1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS ISO 18924:2013Imaging materials Test method for Arrhenius-type predictionsBS ISO 18924:2013 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of
2、ISO 18924:2013. It supersedes BS ISO 18924:2000, which is withdrawn.The UK participation in its preparation was entrusted to Technical Committee CPW/42, Photography.A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport to
3、include all the necessary provisions of a contract. Users are responsible for its correct application. The British Standards Institution 2013. Published by BSI Standards Limited 2013.ISBN 978 0 580 80500 4 ICS 37.040.20 Compliance with a British Standard cannot confer immunityfrom legal obligations.
4、This British Standard was published under the authority of the Standards Policy and Strategy Committee on 28 February 2013.Amendments issued since publicationDate Text affectedBS ISO 18924:2013 ISO 2013Imaging materials Test method for Arrhenius-type predictionsMatriaux dimage Mthode dessai pour les
5、 prdictions de type ArrheniusINTERNATIONAL STANDARDISO18924Second edition2013-02-01Reference numberISO 18924:2013(E)BS ISO 18924:2013ISO 18924:2013(E)ii ISO 2013 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2013All rights reserved. Unless otherwise specified, no part of this publication may b
6、e reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below or ISOs member body in the country of the re
7、quester.ISO copyright officeCase postale 56 CH-1211 Geneva 20Tel. + 41 22 749 01 11Fax + 41 22 749 09 47E-mail copyrightiso.orgWeb www.iso.orgPublished in SwitzerlandBS ISO 18924:2013ISO 18924:2013(E) ISO 2013 All rights reserved iiiContents PageForeword iv1 Scope . 12 Terms and definitions . 13 Bac
8、kground and theory . 23.1 Background 23.2 Theory 33.3 Effects of relative humidity 34 Experimental procedures . 44.1 Outline of Arrhenius test 44.2 Requirements for a meaningful Arrhenius test 44.3 Sealed-bag versus free-hanging testing . 44.4 Effect of heating on sealed bags containing photographic
9、 film or paper .54.5 Determination of test increments 55 Calculations 56 Test report . 5Annex A (informative) Advantages and disadvantages of sealed-bag and free-hanging incubations . 8Annex B (informative) Limitations of the Arrhenius method 9Annex C (informative) Examples of Arrhenius relationship
10、s 11Bibliography .13BS ISO 18924:2013ISO 18924:2013(E)ForewordISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. E
11、ach member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the Internati
12、onal Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.The main task of technical committees is to prepare International Standards. Draft International Standard
13、s adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.Attention is drawn to the possibility that some of the elements of this document may be the subject of
14、 patent rights. ISO shall not be held responsible for identifying any or all such patent rights.ISO 18924 was prepared by Technical Committee ISO/TC 42, Photography.This second edition cancels and replaces the first edition (ISO 18924:2000), of which it constitutes a minor revision with the followin
15、g changes: Clause 2 has been removed; Annex A has been removed.iv ISO 2013 All rights reservedBS ISO 18924:2013INTERNATIONAL STANDARD ISO 18924:2013(E)Imaging materials Test method for Arrhenius-type predictions1 ScopeThis International Standard specifies a test method for the prediction of certain
16、physical or chemical property changes of imaging materials.This International Standard is applicable to the Arrhenius test portion of ISO 18901, ISO 18905, ISO 18909, ISO 18912, and ISO 18919.This International Standard is applicable to the prediction of the optical-density (D) loss or gain of imagi
17、ng materials. Photographic dye images may be produced by chromogenic processing, by formation of diazo dyes, or by non-chromogenic methods such as dye diffusion and silver dye-bleaching processing. This International Standard also covers density changes caused by residual coupler changes in dye imag
18、es, excess residual processing chemicals in silver black-and-white materials, temperature effects on thermally processed silver images.This International Standard is applicable to the prediction of support degradation. One such example is the generation of acetic acid by degradation of cellulose ace
19、tate film support. Another example is the change in tensile energy absorption of black-and-white paper support.2 Terms and definitionsFor the purposes of this document, the following terms and definitions apply.2.1Arrhenius plotplot of the logarithm of the time for a given change in a characteristic
