Additive concentration

Bert, J.A., J.A. Gething, T.J. Hansel, H.K. Newhall, R.J. Peyla and D.A. Voss (1983), A gasoline additive concentrate removes combustion chamber deposits and reduces vehicle octane requirement . SAE paper No. 83-1709, Fuels and Lubricants meeting, San Francisco, CA. 

PhOH] Expt. mol 1" Reagent Additive Concentration mol 1 Isomers (%) Ref. 

HC03 ] + [H2CO3]). Given that the pH of the water is 7.49, what is the actual concentration of HC03 (d) An independent analysis gives the following additional concentrations. 

The carbon blacks used in plastics are usually different from the carbon blacks used in mbber. The effect of carbon black is detrimental to the physical properties of plastics such as impact strength and melt flow. Electroconductive grades of carbon black have much higher surface areas than conventional carbon blacks. The higher surface areas result in a three-dimensional conductive pathway through the polymer at much lower additive levels of the carbon black. The additive concentrations of electroconductive carbon blacks is usually j to that of a regular carbon black (132). 

The cost of the individual colorants plus the method of addition (concentrate, dispersion or raw colorant) may be a significant portion of a colored part s costs. These costs often can be rapidly changing because of raw material avaUabUities. An accurate up to date cost profile of colorant raw materials should be kept for every formulator. 

In the heavy-water plants constmcted at Savannah River and at Dana, these considerations led to designs in which the relatively economical GS process was used to concentrate the deuterium content of natural water to about 15 mol %. Vacuum distillation of water was selected (because there is Httle likelihood of product loss) for the additional concentration of the GS product from 15 to 90% D2O, and an electrolytic process was used to produce the final reactor-grade concentrate of 99.75% D2O. 

The method of stripping voltammetry (SV) is one of the most perspective methods in concentration range of thallium(I) determination of 10 -10 M. Achievement of high sensitivity of thallium(I) determination needs carrying out its additional concentration and sepai ation from other metals which ai e close by electrochemical properties. For these purposes it is offered to use a method of coprecipitation with collector. The combination of SV and a method of coprecipitation on a collector have shown that minimum detectable concentration can be decreased by 2-3 orders of magnitude. 

It is not necessary for a compound to depart from stoichiometry in order to contain point defects such as vacant sites on the cation sub-lattice. All compounds contain such iirndirsic defects even at the precisely stoichiometric ratio. The Schottky defects, in which an equal number of vacant sites are present on both cation and anion sub-lattices, may occur at a given tempe-ramre in such a large concentration drat die effects of small departures from stoichiometry are masked. Thus, in MnOi+ it is thought that the intrinsic concentration of defects (Mn + ions) is so large that when there are only small departures from stoichiometry, the additional concentration of Mn + ions which arises from these deparmres is negligibly small. The non-stoichiometry then varies as in this region. When the departure from non-stoichio-... 

Description of effect Additive concentration (arbitra/y units) Effect... 

As in CE, changing system variables (e.g., pH, ionic strength, additive concentration) is very easy in any of the continuous free flow electrophoresis systems reported here because all the interactions take place in free solution. Indeed, changing system variables may be easier in continuous free flow electrophoresis systems than in a CE system because there are essentially no wall effects. Of course, changing system variables in the continuous free flow electrophoresis apparatus may also be easier... 

The method is based on the complete dissolution of the raw material. Only alkali earth metals and rare earth metals that form insoluble salts do not usually provide any significant preliminary concentration of the material during decomposition. In addition, concentration of tantalum and niobium in the final solution yielding by dissolution depends on the composition of the raw material. 

There is a small additional concentration of H+faqJ, owing to the dissociation of water, but it will be quite negligible compared with the 0.10 M concentration provided by the HQ. 

Note that the concentrations of additive oxides differ. No attempt has been made to scale this effect with additive concentration). This curious reduction effect is not easily understood but emphasizes the complex nature of the glasses including the possible cooperative involvement of the multiple components. Similarly complex phenomena might influence leaching behavior in the complex, multicomponent glasses of interest for radioactive waste storage. 

Dependence of Flame Species Concentrations upon Additive Concentrations. A method of determining the dependence of various ionic, neutral molecule, and excited species concentrations on the concentration of hydrocarbon added to a hydrogen/oxygen or hydrogen/air flame (based on a principle similar to that of flame ionization detectors... 

Different dependencies are obtained at the two pressures and for the different flames. First, consider the difference owing to pressure change in the light of the linear dependence of ion formation rate on additive concentration that is obtained in gas chromatographic experiments. It has been demonstrated that at high pressures the principal ion loss mechanism is dissociative recombination. Thus, with n+ = ne-, we can write... 

