ASTM D2116 FEP Fluorocarbon Resin Testing
FEP resin moulding and extrusion materials that can be melt processed are covered by ASTM D 2116 Standard Specification. These requirements don't include FEP recycled materials. These FEP resins are either modified FEP resins with no more than 2% by weight of additional materials or copolymers of tetrafluoroethylene and hexafluoropropylene.
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ASTM D2116 FEP Fluorocarbon Resin Testing
- Overview
- Scope, Applications, and Benefits
- Test Process
- Specifications
- Instrumentation
- Results and Deliverables
ASTM D2116 FEP Fluorocarbon Resin Testing Overview
ASTM D2116 is the standard test method for determining the melt flow rate (MFR) of fluorinated ethylene propylene (FEP) copolymer resin materials. FEP is a melt-processable fluoropolymer that combines the chemical inertness and low surface energy of PTFE with the ability to be processed by conventional thermoplastic methods -extrusion, injection molding, and blow molding. Melt flow rate is the primary rheological characterization used for quality control and grade differentiation of FEP resins, and it directly affects processing behavior on extrusion and molding equipment.
Melt flow rate is measured by a melt flow indexer -an extrusion plastometer -which melts the resin at a specified temperature under a defined piston load and measures the mass of polymer extruded through a standardized die orifice per unit time. The test temperature for FEP is 372 degrees C (701 degrees F), which is significantly higher than typical thermoplastic MFR test temperatures, reflecting the high melting point of fluoropolymers. The result is reported in grams per 10 minutes.
A higher MFR value indicates a lower viscosity melt that flows more easily -useful for thin-wall extrusion and wire coating applications. A lower MFR indicates a higher viscosity melt better suited to applications requiring higher melt strength. Different FEP grades target different MFR ranges for specific processing windows, and incoming lot-to-lot consistency verification using D2116 is standard practice for FEP converters and end users.
ASTM D2116 FEP Fluorocarbon Resin Testing Scope, Applications, and Benefits
Scope
ASTM D2116 covers the determination of melt flow rate for FEP fluorocarbon resin materials using a melt flow indexer (extrusion plastometer) at 372 degrees C with a 5 kg load applied by a weighted piston. The die orifice geometry and piston dimensions are specified. The test measures the mass of FEP extruded through the die orifice in a 10-minute period, following a defined preheat time to achieve thermal equilibrium. The result is reported in grams per 10 minutes. The standard falls under ASTM Committee D20 on Plastics. Testing must be performed in a well-ventilated area or fume hood due to potential HF generation from FEP at test temperatures.
Applications
- Incoming quality control of FEP resin lots for wire and cable insulation extrusion
- Grade verification and lot-to-lot consistency monitoring for FEP film and sheet production
- Supplier qualification for FEP resin used in chemical process equipment, tubing, and liners
- Resin selection for specific processing equipment -higher MFR for fine wire coating, lower MFR for thick-wall tubing
- Regrind and recycled FEP resin evaluation for property change due to thermal degradation during processing
- Effect of processing conditions on FEP molecular weight -comparing virgin and reprocessed material
- Quality release testing for FEP pellets and powder before processing
- Research and development for new FEP formulations and blends
Benefits
- Simple, fast test that directly characterizes the flow behavior of FEP under processing-relevant conditions
- Single-number result enables direct grade comparison and incoming lot verification
- 372 degrees C test condition is specific to FEP and distinguishes it from other fluoropolymer MFR tests
- Sensitive to molecular weight changes from reprocessing, thermal degradation, or formulation variation
- Widely required in FEP resin and compound specifications from material suppliers and converters
- Correlates directly to extrusion processing behavior, making it a practical quality control parameter
- Applicable to all FEP grades, including standard, low-smoke, and specialty formulations
ASTM D2116 FEP Fluorocarbon Resin Testing Process
Instrument Preparation and Temperature Stabilization
The melt flow indexer barrel and die are cleaned and assembled.
1Sample Loading and Preheat
A measured charge of FEP resin -typically 4 to 6 grams -is loaded into the barrel.
2Extrusion and Sample Collection
The 5 kg piston load is applied and the resin begins extruding through the die.
3Calculation and Reporting
Melt flow rate is calculated from the average mass of extrudate collected per 10-minute equivalent period
4ASTM D2116 FEP Fluorocarbon Resin Testing Technical Specifications
| Parameter | Details |
|---|---|
| Standard | ASTM D2116-18 |
| ASTM Committee | D20 – Plastics |
| Material | FEP (fluorinated ethylene propylene) fluorocarbon resin |
| Test Temperature | 372 degrees C (701 degrees F) |
| Applied Load | 5 kg |
| Die Orifice | Per ASTM D1238 standard die geometry |
Instrumentation Used for ASTM D2116 FEP Fluorocarbon Res
- Melt flow indexer (extrusion plastometer) rated to 400 degrees C minimum
- Standard die and piston assembly per ASTM D1238 / D2116 specifications
- 5 kg dead-weight piston load
- Precision analytical balance for extrudate weighing
- Timer for preheat and collection interval control
- Fume hood or local exhaust ventilation for fluoropolymer vapor management
- Calibrated thermocouple for barrel temperature verification
ASTM D2116 FEP Fluorocarbon Resin Testing Results and Deliverables
- Melt flow rate in grams per 10 minutes at 372 degrees C / 5 kg
- Individual cut weights and calculated the average MFR
- Test temperature confirmation and preheat duration
- Material identification -lot number, grade, and supplier
- Any anomalies observed during testing -surging, color change, or inconsistent extrusion
- Comparison to grade specification MFR range, where applicable
- Full test report formatted for incoming quality control records or material specification documentation
Frequently Asked Questions
ASTM D2116 measures the melt flow rate (MFR) of fluorinated ethylene propylene (FEP) under controlled temperature and load conditions. It indicates how easily the polymer flows when molten, which reflects its processability during extrusion or molding.
MFR directly affects how FEP behaves in processing techniques like wire coating, film extrusion, and molding. A higher MFR generally means easier flow but lower molecular weight, while lower MFR indicates higher viscosity and better mechanical strength.
While ASTM D1238 is a general method for many thermoplastics, ASTM D2116 is specifically tailored for FEP fluorocarbon resins. It uses defined conditions suited to the thermal stability and flow behavior of fluoropolymers, ensuring more accurate and relevant results.
MFR can be affected by molecular weight distribution, thermal degradation, moisture content, and test conditions such as temperature stability and applied load. Even small contamination or overheating can significantly skew results in fluoropolymers.
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