1、Designation:D705004(Reapproved 2014)Standard Practice forRubber from Natural SourcesSampling and Sorting BalesBased on Predicted Processing Properties1This standard is issued under the fixed designation D7050;the number immediately following the designation indicates the year oforiginal adoption or,
2、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 This practice covers the sorting of natural rubber balesof TSR10 or TSR20 in the factor
3、y according to their predictedprocessing performance based on differences in viscoelasticproperties.1.2 This practice determines which bales should be used infactory compounds which benefit from using“soft”naturalrubber versus which work better with“hard”natural rubber.2.Referenced Documents2.1 ASTM
4、 Standards:2D1485 Practice for Rubber from Natural SourcesSampling and Sample PreparationD2227 Specification for Natural Rubber(NR)TechnicalGradesD3194 Test Method for Rubber From Natural SourcesPlasticity Retention Index(PRI)D6204 Test Method for RubberMeasurement of Unvulca-nized Rheological Prope
5、rties Using Rotorless Shear Rhe-ometers3.Significance and Use3.1 In accordance with Specification D2227,shipments ofTSR10 and TSR20 must meet a minimum initial Wallaceplasticity(Po)of 30 to be accepted.However,even with thisminimum restriction,the uncured viscoelastic or“processabil-ity”properties a
6、re allowed to vary greatly.This variation inproperties can significantly affect the quality and efficiency ofa factory operation.3.2 Bales of TSR10 or TSR20 which are lower in theiruncured elastic quality(“soft”rubber)in some cases mayimpart better processing properties to tire innerliners,cushiongu
7、ms,and sidewalls.“Soft”bales sometimes impart betterbuilding tack,better mold flow,and lower extrusion die swellwith better dimensional stability.Also,these“soft”rubberbales may dissolve faster in solvents for adhesion dipping.3.3 Bales of TSR10 or TSR20 that are higher in theiruncured elastic quali
8、ty(“hard”rubber)in some cases generategreater shearing during the initial stages of a factory mix,which result in a faster breakdown and a shorter mix cycle.3.4 Therefore,in a factory operation,sometimes segregatingTSR10 or TSR20 shipments into“soft”and“hard”categoriescan improve the efficiency and
9、quality of a factory operation.4.Sampling4.1 Sample SizeThe number of samples to be selected torepresent the lot may be determined by the size of the lot asindicated in Practice D1485,Table 1.4.2 Alternatively,five bales from a 36-bale pallet may besampled.4.3 Samples from these bales should be take
10、n from withinthe bale,not from the edges,because bale surface exposure tothe air will cause surface samples to not be representative ofthe rubber inside the bale.5.Lot Sorting5.1 The criteria for sorting should be based on a repeatablemeasure of uncured elasticity of the raw natural rubber.5.2 Measu
11、ring uncured elastic modulus G at 1 Hz,100%strain,100C in accordance with Test Method D6204,Part B,has been found to be an effective method for segregating“soft”natural rubber from“hard”natural rubber used in production.See also Test Method D3194.5.3 The segregating elastic modulus value GSEGis esta
12、b-lished as the criteria for separating“soft”natural rubber from“hard”natural rubber as shown in Fig.1.5.4 The value assigned to GSEGwill depend on the factorysetting.It will be dependent on the type of different compoundsbeing mixed.A value must be assigned that will provide thebest balance for qua
13、lity and cost effectiveness for each pro-duction plant site.1This practice is under the jurisdiction ofASTM Committee D11 on Rubber andis the direct responsibility of Subcommittee D11.22 on Natural Rubber.Current edition approved May 1,2014.Published May 2014.Originallyapproved in 2004.Last previous
14、 edition approved in 2009 as D7050 04(2009).DOI:10.1520/D7050-04R14.2For 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 websit
15、e.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 6.Keywords6.1 hard rubber;natural rubber;processability;processingproperties;sampling;soft rubber;sorting balesASTM International takes no position respecting the validity of any patent ri
16、ghts 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 rights,are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised,either reapproved or withdrawn.Your comments are invited either for revision of this standard or for
