Effect of time

Fig. 29. Effects of time and temperature of precipitation treatments on yield strength of alloy 2036—T4 sheet. Numbers represent strength in MPa. To...

Fig. 9. Effect of time and storage temperatures. A, 40°C B, 20°C and C, 0°C, on relative discharge performance of fresh and aged "D"-si2e cells on simulated radio use, 25- Q 4-h/d test for (a) alkaline—manganese, and (b) carbon—2inc batteries (22).

Fig. 8.9 Schematic illustration of the effect of time of exposure upon stress-corrosion crack...

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 reasonable period of time. In this regard, reasonable is a relative term. For applications like rockets and missiles, data obtained over a time period of 4-5 sec to an hour provide the essential information. For structural applications, such as pipelines, data over a period of years are required. 

Processing conditions influence the performance of plastics. For example, heating a crystalline material above its melting point, then quenching it can produce a plastic that has a far more amorphous structure. Its properties can be significantly different than if it is cooled properly (slowly) and allowed to recrystallize during processing it becomes amorphous. The effects of time are similar to those of temperature in the sense that any... 

When the apparent viscosity is a function of the shear rate, the behaviour is said to he shear-dependenf, when it is a function of the duration of shearing at a particular rate, it is referred to as time-dependent. Any shear-dependent fluid must to some extent be time-dependent because, if the shear rate is suddenly changed, the apparent viscosity does not alter instantaneously, but gradually moves towards its new value. In many eases, however, the time-scale for the flow process may be sufficiently long for the effects of time-dependence to be negligible. 

The same azide 67 was utiUzed to study the microwave-assisted synthesis of triazoles using the thermal cycloaddition with acetylenes. To achieve high yields in a short time and avoiding side reactions, the authors analyzed the effects of time, temperature, and concentration (in toluene) on the synthesis of triazoles [55]. 

Effects of Time, Temperature, and Fluids on the Long-Term Service Durability of Elastomers and Elastomeric Components... 

With such a broad subject area, to meet the objectives of the present publication, the general approach for this chapter has been to cover as wide a range as feasible with, where possible, emphasis made on relationships of specific effects with actual service applications. The chapter illustrates various effects of time, temperature, and fluids on long-term service durability of a range of elastomers, mainly by employing various data obtained by Materials Engineering Research Laboratories (MERE) personnel over recent years. 

Considers physics and engineering topics, including reinforcement mechanisms viscoelasticity abrasion, fatigue, adhesion rheology, mixing, and processing and the effects of time, temperature, and fluids... 

Another important factor in diffusion measurements that is often encountered in NMR experiments is the effect of time on diffusion coefficients. For example, Kinsey et al. [195] found water diffusion coefficients in muscles to be time dependent. The effects of diffusion time can be described by transient closure problems within the framework of the volume averaging method [195,285]. Other methods also account for time effects [204,247,341]. 

Fig. 3. The effects of time on stream on the conversions of CO2 and CH4 and tire product distribution over Ni-YSZ-Ce02 catalyst. (Reaction temp. = 800 °C, CH4/CO2 = 1, Total flow rate = 40 cc/min)...

As to the effect of time, there is no universal law that governs the reaction for all metals. Some corrosion rates remain constant with time over wide ranges, others slow down with time, and some alloys have increased corrosion rates with respect to time. Situations in which the corrosion rate follows a combination of these paths can develop. Therefore, extrapolation of corrosion data and corrosion rates should be done with utmost caution. 

Duration of Test Although the duration of any test will be determined by the nature and purpose of the test, an excellent procedure for evaluating the effect of time on corrosion of the metal and also on the corrosiveness of the environment in laboratory tests has been presented by Wachter and Treseder [Chem. Eng. Prog., 315-326 (June 1947)]. This technique is called the planned-interval test, (jther procedures that require the removm of sohd corrosion products between exposure periods will not measure accurately the normal changes of corrosion with time. 

T-violation experiment The effect of time-reversal (7) violation on the transition of photons through a system of magnetized foils that have a Mossbauer transition with comparable M and E2 strength (such as in Ru or Au)... 

Figure 55.2. Effect of time-on-stream on -butane conversion (O ) and selectivity to MA ( ) of catalysts P/V 1.00 (open symbols) and PA 1.06 (full symbols) at 380°C after treatment of the equilibrated catdysts with air at 380°C for 1 h.

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