Glass main components

The ratio Db/Da is a so-called relative sensitivity factor D. This ratio is mostly determined by one element, e. g. the element for insulating samples, silicon, which is one of the main components of glasses. By use of the equation that the sum of the concentrations of all elements is equal to unity, the bulk concentrations can be determined directly from the measured intensities and the known D-factors, if all components of the sample are known. The linearity of the detected intensity and the flux of the sputtered neutrals in IBSCA and SNMS has been demonstrated for silicate glasses [4.253]. For SNMS the lower matrix dependence has been shown for a variety of samples [4.263]. Comparison of normalized SNMS and IBSCA signals for Na and Pb as prominent components of optical glasses shows that a fairly good linear dependence exists (Fig. 4.49). 

In addition to the nature of resin and fibre, the laminate properties also depend on the degree of bonding between the two main components and the presence of other additives including air bubbles. Because of this some parts, fabricated by simple hand building techniques, may exhibit strengths no better or even worse than unreinforced materials. This problem is often worst with glass fibres which are therefore normally treated with special finishes to improve the resin-glass bond. 

Flow Experiments. The main components of the experimental apparatus are illustrated in Figure 2. The most important component is the glass flow cell, shown in detail in Figure 3. 

The key to a controlled molecular weight build-up, which leads to the control of product properties such as glass transition temperature and melt viscosity, is the use of a molar excess of diisopropanolamine as a chain stopper. Thus, as a first step in the synthesis process, the cyclic anhydride is dosed slowly to an excess of amine to accommodate the exothermic reaction and prevent unwanted side reactions such as double acylation of diisopropanolamine. HPLC analysis has shown that the reaction mixture after the exothermic reaction is quite complex. Although the main component is the expected acid-diol, unreacted amine and amine salts are still present and small oligomers already formed. In the absence of any catalyst, a further increase of reaction temperature to 140-180°C leads to a rapid polycondensation. The expected amount of water is distilled (under vacuum, if required) from the hot polymer melt in approximately 2-6 h depending on the anhydride used. At the end of the synthesis the concentration of carboxylic acid groups value reaches the desired low level. 

Some dicyanate-containing compositions, which contain rubbers as flexibilizing components, were described in the preceding chapters. There were also patent applications made, where dicyanates were claimed as additives in typical rubber mixtures. In such mixtures, butadiene-acrylonitrile rubber is used. The main components of such binders are nitrile rubber, BPA/DC and methylethylketone. They contain, moreover, Zn octoate and Fe203 [144] or ZnO and sulfur [145]. Isoprene-acryloni-trile rubber, BPA/DC prepolymer, Zn octoate, DABCO and benzoyl peroxide were dissolved in a methylethylketone-dimethylformamide mixture. Glass fiber was impregnated with the obtained solution [146]. 

A comparatively new group of materials— thermoplastic elastomers or thermoplastic rubbers —combines the ease of processing of thermoplastics with qualities of traditional vulcanized rubbers, especially elasticity. Because of convenience in processing there is much interest too in blends of plastics with elastomers, which may be modified by the inclusion of filler or glass fibre. As an example, a rubber-like material that can be processed as a thermoplastic can be made by blending and melt-mixing an ethylene-propylene rubber with polypropylene. The use of such blends may be helpful when there are needs to reclaim and re-process material, and in order to obtain products with qualities intermediate between those of the main components of the blends. 

There are two general approaches to sampling air, or vaporous emissions from stationary (stack) and mobile (automobile, truck, etc.) sources, for the laboratory determination of volatile analytes.1 Bulk vapor-phase samples can be taken in the field in various containers and transported to a remote or field laboratory for analysis. Containers used for bulk vapor-phase samples include flexible polyvinyl fluoride (Tedlar ) bags, evacuated glass or metal reservoirs, and thermally insulated cryogenic collection vessels. Alternatively, the volatile analytes can be separated from the main components of air in the field and just the analytes and their collection devices transported to the laboratory. The principal techniques used to separate volatile analytes from air in the field are cryogenic traps, impingers, and solid-phase adsorbents. 

Separated Analytes. Cold trapping is used to separate volatile analytes from the main components of air in the field. Air is drawn by a pump through an inert, often nickel, metal tube immersed in a fluid at a very low temperature, for example, -150° C. The tube may be packed with some inert material such as Pyrex glass beads and the temperature is sufficient to condense most analytes but insufficient to condense oxygen or nitrogen. 

Doping a neat glass forming system with smaller molecules leads to a reduction of the glass transition temperature Tg.176 In polymer research, this behavior is well known as polymer/plasticizer effect. However, it applies to any mixture provided that the Tg value of the additive is significantly lower than that of the main component. 

It must be noticed that Ca rich phosphate glasses and glass ceramics having a composition very close to apatite, the main component of bones are bioactive materials capable of bonding to natnral bones and then used for surgery implantation. ... 

Because the cell potential is sensitive to the concentrations of the reactants and products involved in the cell reaction, measured potentials can be used, to determine the concentration of an ion. A pH meter is a familiar example of an instrument that measures concentration from an observed potential. The pH meter has three main components a standard electrode of known potential, a special glass electrode that changes potential depending on the concentration of H+ ion in the solution into which it is dipped, and a potentiometer that measures the potential between the two electrodes. The potentiometer reading is automatically converted electronically to a direct reading of the pH of the solution being tested. 

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