Polyamide-imide surfaces

Zhang, Y., Wang, R., Yi, S., Setiawan, L., Hu, X., Fane, A.G. 2011. Novel chemical surface modification to enhance hydro-phobicity of polyamide-imide (PAI) hollow fiber membranes. J. Membr. Sci. 380 241-250. 

Hydrogenated cottonseed oil Hydrogenated palm oil Hydrogenated vegetable oil Octyidodecyl stearoyl stearate binder, surface coatings Epoxy, bisphenol A Polyamide-imide resin Poly (vinyl propionate) binder, suspension polymerization Methyl hydroxyethylcellulose binder, swimming pool paints Rubber, chlorinated... 

Polyamide-imide resin plastics, reinforced Dipropylene glycol Polypropylene plastics, surface-coating Bismuth subsalicylate plastics, vinyl Ammonium acetate plastisols... 

They are easily bonded with epoxy or urethane adhesives however, the temperature resistance of the adhesives do not match the temperature resistance of the plastic part. No special surface treatment is required other than abrasion and solvent cleaning. Polyetherimide (ULTEM ), polyamide-imide (TORLON ), and polyethersulfone can be solvent cemented, and ultrasonic welding is possible. 

An all aromatic polyetherimide is made by Du Pont from reaction of pyromellitic dianhydride and 4,4,-oxydianiline and is sold as Kapton. It possesses excellent thermal stability, mechanical characteristics, and electrical properties, as indicated in Table 3. The high heat-deflection temperature of the resin limits its processibility. Kapton is available as general-purpose film and used in applications such as washers and gaskets. Often the resin is not used directly rather, the more tractable polyamide acid intermediate is applied in solution to a surface and then is thermally imidized as the solvent evaporates. 

The polyamide-acid solution obtained was cast as a film (ca.. 25 mm thick) onto a glass plate and dried for 12 hours at 80°C under vacuum (30 min). The resulting film was subjected to the following cure cycle under nitrogen on a hot plate monitored with a surface thermometer to effect imidization 100°C (2 hours), 150°C (2 hours), 200°C (1.5 hours) and 300°C (1 hour). High Tg films (Tg > 300°C) were optionally cured for an additional 0.5 hours at a temperature of 480°C in an inert atmosphere oven to ensure imidization and removal of volatiles. 

Another polypyrrole/polyamide composite film was obtained by the electrode coating method [84]. In this work the polyamide film was obtained in situ by coating a stainless steel electrode with a polyamic acid film followed by imidization with pyridine and acetic anhydride. The coated electrode was submitted to a constant current in a pyrrole/LiC104 solution in acetonitrile. The surface conductivity measured after detaching the composite film from the electrode showed a strong dependence on the charge density used in the synthesis, i.e. on the amount of pyrrole polymerized in the composite. The maximum value obtained was 2 S cm . Combination of polypyrrole with this polyamide was shown to increase markedly its thermal and environmental stability. 

Without the introduction of ladder-like moiety induced from benzodioxane, polyimides derived from distorted backbone units have potentials to retain the intrinsic microporosity because the imide linkage itself is formed as very rigid and flat two-dimensional structure. " Similar to Cardo-PIM, these polymers are based on bifluorene units, which have a 90° kink that prevents space-efficient packing or crystallization of the otherwise stiff polymer chains. Weber and Thomas synthesized bi-, tri- and tetra-functional bifluorene and reacted with dianhydride, di(acid chloride) or trimesoyl chloride for contorted polyimide and polyamide. The most microporous polyimide represents the BET surface area of 982 m g , providing much potential for highly permeable gas separation membranes. 

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