Polimeros

Designation: D 1238 – 04

Standard Test Method for

Melt Flow Rates of Thermoplastics by Extrusion Plastometer1
This standard is issued under the fixed designation D 1238; 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 superscriptepsilon (e) indicates an editorial change since the last revision or reapproval.

1. Scope* 1.1 This test method covers measurement of the rate of extrusion of molten resins through a die of a specified length and diameter under prescribed conditions of temperature, load, and piston position in the barrel as the timed measurement is being made. 1.2 Procedure A is a manual cutoff operation based ontime used for materials having flow rates that fall generally between 0.15 and 50 g/10 min. Procedure B is an automatically timed flow rate measurement used for materials having flows from 0.50 to 900 g/10 min. By both procedures, the piston travel is generally the same during the timed measurement; the piston foot is about 46 and 20.6 mm above the die. Comparable flow rates have been obtained bythese procedures in interlaboratory round-robin measurements of several materials described in 13.1. Provision is made for calculation of melt volume-flow rate as well as melt mass-flow rate.
NOTE 1—Round-robin testing indicates this test method may be suitable at flow rates up to 1500 g/10 min if the timing clock resolves the elapsed time to the nearest 0.01 s. NOTE 2—This test method and ISO1133-1991 are technically equivalent.

Determine the Precision of a Test Method 2.2 ANSI Standard: B46.1 on Surface Texture3 2.3 ISO Standard: ISO 1133-1991 Determination of the Melt-Mass Flow Rate (MFR) and the Melt Volume-Flow Rate (MVR) of Thermoplastics3 3. Terminology 3.1 General: 3.1.1 For definition of some of the technical terms used in this test method refer to Terminology D 883. 4. Significanceand Use 4.1 This test method is particularly useful for quality control tests on thermoplastics.
NOTE 3—Polymers having flow rates less than 0.15 or greater than 900 g/10 min may be tested by the procedures in this test method; however, precision data have not been developed.

1.3 This standard does not purport to address the safety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Specific precautionary statements are given in 5.7, 10.2.12, and 14.1.2. 2. Referenced Documents 2.1 ASTM Standards: 2 D 618 Practice for Conditioning Plastics for Testing D 883 Terminology Relating to Plastics E 691 Practice for Conductingan Interlaboratory Study to

1 This test method is under the jurisdiction of ASTM Committee D20 on Plastics and is the direct responsibility of Subcommittee D20.30 on Thermal Properties (Section D20.30.08). Current edition approved March 1, 2004. Published April 2004. Originally approved in 1965. Last previous edition approved in 2001 as D 1238 - 01e1. 2 For referenced ASTM standards, visit theASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards volume information, refer to the standard’s Document Summary page on the ASTM website.

4.2 This test method serves to indicate the uniformity of the flow rate of the polymer as made by an individual process and, in this case, may be indicative of uniformity of other properties.However, uniformity of flow rate among various polymers as made by various processes does not, in the absence of other tests, indicate uniformity of other properties. 4.3 The flow rate obtained with the extrusion plastometer is not a fundamental polymer property. It is an empirically defined parameter critically influenced by the physical properties and molecular structure of the polymer and the...