Other Materials

3 Other Materials - Degradation of polyethylene, polypropylene and polystyrene has also been carried out in the presence of other acidic materials. Trends in the product distributions are similar to those observed for silica-alumina and zeolite catalysts. Degradation studies using mesoporous materials, Lewis acids and sulfated zirconia catalysts are summarized below. 

Aguado et al studied the conversion of polyethylene over MCM-41 with a Si/ Al ratio of 29.4 in a semibatch reactor at 673 K. At a polymer to catalyst mass ratio of 4, the polymer was almost completely converted to low molecular weight products with carbon numbers less than 40. The products were centered in the C5-C12 range (59 wt%), but 20 wt% C1-C4 products and 8 wt% aromatic products 

2 Lewis acids - Early work on the degradation of polymers in the presence of catalytic materials focused on reactions of polyolefins with strong Lewis acids. It was well established that aluminum chloride and other strong 

The results obtained for polystyrene reacted over Zr02/S04 catalysts were similar to those observed over other acidic materials. Lin et al. observed a product distribution for Z1O2/SO4 at 673 K that was comparable to that for reaction over a silica-alumina catalyst the yield of styrene decreased to zero, the yield of benzene increased to 33 wt%, and the amounts of indan and indan derivatives increased. At temperatures above 673 K, SO2 was observed, suggesting that the catalyst decomposed. 

The other usual flooring materials (wood, ceramic tile, etc.) are rarely seen in laboratories. Planners should be aware, however, of new developments in this field and investigate them with the same question in mind How will this material resist the chemicals to be used in this particular laboratory  

Different types of flooring may be used in different parts of a laboratory. In a large university chemistry building, one material was used for the organic laboratories and another for the inorganic because of the different chemicals handled. 

A w ord should be added here about laboratories where highly 

Solubility of materials other than simple oxides is a complex phenomenon, and usually leads to selective leaching of different elements and to changes in the chemical character of the surface. The concentration of more than one element in solution has to be followed. 

Reference [137] reports the absence of significant dissolution of illite. In contrast, [138] reports considerable release of Si and Al from illite. Dissolution of illite, that is, Al, Si, Ca, and Mg concentrations at pH 3-9, was studied in [139]. Dissolution of kaolinite at acidic pH was studied in [140]. Reference [141] reports the release of Si, Fe, Al, and Mg from montmorillonite as a function of pH. Concentrations of Si and Al in solution during titration of smectite are reported in [142]. Solubility of laponite is discussed in [143] and references therein. 

The Al concentration in solutions of synthetic aluminum silicate was studied in [144]. 

Calcium and phosphate concentrations were measured as a function of pH in [20]. The pH was adjusted by the addition of KOH, KF, ( atNO jj, or K2HPO4. Dissolution is inhibited in the presence of high-molecular-weight organic compounds [146]. 

Reference [147] reports nonstoichiometric leaching of components from PbMg,/3Nb2/3O3 (Mg Pb Nb in neutral and basic pH). The lEP depends on the solid-to-liquid ratio. 

In the 1980s it became evident that rubber teats and soothers may release carcinogenic nitrosamines, which are reaction and degradation products from accelerators and stabilisers used in the mbber. Legislation contained in Directive 93/11/EEC prescribes that nitrosamines and nitrosatable substances that can be transformed into nitrosamines in the stomach shall not be released from the teats and soothers in detectable quantities. Methods for the analysis are proposed with the detection limit set to 0.01 mg/kg rubber for nitrosamines and 0.1 mg/kg rubber for nitrosatable substances. 

4 BADGE, BFDGE and NOGE in coated materials, plastics and adhesives 

Although it is specific to these substances, this legislation has been the first to explicitly set out any rules for coatings and adhesives and those plastics not within scope of the rules on food contact plastics. This last point arises from the fact that the legislation covers all plastic materials and articles, not just those within the scope of Directive 2002/72/EC, as amended. 

Intelligent food contact materials are those that provide the consumer with information on the status of the packaged food or the atmosphere in the 

Under some conditions e.g., different temperatures or atmospheres) the thermal decomposition of coordination precursors can lead to different nanomaterials such as metal halides and metal hydroxides. 

