Nickel stabilizer

Although spironaphthooxazines have excellent lightfastness, they decompose slowly on exposure to sunlight. However, lightfastness can be improved by addition of nickel stabilizers (singlet oxygen quenchers) or hindered amines (antioxidants).86 88... 

SD HDPE systems (1% TiOz) are thermally stable up to 250°C, while 1/25 SD specimens withstand 280°C. P.Y.182 does not affect the shrinkage of the plastic. 0.37% pigment is needed to formulate a 1/3 SD HDPE sample. Combining P.Y.182 with nickel stabilizers in polypropylene is to be avoided. The pigment dissolves in polystyrene as the temperature reaches 200°C, a process which is accompanied by considerable color change. P.Y.182 is also an unsuitable candidate for ABS. 

The main consumer of nickel is austenitic stainless sleel, which contains from 3,5 to 22% nickel and 16 to 26% chromium. In these steels, nickel stabilizes the austenite and enhances the ductility of the steel. Nickel, along with chromium, contributes to corrosion resistance. Up to amounts of about 9%, nickel adds strength, hardness, and toughness to many alloy steels. 

The chemoselective reduction of nitro and carbonyl functions with /-PrOH/ KOH over nickel-stabilized zirconia has recently been reported by Upadhya et al. [10]. This catalytic system selectively reduced 4-nitroacetophenone and... 

Table I. Acidity and Nickel Stability Constants for Complexing Ligands "...

Nickel is often used as matrix modifier in the determinations of arsenic and selenium. Nickel stabilizes arsenic up to about 1700 K, and selenium up to about 1500 K. This is presumably due to the formation of thermally stable nickel arsenide and nickel selenide. Nickel can also be used to stabilize bismuth, antimony, and tellurium. In addition, copper, silver, molybdenum, palladium, and platinum salts have been proposed as stabilizers for these elements. Palladium and platinum are the most suitable matrix modifiers for both inorganically and organically bound tellurium. Pretreatment temperatures up to 1320 K can be used. The effect of different matrix modifiers on the determination of antimony are shown in Figure 74. Without matrix modifiers the losses of antimony begin at 1000 K. Palladium, molybdenum, and nickel are the most suitable to stabilize antimony and with these modifiers pretreatment temperatures up to about 1600 K can be used. 

The most resistant to lead are refractory metals followed by chromium steels and austenitic steels being less resistant because of high solubility of incorporated nickel. Stabilization of austenitic steels by Ti, Nb and Mo enhances their resistance to lead. 

Ideally, pigment should provide only color. They are expected to be heat- and light-stable and not have any effect on fiber properties. However interactions do occur. Some are predictable—such as the interaction between some inorganic sulfides with nickel stabilizers. Most interactions are unpredictable and are found only via an Edisonian approach, that is, produce the fiber and test it. 

Calcium laurate Drometrizole 2,2 -Thiobis (4-t-octylphenolato)-n-butylamine nickel stabilizer, heat ABS polymers Dimethyl succinate stabilizer, heat acrylics Drometrizole... 

The combination of HALS with a UV absorber is used in fihns of polypropylene and polyethylene as well as in thick sections. In films of LDPE, nickel quenchers were commonly used with a UV absorber, except in a very thin film, in which a higher concentration of nickel stabilizer is superior to the combination. The low-molecular-weight HALS are not sufficiently compatible with LDPE at the concentrations necessary, possibly as high as 2%, for the required protection. Incompatibility of HALS with LDPE has been overcome with the development of polymeric HALS. It is considerably better than either the UV absorber or nickel quencher or combinations of the two. For thicker films (100-200 ftm), the combination of a benzophenone-type UV absorber with polymeric HALS is significantly superior to an equivalent amount of polymeric HALS. The type of stabilizers used for linear low-density polyethylene (LLDPE) and ethyl vinyl acetate (EVA) copolymer are similar to those for LDPE. Since LLDPE has superior mechanical properties (elongation at break and tensile strength), thinner films can be used for most applications, and the loss of UV stabihty with reduction in thickness has to be compensated for by improving the stabilization system. 

Screening pigments (carbon black, calcium carbonate, titanium dioxide) benzophenones/benzotriazoles. nickel stabilizers, hindered amines (HALSs). polymeric stabilizers... 

These function by returning excited state molecules to their stable ground state. In the absence of a mechanism to achieve this, homolytic bond cleavage can occur, resulting in the formation of free radicals. Nickel stabilizers are believed to function as energy transfer agents. 

The nickel stabilizes the austenitic phase [y, face centered cubic crystal (fee) structure], at room temperature and enhances corrosion resistance. The austenitic phase formation can be influenced by both the Ni and Cr contents as shown in Figure 38.1 for 0.10% carbon stainless steels. The minimum amount of Ni for maintaining austenitic phase is approximately 10%. 

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