Oven aging test

An electrically heated oven supplied with circulating kit, originally used in accelerated ageing tests. 

The reproducibility of heat ageing tests is often relatively poor and it is likely that much of the variability is due to lack of control of the oven and exposure parameters. 

The American standard ASTM D-2307 [12] provides a test method for measuring Relative thermal endurance properties of film insulated magnet wire . The ageing philosophy is similar to that required by IEC 60216 [9] and is based on the Arrhenius ageing model. Oven ageing is carried out at three specific temperatures. The samples are twisted wire... 

The temperature index is the maximum temperature that causes a 50% decay of the studied characteristics in the very long term. It is derived from long-term oven-ageing test runs. The UL Temperature Index depends on ... 

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. 

Further evidence of the heat stability of the PTHF blends with PVC and CPVC was obtained in an oven aging test at 350°F. Samples were removed from the oven at 10-minute intervals and compared with similarly treated blends containing the impact modifier, a styrene/acrylonitrile/butadiene terpolymer. The blends containing PTHF were outstanding in their resistance to discoloration at elevated temperature. The blends containing the terpolymer showed some darkening at 90 minutes and were brown at 370 minutes. The PTHF blends did not discolor at all until 190 minutes, and 920 minutes were required for the... 

Thermal Exposures. The thermal aging tests on coated and uncoated samples were conducted in Precision forced convection ovens. Temperature uniformity was 1 C, which was determined with a thermocouple array that was mounted in the oven containing a set of dummy samples. No change in temperature uniformity was observed as a result of removing samples periodically for analysis. Test temperatures were 150°C, 110 C, 90°C, 80°C and 70°C for... 

To determine how a strong insolubility promoter like cadmium stearate, and a strong insolubility retarder like 2,6-di-ferf-butyl-4-methyl-phenol affects the resin when both are present, a series of one-hour oven-aging tests were run. The results are given in Table IV. Even at very low cadmium concentration the insolubilization effect is great and is only slightly altered by adding the hindered phenol. 

Therefore, additional heat aging tests were conducted to investigate the possibility that hydroquinone-derived phenolic groups might function differently from the monohydric phenols and somehow contribute to the high activity of the phenolic-phosphite systems. Two substituted hydro-quinones, two polymeric phenolic phosphites based on those hydro-quinones, and combinations of the hydroquinones with triphenyl phosphite and tris(nonylphenyl) phosphite were evaluated in the oven-aging test again 0.4% DLTDP was included in the formulations. 

Table I. Days to Failure in Oven-Aging Test at 140°C. ...

The reproducibility and precision of the oven-aging test have already been thoroughly analyzed and discussed by Forsman (4), whose analysis has been corroborated by our early work. With respect to sample thickness (2) we have carried this study further in an attempt to provide an improved method. To achieve good reproducibility, we relied on his analysis of most of the other critical parameters. 

A representation such as Figure 6 allows the test results to be extrapolated over a limited temperature range. However, it is often desirable to extrapolate to much lower temperatures to obtain an indication of the service life of a new formulation. Arrhenius plots may be used as a first approximation. It must be emphasized that the straight lines from oven aging tests at only two temperature levels are a simplification of the results obtained in a more thorough evaluation. 

In our study, slightly but significantly curved lines were always obtained, whenever the oven-aging tests were carried out at more than... 

Ca-stearate (HALS-III, without AO-II). Test specimens compression-molded plates (2.0 mm thick). Weathering test sunshine carbon arc lamp weather meter (WEL-SUN-HC, Suga Test Instruments Co., Ltd.). Black panel temperature 63 3 C, without water spray. Failure criterion time to 507, loss of original elongation (half life time = H.L.T.). IF = H.L.T. with stabilizer/H.L.T. without stabilizer. (b) Test specimens compression-molded sheets (0.5 mm thick). Aging test forced air circulation oven at 150 C. 

As an intermediate experiment between the model reactions in o-di-chlorobenzene and the oven-aging tests of PP stabilized with combinations of phenyl-substituted phenols and -activated thioethers, the behavior of 4-methoxy-2,6-diphenylphenol (Vila) and / ,/ -diphenyldiethylsulfide was studied in PP under realistic processing conditions and in aging of the sample. 

The EMMAQUA test, which includes the effects of UV, heat and moisture, is more representative of solar panel aging than are the oven aging tests. It has a much lower acceleration factor, however, on the order of about 20X which includes approximately 6-8X in UV-visible solar flux and about 3-4X in temperature above which these particular solar panels would ordinarily run. It is therefore a much slower, more elaborate process that should follow oven aging as a screening tool with which to eliminate from further consideration those polymers that have insufficient resistance to long term oxidation. 

In his 1950 review of the history of rubber testing, Buist (IJ observed that prototypes of many of the tests then in use had been tried with varying degrees of success before 1900. and there is no doubt that technologists of that period would still recognize many of the features of the present-day rubber laboratory. The value of tensile stress-strain properties as control measures was appreciated in the late nineteenth century the principles of the indentation hardness test were established before the First World War and the accelerated air-oven aging test dates back at least 80 years. 

Improving test reproducibility is normally identified with the w idc.spread u.sc of the air oven aging test in specifications and in quality control work, with tests being completed in a few days. The value of aging tests for predicting long-term service performance is considered in Chapter 29, but it is appropriate to review features of specific importance... 

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