Photo-stability polyurethane

High molecular weight hindered phenolic antioxidant with photo-and thermo-stability. Provides low volatility and resistance to extraction from polymer compounds. Suitable for PP, PE, polystyrene, ABS, PVC, nylon, and polyurethane. Also used as a radical scavenger providing stabilization for polyolefins. 

Photos 3a and 4a are the photomicrographs of the unexposed thermoplastic polyurethanes and illustrate the initial integrity of the polymer surface. Spectra 3A (neat, no light stabilizer) and 4a (0.5% LS I) represent the MIR spectra of the unexposed polyester urethane. 

Photo 3b is a photomicrograph of the polyurethane that contained no light stabilizers which was exposed outdoors in Florida for six months. Note the deep cracks and extensive surface erosion as well as mildew near the cracks. 

A gel electrolyte consists of an ion conducting polymer, such as polyoxyethylene or a polymer with polyoxyethylene segment, and an ion source. Hexafluorophosphate or tetrafluoroborate salts of lithium are commonly employed as the ion source. Other common components of the gel are liquid electrolytes like ethylene carbonate or propylene carbonate, both of which are used to increase the overall ion conductivity. Cross-linking agents, such as photo cross-linked acrylates or polyurethanes, can be incorporated to improve the mechanical stability of gel electrolytes. 

A practical route to reduce the effects of photo-degradation in PUs (as in the case of other polymers) is the addition of suitable light stabilizers by different ways. The most used procedure is the additive stabilization method. A more effective method to increase the maintenance of the stabilizer in the polymer is the chemical bonding of these compounds to the macromolecular chain even in the course of polyurethane synthesis. Some attempts to introduce in such way the stabilizers in polymers are known. Thus, a benzotriazole UV absorber was mixed with a prepolymer containing isocyanate groups and the chain extender directly into moulding machine (cone. 0.5%) [64, 323]. The stabilizer can be also mixed into polyol component before its reaction with the isocyanate component. The stabilizer that usually contains OH groups could form chemical bonds with the macromolecular chain in some extent [324]. 

Chemical additives are usually used for light-stabilization of plastic materials, while UV resistant coatings (e.g. clear polyurethane coatings) are applied for wood products protection, since photo-degradation processes cause increased water sensitivity and further their biodegradation under outdoor exposure conditions [32]. In most cases, it is preferable to use materials with greater resistance to UV radiation in order to prevent the increased damage of these materials under outdoor exposure to solar radiation. 

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