Model studies industrial films

A wide range of polymer chemical compositions is used in both films and membrane materials. A listing of commonly known polymers, including those found in films and membranes, is foimd in Appendix IV. The focus of this section is on a description of model film studies, industrial film applications and flat film and hollow fiber membranes, with examples of studies which show the morphology of the films and membranes. 

Cast films exhibit a range of morphologies due to the effect of solvents, substrates and orientation. In the case of block copolymers the choice of solvent is quite important to the final structure. Spherulites, a common textural structure observed in crystalline pol5maers, are formed in many industrial processes where the polymer is melted prior to forming the article of interest. Films produced by these industrial processes differ from films used in model studies as the former are usually not thin in the microscopic sense. In true thin films, the spherulitic texture is two dimensional, whereas in these thicker film materials the spherulites are three dimensional. 

Industrial films of such chemical composition as polyethylene, polypropylene and polyester are manufactured for a wide range of applications. Accordingly, the morphology of these materials is studied to determine structure-property relations, to understand how to improve properties and also to control the quality of commercial products. Although model studies provide considerable detail relating to the structure, both before and after deformation of such films, model... 

Films and membranes include a formidable array of materials that are widely used in a range of industrial applications. Films find application as coatings and packaging materials such as food wraps, and membranes are used for separations, controlled release, coating and packaging barriers and contact lenses. Structural studies of films fall into two major categories model film studies and the study of commercial films. Model studies are generally. conducted in university research laboratories where the thin, flat structure of a melt cast or drawn film provides an ideal speci-... 

Not much effort has been made, except for the Tafel studies, to establish the empirical kinetics and models of interfacial reactions to obtain thick polymeric films (>100 nm) of industrial interest from different monomers. However, this is much more than the few kinetic studies performed until now to understand the mechanism of chemically initiated polymerization. Electrochemical models still have an advantage in obtaining priority in the industrial production of tailored materials. 

The nitrile-epoxy structural adhesive systems have moved from an aircraft orientation to include industrial, automotive and electronics areas. These include a host of film adhesive products (21, 22) and thixotropic pastes (23-26). Representative adhesive models have also been studied from a fracture toughness polnt-of-view permitting comparisons of bulk fracture to that of fracture in the adhesive joint (27, 28). 

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