Immersion procedures

The ASTM procedure covers the determination of the relative rate of absorption of water by plastic when immersed. Ideally, diffusion of water (or liquid in general) into plastics for long-time immersion procedure follows the square root of immersion time, with the initial slope of the graph proportional to the diffusion constant of water in the plastic. The plateau region with little or no change in weight represents the saturation water content of the plastic. The ASTM recommends that the saturation level is reached when the increase in weight per 2-week... 

The effect of surface tension of environmental liquids on the stress depression, Aa was studied by straining the materials to 25% and then following the immersion procedure described above using firstly, pure, non-swelling liquids... 

The authors then checked as to whether tribochemical reactions really existed. which would provide evidence of any friction-induced chemical transformations of the chemisorbed species. Zinc and molybdenum dithiophosphute additives (ZDDP and MoDDP) were chemisorbed onto steel plates prior to the friction test, by a conventional immersion procedure in an additive-containing oil. Two immersion times (2 and 24 h) and one immersion time (5 h) were cho-.sen, respectively, for the ZDDP and MoDDP additives. The chemistry of the treated steel surfaces was investigated by XPS/AES and the friction test was carried out in UHV just after the analysis. At the end of the test, in situ post mortem AES microanalysis was performed both inside and outside the wear scars on both the pin and the flat. Unfortunately XPS microanalysis was not possible with the current equipment, so that complete characterization of chemical bonding could not be achieved. 

ASTM D5322, Standard Practice for Laboratory Immersion Procedures for Evaluating the Chemical Resistance of Geosynthetic to Liquids, West Conshohocken, PA, USA. 

The use of the surface ultrasonic waves seems to be convenient for these purposes. However, this method has not found wide practical application. Peculiarities of excitation, propagation and registration of surface waves created before these time great difficulties for their application in automatic systems of duality testing. It is connected with the fact that the surface waves are weakened by soil on the surface itself In addition, the methods of testing by the surface waves do not yield to automation due to the difficulties of creation of the acoustic contact. In particular, a flow of contact liquid out of the zone of an acoustic line, presence of immersion liquid, availability of chink interval leads to the adsorption and reflection of waves on tlie front meniscus of a contact layer. The liquid for the acoustic contact must be located only in the places of contact, otherwise the influence on the amplitude will be uncontrolled. This phenomenon distorts the results of testing procedure. 

A modification of the foregoing procedure is to suspend the plate so that it is partly immersed and to determine from the dry and immersed weights the meniscus weight. The procedure is especially useful in the study of surface adsorption or of monolayers, where a change in surface tension is to be measured. This application is discussed in some detail by Gaines [57]. Equation 11-28 also applies to a wire or fiber [58]. 

In the Wilhelmy slide method, it seems best to partly immerse the slide and determine the change in height with constant upward pull or the change in pull at constant position of the slide. If the latter procedure is used, then... 

In operations similar to the E. ashbjii procedures, the closely related fungus Jishbjagossjpii gave similar yields. Thus, a yield of 7.3 g/L was obtained with a lyoptulked culture in a medium containing fat, leather glue, and com extracts (50), and 6.420 g/L with bone or hide fat, alone or in a mixture with other plant or animal fats as the carbon source (51). The yield from immersed cultures ofM. gossjpii was increased to 6.93—7.20 g/L by use of waste fats or technical cod-Hver oil (52). 

The test colorfastness to potting, ISO 10S-E09, is of importance for dyed wool as potting is one of the processes woven wool fabrics can be given before they are made up iato clothing. The procedure is similar to EOS except that the test conditions are 1 h immersion ia boiling water. 

Top-Feed Procedure The sequence of operations with a top-feed leaf test is the same as in a bottom-feed test, except that the leaf is not immersed in the sluriy. The best method for transferring the slurry to the top-feed leaf is, of course, a function of the characteristics of the sluriy. If the particles in the sluriy do not settle rapidly, the feed can usually be transferred to the leaf from a beaker. If, however, the particles settle veiy rapidly, it is virtually impossible to pour the slurry out of a beaker satisfactorily. In this case, the best method is to make use of an Erlenmeyer flask, preferably one made of plastic. The slurry is swirled in the flask until it is completely suspended and then abruptly inverted over the leaf. This technique will ensure that all of the sohds are transferred to the leaf. 

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