The thermal decomposition of four nano MOCPs, [Pb(4-pyc)(Br)(H20)] 4-Hpyc = 4-pyridinecarboxylic acid) [165], [Pb(3-pyc)Br] (5-Hpyc = 3-pyridinecarboxylic acid) [166], [Pb(p-HPDC)(p-Br)(H20)] H DC = 2,3-pyrazinedicarboxylic acid) [167], and [Pb2(2-pyc)2(Br)J 2-Hpyc = 2-pyridinecarboxilic acid) [168] develops PbBr(OH) nanostructures with nanoparticle and nanorod morphology. 

The present review concerning the thermal transformation of solid coordination compounds and metal-organic polymers compounds toward diverse materials is not, nor was it intended to be, exhaustive. And maybe the selection was not always the most conclusive. 

The main goal of the present chapter is to highlight that an efficient exploitation of coordination compounds and MOCPs as precursors of materials requires (0 a detailed knowledge of their thermoreactivity and (ii) a correlation of their decomposition mechanism with their structural and morphological peculiarities. Only so, some general 

There are a number of materials obligatory in today s technology (metal/carbon and metal oxide/carbon composites, oxynitrides, oxysulfides, etc.) whose synthesis by this procedure has been little or not at all investigation. At least, is worth to try. 

PPV-based devices are commonly constructed in a multilayer structure in which the polymer film is sandwiched between charge injection electrodes. For this reason, the polymer/electrode interface plays an important role on the performance of the devices and will be discussed for different classes of materials in the next sections. 

Low-work-function metals such as Ca, Mg, and A1 are commonly used as electron injection electrodes in organic LEDs, and thin Au films can be used for hole injection electrodes. The interfaces of these and other metals with PPV and its derivatives were investigated by several research groups using different techniques such as X-ray photoelectron spectroscopy (XPS), UV photoelectron spectroscopy (UPS), transmission electron microscopy (TEM), quantum-chemical calculations, and electrical measurements. Some results are summarized in the following paragraphs for different metals. 

The intrinsic electrical conductivity of PPV, at room temperature and on exposure to air, is on the order of S-cm [75]. After 

Electron-donating groups such as alkoxy increase the conductivities of PPVs doped with weak Lewis acids (e.g., I2, BF3), while electron-withdrawing substituents, such as NO2, do the opposite [66]. Plots of log(conductivities) versus Hanunet a values have shown a distinct dependence between conductivity and polar substituent effect [62]. With stronger dopants, such as FeCl3, H2SO4, 

Electrical measurements performed by Nguyen et al. [187] indicate that the aluminum/PPV interface shows a rectifying behavior when aluminum is deposited as a top electrode, as well as a bottom electrode, after polymer conversion and before polymer conversion, respectively. XPS analyses indicate chemical reactions between the polymer and the metal in the presence of ojqrgen to form metal-carbon complexes [187]. 

It is worth noting here that Hart [58] also teaches the use of sodium di-octyl sulfosuccinate (together with a wide range of alkyl sulfonates and alkyl phosphonates) as an antifoam for use in the distillation and coking of crude oils where temperatures range from 150 C to 500 C. Again no physical data are available concerning the state of these materials after dispersal in the crude oil at those temperatures. 

Polyphenylene and polyfluorene have been extensively used as fluorescence-based sensors, and several chromogenic forms of these polymers have been reported. Incorporation of monomers with additional coordination sites into these polymers has led to the development of a variety of different anion sensors, mostly for halide ions (Lee et al. 2004 Zhou et al. 2005 Vetrichelvan et al. 2006 Kim et al. 2007). Extension of these materials toward recognition of more complex analytes should be possible. 

Ahn DJ, Chae EH, Lee GS, Shim HY, Chang TE, Ahn KD, Kim JM. Colorimetric leversihihty of polydiacetylene supramolecules having enhanced hydiogen-honding under thermal and pH stimuh. J Am Chem Soc 2003 125 8976-8977. 

Albert KJ, Lewis NS, Schauer CL, Sotzing GA, Stitzel SE, Vaid TP, Walt DR. Cross-reactive chemical sensor arrays. Chem Rev 2000 100 2595-2626. 

Aldakov D, Anzenbacher P Jr. Sensing of aqueous phosphates by polymers with dual modes of signal transduction. J Am Chem Soc 2004 126 4752-4753. 

