1、Designation: D7308 07 (Reapproved 2012)Standard Practice forSample Preparation of Thermoplastic Traffic MarkingMaterials1This standard is issued under the fixed designation D7308; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the
2、 year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers the proper preparation of testspecimens of thermoplastic traffic marking materials obtai
3、nedto ensure test results are representative of the material beingtested.1.2 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its u
4、se. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D7307 Practice for Sampling of Thermoplastic Traffic Mark-ing Materials3.
5、Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 thermoplastic traffc marking material, na highlyfilled 100 % total solids highway marking material that whenheated to a molten state can be extruded or sprayed onto a roadsurface and when cooled forms a solid, durable delineator.4.
6、Summary of Practice4.1 The thermoplastic traffic marking material is preparedfor the testing of various physical and chemical properties asoutlined in the governing specification by melting a sample ofthe marking material to its application temperature undercontinuous agitation. Depending upon the r
7、equirements of thegoverning specification the sample can then be exposed to therequired heating time and conditions prior to the preparation ofthe test specimens or the test specimens may be preparedimmediately after the material has reached application tem-peratures.4.2 If required by the governing
8、 specification that thesample be subjected to extended periods of heating prior to thepreparation of the test specimen in order to determine the effectof heat history upon various physical or chemical properties,the sample must be melted down in the prescribed manner priorto being subjected to such
9、conditions.5. Significance and Use5.1 This practice provides a standard procedure for thepreparation of thermoplastic traffic marking material test speci-mens prior to testing for various properties as called for in thegoverning specification. Specimens that are prepared using thisstandard methodolo
10、gy yield test results that are consistent withthe material from which it was sampled. Test results fromspecimens can be used to determine compliance of the ther-moplastic traffic marking material to the specification. Thissample preparation guide can also be used by manufacturers ofthese materials t
11、o prepare specimens for testing to determinethe uniformity of thermoplastic traffic marking materials frombatch to batch.5.2 This practice does not address any issues related tospecific testing of the thermoplastic pavement marking mate-rials for any physical or chemical property.6. Apparatus6.1 Pro
12、cedure A (Preferred):6.1.1 Stainless Steel 4000 ml Beaker, 150 by 230-mmdiameter high. Alternatively an unlined 0.95 L (1 qt) or 3.48 L(1 gal) can may be used depending on the sample size.6.1.2 Heating Mantle of sufficient size. Note that aluminumfoil may be used to serve as somewhat of a gasket if
13、an unlinedmetal can is to be used in the heating mantle in place of thestainless steel beaker.6.1.3 Temperature Indicator.6.1.4 Thermocouple, iron.1This practice is under the jurisdiction of ASTM Committee D01 on Paint andRelated Coatings, Materials, and Applications and is the direct responsibility
14、 ofSubcommittee D01.44 on Traffic Coatings.Current edition approved June 1, 2012. Published August 2012. Originallyapproved in 2007. Last previous edition approved in 2007 as D7308 07. DOI:10.1520/D7308-07R12.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Custom
15、er Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States16.1.5 Mechanical Stirrer, capable of s
16、tirring. The stirrershould consist of two impellers with a diameter of approxi-mately 63.5 mm mounted on a 7.95-mm diameter shaft ofsufficient length.6.1.6 Aluminum Lid to cover the top of the container with aslot to clear the shaft of the mechanical stirrer and thethermocouple.6.1.7 Stainless Steel
17、 Ladles with a pouring spout, 60-mlcapacity.6.1.8 Tachometer to measure shaft speed of the mechanicalmixer.6.2 Procedure B (Alternate):6.2.1 Hot Plate with a maximum temperature setting ofapproximately 550C and with sufficient top plate surface areaas to extend beyond the surface area of the contain
18、er to be usedfor melting the sample.6.2.2 Unlined Cans, 0.95 L (1 qt) or 3.48 L (1 gal) asrequired by the specified sample size.6.2.3 Spatula.6.2.4 Gloves.6.2.5 Tongs.6.2.6 Thermometer (capable of measuring up to 450F).7. Hazards7.1 Following this guide requires one to work with materialsthat are he
