Designation:D5099-93(Reapproved1998) 100 Barr Harbor Dr., West Conshohocken, PA 19428 Reprinted from the Annual Book of ASTM Standards. Copyright ASTM Standard TestMethods for RubberMeasurement of Processing Properties Using CapillaryRheometry This standard is issued under the fixed designation D 5099; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (e) indicates an editorial change since the last revision or reapproval. 1. Scope D3835 Test Method for Determination of Properties of 1.1 These test methods describe how capillary rheometry Polymeric Materials by Means of a Capillary Rheometer3 D3896 Practice for Rubber from Synthetic Sources- may be used to measure the rheological characteristics of Sampling? rubber (raw or compounded).Two methods are addressed: D 4483 Practice for Determining Precision for Test Method Method Ausing a piston type capillary rheometer, and Standards in the Rubber and Carbon Black Industries? Method Busing a screw extrusion type capillary rheometer. The two methods have important differences, as outlined in 3. Terminology 7-10 and 11-14, respectively. 3.1 Definitions of Terms Specific to This Standard: 1.2 These test methods cover the use of a capillary rheom- 3.1.1 apparent (uncorrected) shear rate ([gamma J)—shear eter for the measurement of the flow properties of thermoplas- strain rate (or velocity gradient) of the rubber extrudate as it tic elastomers, unvulcanized rubber, and rubber compounds. These material properties are related to factory processing. passes through the capillary die. 3.1.1.1 DiscussionThis velocity gradient is not uniform 1.3 Since piston type capillary rheometers impart only a through the cross-section of the capillary die. The shear rate is small amount of shearing energy to the sample, these measure- calculated for the region of highest shear, at the wall of the ments directly relateto the state of the compound at the time of capillary. By selecting a die diameter and controlling the sampling. Piston capillary rheometer measurements will usu- volume flow per unit time through the die, a specific level of ally differ from measurements with a screw extrusion type apparent shear rate may be achieved. Alternately, the shear rheometer, which imparts shearing energy just before the stress (entrance pressure) may be controlled, and the apparent rheological measurement. shear rate measured. 1.4 Capillary rheometer measurements for plastics are de- 3.1.1.2 Mathematically, the apparent shear rate for a New- scribed in Test Method D 3835. 1.5 The values stated in SI units are to be regarded as tonian fluid at the wall is given as follows: standard. The values given in parentheses are for information 32 Q (1) only. TD3 i.6This standard does not purport to address all of the where: safety problems,if any,associated with its use.It is the = apparent shear rate, responsibility of the user of this standard to establish appro- Q = quantity of fluid extruded in one second, mm3, priate safety and health practices and determine the applica- = the constant pi, approximately 3.142, and bility of regulatory limitations prior to use. D = diameter of the measuring capillary, mm. The units of apparent shear rate are reciprocal seconds (s-'). 2. Referenced Documents 3.1.2 apparent shear stress (↑)—themeasured resistance to 2.1 ASTM Standards: flow through a capillary die; it may be determined by measur- D1349 Practice for Rubber—Standard Temperatures for ing the die entrance pressure for a specified die, then applying Testing appropriate geometric factors. D1485Test Methods for Rubber from Natural Sources- 3.1.2.1 Mathematically, apparent shear stress is given as Sampling and Sample Preparation? follows: D3182 Practice for RubberMaterials, Equipment, and Procedures for Mixing Standard Compounds and Prepar- P (2) ing S