Abstract

This specification provides for the identification of virgin, unmodified homopolymer ultra-high-molecular-weight polyethylene (UHMW-PE) molding and extrusion plastic materials in the form of powder, granules, or pellets. This specification is not intended to differentiate between various molecular weight grades of commercially available UHMW-PE, nor does it function to provide specific engineering data for design purposes. Sampled specimens shall be tested for dilute solution viscosity.

This abstract is a brief summary of the referenced standard. It is informational only and not an official part of the standard; the full text of the standard itself must be referred to for its use and application. ASTM does not give any warranty express or implied or make any representation that the contents of this abstract are accurate, complete or up to date.

1. Scope

1.1 This specification provides for the identification of virgin, natural color, unmodified homopolymer ultra-high-molecular-weight polyethylene (UHMW-PE) plastics molding and extrusion materials. This identification is made in such a manner that the seller and purchaser can agree on the acceptability of different commercial lots or shipments.

1.2 This specification also provides guidance for the characterization of UHMWPE materials based on various mechanical, thermal, electrical, and other analyses.

1.3 It is not intended to differentiate between various molecular weight grades of ultra-high-molecular-weight polyethylene commercially available.

1.4 It is not the function of this specification to provide specific engineering data for design purposes.

1.5 Ultra-high-molecular-weight polyethylenes, as defined in this specification, are those linear polymers of ethylene which have a relative viscosity of 1.44 or greater, in accordance with the test procedures described herein.

1.6 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.

1.7 The following precautionary caveat pertains only to the test method portions in Section 7 and the Annex and Appendixes, of this specification: This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

Note 1This standard and ISO 11542-1 address the same subject matter, but differ in technical content. ISO 11542-1 provides a classification system based on various characteristics and a range of viscosity numbers determined in accordance with ISO 1628-3.

X2.1.1 This test method covers determination of the impact strength of UHMW-PE, which is extremely impact resistant. When tested in accordance with Test Method D256 , Method A, UHMW-PE generally gives the NBF type of failure, rendering the test result invalid. This test method specifies the same type of pendulum impact test machine as that given in Test Method D256 but introduces a much higher degree of stress concentration into the specimen by double notching with a razor blade. Application of this test method shall be limited to the characterization of virgin, unmodified UHMW-PE resins, not commercially processed products. It is advised that the user be familiar with Test Method D256 before attempting to use this test method.

X2.1.2 The values stated in SI units are to be regarded as the standard.

Note X2.1This test method and Annex B of ISO 11542-2 address the same subject matter, but differ in technical content and results shall not be compared between the two test methods.

X4.1.1 This test method covers the determination of elongational stress as a characterization of the melt viscosity of UHMW-PE. The melt flow rate in accordance with test method D1238 cannot be determined for this material because ultra high molecular weight polyethylene does not have a melt flow. The elongational stress is also be referred to as ZST and flow value, or both.

X4.1.2 Application of this test method shall be limited to virgin, unmodified resin. The elongational stress method is invalid on a previous thermally-processed material due to possible crosslinking.

Note X4.1This test method is identical to to Annex A of ISO 11542-2 in the measurement of elongational stress. It is not equivalent to ISO 11542-2 in any other measurement or section

X5.1.1 The measurement of molecular weight of UHMW-PE is nearly impossible to measure by techniques normally used to measure molecular weight of other polymers. Techniques such as gel permeation chromatography (GPC) and light scattering used for other polymers are not useful for UHMW-PE.

X5.1.2 The dilute viscosity test method can provide satisfactory correlations for viscosity average molecular weight within a specific manufacturing process, but this does not necessarily apply for another manufacturing process. As a result, at least five equations have been developed to describe the molecular weight of UHMW-PE.

X5.1.3 Fig. X5.1 shows the relationship between the five equations with respect to nominal viscosity average molecular weight versus intrinsic viscosity.

X5.1.4 This appendix is being provided only as a reference. Only Eq 1 listed in 3.2.1.1 of this specification shall be used to present data to the industry.

X6.1.1 This method is used to determine the resistance of materials to abrasion, measured in terms of percent weight loss, by rotating test specimens in a slurry consisting of 20 grit aluminum oxide and water.

X6.1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.

Note X6.1There is no known ISO equivalent to this method.

2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.

ASTM Standards

C1444 Test Method for Measuring the Angle of Repose of Free-Flowing Mold Powders

D256 Test Methods for Determining the Izod Pendulum Impact Resistance of Plastics

D618 Practice for Conditioning Plastics for Testing

D635 Test Method for Rate of Burning and/or Extent and Time of Burning of Plastics in a Horizontal Position

D638 Test Method for Tensile Properties of Plastics

D648 Test Method for Deflection Temperature of Plastics Under Flexural Load in the Edgewise Position

D790 Test Methods for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating Materials

D792 Test Methods for Density and Specific Gravity (Relative Density) of Plastics by Displacement

D883 Terminology Relating to Plastics

D1601 Test Method for Dilute Solution Viscosity of Ethylene Polymers

D1894 Test Method for Static and Kinetic Coefficients of Friction of Plastic Film and Sheeting

D1895 Test Methods for Apparent Density, Bulk Factor, and Pourability of Plastic Materials

D1921 Test Methods for Particle Size (Sieve Analysis) of Plastic Materials

D2240 Test Method for Rubber Property--Durometer Hardness

D2951 Test Method for Resistance of Types III and IV Polyethylene Plastics to Thermal Stress-Cracking

D4703 Practice for Compression Molding Thermoplastic Materials into Test Specimens, Plaques, or Sheets

E313 Practice for Calculating Yellowness and Whiteness Indices from Instrumentally Measured Color Coordinates

E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method

IEC Standards

ISO Standards

Keywords

extrusion materials; molding materials; plastics; polyethylene; ultra-high-molecular-weight; UHMW-PE; viscosity: Ethylene plastics; Molding/extrusion compounds/materials--specifications; Polyethylene (PE)--specifications; Polyolefin (PO)--specifications; UHMWPE (ultra-high molecular weight polyethylene); Viscosity--plastics;

ICS Code

ICS Number Code 83.140.99 (Other rubber and plastic products)

DOI: 10.1520/D4020-11

ASTM International is a member of CrossRef.

ASTM D4020