Polyurethanes structurally colored

The GMP s process eliminates the use of sheet metal for the skin of the refrigerator door. In this application, the thermoplastic film forms a durable, protective outer skin with a wide choice of color options that are applied directly to the film. In addition more innovations exist apart from the film and thermoplastic interior liner, the doors consist entirely of polyurethane. GMP backs the thermoplastic film with an approximately 4 mm thick layer of the Baydur 110 structural foam polyurethane RIM system from Bayer AG that creates a rigid, dimensionally stable outer shell with no need for sheet metal. Then, GMP fills the space between this shell and the inner liner with insulating polyurethane foam, a rigid, low-density foam. The result is a self-supporting door that satisfies all stability, thermal insulation, and surface finish requirements. 

RIM polyurethanes made with aromatic isocyanates (such as pure or polymeric MDI) have a tendency to darken as a result of the effect of UV light on the chemical ring structure of the MDI component. Soft white limestone or line carbon black is often used as filler to mask the effect of this color change. 

The stressing of polyurethane film in alcoholic solution of DPPH, determined their coloration in red-purple, colour which is maintained after the stress removing, which demonstrates the chemical bounding of the radical acceptor to the polymer mechano-radicals. The presence of DPPH structural units on the main chain were proved by UV spectrometry. Figure 3.317, and of acrylonitrile... 

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