ASTM D7138 Melting Temperature of Synthetic Fibres
ASTM D7138 covers two test methods for determining the melting temperature of synthetic fibres by two different methods.
TRUSTED BY
Precision-driven testing for dimensional accuracy and compliance
- Overview
- Scope, Applications, and Benefits
- Test Process
- Specifications
- Instrumentation
- Results and Deliverables
Overview
ASTM D7138 describes a test method for determining the melting temperature of synthetic fibers using differential scanning calorimetry (DSC). The melting point is a fundamental thermal property that defines processing windows, maximum use temperatures, and fiber identification for synthetic fiber manufacturers and users.
Accurate melting temperature data is essential for fiber producers, textile manufacturers, and quality laboratories characterizing nylon, polyester, polypropylene, and other thermoplastic fiber materials.
Scope, Applications, and Benefits
Scope
ASTM D7138 applies to synthetic thermoplastic fibers and measures:
- Onset melting temperature (Tonset)
- Peak melting temperature (Tm)
- Heat of fusion (ΔHm) related to crystallinity
- Multiple melting peaks indicate different crystal populations
Applications
- Synthetic fiber identification and characterization (PET, PA, PP, PE)
- Quality control in fiber production and extrusion
- Fiber blend composition estimation
- Textile thermal processing window determination
- Research on fiber crystallinity and orientation effects
Benefits
- Precise, reproducible measurement of melting behavior
- Enables fiber identification without complex spectroscopy
- Detects blend components or contamination by unexpected melting peaks
- Provides crystallinity data relevant to fiber mechanical properties
- Small sample requirement suitable for single filaments or fiber bundles
Test Process
Sample Preparation
A small fiber sample (5–10 mg) is cut, weighed, and encapsulated in an aluminum DSC pan.
1DSC Temperature Program
The sample is heated at a controlled rate (typically 10°C/min) through and above the expected melting temperature.
2Melting Peak Analysis
The DSC thermogram is analyzed to identify onset, peak, and endset temperatures of the melting endotherm.
3Reporting
Melting temperatures and heat of fusion are reported; results are compared to reference values for the expected fiber type.
4Technical Specifications
| Parameter | Details |
|---|---|
| Test Principle | Differential scanning calorimetry (DSC) |
| Applicable Materials | Synthetic thermoplastic fibers (PET, PA6, PA66, PP, PE, etc.) |
| Sample Mass | 5–10 mg |
| Heating Rate | 10°C/min (default) |
| Measured Outputs | Tonset (°C), Tm peak (°C), ΔHm (J/g) |
Instrumentation Used for Testing
- Differential scanning calorimeter (DSC) with nitrogen purge
- Precision analytical balance (0.01 mg resolution) | Hermetically sealed or crimped aluminum DSC pans
- Indium and other certified melting point standards for calibration
- Data analysis software for peak integration and baseline subtraction
Results and Deliverables
- DSC thermogram with labeled melting peak
- Onset, peak, and endset melting temperatures (°C)
- Heat of fusion and estimated crystallinity (%)
- Fiber identification based on melting temperature
- Test report with calibration traceability
Why Choose Infinita Lab for ASTM D7138?
At the core of this breadth is our network of 2,000+ accredited labs in the USA, offering access to over 10,000 test types. From advanced metrology (SEM, TEM, RBS, XPS) to mechanical, dielectric, environmental, and standardized ASTM/ISO testing, we give clients unmatched flexibility, specialization, and scale. You’re not limited by geography, facility, or methodology—Infinita connects you to the right testing, every time.
Looking for a trusted partner to achieve your research goals? Schedule a meeting with us, send us a request, or call us at (888) 878-3090 to learn more about our services and how we can support you. Request a Quote
Frequently Asked Questions
PET melts at approximately 250–255°C, nylon 66 at 255–265°C, nylon 6 at 215–225°C, and polypropylene at 160–170°C — these ranges guide identification.
Melting temperature is a strong indicator of fiber identity, but FTIR or other complementary analysis may be needed to definitively distinguish chemically similar fiber types.
A higher heat of fusion indicates a more crystalline fiber structure, which correlates with higher tensile strength, modulus, and reduced elongation in the final fiber product.
Multiple melting peaks can result from different crystal populations, recrystallization during heating, or blended fibers with different compositions — each case requires specific interpretation.
Calibration is performed using certified reference materials with known melting points (e.g., indium at 156.6°C, tin at 231.9°C) to verify temperature accuracy and heat flow calibration.
Request a Quote
Submit your material details and receive testing procedures, pricing, and turnaround time within 24 hours.
Quick Turnaround and Hasslefree process
Confidentiality Guarantee
Free, No-obligation Consultation
100% Customer Satisfaction
