Droop test

Test specimens can also be used to simulate some degree of warpage. Figure 5-8 compares unreinforced and reinforced glass fiber-TS polyester flexural-type specimens at different temperatures in a droop test (with a center support), sag test (end supports), and an expansion test (bolted at three points). The study for this particular test is conducted at various temperatures. 

Stiffness of the films and sheeting can be measured as the tensile modulus of elasticity. Droop or drape tests may be used, particularly for multilayer products. The stiffness is strongly influenced by thickness (to the third power) and temperature, and is important to the processing of film in printing, coating, or end use appHcations where it affects the "hand" of the product. 

Fig. 5-8 Example of droop, sag, and expansion tests using RP samples.

Following a 90-day continuous exposure to 101 mg/m3 of Durad MP280, leukocytosis, kyphosis, and testicular atrophy were observed in rats and 100% mortality, cachexia, head droop, anorexia, and lethargy were observed in rabbits. No effects were observed in either species at 10.3 mg/m3 Durad MP280 (MacEwen and Vemot 1983). Continuous exposure to 100 mg/m3 of Fyrquel 220 for 90 days resulted in kyphosis in rats (MacEwen and Vemot 1983) the NOAEL for this effect was 10.1 mg/m3. No adverse effects were observed in rabbits exposed to 100 mg/m3 Fyrquel 220 continuously for 90 days (MacEwen and Vemot 1983). At the lowest tested concentration of Cellulube 220 (2,000 mg/m3, 4 hours/day,... 

S.Y. Maestrini, M.R. Droop and D.J. Bonin, Test Algae as Indicators of Sea Water Quality Prospects, Algae as Ecological Indicators, Academic Press, 1984. 

I have not come across Black Pyrites myself, and so have been unable to test the above statement. Possibly Pliny is referring to Black Cobalt, which possesses the quality in question. Solinus corroborates Pliny, who also terms Coral Pyrites, because fire can be derived from it. On the same ground he institutes a comparison with Chalcedony and common Flint, while others identify our Cuprine Slate with Pyrites. This Stone is very susceptible to impressions when under the earth. Sometimes it has representations of fishes, serpents, and tree-crickets sometimes an elaborate picture of a cock with drooping feathers and double comb. 

Shown in Figure 5.3, this test measures the extent to which the ends of a known length of tape will droop in a given period of time. In this test, a rectangular sample of tape with a length width ratio of at least 10 1 is centered lengthwise on a flat support. The support plate is notched... 

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