Short-term test application

While the 8-h test results indicated a total petroleum hydrocarbons (TPH) recovery rate of 10 lb/day, this rate probably will not continue. Estimation of the expected long-term recovery rate of TPH by this short-term test data is not a reliable exercise. The data demonstrate the applicability of SVE as a recovery system, but further testing or detailed computer modeling was recommended prior to final design. 

Simmon, V.F. (1981) Applications of the Sa/zwone/to/microsome assay. In Stich, H.F. San, R.H.C., eds. Short-term Tests for Chemical Carcinogens, New York, Springer-Verlag, pp. 120-126... 

Application context of the tests (verification tests, compliance tests, and characterization tests). Most of the compliance tests applied to solidification/ stabilization waste are short term tests involving high liquid to solid ratios and which sometimes include crushing of the materials. Such tests are not appropriate to understanding leaching behavior or for the prediction of release from solidification/stabilization wastes. 

The application of short-term tests to paper and board... 

Testing of liquid lubricants, especially for long-term applications, is a major problem that can lead to erroneous conclusions if care is not taken. Acceleration factors should be chosen with very great care since they influence the lubrication regime in which the component is operating and can thus influence their effective behaviour. In addition, short-term testing, for instance, by cutting out nascent periods in the operation, accurately simulates the motion requirements but does not reflect the true evaporative losses of oils, or the incorporated additives, and this too can lead to over-optimistic conclusions. 

Prediction of carcinogenic potential of pesticides was taken a step further by Dr. S. Nesnow, who described EPA s "phased approach" for the application of short-term tests to these compounds. Phase 1 involved detection of point mutations, DNA damage and chromosomal effects in appropriate microorganisms. 

Concrete has a viscous behaviour when it is loaded with a constant stress it shows a strain that increases with time. Conventionally an elastic deformation is considered when it occurs during application of the load, while subsequent deformation is attributed to creep. It is possible to define a modulus of elasticity for concrete that can be evaluated with short-term tests [9]. Similarly as for the tensile strength, empirical formulae are available that give an approximate correlation of the modulus of elasticity with the compressive strength [1,9]. A dynamic modulus can also be estimated with non-destructive tests that measure the rate of propagation of ultrasonic vibrations through concrete [1],... 

Most measurements of set on rubbers are made not to obtain data to relate to a practical application but as a quality control test to indicate the state of cure. The test conditions are then arbitrary and usually involve straining at an elevated temperature. Short-term tests do not necessarily correlate well with long-term performance [6]. 

In many applications, plastic parts carry reasonably constant mechanical loads over periods up to few years. The polymer will creep during the lifetime of the part. At moderate load levels, long-term prediction of creep from short-term tests is possible, because the viscoelastic response of polymers (creep, stress relaxation) measured at different temperatures superimpose when shifted along the time axis [24]. 

The application of several short-term tests to detect carcinogenic hydrazine derivatives has been of limited success 204a, 260). While a host-mediated assay of 1,2-dimethylhydrazine has been reported to give a positive mutagenic response in S. typhimurium G46 345a), the Ames assay has generally not been sensitive toward this class of compounds. In view of the limited reports on the successful applications of an in vitro metabolic activation system for these compounds, comparisons of such methods are not valid at this time. 

Although there has been much activity to produce totally biodegradable water-soluble polymers for a variety of applications, especially for detergents, few complete successes have been registered beyond poly(vinyl alcohol), poly(ethylene oxides), and poly(aspartic acids). Almost aU efforts to obtain carbon chain polymers that are completely biodegradable have failed, at least in the short-term testing protocols currently in use. Some promising leads are noted in condensation polymers, polyaspartic acids, and acetals and in the modihcation of natural polysaccharides. 

In Section 24.1 we have defined ways of prediction of long-term behavior from short-term tests. Let us now provide more examples of application of these concepts. Creep and stress relaxation have been determined for PET/ 0.6PHB, where PET is the poly(ethylene terephthalate), PHB, the p-hydroxybenzoic acid, and 0.6 is the mole fraction of the latter in the copolymer [58]. PET/0.6PHB is a polymer liquid crystal, see chapter 41 on PECs in this Handbook. In temperature ranges of interest it forms 4 coexisting phases [60]. Conventional wisdom said that prediction methods work only for so-called rheologically simple materials, practically for one-phase polymers. Therefore, we have decided to apply as severe a test as possible to our prediction methods and a multiphase PLC is a good choice. 

Modified PPE resins will soften or dissolve in many halogenated and aromatic hydrocarbons. Laboratory data are available on the chemical resistance of plastics. However, such data should only be used as a screening tool. If a material is found to be incompatible in a short-term test, it wiU usually be found to be incompatible in a similar end-use environment. The converse, however, is not always true. Favorable results in a short-term test are no guarantee of actual performance in long-term, end-use conditions. The amount of molded-in stress found in any particular part wiU have a pronounced effect upon the relative chemical compatibility of a polymer. The acceptable chemical compatibility of a polymer in an application can be determined only by exposure or immersion of prototypes and suitably stressed samples in this type of environment under actual operating conditions [21]. 

Bielefeldt K and Schmachteiibeig E (1990) Development of a Short Term Testing Method for Welded Liners. In Koemer RM (ed) Geosynthetic Testing for Waste Containment Applications, ASTM Special Technical Pnblication 1081. ASTM, Philadelphia, USA, pp 143-154... 

Material selection for elevated temperature applications. The task of evaluating new materials and projecting their performance for specific applications is a challenging one for engineers and designers. Often materials are supplied with short-term test information such as deflection temperature under load (DTUL) (ASTM D693-03a... 

If data are not available on the effects of time, temperature, and strain rate on modulus, creep tests can be performed at various stress levels as a function of temperature over a prescribed period of time. As an example, for rocket and missile stress relaxations data obtained over a time period of 4 to 5 sec to an hour provide the essential information. For structural applications, such as pipelines, data over a period of years are required. Data from relatively short-term tests can be extrapolated by means of theory to long-term problems. However this approach can have its inherent limitations. 

We have also been concerned about the problems in the practical application of various short-term tests in commerical testing laboratories. The problems emerging in the evaluation of potentially important new chemicals have been discussed in a chapter by Brusick et ai... 

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