Active Standard ASTM D4895 | Developed by Subcommittee: D20.15
Book of Standards Volume: 08.02
Historical (view previous versions of standard)
This specification covers dry-powder resins of polytetrafluoroethylene (PTFE) resin produced from dispersion. PTFE mixtures with additives are not covered in this specification. This specification covers type I and type II PTFE. The resins shall be tested for bulk density, particle size, water content, melting peak temperature, tensile strength, elongation at break, standard specific gravity, extrusion pressure, thermal instability index, and stretching void index. Specimen preparation, testing, inspection, and packaging shall be in accordance to the procedures indicated in this specification.
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.
1.1 This specification covers dry-powder resins of polytetrafluoroethylene (PTFE) that have been prepared from dispersions of PTFE by manufacturing techniques that involve controlled coagulation of the dispersion. These resins are generally known as “fine-powder” resins or “coagulated-dispersion powder” resins. The conversion of these resins to finished products normally involves a process called “paste extrusion,” and sometimes involves formative processes such as calendering. A volatile liquid is present as a processing aid during these formative stages of conversion, and is subsequently removed during the finishing stages of conversion. These PTFE resins are homopolymers of tetrafluoroethylene, or, in some cases, modified homopolymers containing not more than 1 % by weight of other fluoromonomers. The usual methods of processing thermoplastics generally are not applicable to these materials because of their viscoelastic properties. The materials covered herein do not include mixtures of PTFE with additives such as colors, fillers, or plasticizers; nor do they include reprocessed or reground resin or any fabricated articles because the properties of such materials have been irreversibly changed when they were fibrillated or sintered. The methods and properties included are those required to identify the various resins. An additional procedure is provided in the appendix for further characterization of the resins.
1.3 The following safety hazards caveat pertains only to the Specimen Preparation Section, Section 9, and the Test Methods Section, Section 10, 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. See Warning note in 9.1.1 for a specific hazards statement.
Note 1—Information in this specification is technically equivalent to related information in ISO 12086-1 and ISO 12086-2.
2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.
D618 Practice for Conditioning Plastics for Testing
D638 Test Method for Tensile Properties of Plastics
D792 Test Methods for Density and Specific Gravity (Relative Density) of Plastics by Displacement
D883 Terminology Relating to Plastics
D1895 Test Methods for Apparent Density, Bulk Factor, and Pourability of Plastic Materials
D3892 Practice for Packaging/Packing of Plastics
D4052 Test Method for Density, Relative Density, and API Gravity of Liquids by Digital Density Meter
D4441 Specification for Aqueous Dispersions of Polytetrafluoroethylene
D4591 Test Method for Determining Temperatures and Heats of Transitions of Fluoropolymers by Differential Scanning Calorimetry
D4894 Specification for Polytetrafluoroethylene (PTFE) Granular Molding and Ram Extrusion Materials
E11 Specification for Woven Wire Test Sieve Cloth and Test Sieves
E29 Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications
E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods
ICS Number Code 83.080.10 (Thermosetting materials)