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D5990-20 – Standard Test Method Technical Guide
ASTM D5990-20a establishes a standard classification system for polyketone (PK) injection molding and extrusion materials. This system provides a structured framework for specifying virgin PK materials based on key mechanical, thermal, and physical properties, using a line callout format derived from the parent standard ASTM D4000. It is crucial to note that this standard is not a material selection guide but a classification tool for specifying materials in procurement and design. The standard explicitly excludes recycled polyketone materials from its scope.
📐 Classification System and Line Callout
The classification system uses an alphanumeric line callout (specification) format to define PK materials. The callout begins with the standard designation “D5990” followed by the broad generic material code “PK”. Subsequent numbers define specific property requirements based on the cell table structure outlined in ASTM D4000. This structure provides a means of calling out plastic materials used in fabricating end items or parts. Suffixes described in Section 5 can be appended to identify particular characteristics important for specialized applications that are not captured by the primary property table.
⚠️ Precautionary Caveat (Section 1.4): 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.
⚙️ Primary Test Methods for Classification
Standardized test methods are mandated by this classification system to determine conformance with the designated material properties. Test specimens must be prepared in accordance with Practice D3641 and conditioned as per Practice D618. The following specific ASTM standards define the protocols for determining the classification properties used in the line callout:
- D638 – Test Method for Tensile Properties of Plastics
- D256 – Test Methods for Determining the Izod Pendulum Impact Resistance of Plastics
- D648 – Test Method for Deflection Temperature of Plastics Under Flexural Load in the Edgewise Position
- D1238 – Test Method for Melt Flow Rates of Thermoplastics by Extrusion Plastometer
- D792 – Test Methods for Density and Specific Gravity of Plastics by Displacement
- D3418 – Test Method for Transition Temperatures and Enthalpies of Fusion and Crystallization of Polymers by Differential Scanning Calorimetry
- D5630 – Test Method for Ash Content in Plastics
Significant digits in the test data are handled in accordance with Practice E29 to determine conformance with the specification.
📊 Key Material Property Requirements (Table 1)
The classification system uses a detailed table of cell limits to define the material grade. The properties included are those required to identify the compositions covered. Below is a summary of the typical property categories and ranges associated with standard grades of polyketone material as structured by the system.
| 🟩 Property | 📏 Test Method | 📐 Unit | 🎯 Typical Value Range |
|---|---|---|---|
| Tensile Strength at Yield | D638 | MPa (psi) | 55 – 75 |
| Tensile Modulus | D638 | MPa (ksi) | 1400 – 2600 |
| Izod Impact (Notched) | D256 | J/m (ft·lb/in) | 40 – 200 |
| Deflection Temperature (1.82 MPa) | D648 | °C (°F) | 90 – 105 |
| Melt Flow Rate | D1238 | g/10 min | 2 – 30 |
| Melting Point (DSC) | D3418 | °C (°F) | ~220 |
Note: The values above are representative ranges from standard classification tables. A specific line callout will precisely define the required cell limits
💡 Technical Guidance: While this classification system provides a standardized basis for specification, it is not intended for material selection. Final material choice should be made by those having expertise in the plastics field after careful consideration of the design, performance requirements, environment, and fabrication process (Section 1.3).
❓ Frequently Asked Questions
🔍 What does “PK” stand for in this standard?
“PK” is the abbreviated term for Polyketone, as designated by this classification system and in accordance with Terminology D1600 for abbreviated terms relating to plastics.
💡 Are there other standards that address the same subject matter?
Yes. As noted in Section 1.2 of the standard, ISO 21970-1 and ISO 21970-2 address the same subject matter for polyketone molding and extrusion materials. However, the standard explicitly states that these ISO documents “differ in technical content” from ASTM D5990-20a.
⚡ Can this standard be applied to recycled polyketone materials?
No. Section 1.1 of the scope clearly states that this classification system “does not address recycled polyketone materials.” This standard is strictly intended for virgin PK materials suitable for injection molding and extrusion.
📌 What is the function of the suffixes in Section 5?
The suffixes provide a mechanism for specifying requirements necessary to identify particular characteristics important for specialized applications that are not covered by the primary properties in the main classification table. This allows for the customization of the standard specification to meet unique end-use requirements.