20、 proportional to the reaction rate (dye loss, tensile strength change, Dminyellowing, etc.) versus the reciprocal of the temperature, in kelvinsNote 1 to entry: The Arrhenius plot may be used to predict behaviour at a temperature lower than those at which the tests are run.2.2glass transitionreversi
21、ble change in an amorphous polymer from, or to, a viscous or rubbery condition to, or from, a hard and relatively brittle one2.3glass transition temperatureTgapproximate mid-point of the temperature range over which glass transition takes placeNote 1 to entry: Tgcan be determined readily only by obs
22、erving the temperature at which a significant change takes place in a specific electrical, mechanical, or other physical property.1Note 2 to entry: Tgcan also be sensitive to the moisture content of the polymer (see 4.4, Annex A, and B.3 of Annex B for information).Note 3 to entry: For imaging mater
23、ials containing gelatin, Tgis very humidity dependent. ISO 2013 All rights reserved 1BS ISO 18924:2013ISO 18924:2013(E)2.4irrelevant physical or chemical reactionschemical or physical reactions that take place only at high temperatures and/or humidities and do not take place at the temperatures at w
24、hich the Arrhenius predictions are to be madeNote 1 to entry: Such reactions may nevertheless affect the quality of the image, binder, or support.2.5morphological changeschanges in the physical structure of the association of the molecules2.6thermodynamic temperaturetemperature measured on the absol
25、ute scale which is based on absolute zero (273,15 C) and having an interval of measurement that is equivalent to degrees CelsiusNote 1 to entry: The temperature unit in the absolute scale is the kelvin.3 Background and theory3.1 BackgroundIn the 1890s, Svante Arrhenius discovered that the rate of so
26、me chemical reactions is proportional to the reciprocal of the absolute temperature. This relationship has been used with phenomena related to a chemical change, such as the loss of a particular physical property or the change in the optical density of film. If a linear relationship exists between t
27、he logarithm of the time for a change of a particular property and the reciprocal of the temperature, then this plot can be extrapolated to lower temperatures than those used in laboratory studies. This allows the prediction of the time required for the change to happen at room temperature or lower.
28、This relationship was first used for the rates of chemical reactions2and was later applied to paper materials.3,4This theory became the basis for TAPPI Standard 453.5The approach was also applied to textiles6and to physical properties of photographic film supports.7,8More recently, it has been used
29、to predict the fading of both chromogenic and non-chromogenic photographic dyes.9-11Predictions based on the Arrhenius equation require the reactions to be run under a series of temperatures at either constant relative humidity (free-hanging) or constant moisture content inside the enclosure. The in
30、vestigator shall determine which of the above conditions is more relevant to the system being tested.There may also be cases where elevated temperatures cause different reaction pathways from those occurring at ambient or sub-ambient conditions. In these cases, the plot of the logarithm of time vers
31、us the reciprocal of the absolute temperature will be nonlinear and great caution shall be taken in drawing conclusions. Only the linear and lower temperature portion of the plot can be extrapolated to ambient conditions or below.The drawback to elimination of higher temperature data is that the exp
32、eriment will then take longer because of the slow reaction rate at lower temperatures. Patience is the only solution for getting the correct answer when this happens. When incubations are limited to a few of the higher temperatures, this can lead to incorrect or misleading results and shall be done
33、with extreme caution.Confidence in the Arrhenius methodology is obtained when predictions for phenomena with reasonably short lifetimes correspond to the real-time results. Such data do exist for the fading of photographic dyes12,13and the stability of cellulose ester film supports.8,142 ISO 2013 Al
34、l rights reservedBS ISO 18924:2013ISO 18924:2013(E)3.2 TheoryThe basic relationship in the study of chemical reaction rates is the Arrhenius equation:log 2,30 kERTC=+ (1)wherek is the rate of reaction (change per time);E is the energy of activation for a specific reaction;R is the gas constant;T is
