Film whitening

Swelling - particularly due to the uptake of water - often creates opacity within the film (whitening) which is undesirable in many applications. This phenomenon is caused by refractive index inhomogeneities created in the film when water penetrates the interstitial regions between the particles. Characterization of film whitening can be done with conventional techniques as discussed above. 

In laminates intended for use out-of-doors papers with superior colourfastness may be used and normally their construction includes an overlay sheet of ultra-violet absorbing thermoplastic film—which helps to reduce fading of the colour, and whitening. 

Compounds 65 have radioactivity protection (84KFZ325), and 68 is useful as a fluorescent whitener for polyester, acetate, acrylic, and polyamide fibers, and for PVC film (80GEP3001424). 

The formation of microvoids (or micropores) in drawn /3-PP is a well-known feature, used successfully to produce breathable films and membranes. Macroscopically their occurrence is correlated with an opacification (i.e. whitening) of the specimen. Their amount can, for example, be measured at given strain rate/draw ratio by liquid porosimetry (e.g. mercury intrusion), gas absorption or by the determination of the density of the deformed sample [129,177,178]. 

Owing to a photocatalytic effect, titanium dioxide may interact with certain active substances, e.g. famotidine. Studies have shown that titanium dioxide monatonically degrades film mechanical properties and increases water vapor permeability of polyviiwl alcohol coatings when used as an inert filler and whitener. ... 

Film formers are used to coat food by providing it with a protective layer and so making it more attractive in appearance or increasing its palatability. Film formers may not impart flavor or mouth feel of their own to the food. Examples are starches to coat proteins to prevent Maillard reactions, mineral oils to seal pores of eggs, and sodium caseinate to encapsulate fat in whiteners. 

Whiten D.G., Russell J.C., and Schmehl, R.H., Photochemical reactions in organized assemblies environmental effects on reactions occurring in micelles, vesicles, films and multilayer assembles and at interfaces . Tetrahedron, 38, 16,2455-2487. (1982)... 

The biaxially oriented film has an excellent anti-curling property. The anti-curling property means that a film hardly remains curled when rolled once and then unrolled. Whitening has rarely been observed at a fold when the film is folded. This property is called delamination resistance and is an important index for the evaluation of both a base film for a magnetic recording medium and a base film for a photo film. 

The usage of a PEN film for a photo film is more satisfactory with respect to mechanical strength, dimensional stability, and in anti-curling property when rolled to a small diameter. However, the PEN film is susceptible to delamination, especially when the film is rolled and perforated. The occurrence of delamination makes it difficult to use it as a base film of a photo film because a delaminated portion is whitened. 

However, this concentration appeared to be excessive as migration of glycerol to the film surface and subsequent leaching and crystallization of urea (or whitening) was observed upon ageing. 

CAS 7128-64-5 EINECS/ELINCS 230-426-4 Uses Fluorescent whitener, optical brightener for thermoplastics (PVC, PE, PP, cellulose acetate, PS, PC, acrylics, polyolefins, PU, linear polyester, polyamides), adhesives, coatings, printing inks (for security bonds, bank notes), dyes, textiles (syn. fibers incl. PVC and acetate), molded articles, films, sheets, syn. leather, waxes, fats, and oils tracer in clear coatings... 

Uses Fluorescent optical brightener for nonaq. systems, acrylics, epoxies, other solv.-based coatings, thermoset and thermoplastic resins, plastics, films, and molded goods fabric brightener or whitener for detergent systems for nylon, silk, wool, and acetates (for use with nonionic, anionic, or cationic surfactants)... 

The biaxially oriented film has an excellent anticurling property. The anti-curling property means that a film hardly remains curled when rolled once and then unrolled. Whitening has rarely been observed at a fold... 

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