Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
  • G01N33/26—Oils; Viscous liquids; Paints; Inks
  • G01N33/28—Oils, i.e. hydrocarbon liquids
  • G01N33/2829—Mixtures of fuels

Definitions

• hydrocarbons have the ability to be absorbed by rubber.
• ASTM D471-72 test for change in properties of elastomeric vulcanizates resulting from immersion in liquids does measure the change in weight or volume of the test elastomer specimen caused by immersion in a liquid.
• the purpose of the test is to measure the effect of a particular liquid on a particular elastomer, not to measure the activity of the liquid.
• the phenomenon of absorption of a hydrocarbon by a rubber matrix may be used as a quantitative assay of a hydrocarbon compound which will enable one to predict the activity of the compound in a number of different circumstances.
• the present invention relies on this absorption phenomenon to determine the aromatic activity of a hydrocarbon which is predictive of a wide variety of chemical and/or physical activities of the hydrocarbon. Additionally, the test is fairly inexpensive, is applicable to liquid, vapor, solid and semisolid hydrocarbons and several samples can be run simultaneously in, for example, a three hour time period.
• the relative aromatic activity of hydrocarbon compositions is determined by measuring and comparing the ability of the hydrocarbon compositions to be sorbed by a polymeric rubber matrix.
• One embodiment of the invention comprises measuring the ability of the hydrocarbon composition under standardized conditions to cause a short term weight gain of a polymeric rubber matrix when in physical contact with the rubber matrix and comparing this value to a predetermined aromatic activity of a standard mixture of hydrocarbons to obtain the aromatic equivalent (AE) value of the hydrocarbon composition.
• Another embodiment comprises measuring the short term weight gains in a polymeric rubber matrix under standardized conditions caused by two or more hydrocarbon compositions and comparing the values to determine the relative aromatic activity of the compositions to each other.
• At least one of the compositions can be a known aromatic compound, such as benzene.
• benzene aromatic equivalent The resulting value from comparing the values of the other compositions to the value of benzene, in any embodiment, is generally termed herein as the benzene aromatic equivalent, as described more fully hereinafter.
• benzene aromatic equivalent value is related to the fact that benzene is recognized as being the most active of the aromatic hydrocarbon series. Because of this, it also has the highest solvency power and the highest human toxicity rating of the same series of hydrocarbons.
• This series of hydrocarbons is defined as the benzenoid series of aromatic hydrocarbons which is based on the unsaturated, six carbon benzene ring molecular structure.
• the BAE value, as well as the AE value to another aromatic compound is useful in predicting various physical, biological and/or chemical activities of hydrocarbons.
• the relative or average toxicity of pure hydrocarbons and mixtures of hydrocarbons is useful in the determination of: the relative or average toxicity of pure hydrocarbons and mixtures of hydrocarbons; the presence of like boiling range aromatic impurities in high purity aliphatic hydrocarbon process streams; the presence of like boiling range aliphatic hydrocarbon impurities in high purity aromatic hydrocarbon streams; dissolved aromatic hydrocarbon contamination of water, an aqueous stream containing inorganic compounds and/or an aliphatic hydrocarbon stream; probable compatibility or stability of a substance within a mixture; compliance with product or process stream specifications defined with respect to AE values; and compliance for a giyen product with air pollution regulations.
• the Figure is a graph of two different curves showing weight gain caused by mixtures of calibration liquids.
• Curve 1 utilizes Tiechert 350 (a low vapor pressure, nonaromatic hydrocarbon solvent mixture manufactured by the Tiechert Techtonics. Company) as the zero calibration point liquid, benzene is the 100 calibration point liquid and the intermediate points are representative of weight gains caused by mixtures of these calibration liquids.
• N-decane is the zero calibration point and benzene is the 100 calibration point of Curve 2.
• the aromatic activity of a hydrocarbon composition is defined as the ability of the hydrocarbon composition to cause a short term weight gain and/or swelling of a polymeric rubber matrix, when in physical contact with the rubber matrix.
• the relative aromatic activity is determined by comparing the weight gains and/or swellings caused by more than one hydrocarbon composition.
• the aromatic equivalent (AE) value of a hydrocarbon composition is defined as the ability of the hydrocarbon composition to cause a short term weight gain and/or swelling of a polymeric rubber matrix, when in physical contact with the rubber matrix, that is equivalent in action to a known volume percent of an aromatic calibration compound, such as benzene, when mixed with a diluent calibration compound having low aromatic activity, e.g., a nonaromatic hydrocarbon, preferably an aliphatic hydrocarbon, such as n-decane or isooctane.