35、the temperature (in kelvins);C is a constant for the specific reaction.By combining all the constant terms (E/2,30 R) into a constant “a” and measuring the time for a given change, this equation can be rewritten as:log (time) =+aTC (2)Consequently, when the logarithm of the time is plotted against t
36、he reciprocal of the absolute temperature, a straight line is produced. This relationship can be used to predict the time required for a given change to occur at lower temperatures where the reaction might require hundreds of years. This is done experimentally by determining the time required for a
37、given change at a number of elevated temperatures (where the times required are reasonable), plotting these points, and extending the straight-line graph to the lower temperatures of interest. This “Arrhenius method” of predicting long-term ageing behaviour is widely used and accepted by experts in
38、the photographic industry.In the chemical literature, the equation has been widely applied to relatively simple, chemical reactions where both reactants and products have been identified. However, there may be circumstances in which the fit of the Arrhenius prediction line is less than perfect. In t
39、hese cases, there may be more than one reaction occurring and this may result in nonlinear behaviour or two distinct linear portions to the prediction line. In other situations, physical properties are measured, although the changes are the result of chemical reactions. More details of these phenome
40、na are given for information in Annex B. However, despite the complex reactions involved, this equation applies very well to many complicated reactions that occur with photographic materials.3.3 Effects of relative humidityThe Arrhenius method is run at either constant relative humidity or constant
41、moisture content in the enclosure. It should be noted that many of the responses evaluated by the Arrhenius method are humidity dependent and that rates can change quite drastically as a function of relative humidity.15The effect of moisture may be determined by several separate experiments at multi
42、ple temperatures, with each experiment at a constant relative humidity or moisture content. ISO 2013 All rights reserved 3BS ISO 18924:2013ISO 18924:2013(E)4 Experimental procedures4.1 Outline of Arrhenius testAn Arrhenius test should have the following steps that are explained in more detail in sev
43、eral of the references.16,17a) Prepare specimens; this may include exposing, processing, cutting, trimming, etc.b) Take initial readings of the property of interest on the non-incubated specimens.c) Incubate the specimens at a minimum of four temperatures, using either the free-hanging or the sealed
44、-bag technique (see 4.3).d) Measure the property of interest on the incubated specimens after different incubation times.e) Determine the incubation time at each incubation temperature for the property of interest to reach a predetermined level.f) Plot the log of the incubation time determined in e)
45、 against the reciprocal of the thermodynamic temperature to obtain an Arrhenius plot.g) Predict the time for the property of interest to change the desired amount at the desired temperature by extrapolation of the Arrhenius plot.h) Examples of Arrhenius plots are given in Annex C.4.2 Requirements fo
46、r a meaningful Arrhenius testAlthough a straight line can be drawn between two points and an Arrhenius prediction may be made by plotting the results of two different incubation temperatures, there can be no evaluation of the statistical significance of this experiment unless three or more temperatu
47、res are used. Because a smaller number of data points is apt to lead to a strongly biased prediction, a minimum of four temperatures shall be run for each prediction.If the effect of relative humidity needs to be considered, experiments at different relative humidities shall be studied. The relative
48、 humidities shall be at least 10 % RH apart and preferably should be 20 % RH apart. The tests shall be run at a humidity range representing the anticipated storage of the material.4.3 Sealed-bag versus free-hanging testingTwo test methods, known as the “sealed-bag” and the “free-hanging” methods, ar
49、e available for accelerated stability testing. These kinds of test conditions tend to give somewhat different results.In the sealed-bag method, the photographic material is stored in a sealed container with very little air. Pre-equilibration of the samples to a constant relative humidity is necessary before they are sealed. This test simulates real-life storage conditions in which substances released by the photographic material are trapped inside the container and can interact with the image or support layers. For exampl
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