ASTM_D_2396_-_94_2012.pdf

Designation:D239694(Reapproved 2012)Standard Test Methods forPowder-Mix Time of Poly(Vinyl Chloride)(PVC)ResinsUsing a Torque Rheometer1This standard is issued under the fixed designation D2396;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the 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 These test methods cover the determination of thepowder-mix time of a general-purpose poly(vinyl chloride)(PVC)resin.1.2 The values stated in SI units are to be regarded asstandard.1.3 This standard does not purport to address all of thesafety concerns,if any,associated with its use.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.NOTE1There is no ISO standard covering the primary subject ofthese ASTM test methods.2.Referenced Documents2.1 ASTM Standards:2D883 Terminology Relating to PlasticsD1600 Terminology forAbbreviated Terms Relating to Plas-tics3.Terminology3.1 General:3.1.1 Definitions are in accordance with Terminology D883and abbreviations are in accordance with Terminology D1600unless otherwise indicated.4.Summary of Test Methods4.1 A sample of resin is heated and mixed in a bowl to thetest temperature.A measured amount of plasticizer is added tothe resin through a dispersing funnel.When the plasticizer isadded to the resin,the mix becomes wet and an increase inmotor torque is needed to maintain the same rotor speed.As themixing continues in the heated bowl,the plasticizer is absorbedinto the resin and the resin granules become dry and free-flowing.When the mix reaches the dry and free-flowing state,its resistance to stirring decreases and the motor torque neededto maintain the same rotor speed decreases.By recording thechanges in motor torque with time,it is possible to measure thetime required for a resin to absorb a plasticizer.4.2 These test methods describe the use of two differentmixing heads that can be mounted on a torque rheometer toperform this test.Test results obtained with these mixing headsare compared in Section 14.4.2.1 A sigma mixing head is used in Test Method A.4.2.2 A planetary mixing head is used in Test Method B.5.Significance and Use5.1 The ability of PVC granules to accept a plasticizer andbecome a dry free-flowing powder is related to the internalpore structure of the resin,resin temperature,plasticizertemperature,and the plasticizer used.By choosing an appli-cable plasticizer and maintaining a uniform temperature for theresin and plasticizer,it is possible to classify resins by howrapidly they absorb plasticizer.Resin suitability for a specificintensive mixing operation can be ascertained using these testmethods.6.Interferences6.1 ResinEach resin has a specific response in accepting aplasticizer.Differences in powder-mix time between resins canbe observed in the graph in the annex.6.2 PlasticizerPlasticizerviscositydirectlyaffectspowder-mix time.Table 1 shows that an increase in diisodecylphthalate viscosity results in an increase in powder-mix time.The data in Table 1 was generated in a single laboratory usingTest Method A.6.3 TemperatureThe temperature at which the test isperformed will affect the powder-mix time.A lower testtemperature will have a longer powder-mix time.NOTE2It is also important to control the temperature of the plasticizeradded to the resin.The powder-mix time can vary by as much as 3 s foreach degree Fahrenheit difference in plasticizer temperature,as seen in thegraph in the annex.1These test methods are under the jurisdiction of ASTM Committee D20 onPlastics and are the direct responsibility of Subcommittee D20.15 on ThermoplasticMaterials.Current edition approved April 1,2012.Published June 2012.Originallyapproved in 1969.Last previous edition approved in 2004 as D2396-94(2004).DOI:10.1520/D2396-94R12.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer 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 States1 6.4 EquipmentDifferences between equipment can resultin differences in powder-mix times.To equate equipment,it issuggested that a specific powder-mix time be chosen and thatthe bowl temperature be adjusted to obtain the same time for allequipment.Table 2 shows the results from three laboratoriesusing this technique to equate to a powder-mix time for ASTMNo.1 resin using Test MethodAto the value set by Laboratory1.6.5 Rotor SpeedObserved with the planetary mixing head(see Test Method B)was a decrease in dry time when the rotorspeed had been increased:60 r/min 82C using DIDP=drytime of 868 s;and 100