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D5927-24 – Standard Test Method Technical Guide
📐 Scope and Standard Structure
ASTM D5927-24 provides a standard classification system for thermoplastic polyester (TPES) materials intended for injection molding and extrusion. This standard is explicitly based on ISO test methods, promoting international consistency in material specification. It covers both virgin and recycled TPES materials, provided the entire line callout is satisfied. Users are reminded that the standard is a callout system for defining end-item or part materials, not a material selection handbook (Section 1.4). SI units are regarded as the standard.
⚠️ Precautionary Caveat: This standard does not purport to address all safety concerns. It is the responsibility of the user to establish appropriate safety, health, and environmental practices before use (Section 1.6).
📊 Classification System and Property Tables
The system groups TPES materials into specific classes based on polymer type (e.g., PBT, PET) and filler/reinforcement level. Basic property requirements for primary grades are defined in the standard tables. The following table summarizes the typical values for unreinforced and glass-fiber-reinforced grades.
| 🟦 Grade Designation | 📐 Tensile Strength (MPa) ISO 527 |
📏 Flexural Modulus (MPa) ISO 178 |
🎯 Izod Impact (kJ/m²) ISO 180 |
⚡ Deflection Temp (°C) ISO 75, 1.8 MPa |
|---|---|---|---|---|
| PBT 014 (Unfilled) | 58 – 65 | 2300 – 2800 | 3.5 – 5.0 | 55 – 60 |
| PBT 024 (30% Glass Fiber) | 125 – 145 | 7500 – 9500 | 7.0 – 10.0 | 200 – 215 |
| PET 014 (Unfilled) | 55 – 65 | 2100 – 2600 | 2.5 – 4.0 | 65 – 70 |
| PET 034 (30% Glass Fiber) | 145 – 165 | 8500 – 10500 | 8.0 – 12.0 | 225 – 240 |
💡 Technical Distinction: ASTM D5927-24 and ISO 7792-1:2012 / ISO 7792-2:2012 address the same subject matter but differ in technical content (Note 1). Engineers must explicitly state which standard governs the material specification.
🧪 Test Methods and Quality Assurance Protocols
All specification testing must adhere strictly to the referenced ISO methods. Tensile testing follows ISO 527, flexural testing follows ISO 178, and Izod impact follows ISO 180. Deflection temperature is determined per ISO 75. Conformance with property limits requires the use of the significant digit rounding rules of Practice E29. Packaging and packing of sampled materials should follow ASTM D3892 to ensure material integrity.
For specialized applications, the suffix system in Section 5 provides a structured method to specify additional requirements. Suffix letters (such as A for tensile strength or Z for tensile strain) paired with numeric codes allow precise tailoring of the material to specific end-use demands.
❓ Frequently Asked Questions
🔍 What materials are included in the TPES classification?
The TPES classification covers thermoplastic polyesters, primarily PBT, PET, PCT, and other copolyesters included in the standard tables. It groups materials by base polymer and classifies them by filler type and level for both molding and extrusion.
💡 How does this standard handle recycled TPES materials?
Section 1.2 explicitly allows recycled materials. The final compound must satisfy every aspect of the designated line callout. The proportion of recycled content and the nature of any contaminants cannot be practically covered by this specification and remain subject to supplier-user agreement.
⚡ What is the purpose of the line callout system?
The line callout system provides a precise, alphanumeric shorthand for defining material property requirements. It serves as the basis for specifications between buyers and sellers, ensuring consistent material characterization across different producers and testing laboratories.
📌 Why are the test methods exclusively ISO based?
This standard was developed to harmonize with international practices. By using ISO 527, 178, 180, and 75, D5927-24 aligns with the global thermoplastic polyester supply chain, facilitating consistent international trade and material qualification.