Home>ASTM Standards>ASTM E1981-98(R2020) pdf free download

ASTM E1981-98(R2020) pdf free download

ASTM E1981-98(R2020) pdf free download.Standard Guide for Assessing Thermal Stability of Materials by Methods of Accelerating Rate Calorimetry
1. Scope
1.1 This guide covers suggested procedures for the opera- tion of a calorimetric device designed to obtain temperature and pressure data as a function of time for systems undergoing a physicochemical change under nearly adiabatic conditions. 1.2 This guide outlines the calculation of thermodynamic parameters from the time, temperature, and pressure data recorded by a calorimetric device. 1.3 The assessment outlined in this guide may be used over a pressure range from full vacuum to the rated pressure of the reaction container and pressure transducer. The temperature range of the calorimeter typically varies from ambient to 500°C, but also may be user specified (see 6.6). 1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appro- priate safety, health, and environmental practices and deter- mine the applicability of regulatory limitations prior to use. Specific safety precautions are outlined in Section 7. 1.6 This international standard was developed in accor- dance with internationally recognized principles on standard- ization established in the Decision on Principles for the Development of International Standards, Guides and Recom- mendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
4. Summary of Guide
4.1 A sample is placed in a reaction container and posi- tioned in the calorimeter (see Fig. 1). 4.2 The bomb is heated to a user-specified initial tempera- ture and allowed to come to equilibrium, whereupon a search for evidence of an exothermic reaction is undertaken. An exotherm is considered to have occurred when the user- specified rate of temperature rise is first exceeded. If no exotherm is detected, the system temperature is raised a specified increment and the system allowed to equilibrate again. This heat-wait-search cycle is repeated until either an exotherm is detected or the upper temperature limit of the test is reached. If an exotherm is detected, the surroundings are kept at the same temperature as the reaction container, allowing the system to be maintained without heat loss as the tempera- ture of the system increases due to the heat evolved during the exotherm. 4.3 Time, temperature, and pressure data are recorded at specified temperature intervals as a function of time. Addi- tional user-selected parameters may also be recorded or stored. 4.4 The recorded data are used to calculate the time rates of changes of pressure and temperature. These data may also be used to calculate a time-to-maximum rate (as defined in 3.1.12) and to obtain kinetic parameters (1-4) 4 for simple, non- autocatalytic exothermic reactions using the equations speci- fied in the vendors’ manual (subject to the limitations of 6.5). These data may also be adjusted for the sample- and container- specific heats to calculate an adiabatic temperature rise and heat of reaction.
5. Significance and Use
5.1 The data from this guide seldom, if ever, directly simulate thermal and pressure events in the processing, storage, and shipping of chemicals. However, the data obtained from this guide may be used, with suitable precautions, to predict the thermal and pressure hazards associated with processing, storage, and shipping of a chemical or mixture of chemicals after appropriate scaling ofthe data. This has been addressed in the literature (1-4) but is beyond the scope of this guide. 5.2 This guide is suitable, under the proper conditions, for the investigation of the effects of catalyst, inhibitors, initiators,reaction atmospheres, materials of construction, or, if available, agitation (see 6.1.2). 5.3 Interpretation of the time-temperature or time-pressure data may be possible for relatively simple systems through the use of suitable temperature-dependent kinetic theories such as the Arrhenius and Absolute Reaction Rate theories (5, 6).

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