Deterioration indices

The oil deterioration mechanism, various deterioration indicators (viscosity change, total base number (TBN), total acid number (TAN), insolubles concentration, etc.) have been proposed and their respective detecting methods were reported. The oil deterioration component is divided into two general categories deterioration of the base oil and ingression of foreign matter. Ultimately, however, particles are considered to exist in engine oil in the form of insoluble elements. Fig. 6.1 shows the mechanism of the oil deterioration (Tomita et ah, 1995). 

When dioctyl phenylphosphonate (DOPP) was introduced into a membrane containing 5% w/w DAPH, this markedly improved its selectivity compared to other CBS systems (Table 1). A response comparable to a PVC-membrane electrode was obtained when 25% w/w DOPP was present. However, because the DOPP present was merely physically entangled within the matrix and not covalently-bound, the lifetime of this system was not good and the selectivity gradually deteriorated indicating that loss of DOPP was occurring. 

T. Sato, H. Abe, S. Kawano, G. Ueno, K. Suzuki, M. Iwamoto. Near-infrared spectroscopic analysis of deterioration indices of soybeans for process control in oil millmg plant. JAm Oil Chem Soc 71 1049-1055, 1994. 

Weathering of polyethylene (LDPE) and enhanced photodegradable poly-(ethylene-co-carbon monoxide) in the marine environment has been studied [128]. The rate of deterioration, indicated by the loss in mean ultimate extension, was found to be slower when the material was weathered in sea water than in air. The difference in rates was explained in terms of the lack of heat buildup in plastic material floating in sea water. In the case of poly(ethylene-co-carbon monoxide) the rapid photodegradation occurs under both exposure conditions. 

APPROXIMATE RANK OF IMPORTANCE OF SPECIHC DETERIORATION INDICES FOR CLASSES OF FOOD... 

We consider an offshore wind farm comprised of N independent and identical wind turbines, each with a continuous deterioration index X,. A deterioration index X, = 0 represents a perfectly functioning wind turbine and X,> L represents the failed state (no production of energy). We assume that M different maintenances are available. We define an interval where the maintenance i is applicable by the degradation index interval (x,., Hereafter, we refer to degradation state i such an interval. Let... 

A d.c. insulation resistance test or polarization index reveals only the surface condition of the insulation and does not allow a realistic assessment of internal condition. Loss tangent values are true reflections of the insulation condition to detect moisture content, voids, cracks or general deterioration. The tan 5 versus test voltage curve may be drawn and compared with the original curve provided by the manufacturer, and inferences drawn regarding the condition of the insulation. The different starting tan lvalues will reveal the condition of the insulation in terms of amount of contamination, as noted in Table 10.4 (See lEE, Vol. 127, May 1980). 

Performance vs Crosslinker Level. Table IV presents tensile and swell Index results on a series of approximately 0 C Tg VAE emulsion copolymers. ABDA containing copolymers had fair swell Index values which deteriorated rapidly as ABDA levels declined, but showed slow declines In wet tensile performance with reduced levels. Possible reasons for this are discussed below. 

The improvements have come by way of petroleum oils with viscosity index improvers, or synthetics with naturally high viscosity index. The problem of packing deterioration, or rusting, is chiefly a chemical matter. Hydraulic fluids for the various applications include those made from petroleum, synthetic oils, and aqueous solutions containing antifreeze and rust inhibitors. Antifoam agents are necessary in some hydraulic fluids. 

The unusual properties of silicones make them useful for some special applications as lubricants (20). They are relatively resistant to deterioration by heat or oxidation, and have the desirable properties of high viscosity index, low pour point, and low volatility. They may promote wear in steel-to-steel bearing surfaces under conditions of sliding friction, and are not generally useful for such applications. Silicones are satisfactory lubricants in antifriction bearings and in some bearing combinations other than steel sliding on steel. 

Most ageing tests are carried out on vulcanised or thermoplastic compounds, but there has been a need to assess the oxidative effects of storage on natural rubber. Various accelerated procedures using ovens or infra-red lamps have been used with visual assessment of deterioration. A more satisfactory procedure based on the measurement of plasticity after oven ageing has been standardised as ISO 293033 and the result is known as the plasticity retention index. 

Food deterioration desiccation/water activity, 61 -66 oil stability index, 541-545 primary lipid oxidation products,... 

Figure 3 shows that the delta Mooney indexes show an abrupt change from negative to positive values in the same region. Thus, there is a clear relationship between the onset of dominant crosslinking and processability. The deterioration in physical characteristics is not coincidental with the formation of gel since, in both of these examples, the gel point occurs at conversions greater than 60%. 

Some volatile aldehydes formed by autoxidation of unsaturated fatty acids are listed in Table 1. The aromas of aldehydes are generally described as green, painty, metallic, beany, and rancid, and they are often responsible for the undesirable flavors in fats and oils. Hexanal has long been used as an index of oxidative deterioration in foods. Some aldehydes, particularly the unsaturated aldehydes, are very potent flavor compounds. Table 2 fists aroma characteristics of some common aldehydes found in fats and oils (8). 

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