Polyamides film casting

Figure II. Effect of film casting conditions on the performance of resulting (a) cellulose acetate (12) and (h) aromatic polyamide-hydrazide membranes. The latter data are tho.se of O. Kutowy and S. Sourirafan (not yet published).

Uses Intermediate for paints mfg. of syn. fibers (esp. nylon 6), plastics, bristles, film, coatings syn. leather plasticizers crosslinking agent for polyurethanes synthesis of amino acid lysine isocyanate blocking agent polyamide 6 casting material... 

There are several other related structures, some of which are thermosets. The significance of these polymers is their physical stability at peak temperatures of 300 C and above, together with high chemical stability. There are combinations of polyimides with polyamides and other modifications that aim at improved processability. The original polyimide is very difficult to process, being shaped only via compression or film casting, or by fiber spinning from solution. 

When drawdown is high, the film may be uniaxially oriented and the properties of the final film isotropic. In the manufacture of strapping tape this effect is accentuated. If the cast or quenched film is to be used to feed an orientation tine, additional attention must be given to the amorphous—crystalline nature of the film ia the draw processes so that maximum strength can be achieved and uniform gauge and optical quality maintained. Slot casting is used for the orientation of these resins, polyesters, polyamides, and a variety of others. 

The predominant RO membranes used in water applications include cellulose polymers, thin film oomposites (TFCs) consisting of aromatic polyamides, and crosslinked polyetherurea. Cellulosic membranes are formed by immersion casting of 30 to 40 percent polymer lacquers on a web immersed in water. These lacquers include cellulose acetate, triacetate, and acetate-butyrate. TFCs are formed by interfacial polymerization that involves coating a microporous membrane substrate with an aqueous prepolymer solution and immersing in a water-immiscible solvent containing a reactant [Petersen, J. Memhr. Sol., 83, 81 (1993)]. The Dow FilmTec FT-30 membrane developed by Cadotte uses 1-3 diaminobenzene prepolymer crosslinked with 1-3 and 1-4 benzenedicarboxylic acid chlorides. These membranes have NaCl retention and water permeability claims. 

Photodissociation of the polyamides (Figures 4 and 5) was carried out in the solid films. Polymer films (1-2 U m) were cast onto quartz substrates and were exposed to monochromatic 250 nm light from a spectroirradiator. The dissociation of the thymine photodimers was followed by monitoring the absorbance at 270 nm. The results obtained for the polyamide prepared from the reaction of propane diamine and the isomers of the thymine photodimer (cis-syn(17a), cis-anti(17b), and... 

Membranes used for the pressure-driven separation processes, microfiltration, ultrafiltration and reverse osmosis, as well as those used for dialysis, are most commonly made of polymeric materials 11. Initially most such membranes were cellulosic in nature. These are now being replaced by polyamide, polysulphone, polycarbonate and a number of other advanced polymers. These synthetic polymers have improved chemical stability and better resistance to microbial degradation. Membranes have most commonly been produced by a form of phase inversion known as immersion precipitation. This process has four main steps (a) the polymer is dissolved in a solvent to 10-30 per cent by mass, (b) the resulting solution is cast on a suitable support as a film of thickness, approximately 100 11 m, (c) the film is quenched by immersion in a non-solvent bath, typically... 

Polyamides. Metallized plastics [40] have been obtained from metal chelates of nylon 4 and nylon 6 by soaking a film of the polyamides cast from formic... 

The polyamide 6 (PA6) used was a cast film of 50 pm thickness made from an unstabilized PA6. The polybutylene terephthalate (PBT) used was a cast film of 25 pm thickness made of an unstabilized PBT. 

Industrial or synthetic polymers find extensive use in modern day society. They are many in number, polyvinyl chloride (PVC) polyamides (Nylon), polyethylene teraphthalate (PET), polystyrene and polyolefins, to name but a few. Polymers are without exception very complex compounds, capable of manifesting themselves in many shapes and forms. They can exist as viscous liquids, powders, coloured granules, cast or extruded sheet, transparent or translucent film, formulated (in some cases in excess of ten different additives may be added) or unformulated. Hence they can present a very daunting task to the analyst or polymer chemist wishing to fully characterise such materials. 

Most commercial UF and NF membranes and many MF membranes are made by the phase-inversion process, where a polymer is dissolved in an appropriate solvent along with appropriate pore-forming chemical agents. The polymer solution is cast into a film, either on a backing or freestanding, and then the film is immersed in a non-solvent solution that causes precipitation of the polymer. Such membranes are Polyamides, such as nylon, polyethersulfon (PESU), or... 

In 1984, Fernandez-Santin et al. reported199 that poly(S-/]AspOiBu), the poly-/j-peptide first described by Yuki,195 does indeed exist in helical conformations when fibers are spun or films are cast from chloroform solutions. This work claimed to be the first report of helical conformations in a polyamide backbone other than chains of a-amino acids. Depending... 

The asymmetric polyamide membranes were prepared using a casting solution consisting of 15 g polymer, 85 g DMAC and 35 wt 2 LiNO, (bop) as the lyotropic salt. Salt concentrations in the casting solution are conveniently expressed as percent based on polymer (BOP). The doped polyamide solution was cast on a Pyrex glass plate using a 25-mil doctor knife. The film was then partially dried to obtain a gel membrane of polymer/solvent/salt. The air side (skin side) was identified and the gel film immersed in ice water. After an hour in ice water, the membrane was transferred to distilled water and stored until it was tested. 

Experimental films were prepared from polyamic acid or polyamide-imide solutions in 1-methyl-2-pyrrolidone (NMP) solvent by casting on soda-lime glass plates and curing in a forced air oven for one hour each at 80°C, 200°C, and 300°C. The resulting films were 25-50 microns thick. 

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. 

Nafion [253], poly(vinyl alcohol) [254], and polyamide-6,6 [255]. A procedure often followed for polymers soluble in tetrahydrofuran (THF) is to add TEOS to a THE solution of the polymer, followed by addition of water (4 moles based on Si) in the form of 0.15 M HCl or 0.1 M NH4OH and allowing the reaction to take place. Films are made by casting on an inert substrate such as Teflon and drying under proper conditions. Nafion composite films are made by impregnating swoDen Nafion films in alcohol solution of TEOS. The micro- or nanocomposite films made by the sol-gel process are expected to have technological opportunities in important arena of gas-liquid separations, heterogeneous catalysis, electronic materials, and ceramic precursors. 

It is possible to condense the aramide directly in an NMP solution and cast the solution. This process directly produces a transparent film from an aromatic polyamide dope without requiring the step of dissolving the aromatic polyamide in concentrated sulfuric acid. The process does not require any acid resistant equipment and is inexpensive. ... 

Mechanical Properties Chen et al. [2007] smdied the dynamic mechanical properties of films prepared by the solution casting method of PHBHV reinforced with HAp. The results indicated that at 75°C the storage tensile modulus of the polymer matrix, E , almost doubled by incorporation of 30 wt% HAp. The decrease in tan S was attributed to the hindrance of polymeric segment mobility by the nanofiller. Polyamide-69 has been reinforced with up to 10 wt% HAp [Sender et al., 2007]. The DMA results have pointed out an enhancement of the mechanical properties as a function of HAp content up to 5 wt% above this limit they deteriorated, probably due to the HAp agglomeration. 

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