Back MG, Stevens RC, Charych DH. Design and synthesis of novel glycopol3thiophene assembhes for colorimetric detection of influenza vims and E. coli. Bioconjug Chem 2000 11 777-788. 

Experiments have shown that capacitance-based gas sensors can detect vapors and gases with concentration in the ppm range. For example, Kitsara et al. (2006) reported on detection limits for PDMS-covered cantilevers below 50 ppm for toluene and 10 ppm for octane. Rodriguez et al. (2004), using frequenqr multiplication and PDMS as the active layer, established that the sensors had sensitivity to concentrations of toluene as low as 25 ppm. For gases the sensitivity is lower. Sivaramakrishnan et al. (2008) found that capacitance-based sensors with membranes coated by a single-walled nanotube (SWNT) film can detect CO with concentrations from 3.2 to 10.4 %. 

High sensitivity to water, due to its abnormally large dielectric constant, is the main problem for capadtance-type devices. This effect is shown in Fig. 16.4 for PEUT-based CMOS sensors (Kummer et al. 2004). Therefore, the compensation of humidity influence or humidity control is required for correct operation of capadtance-type sensors in a real environment. 

In particular, Connolly et al. (2005) designed NH capacitive sensor with 500-nm-thick porous SiC film. The response in humidity was very low for RH 50 %, which was attributed to the porous dimensions. The exact sensing mechanism is still not clear, but NH levels as low as-0.5 ppm were detected. Porous alumina (AI2O3) has also been examined as a sensing material for capacitive gas sensors and in particular for humidity measurements (Nahar and Khanna 1982 Timar-Horvath et al. 2008). The Al Og-based humidity sensor was a volume-effect device based on physical adsorption. At low humidity, the walls of the pores are lined with one-molecular-thickness liquid layer. As the humidity increases, after saturating the walls, due to a capillary condensation effect, the water starts condensing in the pores (Boucher 1976 Neimark and Ravikovitch 2001). It was established that the water molecules, even at a partial pressure higher than the saturated vapor pressure tend to condense in capillary pores with a radius below the Kelvin radius r, which is defined as function (1) (Boucher 1976)  

Molecular sieves can also be apphed for design capacitance gas sensors. It was demonstrated that bipolar interactions between adsorbates and molecular sieves are of potential use in capacitive-type gas sensors. 

In particular, Alberti et al. (1991) proposed zeolite-based sensors for detection of hydrocarbons such as butane and Balkus et al. (1997) used thin film aluminophosphate (AlPO)-5 molecular sieve as the dielectric phase in a capacitance-type chemical sensor for CO and CO. AlPO-n is a family of phosphorus molecular sieves which, similar to zeolites, have ordered molecular-sized pores. The AlPO-5 structure used for the dielectric layer consists of four- and six-membered rings of alternating phosphate and aluminum ions bridged by oxygen. These rings are arranged to produce one-dimensional channels 0.73 nm in diameter. The properties of AlPO-n are reviewed in detail by Ishihara and Takita (1996), and one of the attractive properties of these materials is their heat stability. The properties of zeolites as they relate to zeolite-based gas sensors are discussed in a special section in Vol. 2. 

Amorphous Si has several limitations. The first is that it can be used only in a drum configuration. The limitations of the drum configuration have been discussed in the preceding section. The second is cost. Due to the high substrate costs and low deposition rates, the cost is significantly higher than for 

In addition to the chalcogenide glasses, organic materials, and a-Si, other materials have been used as xerographic photoreceptors. The more common of 

For low-volume applications, where cost is a major consideration, organic-coated drums are the preferred material for virtually all applications. For high-volume applications, organic materials are extensively used, due to the fact that they can be readily prepared in a flexible configuration. For mid-volume applications, all three materials are currently in use. 

Symposium on Polymers for Advanced Technologies (M. Lewin, ed.), VCH, New York. 1988. p. 225. 

Akamichi. H.. Waragai. K.. Hotta, S., Kano, H., and Sakati. H.. Appl Phys. 

Melvin, T., Ensell, G.J., Wilkinson, J. S. and Evans, A.G.R. (2004) A new masking technology for deep glass etching and its microfluidic application, Sensors and Actuators A, AllS, 476—482. 

