Other Heat Test

Another reason for using higher temperatures is that for an application requiring long-term exposure a candidate plastic is often required to have an RTI value higher than the maximum application temperature. The properties tested can include mechanical strength, impact resistance, and electrical characteristics. A plastic s position in a test s RTI is based on the temperature at which it still retains 50% of its original properties. 

The time required to produce a 50% reduction in properties is selected as an arbitrary failure point. These times can be gathered and used to make a linear Arrhenius plot of log time versus the reciprocal of the absolute exposure temperature. An Arrhenius relationship is a rate equation followed by many chemical reactions. A linear Arrhenius plot is extrapolated from this equation to predict the temperature at which failure is to be expected at an arbitrary time that depends on the plastic s heat-aging behavior, which 

There are different heat tests, some being specific to a product environment. There are those for temperature and also humidity. With certain materials, humidity combined with elevated temperatures has a significant effect on the material s behavior. This effect would not be evident in the conventional heat distortion test (HDT). 

Thus by analyzing the thermal limits of the various materials available, starting with the maximum and minimum environmental temperatures under which a product must operate and adding any thermal increase 

A general definition for a high-tempera-ture plastic is one having a thermal value in terms of ASTM D 648 and UL 746B higher than 149°C (300°F). There are numerous plastics that are both processable and have 

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The code provides for the testing of gas turbines supplied with gaseous or liquid fuels (or solid fuels converted to liquid or gas prior to entrance to the gas turbine). Test of gas turbines with water or steam injection for emission control and/or power augmentation are included. The tests can be applied to gas turbines in combined-cycle power plants or with other heat recovery systems. 

At the risk of oversimplification it might be said that the Vicat test gives a measure of the temperature at which a material loses its form stability whilst the higher stress level heat distortion temperature (1.82 MPa) test provides a measure of the temperature at which a material loses its load-bearing capacity. The lower stress (0.45 MPa) heat distortion temperature test gives some rather intermediate figures and it is perhaps not surprising that it is today less often quoted than the other two tests. 

The end point may be ehecked by noting the extent of flow of a heated pellet down a given slope or by melting point measurements. Other control tests include alcohol solubility, free phenol eontent and gelation time with 10% hexa. 

PA. Rifle bullet impact in welded cans gave 4/4 high order detonations. Thermal stability at 135°, acid in 15—30 minutes at 82.2° heat test, 10 minutes at 82.2°. This material and its homologs from other aliphatic nitro compounds and aldehydes have been suggested as substitutes for NG... 

Other cubic tests in which a sample is heated in an oven by a controlled temperature program are described in [137]. 

Other screening tests, including shock sensitivity and flammability tests, and thermodynamic computations raised no specific concerns. After the explosion, the material was tested in an ARC. Such testing showed that a typical batch of the compound could self-heat to full decomposition if held under adiabatic conditions at 120 to 125°C for 24 hours. These tests were run within the normal processing temperature range, and the ARC test results were hailed as demonstrating the likely cause of the accident. 

The damp heat test can be made under steady state conditions when 40 °C and 93% relative humidity (RH) are specified, or under dynamic conditions when the temperature is cycled from 25 °C to 40 °C or 55 °C. Clearly, other conditions could be chosen to suit the application. 

Lin et al. ( 6) measured the emulsion capacity of defatted sunflower seed products. Data in Table VII show that sunflower flour was superior in emulsifying capacity to all other products tested. The emulsions were in the form of fine foams and were stable during subsequent heat treatments. The diffusion-extraction processes employed to remove phenolic compounds dramatically reduced emulsion capacity, although isolating the protein improved emulsion capacity to some extent. 

Quantitative tests are rarely conducted in magazines and for production inspection purposes except for a test devised by Bergmann and Junk [62] in which the quantity of acid products (calculated as NO) evolved by the powder is determined by titration. The quantity of NO evolved on heating for 2 hr at a temperature of 132°C should not exceed 2.5 cm3 NO per 1 g of powder. (For more details see Vol. II p. 26.) Other quantitative tests are usually employed in research. 

Dynamite nitrocotton is pulped within as short a period of time as possible, e.g. 2 hr, because excessive beating of the product reduces the viscosity of the nitrocellulose solutions. The pulping is followed by washing or by a short poaching in boilers, after which the purity is checked by means of the heat test. After stabilization, the nitrocotton is freed from sand and. other impurities. 

Prepare 10 mL of a DNA solution in Tris buffer I at a DNA concentration of about 20 ng/mL. Measure and record the Am. It should be around 0.4 absorbance units. Transfer 3.0 mL of the DNA solution into each of three test tubes. Place a marble over the top of each tube. Maintain one tube at room temperature and place the other two in a 90°C water bath for 15 minutes. After the incubation period, remove the tubes. Quick-cool one heated tube in an ice bath and allow the other heated tube to cool slowly to room temperature over a period of about 1 hour. Measure and record final A26q readings on each of the three tubes. 

Its expl and other props, given in R.efs 2,3,4 5), are as follows Ballistic Mortar Value (Power) 127%TNT Explosion Temperature ignites ca 340°, but does not expl even at 360° (same as for TNT) Friction Sensitivity- si less sensitive than RDX Heat of Combustion, Qc 769.8 kcal/mole Heat of Explosion, Qe 272.6 kcal/mole Heat of Formation, 27.8 kcal/mol Hygroscopicity- increase in wt at 100% RH 0.09% vs 0.03% for TNT not hygroscopic at 90% RH Impact Sensitivity, detd by BurMinesApp No 5- si less sensitive than PETN 75° International Heat Test loss of wt in 48 hrs 0.1% vs 0.2% for TNT Power- see Ballistic Mortar Value and Trauzl Value Stability. Thermal at 100°- no expln in 300+ mins(same as for TNT) Stability, Thermal at 2 35°- methyl violet turned salmon pink in 30 mins vs 300+ mins for TNT Temperature of Explosion 3885°K Trauzl Test Value 135% TNT ... 

Metz(Ref 3) compared Brunswig s Test method with other quantitative stability tests(such as Mayrhofer, Mayrhofer-Will, Hansen and the 85° 110° Hydrolysis Tests) and with qualitative tests(such as Abel the 134.5° Heat Tests). Brunswig s method is indicated to be applicable only to extremely stable powders. For example, if a powd is of moderate stability and just passes other quantitative tests, it might not pass Brunswig s Test. On the other hand, if a powd passes Btunswig s Test it usually passes other quantitative tests but may not pass qualitative tests, such as Abel s, Zinc-Iodide-Starch Test others... 

In addn to requirements with respect to nitrogen content, NC must comply with requirements of the 65.5°KI 134.5°Heat Tests. Grades A D NC must not be less than 99% sol in eth-alc mixt. Grade AfType I), Gd C Gd D NC must contain not more than 0.4% ash and not more than 0.4% material insol in acet. Other requirements such as fineness viscosity may,also be specified. Explosive other props of military grade NC are discussed under individual types, below... 

There are many other variations of the heat test.101 They are sometimes called stability tests, but most of them, it will be noted, involve the self-catalyzed decomposition of the sample in an atmosphere of air or of red fumes. They indicate the comparative stability only 6f materials which are physically alike. True indications of the stability of nitric esters are to be secured only by studying the decomposition of the substances in vacuum. For this purpose the 120° vacuum stability test is most generally preferred. 

Vacuum stability tests and other types of standard heat tests differ from the Taliani test in that they are performed in closed systems... 

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