Blackness effect

Carbon Black Effects on Resins Possible Pitfalls... 

Iridium black effects the stereoselective ( 98%) complete hydrogenation of 4 to 5, whereas mixtures of isomers are obtained when 4 is hydrogenated with Pd-on-carbon or finely divided Ni ... 

Wolf R.B. J.F. Cavins R. Kleiman L.T. Black. Effect of temperature on soybean seed constituents oil, protein, moisture, fatty acids, amino acids and sugars. /. Am. Oil Chem. Soc. 1982, 59, 230-232. 

The so-called black absorber method may be used for the determination offs- This uses the saturation effect offs when the effective thickness, Ta (see Eq. (25.30)), approaches infinity. In this case, the asymptotic form of the spectral peak amplitude can be used to obtain fs. The measurement of the /factor of the absorber, is based on Eq. (25.33) and the corresponding nonlinear dependence of the intensity, amplitude, and width of the Mdssbauer spectrum peak on the effective thickness (see later in Fig. 25.17). This latter is the so-called blackness effect. For the determination of the peak intensity and the peak amplitude should be measmed for at least two absorbers of different thicknesses (Vertes and Nagy 1990). 

Nonblack fillers such as the precipitated silicas can reduce both rate and state of cure because of their strong physical interactions with the polar activator and accelerator chemicals. Neutral fillers such as calcium carbonate (whiting) and clays have little or no effect on the cure properties. Carbon black effects are small. 

Coloma F, Sepulveda-Escribano A, Fierro JLG, Rodrfguez-Reinoso F. Crotonaldehyde hydrogenation over bimetallic Pt-Sn catalysts on pre-graphitized carbon black. Effect of the Sn/Pt atomic ratio. Appl CatalA Gen 1996 136 231-248. 

These effects can be illustrated more quantitatively. The drop in the magnitude of the potential of mica with increasing salt is illustrated in Fig. V-7 here yp is reduced in the immobile layer by ion adsorption and specific ion effects are evident. In Fig. V-8, the pH is potential determining and alters the electrophoretic mobility. Carbon blacks are industrially important materials having various acid-base surface impurities depending on their source and heat treatment. 

The mixed oxide Fc304 (tri-iron tetroxide) is a black solid, which occurs naturally as magnetite it is formed when iron(III) oxide is strongly heated, and its structure is effectively made up of oxide (O ) and iron(II) and iron(III) ions. 

Ozone s presence in the atmosphere (amounting to the equivalent of a layer 3 mm thick under ordinary pressures and temperatures) helps prevent harmful ultraviolet rays of the sun from reaching the earth s surface. Pollutants in the atmosphere may have a detrimental effect on this ozone layer. Ozone is toxic and exposure should not exceed 0.2 mg/m (8-hour time-weighted average - 40-hour work week). Undiluted ozone has a bluish color. Liquid ozone is bluish black and solid ozone is violet-black. 

Commercially produced elastic materials have a number of additives. Fillers, such as carbon black, increase tensile strength and elasticity by forming weak cross links between chains. This also makes a material stilfer and increases toughness. Plasticizers may be added to soften the material. Determining the effect of additives is generally done experimentally, although mesoscale methods have the potential to simulate this. 

Antistatic agents require ambient moisture to function. Consequently their effectiveness is dependent on the relative humidity. They provide a broad range of protection at 50% relative humidity. Much below 20% relative humidity, only materials which provide a conductive path through the bulk of the plastic to ground (such as carbon black) will reduce electrostatic charging. 

Stretching a polymer sample tends to orient chain segments and thereby facilitate crystallization. The incorporation of different polymer chains into small patches of crystallinity is equivalent to additional crosslinking and changes the modulus accordingly. Likewise, the presence of finely subdivided solid particles, such as carbon black in rubber, reinforces the polymer in a way that imitates the effect of crystallites. Spontaneous crystal formation and reinforcement... 

The explanation of the hydrogen atom spectmm and the photoelectric effect, together with other anomalous observations such as the behaviour of the molar heat capacity Q of a solid at temperatures close to 0 K and the frequency distribution of black body radiation, originated with Planck. In 1900 he proposed that the microscopic oscillators, of which a black body is made up, have an oscillation frequency v related to the energy E of the emitted radiation by... 

The value of imports rose to record levels in 1986 due to a twofold increase in the price of pepper, the second highest imported spice in volume, averaging about 4.00/kg. The effect on import values was pronounced, ie, approximately one-third higher, than 1985 imports. The upward price trend on black pepper continued in 1987 because the vines had been exhausted and the volume was lower. 

BHA and BHT, which are both fat soluble, are effective ia protecting animal fat from oxidation, and are often added duting the rendering process. Propyl gallate is also effective, but it has limited fat solubiUty, and turns bluish black ia the presence of iron. It is typically used as a synergist ia combination with BHA or BHT. TBHQ is most effective against oxidation ia polyunsaturated vegetable oils (qv), and is often used ia soybean oil (19). 

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