19、ated to very high temperatures (350 to 450F). Caremust be taken to prevent accidental burns.7.2 Consult the MSDS for the thermoplastic material beingtested to understand the proper way to handle any accidentalburns.7.3 Wear protective clothing, thermal resistant gloves, andeye protection.8. Procedur
20、e8.1 Obtaining a representative sample is critical in deter-mining the suitability of the material being tested in meetingthe required specification or in determining the batch-to-batchconsistency of the thermoplastic traffic marking material.Obtain a representative sample by following Practice D730
21、7.The size of the sample being tested may vary depending uponthe objective of the person conducting the test, varying from anapproximate 0.95 L (1 qt) or 1 000 g sample to a 3.48 L (1 gal)or 4 000 g sample. An approximate 0.95 L (1 qt) or 1 000 gsample should be the minimum sample size tested.8.2 Pr
22、ocedure A (Preferred):8.2.1 This procedure covers the melting of thermoplasticpavement marking material using a heating mantle and amechanical stirrer. This procedure simulates closely whatoccurs in the actual use of this material.8.2.1.1 Set up the apparatus as shown in Fig. 1. Wire theheating mant
23、le power cord to the temperature indicator con-troller in accordance with the manufactures instructions.Mount the controller-indicator in a panel that can be wallmounted to keep the unit away from heat, dirt, and vibrations.When the unit is ready for operation, make a test melt in orderto set the pr
24、oportional band and other adjustment to give acontrolled temperature of 218 6 1C (425 6 2F).8.2.1.2 Place one-third to one-half of the granular sampleinto the container residing in the heating mantle. Attach thestirring shaft to the mechanical stirrer.8.2.1.3 Turn on the power to the heating mantle
25、and thecontroller. Start the variable speed mechanical stirrer when thethermoplastic material has softened sufficiently.8.2.1.4 Slowly add the remainder of the granular sample ata rate so as to maintain continuous stirring.8.2.1.5 After the entire granular sample has been added tothe container set t
26、he speed of the mechanical stirrer with thetachometer to a speed of about 100 rpm. Cover the containerusing the aluminum lid, positioning the lid such that it clearsthe mixer shaft and the thermocouple.8.2.1.6 Allow the material to heat and mix until it reaches atemperature of approximately 425F (21
27、8 6 1C).8.2.1.7 Using a 60 ml (2 oz.) ladle remove some of themolten thermoplastic material and prepare the test specimensas required by the specific test method that is to be used.8.2.1.8 If required by the specification, the sample can bemaintained at the required temperature for the required peri
28、odof time prior to the preparation of the test specimens.8.3 Procedure B (Optional):8.3.1 This option covers the melting of thermoplastic pave-ment marking material using a hot plate and manual stirring.8.3.1.1 Place an empty can of sufficient size to melt thesample on the hot plate set on high. The
29、 surface of the hotplateshould extend beyond the area covered by the can. Failure touse a hot plate with sufficient top plate area can cause the topplate to crack.8.3.1.2 Add approximately one-fifth of the granular thermo-plastic into the container and allow the material to heat, stirringregularly w
30、ith a spatula.8.3.1.3 Once the material is molten continue to add drymaterial incrementally with constant agitation in order to keepthe material molten and avoid scorching.8.3.1.4 After all of the dry material has been added continueto stir the material with the spatula checking the temperatureregul
31、arly with a thermometer.8.3.1.5 When the material reaches 425F, maintain thetemperature between 400 and 425 degrees for approximately10 min with constant stirring.8.3.1.6 Remove the material from the hotplate and preparethe test specimens as required by the specific test methods thatare to be used.8
32、.3.1.7 If required by the specification, the sample can bemaintained at the required temperature for the required periodof time prior to the preparation of the test specimens.9. Keywords9.1 sample preparation; thermoplastic traffic markingsD7308 07 (2012)2FIG. 1 Thermoplastic Melter ApparatusD7308 0
33、7 (2012)3ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such ri
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36、M Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).D7308 07 (2012)4