LC Additive Concentration Surface Tension (mN-m- ) 25 C Apparent Dynamic Viscosity (mPas) 22 C... 

Parts per million (ppm) and parts per billion (ppb) are additional concentration measures related to mole fraction. As described in Section 5-, parts per million is the number of items of one kind present in a sample containing a million (10 ) total items. Parts per billion is the number of items of one kind present in a sample containing a... 

Experiments have been conducted to investigate the effect of a soapy industrial cleaner on reducing the skin friction of a Jordanian crude oil flowing turbulently in pilot-scale pipes of different sizes. Experiments showed that a concentration of only 2 ppm of the chemical additive injected into the crude oil line caused an appreciable amount of drag reduction [1165]. The effects of additive concentration and pipe diameter on drag reduction have been investigated. 

Even a low addition concentration of a heavily contaminated raw material can introduce significant levels of micro-organisms into a product. This can then provide the focus for a much more serious problem. 

Figure 1.1 shows that the methods of manufacturing (semi-)finished plastic parts involve various players equipment manufacturers, polymer producers, additive suppliers, compounders and final processors. It can be safely assumed that the compounder will continue to be the main customer for additives and additive concentrates also in the future. Finally, the recently established Plastics Additive Museum (Lingen, Bavaria), by a pioneer in PVC additives (Barlocher GmbH), shows that the business is coming to age. 

Wide additive concentration range (restricting the analytical choice of method)... 

Some typical applications in SFE of polymer/additive analysis are illustrated below. Hunt et al. [333] found that supercritical extraction of DIOP and Topanol CA from ground PVC increased with temperature up to 90 °C at 45 MPa, then levelled off, presumably as solubility became the limiting factor. The extraction of DOP and DBP plasticisers from PVC by scC02 at 52 MPa increased from 50 to 80 °C, when extraction was almost complete in 25 min [336]. At 70 °C the amount extracted increased from 79 to 95 % for pressures from 22 to 60 MPa. SFE has the potential to shorten extraction times for traces (<20ppm) of additives (DBP and DOP) in flexible PVC formulations with similar or even better extraction efficiencies compared with traditional LSE techniques [384]. Marin et al. [336] have used off-line SFE-GC to determine the detection limits for DBP and DOP in flexible PVC. The method developed was compared with Soxhlet liquid extraction. At such low additive concentrations a maximum efficiency in the extractive process and an adequate separative system are needed to avoid interferences with other components that are present at high concentrations in the PVC formulations, such as DINP. Results obtained... 

Applications Applications of UV/VIS spectrophotometry can be found in the areas of extraction monitoring and control, migration and blooming, polymer impregnation, in-polymer analysis, polymer melts, polymer-bound additives, purity determinations, colour body analysis and microscopy. Most samples measured with UV/VIS spectroscopy are in solution. However, in comparison to IR spectroscopy additive analysis in the UV/VIS range plays only a minor role as only a limited class of compounds exhibits specific absorption bands in the UV range with an intensity proportional to the additive concentration. Characteristic UV absorption bands of various common polymer additives are given in Scheirs [24],... 

Infrared measurement of additive concentrations is a more complex analysis than initially expected, as some additives may undergo a variety of chemical reactions during processing, as shown by Reeder et al. [128] for the FTIR analysis of phosphites in polyolefins. Some further examples of IR work refer to PVC/metal stearates [129], and PE/Santonox R [68,130]. Klingbeil [131] has examined the decomposition of various organic peroxyesters (TBPB, TBPP, TBPA and TBPO) and a peroxidicarbonate (BOPD) as a function of pressure, temperature and solvent by means of quantitative FTIR using an optical high p, T reaction cell. 

XRF is widely used in production control, e.g. for the determination of catalyst residues in polyolefins [270], Table 8.48 shows the typical results of a standardless analysis of PP. Industrial XRF analyses of additives in polymers (QC) are usually carried out by either calibration curve or monitor programming. Use of calibration curves allows measuring the full additive concentration range, and is not restricted to a given additive. Consequently, there is no need to implement a new calibration curve upon adjustments of additive or additive contents. For a calibration curve, at least... 

Workplace safety has been taken care of by the reworking of some classes of additives into more environmentally acceptable forms. Some trends are the increased use of additive concentrates or masterbatches and the replacement of powder versions by uniform pellets or pastilles which release less dust and flow more easily. Moreover, the current move to multicomponent formulations of stabilisers and processing aids in a low- or nondusting product also takes away the risk of operator error, aids quality control, ISO protocols and good housekeeping. An additional benefit is more homogeneous incorporation of the additives in the polymeric matrix. 

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