Applications cast films

An important application for polypropylene is film tape. This is made by slitting unoriented film (cast or blown) into tapes 2 or 3.5 mm wide and stretching under heat about seven-fold. With cast film the orientation is more completely monoaxial and there is a tendency for the film to split along its length (fibrillate). Tubular film does not self-split so easily and also has a somewhat softer feel. Such tapes may be woven into sacks and these have... 

P. C. Wu, Metallocene ethylene based resins in cast film extrusion and application, MetCon 94 Proceedings, USA, May 1994. 

Organic compounds which show reversible color change by a photochemical reaction are potentially applicable to optical switching and/or memory materials. Azobenzenes and its derivatives are one of the most suitable candidates of photochemical switching molecular devices because of their well characterized photochromic behavior attributed to trans-cis photoisomerization reaction. Many works on photochromism of azobenzenes in monolayers LB films, and bilayer membranes, have been reported. Photochemical isomerization reaction of the azobenzene chromophore is well known to trigger phase transitions of liquid crystals [29-31]. Recently we have found the isothermal phase transition from the state VI to the state I of the cast film of CgAzoCioN+ Br induced by photoirradiation [32]. 

At pHs5.6, both UDI and PVI-1 cast films produce passivation, UDI reducing the anodic currents by an order of magnitude more than PVI-1. Linear polarization measurements on Cu in UDI solution (pHs5.6) indicate that UDI may have practical application as a corrosion inhibitor for copper. 

Polypropylenes are available as molding powder, extruded sheet, cast film, textile staple, and continuous-filament yarn. They find use in packaging film molded parts for automobiles, appliances, and housewares wire and cable coating food container closures bottles, printing plates carpet and upholstery fibers storage battery cases crates for soft-drink bottles laboratory ware trays fish nets surgical casts and a variety of other applications. 

Solution-cast film is produced on a larger scale for medical applications, battery separators, or other specialty uses with machinery of the type shown in Figure 3.2 [2], Viscous film is made by this technique. The solution is cast onto the surface of a rotating drum or a continuous polished stainless steel belt. These machines are generally enclosed to control water vapor pickup by the film as it dries and to minimize solvent vapor losses to the atmosphere. 

The first successful application of this method was reported by Mullen and coworkers [18]. The removal of their solubilizing group occurs thermally at temperatures as low as 180 °C, yielding pentacene and a volatile tetrahalobenzene. The tetrachloro compound 4 (Fig. 3.3) formed good-quality films from spin-cast solution, and heating the film of the soluble precursor at 200 °C for 5 s yielded the desired acene film. FET properties for devices made from solution-cast films were quite good - measured mobilities were as high as 0.2 cm2 V-1 s-1 with on/off current ratios of 106. 

A cast film of 28 also responded to the chirality of liquid and solid chiral amines, and exhibited an ICD in the UV-visible region. The observed Cotton effect patterns were similar to those of 28 induced by the chiral amines in solution [147]. These methods are more convenient and practically feasible to sense the chirality of chiral amines than the solution method, and may be applicable to other dynamic helical polyacetylenes. 

Polymer solutions and dispersions find many practical applications. We can cast films from some polymers, and we use many others to form coatings. Coatings can be produced from either solutions or dispersions such as polymer emulsions (latexes). Examples include paint, varnish, textile finishes, adhesives, and floor waxes. Other useful latex products are latex gloves, condoms, and balloons. 

Gamma Ray Method. Cellulose acetate (powder, acetic acid content by weight, 58% ) was recrystallized from an acetone solution of the polymer by the addition of 10 volumes of water the acetate was removed by filtration and dried under vacuum. Cellulose acetate was cast into films (20 cm X 20 cm X 0.09 mm) by application of a solution in acetone (20% w/v) to glass plates using a TLC layer applicator. The films were dried at room temperature for 2 h, peeled from the plates, and cut into strips (1.5 X 4.5 cm). The strips were then dried under vacuum for 48 h. 

Based on the PANi model, it is generally assumed that this method is applicable to all CPs as a means of processing. It is known that some CPs exhibit some solubility in organic solvents in their de-doped states, but the fractions with the highest molecular weight do not dissolve and cast films frequently do not re-dissolve. 

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