【国外标准】 Standard Classification System and Basis for Specification for Filled Polytetrafluoroethlyene (PTFE) Molding and Extrusion Materials Using ASTM Methods

This specification covers polytetrafluoroethylene(PTFE) filled molding compounds made with virgin PTFE resins defined in a certain specification except Types I, IV, V, and VI. PTFE compounds are classified into two types which are Type I as the nonpelletized material use for general purpose compression molding and Type II as the pelletized or free-flowing material use for molding, automatic molding or ram extrusion. Each type is further classified into thirteen grades distinguished by the nature of the filler. Different tests shall be conducted in order to determine the following properties: filler content, bulk density, specific gravity, and tensile properties.1.1 This standard classification system and basis for specification covers polytetrafluoroethylene (PTFE) filled molding compounds made with virgin PTFE resins defined in Specification D4894, as Types II and III.NOTE 1: This system can be used as a model for other PTFE compounds having particulate fillers that can survive the sintering temperatures of PTFE as can those listed in this standard. This system is restricted to virgin PTFE base resin for technical reasons. Recycled or reprocessed material cannot be processed successfully.NOTE 2: The properties measured on commercially fabricated parts may differ from the listed values for samples prepared by the procedures given in this specification, depending on part geometry and processing parameters. Compounds used for ram extrusion are made from resins that comply with ASTM-D4745 Type II prior to their pre-sintering process. Property values measured on extruded products will vary from the listed values for Type II compounds which are prepared by the procedures given below which standardize mold diameter and sintering cycle. End users should assess these expected variations in ram extruded products to ensure their suitable use in their specific application.1.2 The values stated in SI units are to be regarded as standard.1.3 The following statement applies to the test method portion, Section 11, 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use. See Note 5 for a specific warning statement.NOTE 3: There is no known ISO equivalent to this standard.1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.