5 Einfuhrung in die Mikrosystemtechnik, F Volklein, Th. Zetterer, Vieweg, Braunschweig, Wiesbaden, 2000. 

6 Ri-Choudhury, P. (ed.) (2000) MEMS and MOEMS Technologies and Applications, SPIE Press, Washington. 

As solvents or milling liquid in grade powder milling, several organic compounds are employed alcohols, acetone, hexane, heptane, gasoline, and tetraline. Hexane, heptane, and acetone are the most preferred today. 

The most popular lubricant is paraffin wax, other than bees wax, camphor, and polyethylene-glycol. Besides its lubricating properties, its purity is essential. It must be removable by heating without any residue. 

Pigments and Dyes, Mortars and Cement, Shell 

The list above includes only some of the kinds of raw materials and finished products that can be found on an archaeological site in addition to the more common stone, ceramic, bone sediments, and metal and we have already discussed. All of the kinds of things that people originally used and made may be present either physically or chemically. 

Material Normal survival time Conditions for preservation Conditions against preservation 

Stone Millions of years Most Exposure in erosional 

Copper/bronze Millions of years Most Moisture, oxygen 

When the coloring of latex-modified mortar and concrete is required, alkali-resistant, weatherproof pigments are used. Furthermore, it is important that the pigments do not obstruct the stability of polymer latexes and the hydration of cements. Alkali-resistant glass, steel, polyamide, polypropylene, polyvinyl alcohol (poval), aramid and carbon fibers are employed as mixable reinforcements. Reinforcing bars for ordinary cement concrete are also used for the reinforcement of the latex-modified concrete. 

Calcium carbonate whiskers can significantly improve the antifriction performance of a polyoxymethylene matrix composite. When the whisker content is 12%, the friction and wear rate of the composite are minimum under either water lubrication conditions or dry conditions. 

Wu et al.3 compared the friction and wear properties of phenolic resin-filled calcium carbonate whiskers and potassium titanate whiskers. They found that calcium carbonate whisker-filled friction material shows the lowest sensitivity to speed and easy to cause surface abrasion whereas potassium titanate whiskers-filled friction material shows the lowest sensitivity to load and the highest sensitivity to speed. 

Inorganic whisker. Beijing Chemical Industry Press, 

Kewei Hu, Dongsheng Li, Hui Zhong. Preparation and prospect of calcium carbonate whisker as filler. Guangzhou Chemistry, 3K3) 57-63, 2006. 

Jiuxing Xiang, Qiuju Sun, Shiwei Wu et al. Advances in the application of calcium carbonate whiskers. Fine and Specialty Chemicals, 18(l) 27-30, 2010. 

1 Hiilsenberg, D., Harnisch, A., and Bismarck, A. (2008) Microstructuring of Glasses, 87, Springer. 

2 Heuberger, A. (1989) Mikromechanik Mikrofcrtigung mit Methoden dcr Halbleitcrtcchnologic, Springer. 

4 Nguyen, N.T. and Wereley, S.T. (2002) Fundamentals and Applications of Microjluidics, Artech House. 

6 Gerlach, G. and Dotzel, W. (2006) Einjuhrung in die Mikrosystemtechnik Ein Kurshuchfur Studierende, Hanser Verlag. 

7 Elwenspoek, M. and Jansen, H.V. (2004) Silicon Micromachining, Cambridge University Press. 

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Eliminate extraneous materials for separation. The third option is to eliminate extraneous materials added to the process to carry out separation. The most obvious example would be addition of a solvent, either organic or aqueous. Also, acids or alkalis are sometimes used to precipitate other materials from solution. If these extraneous materials used for separation can be recycled with a high efficiency, there is not a major problem. Sometimes, however, they cannot. If this is the case, then waste is created by discharge of that material. To reduce this waste, alternative methods of separation are needed, such as use of evaporation instead of precipitation. 

Urea is largely used as a fertilizer (ISy ), and as a non-protein feed supplement for sheep and cattle. The most important chemical use, which however accounts for only a small part of urea production, is in the manufacture of urea-formaldehyde resins. U is also used in the manufacture of adhesives, pharmaceuticals, dyes and various other materials. U.S. production 1981 7 0 megatonnes urea resins 1983 6 megatonnes. 

As discussed in Section 2.0 (Exploration), the earth s crust is part of a dynamic system and movements within the crust are accommodated partly by rock deformation. Like any other material, rocks may react to stress with an elastic, ductile or brittle response, as described in the stress-strain diagram in Figure 5.5. 