• a 100 volume precent concentration of the aromatic calibration compound gives an AE value of 100 and a 100 volume percent concentration of the diluent calibration compound gives an AE value of zero.
• each of the calibration compounds be pure compounds, not mixtures, and that the diluent calibration compound have a vapor pressure no greater than that of the aromatic calibration compound.
• the aromatic calibration compound for example, benzene, toluene, chlorinated aromatic compounds and naphthene.
• the particular aromatic calibration compound selected will be dependent upon the purpose for determining the AE value of a hydrocarbon composition. Since benzene is readily available, many of its physical and chemical properties are known and it has a high aromatic activity, it is a convenient aromatic calibration compound to use.
• the AE value is determined by comparing the corrected and normalized short term weight gain of a polymeric matrix caused by a hydrocarbon composition to a predetermined aromatic activity of a standard mixture of known hydrocarbon calibration compounds.
• Predetermined aromatic activity values and predetermined aromatic activity of a standard mixture refer to any data which establish corrected and/or normalized weight gains of a polymeric matrix by known hydrocarbon compositions.
• the polymeric rubber coupons useful in this analytical technique consist of synthetic rubbers which are not readily dissolved by either the calibration compounds of the standard mixture used in establishing the predetermined aromatic activity or by the hydrocarbon compositions being tested.
• the synthetic rubbers must have the ability to exhibit a preferential sorption between aliphatic and aromatic hydrocarbons. Generally, they will exhibit a preference for aromatic hydrocarbons. However, if a synthetic rubber exhibits a preference for the sorption of aliphatic hydrocarbons, then the technique is used to show the aliphatic activity equivalence of the hydrocarbon composition and the
• AE value will be an inverse measure of the aliphatic activlty equivalence.
• Viton ® (trademark of the duPont Company), a copolymer of vinylidene fluoride and hexafluoropropylene, and H-1262, a blend of hycar rubber (polyacrylic rubber) and styrene butadiene rubber manufactured by the Mercer Rubber Company of Trenton, N.J., are examples of suitable rubbers for the test coupons.
• JH-21 manufactured by the Mercer
• Neoprene and Hypalon ® a chlorosulfonated polyethylene elastomer, are not suitable rubbers for determining BAE values inasmuch as they are partially dissolved by benzene.
• the standardized rubber coupons are prepared from sheets of specially compounded rubber as described above. These sheets should be of uniform thickness of from about 0.0625 (0.16 cm.) to about 0.125 (0.32 cm.) inches thick and cut into strips that are about 0.5 inches (1.3 cm.) wide. These strips are then cut into lengths which will give a coupon weight of 1.0 - 0.25 grams. To obtain standardized results, all of the AE test results are standardized, for example, to a 1.0000 gram rubber coupon. The percentage correction required for tests in which the coupon weight is other than 1.0000 grams is defined by the following curve fitting equation:
• X the percentage difference of results from results that would have been obtained had the coupon weight been 1.0000 grams.
• Y actual coupon weight in grams.
• a 1 a constant
• a o a constant
• the corrected weight of the coupon for each test (X 1 ) is obtained by adding or subtracting the indicated correction to obtain the weight corrected X 1 which is X 1w .
• the test is generally standardized using a two hour exposure time. Different exposure times may be used; however, the results will differ from those obtained from a standard two hour test. Thus, the results from a test of a different time period must be corrected to the X 1 of a two hour test by applying the equation shown below. This will allow the determination of the percentage difference of the test time from the two hour standard based on the standardized coupon weight. This correction is determined by the same curve fitting equation:
• X the percentage difference of the results from the results that would have been obtained with a two hour test.
• Y the percentage difference of the test time from the two hour standard.
• a 1 a constant
• a o a constant
• a is 0.5620 and a is -0.0800.
• the indicated correction is applied in the same manner as the weight correction to the X 1 or X 1w of the applicable test to obtain a corrected X 1 (X 1 corrected for time is X 1T , or corrected for time and coupon weight is X 1TW ).
• the corrected weight gain and/or swelling of a polymeric rubber matrix caused by the standard mixture may cause the AE value of the aromatic calibration compound to deviate from a value of 100. Therefore, so that comparative values may be obtained, the weight gain percentages of all samples after being corrected should be normalized with respect to the predetermined aromatic activity of a standard mixture in accordance with the following formula:
• the predetermined aromatic activity values are standardized not only with respect to the form of the compound being tested, i.e., liquid or vapor, but also with respect to batches of reagents, volume of compound tested, time of contact between the compound and the rubber coupon, etc.
