Glass deterioration

The organisms selected for the initial tests were ones isolated from a previous study on calcite and dolomite stone (Koestler et al., 1985), and have not been associated with glass deterioration before. Isolates of a Tricothecium spp. fungus, a chlorophyte of the chlorococcales family, and a cyanobacterium were collected in that study. Isolates were kept in culture in Sabaroud s medium for the fungus, and soil extract for the alga and bacterium. 

The reagent is conveniently stored as a solution in isopropyl alcohol. The molten (or solid) alkoxide is weighed out after distillation into a glass-stoppered bottle or flask and is dissolved in sufficient dry isopropyl alcohol to give a one molar solution. This solution may be kept without appreciable deterioration provided the glass stopper is sealed with paraffin wax or cellophane tape. Crystals of aluminium isopropoxide separate on standing, but these may be redissolved by warming the mixture to 65-70°. 

The properties of SAN resins depend on their acrylonittile content. Both melt viscosity and hardness increase with increasing acrylonittile level. Unnotched impact and flexural strengths depict dramatic maxima at ca 87.5 mol % (78 wt %) acrylonitrile (8). With increasing acrylonitrile content, copolymers show continuous improvements in barrier properties and chemical and uv resistance, but thermal stabiUty deteriorates (9). The glass-transition... 

In the sintering of such materials as silicon nindde, a silica-rich liquid phase is formed which remains in the sintered body as an intra-granular glass, but this phase, while leading to consolidation, can also lead to a deterioration in the high-temperature mechanical properties. 

Calcium hexacyanoferrate (II) (IIH2O) [ 13821 -08-4] M 490.3. Recrystd three times from conductivity H2O and air dried to constant weight over partially dehydrated salt. [Trans Faraday Soc 45 855 1949.] Alternatively the Ca salt can be purified by pptn with absolute EtOH in the cold (to avoid oxidation) from an air-free saturated aqueous soln. The pure lemon yellow crystals are centrifuged, dried in a vacuum desiccator first over dry charcoal for 24h, then over partly dehydrated salt and stored in a dark glass stoppered bottle. No deterioration occurred after 18 months. No trace of Na, K or NH4 ions could be detected in the salt from the residue after decomposition of the salt with cone H2SO4. Analyses indicate 1 Imols of H2O per mol of salt. The solubility in H2O is 36.45g (24.9 ) and 64.7g (44.7 ) per lOOg of solution. [J Chem Soc 50 1926.]... 

On the other hand, corrosion has been defined as the undesirable deterioration of a metal or alloy, i.e. an interaction of the metal with its environment that adversely affects those properties of the metal that are to be preserved. This definition —which will be referred to as the deterioration definition —is also applicable to non-metallic materials such as glass, concrete, etc. and embodies the concept that corrosion is always deleterious. However, the restriction of the definition to undesirable chemical reactions of a metal results in anomalies which will become apparent from a consideration of the following examples. 

In flame spectrophotometric measurements we are concerned with solutions having very small concentrations of the element to be determined. It follows that the standard solutions which will be required for the analyses must also contain very small concentrations of the relevant elements, and it is rarely practicable to prepare the standard solutions by weighing out directly the required reference substance. The usual practice therefore is to prepare stock solutions which contain about 1000 ig mL 1 of the required element, and then the working standard solutions are prepared by suitable dilution of the stock solutions. Solutions which contain less than 10 igmL 1 are often found to deteriorate on standing owing to adsorption of the solute on to the walls of glass vessels. Consequently, standard solutions in which the solute concentration is of this order should not be stored for more than 1 to 2 days. 

Moisture Deteriorating effects of moisture are well known as reviewed early in this chapter (OTHER BEHAVIOR, Drying Plastic). Examples for high moisture applications include polyphenylene oxide, polysulfone, acrylic, butyrate, diallyl phthalate, glass-bonded mica, mineral-filled phenolic, chlorotrifluoroethylene, vinylidene, chlorinated polyether chloride, vinylidene fluoride, and fluorocarbon. Diallyl phthalate, polysulfone, and polyphenylene oxide have performed well with moisture/steam on one side and air on the other (a troublesome... 

Koshy G, Das NM, Nair MR, etal. 1973. Deterioration of insecticides on glass and on leaf surface. Agricultural Research Journal of Kerala 10 128-132. 

Materials of Construction MIC processes are those processes by which manufactured materials deteriorate through the presence and activities of microbes. These processes can be either direct or indirect. Microbial biodeterioration of a great many materials (including concretes, glasses, metals and their alloys, and plastics) occurs by diverse mechanisms and usually involves a complex community consisting of many different species of microbes. 

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