This automatic velocity measurement method (AUTO-V) has also been suecessfijlly applied to other materials sueh as non-ferrous metals and even eeramics and plasties. The only requirement for this type of sequential velocity and thickness measurement is a certain isotropy of the material materials having anisotropie properties will lead to incorrect thickness readings due to the velocity difference in the two orthogonal directions. 

The modern Russian MIA flaw detectors use pulse version of the method [1-3], which peirnits to produce very portable (0.7 - 1.5 kg) and simple instruments, convenient especially for in-service testing. The objects to be tested are multilayer structures of reinforced plastics, metals and other materials honeycomb panels, antenna fairings, propellers, helicopter rotors and so on. In mentioned instruments amplitude-frequency analog signal processing is used. 

Similarly strange tilings happen to other materials. Above 5 GPa, CO spontaneously polymerizes the... 

Studies of the waveguiding of light in multilayers of certain polymers showed that it is possible to propagate light with an attenuation that is still large compared to many other materials but small compared to other LB materials... 

In addition to the apparent viscosity two other material parameters can be obtained using simple shear flow viscometry. These are primary and secondary nomial stress coefficients expressed, respectively, as... 

Determination of purity. The ultraviolet and visible absorption is often a fairly intensive property thus e values of high intensity bands may be of the order of 10 -10 . In infrared spectra e values rarely exceed 10 . It is therefore often easy to pick out a characteristic band of a substance present in small concentration in admixture with other materials. Thus small amounts of aromatic compounds can be detected in hexane or in cyclohexane. 

Quantitative analysis. Spectroscopic analysis is widely used in the analysis of vitamin preparations, mixtures of hydrocarbons (e.y., benzene, toluene, ethylbenzene, xylenes) and other systems exhibiting characteristic electronic spectra. The extinction coefficient at 326 mp, after suitable treatment to remove other materials absorbing in this region, provides the best method for the estimation of the vitamin A content of fish oils. 

The exereises are brief and highly foeused on learning a partieular skill. They allow the student to praetiee the mathematieal steps and other material introdueed in the seetion. The problems are more extensive and require that numerous steps be exeeuted. They illustrate applieation of the material eontained in the ehapter to ehemieal phenomena and they help teaeh the relevanee of this material to experimental ehemistry. In many eases, new material is introdueed in the problems, so all readers are eneouraged to beeome aetively involved in solving all problems. 

Termination steps are m general less likely to occur than the propagation steps Each of the termination steps requires two free radicals to encounter each other m a medium that contains far greater quantities of other materials (methane and chlorine mol ecules) with which they can react Although some chloromethane undoubtedly arises via direct combination of methyl radicals with chlorine atoms most of it is formed by the propagation sequence shown m Figure 4 21... 

Spermaceti is a wax obtained from the sperm whale It contains among other materials an ester known as cetyl palmitate which is used as an emollient in a number of soaps and cosmetics The systematic name for cetyl palmi tate IS hexadecyl hexadecanoate Write a structural formula for this substance... 

For apparatus made of any other material, the volume contained or delivered at the temperature t is... 

This table lists values of /3, the cubical coefficient of thermal expansion, taken from Essentials of Quantitative Analysis, by Benedetti-Pichler, and from various other sources. The value of /3 represents the relative increases in volume for a change in temperature of 1°C at temperatures in the vicinity of 25°C, and is equal to 3 a, where a is the linear coefficient of thermal expansion. Data are given for the types of glass from which volumetic apparatus is most commonly made, and also for some other materials which have been or may be used in the fabrication of apparatus employed in analytical work. 

Many materials need to be dried prior to their analysis to remove residual moisture. Depending on the material, heating to a temperature of 110-140 °C is usually sufficient. Other materials need to be heated to much higher temperatures to initiate thermal decomposition. Both processes can be accomplished using a laboratory oven capable of providing the required temperature. 

Ionization can be improved in many cases by placing the sample in a matrix formed from sinapic acid, nicotinic acid, or other materials. This variant of laser desorption is known as matrix-assisted laser desorption ionization (MALDI). The vaporized acids transfer protons to sample molecules (M) to produce protonated ions [M + H]+. 

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