• any parameter of the testing technique is altered, it is best to generate new predetermined aromatic activity values or at least run comparative samples reflecting this change in parameter so that if this change affects the AE value, its effect will be known.
• predetermined aromatic activity values of standardized conditions are already established, if samples are tested infrequently, it is a good practice to include a zero percent, a 100 percent and an intermediate percentage calibration tests with each test series. This will give confidence as to the results by ensuring that nothing has changed the effectiveness of the coupons or calibration reagents.
• n number of inputs and wherein X and Y are values taken from the predetermined aromatic activity of a standard mixture or from a plotted curve of those aromatic activity values.
• the predetermined aromatic values should be used directly, e.g., in the form of a curve, to determine the AE value or a better equation which more accurately fits the curve should be derived. Similar equations can be readily derived, including ones which may more accurately fit the curve.
• the tests should always be run with a standardized volume of either a liquid sample or a vapor sample inasmuch as different volumes have a significant effect which is nonlinear. Therefore, all sample volumes should be the same.
• V b volume percent of the blend, assumed to be 100 percent
• V s volume percent of the solvent in the blend
• V x volume percent of the unknown in the blend
• Y b volume percent AE of the blend
• Y s volume percent AE of the solvent
• Y x volume percent AE of the hydrocarbon or hydrocarbon mixture
• AE values can be very useful in the research and development of new and useful products made from blended or reacted organic materials.
• One of the problems in developing such products is that not all organic materials are compatible with one another.
• AE values are useful in determining the stability and compatibility of hydrocarbon compositions with each other.
• the AE values of known hydrocarbon compositions with known desired characteristics are determined empirically.
• the AE values of these hydrocarbon compositions are then used to establish AE ranges indicative of stable and compatible mixtures of the type of product sought, thereby allowing one to predict the stability of other known and unknown hydrocarbon compositions when blended.
• the compatible AE value ranges will vary depending upon the type of product being manufactured, its desired properties and the type starting materials used.
• the AE value of the hydrocarbon composition should be at least equal to or greater than the AE value of the hydrocarbon asphaltene mixture.
• the BAE value of the hydrocarbon mixture being added should be about 100-110 percent and about 100-120 percent, respectively, of the BAE value of the asphaltene mixture.
• the technique is useful in the formulation of a number of products containing asphaltenes, including, pavement sealers, ground sealers, rubberized asphalt membranes, pond liners and water stop coatings.
• AE determinations can detect like boiling range aromatic impurities in high purity aliphatic hydrocarbon process streams or they can indicate like boiling range aliphatic hydrocarbon impurities in high purity aromatic hydrocarbon streams.
• a stream containing an aromatic impurity will have a higher AE value than the pure aliphatic hydrocarbon stream.
• an aliphatic hydrocarbon, an aqueous and/or inorganic impurity is indicated by a lower AE value than the AE value of the high purity aromatic hydrocarbon stream alone.
• dissolved aromatic hydrocarbon contaminants can be detected in water through the use of AE values.
• Example 1 Rubber coupons were prepared from samples of H-1262 synthetic rubber which were of a uniform thickness of between 0.625 and 0.125 inches and cut into strips of 0.5 inches wide and a length such that each coupon had a weight of from between 0.7 and 1.0 grams. To prevent contamination, the rubber coupons were handled with gloves and they were stored in airtight containers until used. Exactly 25 milliliters of each liquid to be tested were placed in separate, numbered 250 milliliter Erlenmeyer flasks. The numbers on the flasks correspond to numbers given to the coupons. To each flask was added the corresponding rubber coupon, a cork stopper was tightly installed and the flask was lightly swirled, and set aside for a period of two hours at a temperature of 65-75°F.
• Tichert 350 (a low vapor pressure nonaromatic mixture of hydrocarbons) was used for the zero point and its true value was subtracted as a blank from all the other calibration points. Benzene was used at the 100 percent point and the ratio required to bring its true value to 100 percent was applied to all the other calibration points after subtracting the blank. The rubber coupons were not corrected for their differences in weight; however, the weight increase experienced by each rubber coupon was normalized. The data is given below in Table 1 and it is plotted in the Figure as curve 1.
• Example 3 the BAE volume percentages of six different hydrocarbon compositions were determined. These are shown in Table 3 along with the threshold limit values for the same compounds.
• the threshold limit values are published by the American Conference of Governmental Industrial Hygenists (May 21, 1973) and often form the basis for threshold limit values of a compound which are allowable under state laws. For example, regulatory agencies of the State of Colorado have used these values to define acceptable limits of compounds to which people can be exposed.

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• 1980
  • 1980-06-27 JP JP50174580A patent/JPS56501022A/ja active Pending
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