filtration and separation market. 

Table A.31 Chemical resistance of polyimide (Pi), polyamide imide (PAI), polyphenylene ether (PPE). and polyether ether ketone (PEEK) sc = semi-crystalline [1039]...

Polyamide-imides (PAIs) are thermoplastic amorphous polymers prepared by the condensation of an aromatic diamine, such as methylene diamine, and an anhydride, such as trimellitic add chloride. PAIs have good mechanical, thermal, chemical resistance, high strength, melt processability, and high heat capacity. They can be processed into a variety of forms, such as injection or compression molded articles, coatings, films, fiber, and adhesives. The typical heat deflection temperature for neat molded PAI is 278°C,but reinforcements are often used to improve mechanical properties. PAIs are generally soluble in strong aprotic solvents such as NMP and DMAc, and thus misdble blends with PBI are feasible. 

PAIs are unique materials that have elements of PA (aka nylon) chemistry, as well as aromatic polyimide chemistry. They have exceptional mechanical, chemical, and thermal properties and are considered by some to be at the top of the thermoplastic performance chart. They have high strength, exceptional high heat capability, and broad chemical resistance. Polyamide-imide polymers are melt processible and can be processed into a wide variety of forms—from injection- or compression-molded parts and ingots— to coatings, films, fibers, and adhesives. PAI is often lower in cost than TPI. 

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