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4.1 The methods by which sample materials are prepared and molded influence the mechanical properties of the specimen. Unlike injection molding, the objective of compression molding is to produce test specimens or sheets that are both homogeneous and isotropic. Specimens can be molded from powder or pellets such as are received directly from a material manufacturer, particles produced in a recycle recovery operation, or from a milled preform or sheet prepared on a two-roll mill. The powder, pellets, particles, preform, or sheet are melted and molded in a mold designed to produce a finished specimen of a given geometry, size, and thickness, or melted and molded in the form of a smooth plaque or sheet of uniform thickness from which desired specimens are cut, punched, or machined. Working a compound on a two-roll mill prior to molding will disperse and distribute the compound additives in a manner that will affect the physical properties of the compound. The relevant material specification or the material manufacturer shall be consulted to determine the need for milling a sample prior to compression molding. It is important to treat different samples of the same type of material in the same way: if milling was done prior to molding on a material which is to be used as a standard for comparison, all new materials to be tested against this practice shall be prepared and molded in a similar manner.4.2 The apparatus and exact conditions required to prepare adequate specimens will usually vary for each plastic material. Apparatus and procedures satisfactory for molding many different plastic materials are given in this practice in Sections 5 and 6. The apparatus and procedures which have been found satisfactory for molding certain specific materials are given in the Appendixes. In any case, the specific apparatus and procedures to be used in producing compression-molded specimens of a given material shall be obtained by reference to the relevant material specification or by agreement between the purchaser and the supplier.1.1 This practice covers the compression molding of thermoplastic granules and milled stock for the preparation of test specimens.21.2 While conditions for certain materials are given, the primary source of specific conditions shall be the material specification standards for each type of material.1.3 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.4 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 appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.NOTE 1: The main body of this practice is equivalent to ISO 293-1986. Annex A1 and ISO 293-1986 differ in some details; however, specimens prepared using Annex A1, Procedure A should be equivalent to those prepared using ISO 293-1986, Cooling Method D. Specimens prepared using Annex A1, Procedure C should be equivalent to those prepared using ISO 293-1986, Cooling Method B. However, due to the greater cooling rate tolerances of the ISO standard, specimens prepared in accordance with ISO Cooling Method B may not be equivalent to Annex A1, Procedure C.

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5.1 The significance of this test is to determine the thermoplastic pavement marking material’s resistance to impact, under laboratory conditions. The method provides a numerical result for impact failure which can be used to assess quality and determine relative performance between materials.5.2 When the pendulum-impact test is performed on thermoplastic pavement marking materials, the results can indicate the strength and brittleness properties helpful in researching and improving their field durability. Anyone attempting to perform this test should initially review Test Methods D256 and Test Method D4812; especially the equipment setup.5.3 The following sample preparation and testing setup method is important so inconsistencies in sample preparation do not cause more inconsistency in the results that are inherent when testing thermoplastic pavement marking materials.1.1 This test method covers the sample preparation for cantilever beams and test methodology of thermoplastic pavement marking materials, similar to the “Izod Impact” method listed in Test Method D4812.1.1.1 Some methods call for results in inch pound-force (in.·lbf) as opposed to the common foot pound-force/inch (ft·lbf/in.) or Joule/meter (J/m) (energy absorbed per unit of specimen of similar cross-section). This method does not purport to cover all the issues involved with the pendulum impact of cantilever beams and suggests that Test Method D4812 and Test Methods D256 be reviewed before this methodology is attempted.1.1.2 Thermoplastic pavement marking materials are a highly filled polymer matrix. Depending on the formula the resulting matrix may be brittle, therefore possibly resulting in inconsistent test results.1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.1.3 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 appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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